TEXAS INSTRUMENTS bq2060 Technical data

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1 2 3 4 5 6 7 8 9 10 11 12 13 14

28 27 26 25 24 23 22 21 20 19 18 17 16 15

HDQ16

ESCL

ESDA

RBI

REG

OUT

DISP LED

LED

SMBC SMBD VCELL

VCELL

SRC TS THON CVON CFC DFC

28-pin 150-mil SSOP

SLUS035E – JANUARY 2000 – REVISED OCTOBER 2005

SBS V1.1-COMPLIANT GAS GAUGE IC

bq2060

FEATURES

• Provides Accurate Measurement of Available

Charge in NiCd, NiMH, Li-Ion, and Lead-Acid Batteries

• Supports SBS Smart Battery Data

Specification v1.1

• Supports the 2-Wire SMBus v1.1 Interface

with PEC or 1-Wire HDQ16

• Reports Individual Cell Voltages

• Monitors and Provides Control to Charge and

Discharge FETs in Li-Ion Protection Circuit

• Provides 15-Bit Resolution for Voltage,

Temperature, and Current Measurements

• Measures Charge Flow Using a V-to-F

Converter with Offset of Less Than 16 µV After Calibration

• Consumes Less Than 0.5 mW Operating

• Drives a 4- or 5-Segment LED Display for

Remaining Capacity Indication

• 28-Pin 150-mil SSOP

DESCRIPTION

The bq2060 SBS-compliant gas gauge IC for battery pack or in-system installation maintains an accurate record of available charge in rechargeable batteries. The bq2060 monitors capacity and other critical battery parameters for NiCd, NiMH, Li-ion, and lead-acid chemistries. The bq2060 uses a V-to-F converter with automatic offset error correction for charge and discharge counting. For voltage, temperature, and current reporting, the bq2060 uses an A-to-D converter. The onboard ADC also monitors individual cell voltages in a Li-ion battery pack and allows the bq2060 to generate control signals that may be used with a pack supervisor to enhance pack safety.

The bq2060 supports the smart battery data (SBData) commands and charge-control functions. It communicates data using the system management bus (SMBus) 2-wire protocol or the Benchmarq 1-wire HDQ16 protocol. The data available include the battery’s remaining capacity, temperature, voltage,

PRODUCTION DATA information is current as of publication date. Products conform to specifications per the terms of the Texas Instruments standard warranty. Production processing does not necessarily include testing of all parameters.

Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.

current, and remaining run-time predictions. The bq2060 provides LED drivers and a push-button input to depict remaining battery capacity from full to empty in 20% or 25% increments with a 4- or 5-segment display.

The bq2060 works with an external EEPROM. The EEPROM stores the configuration information for the bq2060, such as the battery’s chemistry, self-discharge rate, rate compensation factors, measurement calibration, and design voltage and capacity. The bq2060 uses the programmable self-discharge rate and other compensation factors stored in the EEPROM to accurately adjust remaining capacity for use and standby conditions based on time, rate, and temperature. The bq2060 also automatically calibrates or learns the true battery capacity in the course of a discharge cycle from near full to near empty levels.

The REG output regulates the operating voltage for the bq2060 from the battery cell stack using an external JFET.

PIN CONNECTIONS

These devices have limited built-in ESD protection. The leads should be shorted together or the device placed in conductive foam during storage or handling to prevent electrostatic damage to the MOS gates.

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bq2060

SLUS035E – JANUARY 2000 – REVISED OCTOBER 2005

TERMINAL

NAME NO.

