TEXAS INSTRUMENTS bq20z60-R1, bq20z65-R1 Technical data

bq20z60-R1/bq20z65-R1

Technical Reference

Literature Number: SLUU386

January 2010

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Contents

1 Preface .............................................................................................................................. 7

1.1 Read This First .............................................................................................................. 7

1.2 Notational Conventions ..................................................................................................... 7

2 Detailed Description ............................................................................................................ 9

2.1 JEITA Temperature Ranges ............................................................................................... 9

2.2 1st Level Protection Features ............................................................................................ 10

2.2.1 Cell Overvoltage (COV) and Cell Undervoltage (CUV) ...................................................... 10

2.2.2 Charge and Discharge Overcurrent ............................................................................ 13

2.2.3 Short-Circuit Protection .......................................................................................... 18

2.2.4 Overtemperature Protection ..................................................................................... 19

2.2.5 Host Watchdog ................................................................................................... 21

2.2.6 AFE Watchdog .................................................................................................... 21

2.3 2nd Level Protection Features ........................................................................................... 21

2.3.1 2nd Level (Permanent) Failure Actions ........................................................................ 22

2.3.2 Time-Limit-Based Protection .................................................................................... 23

2.3.3 Limit-Based Protection ........................................................................................... 25

2.3.4 Clearing Permanent Failure ..................................................................................... 27

2.4 Gas Gauging ............................................................................................................... 27

2.4.1 Impedance Track Configuration ................................................................................ 27

2.4.2 Gas Gauge Modes ............................................................................................... 28

2.4.3 Qmax ............................................................................................................... 30

2.5 Charge Control ............................................................................................................. 32

2.5.1 Charge Control SMBus Broadcasts ............................................................................ 32

2.5.2 Cell Balancing ..................................................................................................... 32

2.5.3 Charge-Inhibit Mode ............................................................................................. 33

2.5.4 Charge-Suspend Mode .......................................................................................... 35

2.5.5 Charging and Temperature Ranges ........................................................................... 37

2.5.6 Precharge .......................................................................................................... 40

2.5.7 Primary Charge Termination .................................................................................... 41

2.5.8 Charging Faults ................................................................................................... 42

2.5.9 Discharge and Charge Alarms .................................................................................. 45

2.6 Discharge-Inhibit Mode ................................................................................................... 45

2.7 LED Display ................................................................................................................ 46

2.7.1 Display Activation ................................................................................................. 46

2.7.2 Display Configuration ............................................................................................ 47

2.7.3 Display Format .................................................................................................... 48

2.7.4 Permanent Failure Error Codes ................................................................................ 49

2.7.5 LED Current Configuration ...................................................................................... 50

2.8 Device Operating Mode .................................................................................................. 50

2.8.1 Normal Mode ...................................................................................................... 50

2.8.2 Battery Pack Removed Mode/System Present Detection ................................................... 51

2.8.3 Sleep Mode ........................................................................................................ 51

2.8.4 Wake Function .................................................................................................... 52

2.8.5 Shutdown Mode .................................................................................................. 53

2.8.6 Ship Mode ......................................................................................................... 53

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2.9 Security (Enables and Disables Features) ............................................................................. 53

2.10 Calibration .................................................................................................................. 56

2.10.1 Coulomb-Counter Dead Band ................................................................................. 56

2.10.2 Autocalibration ................................................................................................... 56

2.11 Communications ........................................................................................................... 56

2.11.1 SMBus On and Off States ...................................................................................... 56

2.11.2 Packet Error Checking .......................................................................................... 56

2.11.3 bq20z60-R1/bq20z65-R1 Slave Address .................................................................... 56

2.11.4 Broadcasts to Smart Charger and Smart Battery Host ..................................................... 57

A Standard SBS Commands .................................................................................................. 59

A.1 ManufacturerAccess (0x00) .............................................................................................. 59

A.1.1 System Data ...................................................................................................... 59

A.1.2 System Control ................................................................................................... 61

A.1.3 Extended SBS Commands ...................................................................................... 65

A.2 RemainingCapacityAlarm (0x01) ........................................................................................ 66

A.3 RemainingTimeAlarm (0x02) ............................................................................................. 66

A.4 BatteryMode (0x03) ....................................................................................................... 67

A.5 AtRate (0x04) .............................................................................................................. 68

A.6 AtRateTimeToFull (0x05) ................................................................................................. 69

A.7 AtRateTimeToEmpty (0x06) ............................................................................................. 69

A.8 AtRateOK (0x07) .......................................................................................................... 69

A.9 Temperature (0x08) ....................................................................................................... 70

A.10 Voltage (0x09) ............................................................................................................. 70

A.11 Current (0x0a) .............................................................................................................. 70

A.12 AverageCurrent (0x0b) ................................................................................................... 71

A.13 MaxError (0x0c) ............................................................................................................ 71

A.14 RelativeStateOfCharge (0x0d) ........................................................................................... 71

A.15 AbsoluteStateOfCharge (0x0e) .......................................................................................... 72

A.16 RemainingCapacity (0x0f) ................................................................................................ 72

A.17 FullChargeCapacity (0x10) ............................................................................................... 73

A.18 RunTimeToEmpty (0x11) ................................................................................................. 73

A.19 AverageTimeToEmpty (0x12) ............................................................................................ 73

A.20 AverageTimeToFull (0x13) ............................................................................................... 74

A.21 ChargingCurrent (0x14) ................................................................................................... 74

A.22 ChargingVoltage (0x15) .................................................................................................. 74

A.23 BatteryStatus (0x16) ...................................................................................................... 75

A.24 CycleCount (0x17) ......................................................................................................... 76

A.25 DesignCapacity (0x18) .................................................................................................... 76

A.26 DesignVoltage (0x19) ..................................................................................................... 76

A.27 SpecificationInfo (0x1a) ................................................................................................... 77

A.28 ManufactureDate (0x1b) .................................................................................................. 77

A.29 SerialNumber (0x1c) ...................................................................................................... 78

A.30 ManufacturerName (0x20) ............................................................................................... 78

A.31 DeviceName (0x21) ....................................................................................................... 78

A.32 DeviceChemistry (0x22) .................................................................................................. 79

A.33 ManufacturerData (0x23) ................................................................................................. 79

A.34 Authenticate (0x2f) ........................................................................................................ 80

A.35 CellVoltage4..1 (0x3c..0x3f) .............................................................................................. 80

A.36 SBS Command Values ................................................................................................... 80

B Extended SBS Commands .................................................................................................. 83

B.1 AFEData (0x45) ............................................................................................................ 83

B.2 FETControl (0x46) ......................................................................................................... 83

B.3 StateOfHealth (0x4f) ...................................................................................................... 84

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B.4 SafetyAlert (0x50) ......................................................................................................... 85

B.5 SafetyStatus (0x51) ....................................................................................................... 85

B.6 PFAlert (0x52) .............................................................................................................. 86

B.7 PFStatus (0x53) ........................................................................................................... 87

B.8 OperationStatus (0x54) ................................................................................................... 88

B.9 ChargingStatus (0x55) .................................................................................................... 88

B.10 ResetData (0x57) .......................................................................................................... 89

B.11 WDResetData (0x58) ..................................................................................................... 89

B.12 PackVoltage (0x5a) ....................................................................................................... 89

B.13 AverageVoltage (0x5d) ................................................................................................... 89

B.14 TS1Temperature (0x5e) .................................................................................................. 90

B.15 TS2Temperature (0x5f) ................................................................................................... 90

B.16 UnSealKey (0x60) ......................................................................................................... 90

B.17 FullAccessKey (0x61) ..................................................................................................... 90

B.18 PFKey (0x62) .............................................................................................................. 91

B.19 AuthenKey3 (0x63) ........................................................................................................ 91

B.20 AuthenKey2 (0x64) ........................................................................................................ 91

B.21 AuthenKey1 (0x65) ........................................................................................................ 91

B.22 AuthenKey0 (0x66) ........................................................................................................ 92

B.23 SafetyAlert2 (0x68) ........................................................................................................ 92

B.24 SafetyStatus2 (0x69) ...................................................................................................... 92

B.25 PFAlert2 (0x6a) ............................................................................................................ 93

B.26 PFStatus2 (0x6b) .......................................................................................................... 93

B.27 ManufBlock1..4 (0x6c..0x6f) ............................................................................................. 94

B.28 ManufacturerInfo (0x70) .................................................................................................. 95

B.29 SenseResistor (0x71) ..................................................................................................... 95

B.30 TempRange (0x72) ........................................................................................................ 95

B.31 LifetimeData1 (0x73) ...................................................................................................... 96

B.32 LifetimeData2 (0x74) ...................................................................................................... 97

B.33 DataFlashSubClassID (0x77) ............................................................................................ 97

B.34 DataFlashSubClassPage1..8 (0x78..0x7f) ............................................................................. 98

B.35 Extended SBS Command Values ....................................................................................... 98

C Data Flash ....................................................................................................................... 101

C.1 Accessing Data Flash ................................................................................................... 101

C.1.1 Data Flash Interface ............................................................................................ 101

C.1.2 Reading a SubClass ............................................................................................ 102

C.1.3 Writing a SubClass ............................................................................................. 102

C.1.4 Example .......................................................................................................... 102

C.2 1st Level Safety Class ................................................................................................... 103

C.2.1 Voltage (Subclass 0) ........................................................................................... 103

C.2.2 Current (Subclass 1) ............................................................................................ 108

C.2.3 Temperature (Subclass 2) ..................................................................................... 114

C.2.4 Host Comm (Subclass 4) ...................................................................................... 118

C.3 2nd Level Safety ......................................................................................................... 118

C.3.1 Voltage (Subclass 16) .......................................................................................... 118

C.3.2 Current (Subclass 17) .......................................................................................... 125

C.3.3 Temperature (Subclass 18) .................................................................................... 126

C.3.4 FET Verification (Subclass 19) ................................................................................ 130

C.3.5 AFE Verification (Subclass 20) ................................................................................ 131

C.3.6 Fuse Verification (Subclass 21) ............................................................................... 132

C.4 Charge Control ........................................................................................................... 134

C.4.1 Charge Temp Cfg (Subclass 32) .............................................................................. 134

C.4.2 Pre-Charge Cfg (Subclass 33) ................................................................................ 136

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C.4.3 Charge Cfg (Subclass 34) ..................................................................................... 137

C.4.4 Termination Cfg. (Subclass 36) ............................................................................... 143

C.4.5 Cell Balancing Cfg (Subclass 37) ............................................................................. 145

C.4.6 Charging Faults (Subclass 38) ................................................................................ 146

C.5 SBS Configuration ....................................................................................................... 152

C.5.1 Data (Subclass 48) ............................................................................................. 152

C.5.2 Configuration (Subclass 49) ................................................................................... 157

C.6 System Data .............................................................................................................. 160

C.6.1 Manufacturer Data (Subclass 56) ............................................................................. 160

C.6.2 Manufacturer Info (Subclass 58) .............................................................................. 161

C.6.3 Manuf. Block 2 (Offset 53) ..................................................................................... 161

C.6.4 Manuf. Block 3 (Offset 74) ..................................................................................... 162

C.6.5 Manuf. Block 4 (Offset 95) ..................................................................................... 162

C.6.6 Lifetime Data (Subclass 59) ................................................................................... 162

C.6.7 Lifetime Temp Samples (Subclass 60) ....................................................................... 169

C.7 Configuration ............................................................................................................. 169

C.7.1 Registers (Subclass 64) ........................................................................................ 169

C.7.2 AFE (Subclass 65) .............................................................................................. 178

C.8 LED Support .............................................................................................................. 179

C.8.1 LED Cfg (Subclass 67) ......................................................................................... 179

C.9 Power ...................................................................................................................... 184

C.9.1 Power (Subclass 68) ........................................................................................... 184

C.10 Gas Gauging .............................................................................................................. 188

C.10.1 IT Cfg (Subclass 80) .......................................................................................... 188

C.10.2 Current Thresholds (Subclass 81) .......................................................................... 191

C.10.3 State (Subclass 82) ........................................................................................... 193

C.11 Ra Table .................................................................................................................. 195

C.11.1 R_a0 (Subclass 88) ........................................................................................... 195

C.11.2 R_a1 (Subclass 89) ........................................................................................... 196

C.11.3 R_a2 (Subclass 90) ........................................................................................... 197

C.11.4 R_a3 (Subclass 91) ........................................................................................... 198

C.11.5 R_a0x (Subclass 92) .......................................................................................... 199

C.11.6 R_a1x (Subclass 93) .......................................................................................... 200

C.11.7 R_a2x (Subclass 94) .......................................................................................... 201

C.11.8 R_a3x (Subclass 95) .......................................................................................... 202

C.12 PF Status .................................................................................................................. 203

C.12.1 Device Status Data (Subclass 96) .......................................................................... 203

C.12.2 AFE Regs (Subclass 97) ..................................................................................... 208

C.13 Calibration ................................................................................................................. 208

C.13.1 Data (Subclass 104) .......................................................................................... 208

C.13.2 Config (Subclass 105) ........................................................................................ 210

C.13.3 Temp Model (Subclass 106) ................................................................................. 212

C.13.4 Current (Subclass 107) ....................................................................................... 213

C.14 Data Flash Values ....................................................................................................... 214

D Glossary ......................................................................................................................... 227

Index ....................................................................................................................................... 229

Contents SLUU386–January 2010

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1.1 Read This First

This manual discusses modules and peripherals of the bq20z60-R1/bq20z65-R1 and its use to build a complete battery pack gas gauge and protection solution.

1.2 Notational Conventions

The following notation is used when SBS commands and data flash values are mentioned within a text block:

• SBS commands are set in italic, e.g., Voltage

• SBS bits and flags are capitalized, set in italic and enclosed with square brackets, e.g., [LED1]

• Data flash values are set in bold italic e.g., COV Threshold

• All data flash bits and flags are capitalized, set in bold italic and enclosed with square brackets, e.g.,

[NR]

All SBS commands, data flash values and flags mentioned in a section are listed at the end of each section for reference.

The reference format for SBS commands is SBS:Command Name(Command No.)[Flag], or SBS:ManufacterAccess(0x00):Manufacturer Access Command(MA No.), for example:

SBS:Voltage(0x09), or SBS:ManufacterAccess(0x00):Seal Device(0x0020) The reference format for data flash values is DF:Class Name:Subclass Name(Subclass ID):Value

Name(Offset)[Flag], for example: DF:1st Level Safety:Voltage(0):COV Threshold(0), or DF:Configuration:Registers(64):Operation Cfg A(0)[LED1].

Chapter 1

SLUU386–January 2010

Preface

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SLUU386–January 2010 Preface

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Preface SLUU386–January 2010

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2.1 JEITA Temperature Ranges

The bq20z60-R1/bq20z65-R1 follows the JEITA guidelines which specify that charging voltage and charging current depend on the temperature. Temperature ranges are used for specifying both what the charging voltage and charging current should be.

There are three temperature ranges in which charging is allowed and they are defined as:

• T1 – T2: Low charging temperature range (T1 ≤ Temperature < T2)

• T2 – T3: Standard charging temperature range (T2 ≤ Temperature < T3)

• T3 – T4: High charging temperature range (T3 ≤ Temperature < T4) For added flexibility the standard temperature range is divided into 2 sub-ranges: standard range 1 and

standard range 2. An additional temperature value (T2a) is needed to specify these 2 ranges. These temperature ranges will be configurable in the gas gauge through the following data flash constants.

• JT1: Lower bound of low charging temperature range, in °C.

• JT2: Upper bound of low charging temperature range and lower bound of standard charging

temperature range 1, in °C.

• JT2a: Upper bound of standard charging temperature range 1 and lower bound of standard charging

temperature range 2, in °C

• JT3: Upper bound of standard charging temperature range 2 and lower bound of high charging

temperature range, in °C.

• JT4: Upper bound of high charging temperature range, in °C.

Chapter 2

SLUU386–January 2010

Detailed Description

Additional temperature parameters are defined for discharging.

• OT1D and OT2D: The temperature at which discharge will be suspended.

• Hi Dsg Start Temp: If the temperature is above Hi Dsg Start Temp when starting discharge then

discharge is not started.

The bq20z60-R1/bq20z65-R1 implements hysteresis for the temperature ranges above using the DF variable (Temp Hys). This variable specifies the number of degrees of hysteresis that should be used before switching charging temperature ranges.

Table 2-1. Temperature Ranges in bq20z60-R1/bq20z65-R1

Flag JEITA Temperature Range Charging Mode

TR1 Temp < JT1 Charge Suspend or Charge Inhibit TR2 JT1 < Temp < JT2 Low Temp Charge TR3 JT2 < Temp < JT2a Std Temp Charge 1 TR4 JT2a < Temp < JT3 Std Temp Charge 2 TR5 JT3 < Temp < JT4 High Temp Charge or Charge Inhibit TR6 JT4 < Temp Charge Suspend or Charge Inhibit

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1st Level Protection Features

The active temperature range is indicated using a set of flags. Since hysteresis is implemented for the temperature ranges, determining the active temperature range depends on the previous state, in addition to the actual temperature. These flags reside in a status register called TempRange.

2.2 1st Level Protection Features

The bq20z60-R1/bq20z65-R1 supports a wide range of battery and system protection features that are easily configured or enabled via the integrated data flash.

2.2.1 Cell Overvoltage (COV) and Cell Undervoltage (CUV)

The bq20z60-R1/bq20z65-R1 can detect cell overvoltage/undervoltage and protect battery cells from damage from battery cell overvoltage/undervoltage. If the over/undervoltage remains over an adjustable time period, the bq20z60-R1/bq20z65-R1 goes into overvoltage/undervoltage condition and switches off the CHG/DSG FET. The bq20z60-R1/bq20z65-R1 recovers from a cell overvoltage condition if all the cell voltages drop below the cell overvoltage recovery threshold. The bq20z60-R1/bq20z65-R1 recovers from cell undervoltage condition if all the cell voltages rise above the cell undervoltage recovery threshold. An additional charge current detection requirement for cell undervoltage recovery can be enabled by setting the CUV_RECOV_CHG bit in the Operation Cfg C register to a 1.

Per JEITA guidelines, the cell overvoltage threshold changes depending on the temperature. Three cell overvoltage thresholds are specified, one for each operating temperature range.