HDQ16 1

ESCL 2

ESDA 3 and data to and from the bq2060 and the external nonvolatile configuration

RBI 4 registers during periods of low operating voltage. RBI accepts a storage

REG 5

OUT

DISP 9 Display control input. Input that controls the LED drivers LED1–LED5 LED

-LED

DFC 15

CFC 16

CVON 17 connect the cells to the external voltage dividers during cell voltage

THON 18

TS 19 SRC 20 Current sense input. Input to monitor instantaneous current SR

-SR

VCELL

- 23,24,25,2 Single-cell voltage inputs. Inputs that monitor the series element cell

VCELL

SMBD 27

SMBC 28

10,11,12,

Serial communication input/output. Open-drain bidirectional communications port

Serial memory clock. Output to clock the data transfer between the bq2060 and the external nonvolatile configuration memory

Serial memory data and address. Bidirectional pin used to transfer address memory

Regulator output. Output to control an n-JFET for V bq2060 from the battery potential

Supply output. Output that supplies power to the external EEPROM

configuration memory 7 Supply voltage input 8 Ground.

13,14

LED display segment outputs. Outputs that each may drive an external LED

Discharge FET control output. Output to control the discharge FET in the

Li-ion pack protection circuitry

Charge FET controll output. Output to control the charge FET in the Li-ion

pack protection circuitry

Cell voltage divider controll output. Output control for external FETs to

measurements

Thermistor bias control output. Output control for external FETs to connect

the thermistor bias resistor during a temperature measurement

Thermistor voltage input. Input connection for a thermistor to monitor

temperature

21,22

Charge-flow sense resistor inputs. Input connections for a small value sense

resistor to monitor the battery charge and discharge current flow

6 voltages

SMBus data. Open-drain bidirectional pin used to transfer address and data

to and from the bq2060

SMBus clock. Open-drain bidirectional pin used to clock the data transfer to

and from the bq2060

PIN DESCRIPTIONS

DESCRIPTION

regulation to the

ORDERING INFORMATION

For the most current package and ordering information, see the Package Option Addendum at the end of this document, or see the TI Web site at www.ti.com.

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SLUS035E – JANUARY 2000 – REVISED OCTOBER 2005

ABSOLUTE MAXIMUM RATINGS

(1)

SYMBOL PARAMETER MIN MAX UNIT NOTES

VCC–Supply voltage Relative to V VIN–All other pins Relative to V T

OPR

Operating temperature –20 +70 ° C Commercial Junction temperature –40 +125 ° C

SS SS

–0.3 +6 V –0.3 +6 V

(1) Permanent device damage may occur if absolute maximum ratings are exceeded. Functional operation should be limited to the

Recommended DC Operating Conditions detailed in this data sheet.

DC ELECTRICAL CHARACTERISTICS

= 2.7 V to 3.7 V, T

SYMBOL PARAMETER TEST CONDITIONS MIN TYP MAX UNIT

SLP

LVOUT

VOUT

OLS

ILS

IHS

RBI

AI1

AI2

Supply voltage 2.7 3.3 3.7 V Operating current V Low-power storage mode current 1.5 V < V V

leakage current V

OUT

source current – 5 mA

OUT

Output voltage low: LED Output voltage low: THON, CVON I Input voltage low DISP –0.3 0.8 V Input voltage high DISP 2 VCC+ 0.3 V Output voltage low SMBC, SMBD, HDQ16,

ESCL, ESDA Input voltage low SMBC, SMBD, HDQ16,

ESCL, ESDA Input voltage high SMBC, SMBD, HDQ16,

ESCL, ESDA Input voltage range VCELL RBI data-retention input current V RBI data-retention voltage 1.3 V Input impedance: SR1, SR2 0–1.25 V 10 M Ω Input impedance: VCELL

= –20 ° C to 70 ° C, unless otherwise noted)

OPR

–LED

, CFC, DFC I

, TS, SRC VSS– 0.3 1.25 V

1–4

, TS, SRC 0–1.25 V 5 M Ω

1–4

inactive 180 235 µ A

OUT

< 3.7 V 5 10 µ A

inactive – 0.2 0.2 µ A

OUT

active,

OUT

= VCC– 0.6 V

OUT

= 5 mA 0.4 V

OLS

= 5 mA 0.36 V

OLS

IOL= 1 mA 0.4 V

– 0.3 0.8 V

1.7 6 V

> 3 V, V

RBI

< 2.0 V 10 50 nA

bq2060

VFC CHARACTERISTICS

= 3.1 to 3.6 V, T

SYMBOL PARMETER TEST CONDITIONS MIN TYP MAX UNIT

SROS

SRCOS

VCO

TCO

Input voltagerange,V V

input offset –250 –50 250 µV

Calibrated offset –16 +16 µ V Supply voltage gain coefficient

Temperature gain coefficient

INL Integral nonlinearity error T

(1) RM

total deviation is from the nominal gain at 25 ° C.