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Detailed Description SLUU386–January 2010

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CUV Alert

CUVCondition

Charging Allowed

DischargingDisabled

Stop andReset Timer

CellVoltagesWithinLimit

Any CellVoltage

4..1 ≤ CUVThreshold

All CellVoltage

4..1 > CUVThreshold AND

timer <

CUVTime

Any CellVoltage

4..1 ≤ CUVThreshold

AND

timer ≥ CUVTime

All CellVoltage

4..1 ≥ CUVRecovery

Start

Timer

COV Alert

COVCondition

ChargingDisabled

Discharging Allowed

Stop

& Reset Timer

Any CellVoltage4..1

≥ COVThreshold

All CellVoltage

4..1 < COVThreshold

ANDtimer

< COVTime

All CellVoltage

4..1 ≤ COVRecovery*

Stop andReset Timer

Wait

Any CellVoltage

4..1

≤ CUVThreshold

Start

Timer

Wait

Any CellVoltage

4..1

≥ COVThreshold

[CUV] SafetyAlert

[COV] SafetyAlert

[CUV] SafetyStatus

[COV] SafetyStatus

*TheappropriatCOVthresholdandrecoveryvaluesareused

dependingonthetemperaturerange.

( )ANDchargecurrentdetectedIF CUV_RECOV_CHG=1

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1st Level Protection Features

Figure 2-1. COV and CUV

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1st Level Protection Features

Condition: COV Alert COV Condition Normal CUV Alert CUV Condition Flags: BatteryStatus [TCA] [TDA], [FD]

SafetyAlert [COV] [CUV] SafetyStatus [COV] [CUV] OperationStatus [XDSG]

FET: Normal CHG FET disabled, Normal Normal DSG FET disabled,

SBS ChargingCurrent Charging 0 Charging Charging Charging algorithm Comman algorithm algorithm algorithm d:

ChargingVoltage Charging 0 Charging Charging Charging algorithm

The bq20z60-R1/bq20z65-R1 indicates cell overvoltage by setting the [COV] flag in SafetyAlert if any CellVoltage4..1 reaches or surpasses the cell overvoltage limit (LT COV Threshold, ST COV Threshold, or HT COV Threshold, depending on the current temperature range). The bq20z60-R1/bq20z65-R1 goes into cell overvoltage condition and changes the [COV] flag in SafetyAlert to the [COV] flag in SafetyStatus if any of CellVoltage4..1 stays above cell overvoltage for a minimum time period of COV Time. This function is disabled if COV Time is set to zero.

In cell overvoltage condition, charging is disabled and CHG FET and ZVCHG FET (if used) are turned off,

ChargingCurrent and ChargingVoltage are set to zero, [COV] flag in SafetyAlert is reset, [TCA] flag in BatteryStatus and [COV] flag in SafetyStatus are set.

The bq20z60-R1/bq20z65-R1 recovers from a cell overvoltage condition if all CellVoltages4..1 are equal to or lower than the appropriate COV Recovery limit (LT COV Recovery, ST COV Recovery, or HT COV

Recovery) . On recovery the [COV] flag in SafetyStatus is reset, [TCA] flag in BatteryStatus is reset, and ChargingCurrent and ChargingVoltage are set back to appropriate values per the charging algorithm.

In a cell overvoltage condition, the CHG FET is turned on during discharging to prevent overheating of the CHG FET body diode.

The bq20z60-R1/bq20z65-R1 indicates cell undervoltage by setting the [CUV] flag in SafetyAlert if any CellVoltage4..1 reaches or drops below the CUV Threshold limit during discharging. The bq20z60-R1/bq20z65-R1 goes into cell undervoltage condition and changes the [CUV] flag in SafetyAlert to the [CUV] flag in SafetyStatus if any of CellVoltage4..1 stays below CUV Threshold limit for a minimum time period of CUV Time. This function is disabled if CUV Time is set to zero.

In a cell undervoltage condition, discharging is disabled and DSG FET is turned off, the [CUV] flag in SafetyAlert is reset, the [TDA] and [FD] flags in BatteryStatus and the [CUV] flag in SafetyStatus are set.

The bq20z60-R1/bq20z65-R1 recovers from cell undervoltage condition if all CellVoltages4..1 are equal to or higher than CUV Recovery limit (and charge current detected if CUV_RECOV_CHG is set). On recovery, the [CUV] flag in SafetyStatus is reset, [XDSG] flag is reset, the [TDA] and [FD] flags are reset, and ChargingCurrent and ChargingVoltage are set back to appropriate values per the charging algorithm.

In cell undervoltage condition, the DSG FET is turned on during charging to prevent overheating of the DSG FET body diode.

Related Variables:

• DF:1st Level Safety:Voltage(0): LT COV Threshold(0)

• DF:1st Level Safety:Voltage(0): ST COV Threshold(4)

• DF:1st Level Safety:Voltage(0): HT COV Threshold(8)

• DF:1st Level Safety:Voltage(0):COV Time(12)

• DF:1st Level Safety:Voltage(0): LT COV Recovery(2)

• DF:1st Level Safety:Voltage(0): ST COV Recovery(6)

• DF:1st Level Safety:Voltage(0): HT COV Recovery(10)

• DF:1st Level Safety:Voltage(0):CUV Threshold(13)

• DF:1st Level Safety:Voltage(0):CUV Time(15)

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Table 2-2. COV and CUV

enabled during enabled during charge discharge

algorithm algorithm algorithm

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• DF:1st Level Safety:Voltage(0):CUV Recovery(16)

• DF:Charge Control:Charge Cfg(34):LT Chg Current1(2)

• SBS:ChargingCurrent(0x14)

• SBS:ChargingVoltage(0x15)

• SBS:BatteryStatus(0x16)[TCA],[TDA],[FD],[DSG]

• SBS:CellVoltage4(0x3c)

• SBS:CellVoltage3(0x3d)

• SBS:CellVoltage2(0x3e)

• SBS:CellVoltage1(0x3f)

• SBS:SafetyAlert(0x50)[CUV],[COV]

• SBS:SafetyStatus(0x51)[CUV],[COV]

• SBS:OperationStatus(0x54)[XDSG]

2.2.2 Charge and Discharge Overcurrent

The bq20z60-R1/bq20z65-R1 has two independent tiers (levels) of overcurrent protection for charge and discharge. These two tiers require the Current value to be greater than or equal to a programmed OC Threshold in either charge or discharge state for a period greater than OC Time Limit. If the OC Time Limit for any of the overcurrent protections is set to 0, that specific feature is disabled.

Table 2-3. Charge and Discharge Overcurrent

Protection OC Threshold OC Time Limit OC Recovery Threshold

Tier-1 [OCC] [OCC] Charge

Tier-2 [OCC2] [OCC2] Charge

Tier-1 [OCD] [OCD] Discharge

Tier-2 [OCD2] [OCD2] Discharge

Tier-3 AFE OC DsgRecovery for – [AOCD] Discharge Current Recovery Time

OC (1st Tier)Chg OC(1st Tier) Chg Time

OC (2nd Tier) Chg OC (2nd Tier) Chg Time

OC (1st Tier) Dsg OC (1st Tier) Dsg Time

OC (2nd Tier) Dsg OC (2nd Tier Dsg Time

AFE OC Dsg AFE OC Dsg Time

1st Level Protection Features

SafetyAlert SafetyStatus

Flag Flag

OC Chg Recovery

OC Dsg Recovery

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OC Alert

OCCondition

CurrentWithinLimit

Current

≥ OCThreshold

Current < OCThreshold

AND Timer < OCTimeLimit

Stopand Reset Timer

Start

Timer

Wait

Current

≥ OC Threshold

Current ≥ OCThreshold

AND Timer ≥ OC TimeLimit

[PRES]= 0

PackRemoved

Non-RemovableRecovery

Start

Timer

Wait

[NR] = 1 AND

AverageCurrent > OCRecovery

Threshold

AND Timer < CurrentRecovery

Time

[NR] = 1 AND

Current

≤ OCRecoveryThreshold

AverageCurrent

≤ OCRecoveryThreshold

[NR] = 0 AND [PRES

] transitionsfrom 1 to 0 ANDNon-removableConfiguration Conditionbitnotset

ReinsertBatteryPack [PRES

] transitionsfrom

0 to 1

AverageCurrent ≤ OCRecovery

Threshold

AND Timer ≥ CurrentRecovery

Time

SafetyAlertFlagset

SafetyStatusFlagset

Stopand Reset Timer

1st Level Protection Features

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Figure 2-2. OC Protection

For the first two tiers of overcurrent protection, the specific flag in SafetyAlert is set if Current exceeds the OC Threshold. The bq20z60-R1/bq20z65-R1 changes the specific flag in SafetyAlert to the specific flag in SafetyStatus if the Current stays above the OC Threshold limit for at least OC Time Limit period. This function is disabled if the OC Time Limit is set to zero. The SafetyStatus flag is reset if the Current falls below the OC Recovery Threshold.

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If the timer of any tier expires during charging, the CHG FET is turned off and ZVCHG FET (if used) is turned off. When this occurs, the OC Time Limit timer is started from 0, ChargingCurrent and ChargingVoltage are set to 0, the [TCA] flag in BatteryStatus is set, and the appropriate SafetyStatus tier flag is set.

However, when the bq20z60-R1/bq20z65-R1 has either of [OCC] or [OCC2] flags in SafetyStatus set, the CHG FET are turned on again during discharge (Current ≤ (–)Dsg Current Threshold). This prevents overheating of the CHG FET body diode during discharge. No other flags change state until full recovery is reached. This action is not affected by the setting of the [NR] bit.

If the timer of either of the first two tiers expires during discharging, the DSG FET is turned off and the ZVCHG FET (if used) is turned on. When this occurs, the OC Time Limit timer is started from 0, ChargingCurrent is set to Pre-chg Current, [XDSGI] flag is set, [TDA] flag is set, and [OCD] tier flag is set.

When the AFE detects a discharge-overcurrent fault, the charge and discharge FETs are turned off. When the bq20z60-R1/bq20z65-R1 identifies the overcurrent condition and the OC Time Limit timer is started from 0, [TDA] flag is set, ChargingCurrent is set to 0, and [AOCD] is set.

However, when the bq20z60-R1/bq20z65-R1 has any [OCD], [OCD2], [AOCD] set, the DSG FET is turned on again during charging (Current ≥ Chg Current Threshold). This prevents overheating of the discharge-FET body diode during charge. No other flags change state until full recovery is reached. This action is not affected by the state of [NR] bit.

1st Level Protection Features

Table 2-4. Overcurrent Conditions

Protection Flags FET

Tier-1 OC alert [OCC] Normal Charging Charging Charge algorithm algorithm

Tier-2 OC alert [OCC2] Normal Charging Charging Charge algorithm algorithm

Tier-1 OC alert [OCD] Normal Charging Charging Discharge algorithm algorithm

Tier-2 OC Alert [OCD2] Normal Charging Charging Discharge algorithm algorithm

Tier-3 OC [AOCD] [TDA] [XDSGI] CHG FET and DSG 0 Charging Discharge condition FET disabled algorithm

Conditio Charging Charging n Current Voltage

SafetyAlert SafetyStatus BatteryStatus OperationStatus

OC [OCC] [TCA] CHG FET disabled, 0 0 condition enabled during

discharge

OC [OCC2] [TCA] CHG FET disabled, 0 0 condition enabled during

discharge

OC [OCD] [TDA] [XDSGI] DSG FET disabled, Pre-chg Charging condition enabled during charge Current algorithm

OC [OCD2] [TDA] [XDSGI] DSG FET disabled, Pre-chg Charging condition enabled during charge Current algorithm

The bq20z60-R1/bq20z65-R1 can individually configure each overcurrent-protection feature to recover via two different methods, based on the state of the [NR] bit.

Standard Recovery, where [NR] = 0 and the overcurrent tier is not selected in Non-Removable Cfg register. When the pack is removed and reinserted, the condition is cleared. Pack removal and reinsertion is detected by a low-to-high-to-low transition on the PRES input. When the overcurrent tier is selected in Non-Removable Cfg, that particular feature uses the Non-Removable Battery Mode recovery.

Non-Removable Battery Mode Recovery, where [NR] = 1. The state of Non-Removable Cfg has no consequence. This recovery requires AverageCurrent to be ≤ the recovery threshold and for the OC Time Limit timer ≥ Current Recovery Time.

When a charging-fault recovery condition is detected, then the CHG FET is allowed to be turned on, if other safety and configuration states permit, [TCA] in BatteryStatus is reset, ChargingCurrent and

ChargingVoltage are set to the appropriate value per the charging algorithm, and the appropriate SafetyStatus flag is reset.

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Time

Discharge

Current

AFESCDsgCfg

Bit3–Bit0

AFE SC Dsg Cfg

Bit7–Bit 4

(0µs–915µs)

AFE

SCDSG

AFE

OCDSG

AFEOCDsg

AFE OC Dsg Time

(1ms–31ms)

SOCDsg

SOC Dsg Time

(1s–60s)

2ndLevel

SOCDSG

Level

OC (1stTier) Dsg

Level

OC (2ndTier) Dsg

OC (1stTier) Dsg

OC (2ndTier) Dsg

OC (1st Tier) Dsg Time

)

OC (2nd Tier) Dsg Time

)

GasGauge

SoftwareProtection

(1-secondupdateinterval)

AFE Hardware Protection

(1s–60s)

1st Level Protection Features

When a discharging-fault recovery condition is detected, the DSG FET is allowed to be turned on if other safety and configuration states permit, [TDA] flag is reset, ChargingCurrent and ChargingVoltage are set to the appropriate value per the charging algorithm and the [XDSG] and the appropriate SafetyStatus flag is reset.

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Figure 2-3. Overcurrent Protection Levels

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AOCDCondition

Charging Allowed DischargingDisabled

DischargeCurrentBelow

AFELimit

AFEdetectsovercurrent dischargefault

GasGaugeidentifiesovercurrentcondition

[PRES]= 0

PackRemoved

Non-RemovableRecovery

Start

Timer

Wait

[DSG] = 1 AND

AverageCurrent > AFEOC

DsgRecovery

AND Timer < Current

RecoveryTime

[DSG] = 1 AND AverageCurrent

≤ AFEOCDsgRecovery

AverageCurrent

≤ AFEOCDsgRecovery

[DSG] = 0 AND [PRES

] transitionsfrom 1 to 0 AND AOCDnotsetinnonremovableconfiguration

ReinsertBatteryPack [PRES

] transitionsfrom 0 to 1

AverageCurrent ≤ AFE

OCDsgRecovery

AND Timer ≥ Current

RecoveryTime

AFEFaultCondition

ChargingDisabled DischargingDisabled

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1st Level Protection Features

Figure 2-4. AFE Discharge Overcurrent Protection

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Related Variables:

• DF:1st Level Safety:Current(1):OC(1st Tier) Chg(0)

• DF:1st Level Safety:Current(1):OC(1st Tier) Chg Time(2)

• DF:1st Level Safety:Current(1):OC Chg Recovery(3)

1st Level Protection Features

• DF:1st Level Safety:Current(1):OC(1st Tier) Dsg(5)

• DF:1st Level Safety:Current(1):OC(1st Tier) Dsg Time(7)

• DF:1st Level Safety:Current(1):OC Dsg Recovery(8)

• DF:1st Level Safety:Current(1):OC(2nd Tier) Chg(10)

• DF:1st Level Safety:Current(1):OC(2nd Tier) Chg Time(12)

• DF:1st Level Safety:Current(1):OC(2nd Tier) Dsg(13)

• DF:1st Level Safety:Current(1):OC(2nd Tier) Dsg Time(15)

• DF:1st Level Safety:Current(1):Current Recovery Time(16)

• DF:1st Level Safety:Current(1):AFE OC Dsg(17)

• DF:1st Level Safety:Current(1):AFE OC Dsg Time(18)

• DF:1st Level Safety:Current(1):AFE OC Dsg Recovery(19)

• DF:Charge Control:Charge Cfg(33):Pre-chg Current (4)

• DF:Configuration:Registers(64):Operation Cfg B(2)[NR]

• DF:Configuration:Registers(64):Non-Removable Cfg(8)

• SBS:Current(0x0a)

• SBS:AverageCurrent(0x0b)

• SBS:ChargingCurrent(0x14)

• SBS:ChargingVoltage(0x15)

• SBS:BatteryStatus(0x16)[TCA],[TDA]

• SBS:SafetyAlert(0x50)

• SBS:SafetyStatus(0x51)

• SBS:OperationStatus(0x54)[XDSGI]

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2.2.3 Short-Circuit Protection

The bq20z60-R1/bq20z65-R1 short-circuit protection is controlled by the AFE, but is recovered by the gas gauge. This allows different recovery methods to accommodate various applications.

AFE charge short-circuit and discharge short-circuit protection are configured by the data flash AFE SC Chg Cfg and AFE SC Dsg Cfg registers, respectively.

When the AFE detects a short-circuit-in-charge or short-circuit-in-discharge fault, the charge and discharge FETs are turned off. The bq20z60-R1/bq20z65-R1 identifies the short-circuit condition (charge or discharge current direction) and the internal Current_Fault timer is started from 0, either [TCA] or [TDA] in BatteryStatus is set, ChargingCurrent and ChargingVoltage are set to 0 (only if in charge mode), and either [SCC] or [SCD] is set. If the short-circuit condition is in discharge, then [XDSG] flag is also set.

Each bq20z60-R1/bq20z65-R1 short-circuit protection feature can be individually configured to recover via two different methods, based on the setting of the [NR] bit.

Standard Recovery is where [NR] = 0 and the overcurrent tier is not selected in Non-Removable Cfg. When the pack is removed and re-inserted, the condition is cleared. Pack removal and re-insertion is detected by transition on the PRES input from low to high to low. When the overcurrent tier is selected in Non-Removable Cfg, that particular feature uses the Non-Removable Battery Mode recovery.

Non-Removable Battery Mode Recovery is where [NR] = 1. The state of Non-Removable Cfg has no consequence when the [NR] bit is set to 1. This recovery requires AverageCurrent to be ≤ the AFE SC Recovery threshold and for the internal Current_Fault timer to be ≥ Current Recovery Time.

When the recovery condition for a charging fault is detected, the CHG FET is allowed to be turned on if other safety and configuration states permit. The ZVCHG FET also returns to previous state. When this occurs, [TCA] in BatteryStatus is reset, ChargingCurrent and ChargingVoltage are set to the appropriate values per the charging algorithm, and the appropriate SafetyStatus flag is reset.

When the recovery condition for a discharging fault is detected, the DSG FET is allowed to be turned on if other safety and configuration states permit. The ZVCHG FET also returns to its previous state. When this occurs, [TDA] is reset, ChargingCurrent and ChargingVoltage are set to the appropriate value per the charging algorithm, and [XDSG] and the appropriate SafetyStatus flags are reset.

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Short Charging Charging Clear Circuit Current Voltage Threshold

Charge AFE SC Chg Cfg [SCC] SafetyStatus, CHG FET disabled, 0 0

Discharge AFE SC Dsg Cfg [SCD] SafetyStatus, DSG FET disabled, 0 per

Condition Flags set FET

[TCA] BatteryStatus enabled during discharge

[TDA] BatteryStatus, enabled during charge charging [XDSG]OperationStatus algorithm

Related Variables:

• DF:1st Level Safety:Current(1):AFE SC Chg Cfg(21)

• DF:1st Level Safety:Current(1):AFE SC Dsg Cfg(22)

• DF:1st Level Safety:Current(1):AFE SC Recovery(23)

• DF:Configuration:Registers(64):Operation Cfg B(2)[NR]

• DF:Configuration:Registers(64):Non-Removable Cfg(8)

• SBS:AverageCurrent(0x0b)

• SBS:BatteryStatus(0x16)[TCA],[TDA]

• SBS:SafetyStatus(0x51)[SCC],[SCD]

• SBS:OperationStatus(0x54)[XDSG]

2.2.4 Overtemperature Protection

The bq20z60-R1/bq20z65-R1 has overtemperature protection for both charge and discharge conditions with separate thresholds and alarms for the 2 temperature sensors TS1 and TS2.

The bq20z60-R1/bq20z65-R1 sets the overtemperature charging [OT1C] flag in SafetyAlert if the pack temperature measured on TS1 reaches or surpasses the OT1 Chg Threshold during charging. The bq20z60-R1/bq20z65-R1 changes [OT1C] in SafetyAlert to an overtemperature charging condition if the temperature on TS1 stays above the OT1 Chg Threshold limit for a time period of OT1 Chg Time. This function is disabled if OT1 Chg Time is set to zero. Similarly, the bq20z60-R1/bq20z65-R1 sets the overtemperature charging [OT2C] flag in SafetyAlert2 if the pack temperature measured on TS2 reaches or surpasses the OT2 Chg Threshold during charging. The bq20z60-R1/bq20z65-R1 changes [OT2C] inSafetyAlert2 to an overtemperature charging condition if the temperature on TS2 stays above the OT2 Chg Threshold limit for a time period of OT2 Chg Time. This function is disabled if OT2 Chg Time is set to zero.

If [OTFET] is set and the bq20z60-R1/bq20z65-R1 is in overtemperature charging condition, charging is disabled and the CHG FET is turned off, the ZVCHG FET is turned off if configured for use,

ChargingCurrent and ChargingVoltage are set to zero, the [OT1C] flag in SafetyAlert (or [OTC2] in SafetyAlert2) is cleared, and [TCA] in BatteryStatus and the [OT1C] flag in SafetyStatus (or [OTC2] in SafetyStatust2) are set.

The bq20z60-R1/bq20z65-R1 recovers from an [OT1C] condition if TS1Temperature is equal to or below the OT1 Chg Recovery limit. The bq20z60-R1/bq20z65-R1 recovers from an [OTC2] condition if

TS2Temperature is equal to or below the OT2 Chg Recovery limit. On recovery the [OT1C] flag in SafetyStatus (or [OTC2] flag in SafetyStatus2) is cleared, [OTA] and [TCA] in BatteryStatus are cleared, ChargingCurrent and ChargingVoltage are set back to their appropriate values per the charging algorithm,

and the CHG FET returns to its previous state.

1st Level Protection Features

Table 2-5. Short-Circuit Protection

AFE SC Recovery

In an [OT1C] or [OT2C] condition, the CHG FET is turned on during discharging to prevent overheating of the CHG FET body diode.

The bq20z60-R1/bq20z65-R1 sets the overtemperature discharging [OT1D] flag in SafetyAlert if the pack temperature measured on TS1 reaches or surpasses the OT1 Dsg Threshold during discharging. The bq20z60-R1/bq20z65-R1 changes [OT1D] SafetyAlert to an overtemperature discharging condition if the temperature on TS1 stays above the OT1 Dsg Threshold limit for a time period of OT1 Dsg Time. This function is disabled if OT1 Dsg Time is set to zero. Similarly, the bq20z60-R1/bq20z65-R1 sets the

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1st Level Protection Features

overtemperature discharging [OT2D] flag in SafetyAlert2 if the measured temperature on TS2 reaches or surpasses the OT2 Dsg Threshold during discharging. The bq20z60-R1/bq20z65-R1 changes [OT2D] in SafetyAlert2 to an overtemperature discharging condition if the temperature on TS2 reaches or surpasses the OT2 Dsg Threshold limit for a time period of OT2 Dsg Time. This function is disabled if OT2 Dsg Time is set to zero.

If [OTFET] is set and bq20z60-R1/bq20z65-R1 is in an overtemperature discharging condition, discharging is disabled and the DSG FET is turned off, ChargingCurrent is set to zero, the [OT1D] flag in SafetyAlert (or [OT2D] in SafetyAlert2) is cleared, [TDA] is set, [XDSG] flag is set and the [OT1D] flag in SafetyStatus (or [OT2D] flag in SafetyStatus2) is set.

The bq20z60-R1/bq20z65-R1 recovers from an [OT1D] condition if TS1Temperature is equal to or below the OT1 Dsg Recovery limit. The bq20z60-R1/bq20z65-R1 recovers from an [OT2D] condition if

TS2Temperature is equal to or below the OT2 Dsg Recovery limit. On recovery, [OT1D] flag in SafetyStatus (or [OT2D] flag in SafetyStatus2) is cleared, [TDA] and [OTA] are cleared, ChargingCurrent

is set back to the appropriate value per the charging algorithm, [XDSG] is cleared, and the DSG FET is allowed to switch on again.

In an overtemperature discharging condition, the DSG FET is turned on during charging to prevent overheating of the DSG FET body diode

Alert Threshold Overtemp Condition

Charge OT1 Chg Threshold, OT1 Chg Time, [OT1C], [OT1C] SafetyStatus Flag (or [OT2C]

OT2 Chg Threshold OT2 Chg Time [OT2C] SafetyStatus2 Flag) set, [TCA] and

Discharge OT1 Dsg Threshold, OT1 Dsg Time, [OT1D], [OT1D] SafetyStatus Flag (or [OT2D]

OT2 Dsg Threshold OT2 Dsg Time [OT2D] SafetyStatus2 Flag) set, [TDA] and

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Table 2-6. Overtemperature Protection

Alert Time SafetyAlert Recovery

Limit Flags set Threshold

[OTA] BatteryStatus set, OT1 Chg Recovery,

ChargingCurrent = 0, OT2 Chg Recovery

ChargingVoltage = 0, if [OTFET] is

set then CHG FET is turned off

[OTA] BatteryStatus set, OT1 Dsg Recovery,

ChargingCurrent = 0, OT2 Dsg Recovery

if [OTFET] is set then [XDSG] set

and DSG FET off

Related Variables:

• DF:1st Level Safety:Temperature(2):OT1 Chg Threshold(0)

• DF:1st Level Safety:Temperature(2):OT1 Chg Time(2)

• DF:1st Level Safety:Temperature(2):OT1 Chg Recovery(3)

• DF:1st Level Safety:Temperature(2):OT2 Chg Threshold(5)

• DF:1st Level Safety:Temperature(2):OT2 Chg Time(7)

• DF:1st Level Safety:Temperature(2):OT2 Chg Recovery(8)

• DF:1st Level Safety:Temperature(2):OT1 Dsg Threshold(10)

• DF:1st Level Safety:Temperature(2):OT1 Dsg Time(12)

• DF:1st Level Safety:Temperature(2):OT1 Dsg Recovery(13)

• DF:1st Level Safety:Temperature(2):OT2 Dsg Threshold(15)

• DF:1st Level Safety:Temperature(2):OT2 Dsg Time(17)

• DF:1st Level Safety:Temperature(2):OT2 Dsg Recovery(18)

• DF:Configuration:Registers(64):Operation Cfg B(2)[OTFET]

• SBS:TS1Temperature(0x5e)

• SBS:TS2Temperature(0x5f)

• SBS:ChargingCurrent(0x14)

• SBS:ChargingVoltage(0x15)

• SBS:BatteryStatus(0x16)[TCA],[TDA], [OTA]

• SBS:SafetyAlert(0x50)[OT1C],[OT1D]

• SBS:SafetyStatus(0x51)[OT1C],[OT1D]

• SBS:SafetyAlert2(0x68)[OT2C],[OT2D]

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• SBS:SafetyStatus2(0x69)[OT2C],[OT2D]

• SBS:OperationStatus(0x54)[XDSG]

2.2.5 Host Watchdog

The bq20z60-R1/bq20z65-R1 can be configured to require the host system to communicate with the battery periodically, else the battery disables charging and discharging. The Host Watchdog function is only active in Normal Power mode and is disabled if Host Watchdog Timeout is set to 0.

If the bq20z60-R1/bq20z65-R1 does not receive any valid SMBus communications for Host Watchdog Timeout period of time, the FETs are turned off, ChargingVoltage and ChargingCurrent are set to 0, [TCA] and [TDA] in BatteryStatus, [XDSG] in OperationStatus, and [HWDG] in SafetyStatus are all set.

For normal recovery to be achieved, normal SMBus communication must be resumed. When this occurs, the FETs are returned to the normal operating state, [TCA] and [TDA] in BatteryStatus are cleared,

ChargingCurrent and ChargingVoltage are set to the appropriate value per the charging algorithm, and [XDSG] and [HWDG] are cleared.

Related Variables:

• DF:1st Level Safety:Host Comm(3):Host Watchdog Timeout(0)

• SBS:ChargingCurrent(0x14)

• SBS:ChargingVoltage(0x15)

• SBS:BatteryStatus(0x16)[TCA],[TDA]

• SBS:SafetyStatus(0x51)[HWDG]

• SBS:OperationStatus(0x54)[XDSG]

2nd Level Protection Features

2.2.6 AFE Watchdog

The AFE automatically turns off the CHG FET, DSG FET and ZVCHG FET (if used), if it does not receive the appropriate frequency on the WDI input from gas gauge. The gas gauge has no warning that this is about to happen, but it can report the occurrence once the bq20z60-R1/bq20z65-R1 is able to interrogate the AFE.

When the XALERT signal is triggered, the bq20z60-R1/bq20z65-R1 reads the STATUS register of the AFE. If [WDF] is set, the bq20z60-R1/bq20z65-R1 also sets [WDF] in SafetyStatus, and periodic verification of the AFE RAM is undertaken. If verification of the AFE RAM fails, then the FETs turn off. Verification of the AFE RAM continues once every second. If the periodic verification passes, then [WDF] in SafetyStatus is cleared and the FETs return to normal operation.

Related Variable:

• SBS:SafetyStatus(0x51)[WDF]

2.3 2nd Level Protection Features

The bq20z60-R1/bq20z65-R1 provides features that can be used to indicate a more serious fault via the SAFE output. This output can be used to blow an in-line fuse to permanently disable the battery pack from charge or discharge activity.

If any PF Threshold condition is met, the appropriate PFAlert flag is set. If the PF Threshold condition is cleared within the PF time limit, the appropriate PFAlert flag is cleared. But if the PF Threshold condition continues over the PF Time Limit, then the bq20z60-R1/bq20z65-R1 goes into a permanent failure condition and the PFStatus flag is set, ad the PFlert flag is cleared.

When any NEW cause of a permanent failure is set in PFStatus function, the NEW cause is added to Saved PF Flags 1..2. This allows Saved PF Flags 1..2 to show ALL permanent failure conditions that have occurred.

On the first occasion of a permanent failure indicated by PFStatus or PFStatus2 change from 0x00, the PFStatus and PFStatus2 value is stored in Saved 1st PF Flags 1..2.

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NoPF

PF Alert

PFCondition

CHG, DSG, ZVCHGFET turns off. [TCA] flag set, [TDA] flag set. Data Flash Access Read-Only.

ChargingCurrent =0 ChargingVoltage =0

Ifbit in Permanent Fail Cfg or

is set,Permanent Fail Cfg2

drive SAFEpin high and [PF] flag in

or is setSafetyStatus SafetyStatus2

MonitoredValue ≥ PFThreshold

(MonitoredValue ≥ PFThreshold

AND Timer ≥ PFTimeLimit)

(AFE_Fail_Counter ≥ MaxErrorLimit )

PFKey to ManufacturerAccess

Stop and Reset Timer

Start

Timer

Wait

MonitoredValue

≥ PFThreshold

MonitoredValue < PFThreshold OR

AFE_Fail_Counter = 0

Start AFE

Timer

Decrement

AFE_Fail_

Counter

AFE Timer

≥ AFEFail

RecoveryTime

2nd Level Protection Features

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2.3.1 2nd Level (Permanent) Failure Actions

When the PFStatus or PFStatus2 register changes from 0x00 to indicate a permanent failure, then the

following actions are taken in sequence.

• CHG, DSG, and ZVCHG FETs are turned OFF.

• The [TCA] and [TDA] flags in BatteryStatus are set.

• Data flash write access is then disabled, but the data flash can be read.

• ChargingCurrent and ChargingVoltage are set to 0.

• The appropriate bit in Saved PF Flags 1 or Saved PF Flags 2 is set.

• If the appropriate bit in Permanent Fail Cfg is set, then 0x3672 is programmed to Fuse Flag, and the SAFE pin is driven and latched high. The [PF] flag in SafetyStatus is also set.

Related Variables:

• DF:Configuration:Registers(64):Permanent Fail Cfg 1(6), Permanent Fail Cfg 2(8)

• DF:PF Status:Device Status Data(96):Saved PF Flags 1(0), Saved PF Flags 2(2)

• DF:PF Status:Device Status Data(96):Fuse Flag(2)

• DF:PF Status:Device Status Data(96):Saved 1st PF Flags 1(32), Saved 1st PF Flags 2(34)

• SBS:ChargingCurrent(0x14)

• SBS:ChargingVoltage(0x15)

• SBS:BatteryStatus(0x16)[TCA],[TDA]

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Figure 2-5. 2nd Level Protection

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• SBS:SafetyStatus(0x51)[PF]

• SBS:PFStatus(0x53)

2.3.2 Time-Limit-Based Protection

The bq20z60-R1/bq20z65-R1 reports a 2nd level protection alert by setting the appropriate flag in the PFAlert or PFAlert2 register if the monitored value goes beyond the Protection Threshold. If the monitored value stays beyond the Protection Threshold over the Max Alert duration, the bq20z60-R1/bq20z65-R1 reports a 2nd level permanent failure, clears the appropriate PFAlert flag, and sets the appropriate PFStatus flag. See Table 2-7 for all Protection Thresholds and Max Alert durations.

Safety Overvoltage Protection— The bq20z60-R1/bq20z65-R1 monitors the individual cell voltages for

extreme values.

Safety Undervoltage Protection— The bq20z60-R1/bq20z65-R1 monitors the individual cell voltages for

extreme undervoltage values. Additionally, the bq20z60-R1/bq20z65-R1 can check cell voltages upon wakeup from shutdown mode while the charge and precharge FETs are turned off (to detect copper deposition).

Cell Imbalance Fault— Two methods of cell imbalance detection are implemented to provide CIM

detection both while charging and at rest. Two safety CIM flags are used, one for each detection methods. CIM_A reflects faults detected using the active CIM detection and CIM_R reflects faults detected using the at rest CIM detection. These flags and the bits associated with them are shown in Table 2-7.

2nd Level Protection Features

At Rest Detection

The at rest detection mechanism starts detection if all of following conditions are reached:

• Any (CellVoltage4..1) > Rest CIM Check Voltage

• |Current| ≤ Rest CIM Current for CIM Battery Rest Time

The bq20z60-R1/bq20z65-R1 sets [CIM_R] in PFAlert if the following condition is met:

• Max difference between any (CellVoltage4..1) > Rest CIM Fail Voltage

If the above condition remains active for more than Rest CIM Time, the device goes into permanent fail condition and moves [CIM_R] from PFAlert to PFStatus. Set Rest CIM Time to 0 to disable this CIM detection.

Active Detection

The active detection method during charging is activated when the following conditions are met:

• Any (CellVoltage4..1) > Active CIM Check Voltage

• Current ≥ Charge Threshold Current

The bq20z60-R1/bq20z65-R1 sets [CIM_A] in PFAlert2 if the following condition is met:

• Max difference between any (CellVoltage4..1) > Active CIM Fail Voltage

If above condition remains active for more than Active CIM Time, the bq20z60-R1/bq20z65-R1 goes into permanent fail condition and moves [CIM_A] from PFAlert2 to PFStatus2. Set Active CIM Time to 0 to disable this CIM detection.

2nd Level Protection IC Input— The PFIN input of the bq20z60-R1/bq20z65-R1 can be used to

determine the state of an external protection device such as the bq294xx. The bq20z60-R1/bq20z65-R1 watches for the PFIN pin being driven low by an external device.

Safety Overcurrent Protection— The bq20z60-R1/bq20z65-R1 monitors the current during charging and

discharging. The overcurrent thresholds and time limits can be set independently for charging and discharging.

Safety Overtemperature Protection— The bq20z60-R1/bq20z65-R1 monitors the pack temperature

during charging and discharging. The overtemperature thresholds and time limits can be set independently for charging and discharging. Additionally, the two temperature sensors (TS1 and TS2) have separate alarms, thresholds, and time limits.

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2nd Level Protection Features

Open Thermistor— The bq20z60-R1/bq20z65-R1 monitors the thermistor temperature readings and can

detect open thermistors by their unusually low readings. Two separate safety flags are used one for each thermistor.

Charge and Zero-Volt Charge FET Fault Protection— The bq20z60-R1/bq20z65-R1 monitors if there

is, at any time, an attempt to turn off the CHG FET or ZVCHG FET or if the CHG bit in the AFE OUTPUT register is set and the current still continues to flow.

Discharge FET Fault Protection— The bq20z60-R1/bq20z65-R1 monitors if there is, at any time, an

attempt to turn off the DSG FET or if the DSG bit in the AFE OUTPUT register is set and the current still continues to flow.

Fuse State Detection— The bq20z60-R1/bq20z65-R1 can detect if an attempt has been made to blow

the fuse, but the attempt has failed. The bq20z60-R1/bq20z65-R1 monitors if the Fuse Flag is set to 0x3672 and current is still flowing.

Protection Conditions Monitored Value PF Threshold PF Time Limit PFStatus Fail Cfg

Safety overvoltage – Voltage LT SOV Threshold, or SOV Time [SOV] [XSOV]

Safety undervoltage – Voltage SUV Threshold SUV Time [SUV] [XSUV] Cell imbalance fault Max difference Rest CIM Fail Voltage Rest CIM Time [CIM_R] [XCIM_R]

(at rest) Any

Cell imbalance fault Max difference Active CIM Fail Active CIM Time [CIM_A] [XCIM_A] (active) Any Voltage

2nd level protection – PFIN pin PFIN pin low PFIN Detect Time [PFIN] [XPFIN] IC input

Safety overcurrent Current> 0 Current SOC Chg SOC Chg Time [SOCC] [XSOCC] charge

Safety overcurrent Current< 0 Current SOC Dsg SOC Dsg Time [SOCD] [XSOCD] discharge

Safety Current > 0 TS1Temperature SOT1 Chg Threshold SOT1 Chg Time [SOT1C] [XSOT1C] overtemperature chg

Safety Current < 0 TS1Temperature SOT1 Dsg Threshold SOT1 Dsg Time [SOT1D] [XSOT1D] overtemperature dsg

Open thermistor 1 – TS1Temperature Open Thermistor Open Time [SOPT1] [XSOPT1] Open thermistor 2 – TS2Temperature Open Thermistor Open Time [SOPT2] [XSOPT2] Charge and zero-volt (CHG FET or ZVCHG Current FET Fail Limit FET Fail Time [CFETF] [XCFETF]

charge FET fault FET turn off attempt or

CHG Flag in AFE OUTPUT register set) and Current > 0

Discharge FET fault (DSG FET turn off (–)Current FET Fail Limit FET Fail Time [DFETF] [XDFETF]

attempt or DSG Flag in AFE OUTPUT register set) and Current < 0

Fuse state Fuse Flag = 0x3672 |Current| Fuse Fail Limit Fuse Fail Time [FBF] [XFBF]

Table 2-7. Time-Limit-Based 2ndLevel Protection

• Any (CellVoltage4..1) > Rest CIM

Check Voltage

• |Current| ≤ Rest CIM Current for CIM Battery Rest Time

• Any (CellVoltage4..1) > Active CIM

Check Voltage

• |Current| ≥

Charge Detection Current

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PFAlert Flag, Permanent Flag Flag

ST SOV Threshold, or HT SOV Threshold

CellVoltage4..1

TS2Temperature SOT2 Chg Threshold SOT2 Chg Time [SOT2C] [XSOT2C]

TS2Temperature SOT2 Dsg Threshold SOT2 Dsg Time [SOT2D] [XSOT2D]

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Related Variables:

• DF:2nd Level Safety:Voltage(16): LT SOV Threshold(0)

• DF:2nd Level Safety:Voltage(16): ST SOV Threshold(2)

• DF:2nd Level Safety:Voltage(16): HT SOV Threshold(4)

• DF:2nd Level Safety:Voltage(16): SOV Time(6)

• DF:2nd Level Safety:Voltage(16):SUV Threshold(7)

• DF:2nd Level Safety:Voltage(16):SUV Time(9)

• DF:2nd Level Safety:Voltage(16):Rest CIM Current(12)

• DF:2nd Level Safety:Voltage(16):Rest CIM Fail Voltage(13)

• DF:2nd Level Safety:Voltage(16):Rest CIM Time(15)

• DF:2nd Level Safety:Voltage(16):CIM Battery Rest Time(16)

• DF:2nd Level Safety:Voltage(16): Rest CIM Check Voltage(18)

• DF:2nd Level Safety:Voltage(16): Active CIM Fail Voltage(20)

• DF:2nd Level Safety:Voltage(16): Active CIM Time(22)

• DF:2nd Level Safety:Voltage(16): Active CIM Check Voltage(23)

• DF:2nd Level Safety:Voltage(16):PFIN Detect Time(25)

• DF:2nd Level Safety:Current(17):SOC Chg(0)

• DF:2nd Level Safety:Current(17):SOC Chg Time(2)

• DF:2nd Level Safety:Current(17):SOC Dsg(3)

• DF:2nd Level Safety:Current(17):SOC Dsg Time(5)

• DF:2nd Level Safety:Temperature(18):SOT1 Chg Threshold(0)

• DF:2nd Level Safety:Temperature(18):SOT1 Chg Time(2)

• DF:2nd Level Safety:Temperature(18):SOT2 Chg Threshold(3)

• DF:2nd Level Safety:Temperature(18):SOT2 Chg Time(5)

• DF:2nd Level Safety:Temperature(18):SOT1 Dsg Threshold(6)

• DF:2nd Level Safety:Temperature(18):SOT1 Dsg Time(8)

• DF:2nd Level Safety:Temperature(18):SOT2 Dsg Threshold(9)

• DF:2nd Level Safety:Temperature(18):SOT2 Dsg Time(11)

• DF:2nd Level Safety:Temperature(18):Open Thermistor(12)

• DF:2nd Level Safety:Temperature(18):Open Time(14)

• DF:2nd Level Safety:FET Verification(19):FET Fail Limit(0)

• DF:2nd Level Safety:FET Verification(19):FET Fail Time(2)

• DF:2nd Level Safety:Fuse Verification(21):Fuse Fail Limit(0)

• DF:2nd Level Safety:Fuse Verification(21):Fuse Fail Time(2)

• DF:Configuration:Registers(64):Permanent Fail Cfg 1(6), Permanent Fail Cfg 2(8)

• DF:PF Status:Device Status Data(96):Saved PF Flags 1(0), Saved PF Flags 2(2)

• SBS:TS1Temperature(0x5e)

• SBS:TS2Temperature(0x5f)

• SBS:Voltage(0x09)

• SBS:Current(0x0a)

• SBS:CellVoltage4..1(0x3c..0x3f)

• SBS:PFStatus(0x53)

2nd Level Protection Features

2.3.3 Limit-Based Protection

The bq20z60-R1/bq20z65-R1 reports a 2nd level permanent failure and sets the appropriate PFStatus flag if the internal error counter reaches the maximum error limit. The internal error counter is incremented by one if the error happens and reset to zero (0) for every good communication cycle.

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2nd Level Protection Features

AFE Communication Fault Protection— The gas gauge in the bq20z60-R1/bq20z65-R1 periodically

validates its read and write communications with the AFE. If either a read or write verify fails, an internal AFE_Fail_Counter is incremented. If the AFE_Fail_Counter reaches AFE Fail Limit, the bq20z60-R1/bq20z65-R1 reports an [AFE_C] permanent failure. The AFE_Fail_Counter is reset to zero (0) for every good communication cycle. If the AFE Fail Limit is set to 0, this feature is disabled. An [AFE_C] fault can also be declared if, after a full reset, the initial gain and offset values read from the AFE cannot be verified. These values are A/D readings of the AFE VCELL output. The AFE offset values are verified by reading the values twice and confirming that the readings are within acceptable limits. The maximum difference between two readings is set with AFE Init Limit. The maximum number of read retries, if offset and gain value verification fails and an [AFE_C] fault is declared, is set in AFE Fail Limit.

Periodic AFE Verification— The gas gauge in the bq20z60-R1/bq20z65-R1 periodically

(AFE Check Time) compares certain RAM content of the AFE with that of the data flash and the expected control-bit states. This function is disabled if AFE Check Time is set to 0. If an error is detected, the internal AFE_Fail_Counter is incremented. If the internal AFE_Fail_Counter reaches the AFE Fail Limit, the bq20z60-R1/bq20z65-R1 reports a permanent failure.

AFE Init Verification— After a full reset, the bq20z60-R1/bq20z65-R1 gas gauge and the AFE offset and

gain values are read twice and compared. The AFE Init Limit sets the maximum difference in A/D counts of two successful readings of offset and gain, which the bq20z60-R1/bq20z65-R1 still considers as the same value. If the gain and offset values are still not considered the same after AFE Init Retry Limit comparison retries, the bq20z60-R1/bq20z65-R1 reports a permanent failure error.

Data Flash Failure— The bq20z60-R1/bq20z65-R1 can detect if the data flash is not operating correctly.

A permanent failure is reported when either: (i) After a full reset the instruction flash checksum does not verify; (ii) if any data flash write does not verify; or (iii) if any data flash erase does not verify.

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Table 2-8. Error-Based 2nd Level Protection

Protection Monitored Value Fail Recovery

AFE Periodic communication AFE_Fail_Counter is reset to AFE Fail Limit [AFE_C] [XAFE_C] communication with the AFE zero (0) per each fault AFE Fail Recovery Time period

Periodic AFE Check RAM of the AFE with Decrement of internal AFE Fail Limit [AFE_P] [XAFE_P] verification AFE Check Time period AFE_Fail_Counter by one per

AFE Fail Recovery Time

period.

AFE initialization Initial gain and offset values – AFE Init Retry Limit [AFE_C] [XAFE_C]

from the AFE after full reset

Data flash failure Data flash – Falseflash checksum after [DFF] [XDFF]

Max Error Limit (Set to 0 PFAlert Flag, Permanent Fail to Disable Protection) PFStatus Flag Cfg Flag

reset, data flash write not verified, data flash erase not verified

Related Variables:

• DF:2nd Level Safety:FET Verification(19):FET Fail Limit(0)

• DF:2nd Level Safety:FET Verification(19):FET Fail Time(2)

• DF:2nd Level Safety:AFE Verification(20):AFE Check Time(0)

• DF:2nd Level Safety:AFE Verification(20):AFE Fail Limit(1)

• DF:2nd Level Safety:AFE Verification(20):AFE Fail Recovery Time(2)

• DF:2nd Level Safety:AFE Verification(20):AFE Init Retry Limit(3)

• DF:2nd Level Safety:AFE Verification(20):AFE Init Limit (4)

• DF:Configuration:Registers(64):Permanent Fail Cfg(6)

• DF:PF Status:Device Status Data(96):Saved PF Flags 1(0)

• SBS:PFStatus(0x53)

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2.3.4 Clearing Permanent Failure

A bq20z60-R1/bq20z65-R1 permanent failure can be cleared by sending two ManufacturerAccess commands in sequence: the first word of the PFKey followed by the second word of the PFKey. After sending these two commands in sequence, PFStatus flags are cleared. Refer to Permanent Fail Clear (PFKey) Manufacturer access for further details.

Related Variables:

• SBS:ManufacturerAccess(0x00)

• SBS:PFStatus(0x53)

2.4 Gas Gauging

The bq20z60-R1/bq20z65-R1 features Impedance Track™ (IT) gauging algorithm and is capable of supporting a maximum battery pack capacity of 32Ah. The gas gauge measures individual cell voltages, pack voltage, temperature, and current using features of the AFE. The bq20z60-R1/bq20z65-R1 determines battery state of charge by analyzing individual cell voltages when a time exceeding 35 minutes has passed since the last charge or discharge activity of the battery. The bq20z60-R1/bq20z65-R1 measures charge and discharge activity by monitoring the voltage across a small-value series sense resistor (10 mΩ typ.) between the cell stack negative terminal and the negative terminal of the battery pack. The battery state of charge is subsequently adjusted during load or charger application using the integrated charge passed through the battery.

2.4.1 Impedance Track Configuration

Load Mode— During normal operation, the battery-impedance profile compensation of the Impedance

Track algorithm can provide more-accurate full-charge and remaining state-of-charge information if the typical load type is known. The two selectable options are constant current (Load Mode = 0) and constant power (Load Mode = 1).

Gas Gauging

Load Select— In order to compensate for the I × R drop near the end of discharge, the

bq20z60-R1/bq20z65-R1 must be configured for whatever current (or power) will flow in the future. While it cannot be exactly known, the bq20z60-R1/bq20z65-R1 can use load history such as the average current of the present discharge to make a sufficiently accurate prediction. The bq20z60-R1/bq20z65-R1 can be configured to use several methods of this prediction by setting the Load Select value. Because this estimate has only a second-order effect on remaining capacity accuracy, different measurement-based methods (0 to 3, and method 7) result in only minor differences in accuracy. However, methods 4 to 6, where an estimate is arbitrarily assigned by the user, can result in significant error if a fixed estimate is far from the actual load. For highly variable loads, selection 7 will give the most conservative estimate and is preferable.

Constant Current (Load Mode = 0) Constant Power (Load Mode = 1) 0 = Avg I Last Run Avg P Last Run 1 = Present average discharge current Present average discharge power 2 = Current Current × Voltage 3 = AverageCurrent (default) AverageCurrent × average Voltage 4 = Design Capacity / 5 Design Energy / 5 5 = AtRate (mA) AtRate (10 mW) 6 = User Rate-mA User Rate-mW

7= Max Avg I Last Run Max Avg P Last Run

Pulsed Load Compensation and Termination Voltage— In order to take into account pulsed loads

while calculating remaining capacity until Term Voltage threshold is reached, the bq20z60-R1/bq20z65-R1 monitors not only average load but also short load spikes. The maximum voltage deviation during a load spike is continuously updated during discharge and stored in Delta Voltage.

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Gas Gauging

Reserve Battery Capacity— The bq20z60-R1/bq20z65-R1 allows an amount of capacity to be reserved

Related Variables:

• DF:SBS Configuration:Data(48):Design Capacity(22)

• DF:SBS Configuration:Data(48):Design Energy(24)

• DF:Configuration:Operation Cfg B(2)[RESCAP]

• DF:Gas Gauging:IT Cfg(80):Load Select(0)

• DF:Gas Gauging:IT Cfg(80):Load Mode(1)

• DF:Gas Gauging:IT Cfg(80):Term Voltage(59)

• DF:Gas Gauging:IT Cfg(80):User Rate-mA(76)

• DF:Gas Gauging:IT Cfg(80):User Rate-mW(78)

• DF:Gas Gauging:IT Cfg(80):Reserve Cap-mAh(80)

• DF:Gas Gauging:IT Cfg(80):Reserve Cap-mWh(82)

• DF:Gas Gauging:State(82):Avg I Last Run(21)

• DF:Gas Gauging:State(82):Avg P Last Run(23)

• DF:Gas Gauging:State(82):Delta Voltage(25)

• DF:Gas Gauging:State(82):Max I Last Run(31)

• DF:Gas Gauging:State(82):Max P Last Run(33)

• SBS:BatteryMode(0x03)[CapM]

• SBS:Voltage(0x09)

• SBS:Current(0x0a)

• SBS:AverageCurrent(0x0b)

• SBS:OperationStatus(0x54)[LDMD]

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in either mAh (Reserve Cap-mAh, Load Mode = 0) or 10 mWh (Reserve Cap-mWh, Load Mode = 1) units between the point where the RemainingCapacity function reports zero capacity, and the absolute minimum pack voltage, Term Voltage. This enables a system to report zero energy, but still have enough reserve energy to perform a controlled shutdown, or to provide an extended sleep period for the host system.

Also, if the [RESCAP] bit is set to 0, the reserve capacity is compensated at a no-load condition. However, if [RESCAP] bit is set to 1, then the reserve capacity is compensated at the present discharge rate as selected by Load Select.

2.4.2 Gas Gauge Modes

Resistance updates take place only in discharge mode, while OCV and Qmax updates only take place in relaxation mode. Entry and exit of each mode is controlled by data flash parameters in the subclass Gas

Gauging: Current Thresholds section. In relaxation mode or discharge mode, the DSG flag in BatteryStatus is set.

In order to prevent abnormally fast resistance change, resistance change is limited to old value +- Ra Max Delta (mOhm). Recommended setting is 15% of 4 Ra grid point value, after optimized values of Ra are obtained from optimization cycle.

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DischargeMode

RelaxationMode

Current < (–) DsgCurrentThreshold

Current >(–) forQuitCurrent

DsgRelaxTime

period

ChargeMode

Current

> ChgCurrentThreshold

Current

< QuitCurrent

for ChgRelaxTime

period

OCVupdate

Qmax update

[DSG]

CellImpedance update

[DSG]

Current

> ChgCurrentThreshold

Current <(–) DsgCurrentThreshold

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Gas Gauging

Figure 2-6. Gas Gauge Operating Modes

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QuitCurrent

(–)QuitCurrent

Current

Time

RelaxationMode ChargeMode DischargeModeRelaxationMode ChargeMode DischargeMode RelaxationMode

ChgRelaxTime

DsgRelaxTime

1 10 1 1 10[DSG]

Gas Gauging

Charge mode is exited and relaxation mode is entered when Current goes below Quit Current for a period of Chg Relax Time. Discharge mode is entered when Current goes below (–)Dsg Current Threshold. Discharge mode is exited and relaxation mode is entered when Current goes above (–)Quit Current threshold for a period of Dsg Relax Time. Charge mode is entered when Current goes above Chg Current Threshold.

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Figure 2-7. Gas Gauge Operating Mode Example

Related Variables:

• DF:Gas Gauging:Current Thresholds(81):Dsg Current Threshold(0)

• DF:Gas Gauging:Current Thresholds(81):Chg Current Threshold(2)

• DF:Gas Gauging:Current Thresholds(81):Quit Current(4)

• DF:Gas Gauging:Current Thresholds(81):Dsg Relax Time(6)

• DF:Gas Gauging:Current Thresholds(81):Chg Relax Time(7)

• SBS:Current(0x0a)

• SBS:BatteryStatus(0x16)[DSG]

• SBS:OperationStatus(0x54)[VOK],[R_DIS],[QEN]

2.4.3 Qmax

The total battery capacity is found by comparing states of charge before and after applying the load with the amount of charge passed. When an applications load is applied, the impedance of each cell is measured by comparing the open circuit voltage (OCV) obtained from a predefined function for present state of charge with the measured voltage under load.

Measurements of OCV and charge integration determine chemical state of charge and Chemical Capacity (Qmax).

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