TCO

= –0 ° C to 70 ° C, Unless Otherwise Noted

OPR

and V

SR2

SR1

(1)

= V

SR2

autocorrection disabled

Slope for T Total deviation T Slope for T Total deviation T

OPR

– V

SR2

SR1

= V

SR1

= 3.3 V 0.8 1.2 %/V

= –20 ° C to 70 ° C – 0.09 +0.09 % / ° C

OPR

= –20 ° C to 70 ° C –1.6% 0.1%

OPR

= –0 ° C to 50 ° C –0.05 +0.05 % / ° C

OPR

= –0 ° C to 50 ° C –0.6% 0.1%

OPR

= 0 ° C –50 ° C 0.21%

– 0.25 +0.25 V

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bq2060

SLUS035E – JANUARY 2000 – REVISED OCTOBER 2005

REG CHARACTERISTICS

= –20 ° C to 70 ° C)

OPR

SYMBOL PARAMETER TEST CONDITIONS MIN TYP MAX UNIT

Normal Mode: REG controlled

output voltage Sleep Mode: REG controlled

JFET: Rds(on) < 150 Ω Vgs(off) < –3 V at 10 µA

output voltage

REG

REG output current 1 µ A

SMBus AC SPECIFICATIONS

= 2.7 V to 3.7 V, T

SYMBOL PARAMETER TEST CONDITIONS MIN TYP MAX UNIT

SMB

MAS

BUF

HD:STA

SU:STA

SU:STO

HD:DAT

SU:DAT

TIMEOUT

LOW

HIGH

LOW:SEXT

LOW:MEXT

SMBus operating frequency Slave mode, SMBC 50% duty cycle 10 100 kHz SMBus master clock frequency 51.2 kHz Bus free time between start and stop 4.7 µs

Hold time after (repeated) start 4 µ s Repeated start setup time 4.7 µ s Stop setup time 4 µ s

Data hold time

Data setup time 250 ns Error signal/detect See Clock low period 4.7 µ s Clock high period See Cumulative clock low slave extend time See Cumulative clock low master extend time See

(1) The bq2060 times out when any clock low exceeds t (2) t

HIGH Max

progress.

(3) t

LOW:SEXT

bq2060 typically extends the clock only 20 ms as a slave in the read byte or write byte protocol.

(4) t

LOW:MEXT

bq2060 typically extends the clock only 20 ms as a master in the read byte or write byte protocol.

is minimum bus idle time. SMBC = SMBD = 1 for t > 50 ms causes reset of any transaction involving bq2060 that is in

is the cumulative time a slave device is allowed to extend the clock cycles in one message from initial start to the stop. The is the cumulative time a master device is allowed to extend the clock cycles in one message from initial start to the stop. The

= –20 ° C to 70 ° C, unless otherwise noted

OPR

Master mode, no clock low slave extend

Receive mode 0 ns Transmit mode 300 ns

(1)

(2) (3) (4)

TIMEOUT

3.1 3.3 3.6

25 35 ms

4 50 µs

4.1

25 ms 10 ms

HDQ16 AC SPECIFICATIONS ()

= 2.7 V to 3.7 V, T

SYMBOL PARAMETER TEST CONDITIONS MIN TYP MAX UNIT

CYCH

CYCB

STRH

STRB

DSU

DSUB

SSU

SSUB

RSPS

]

Cycle time, host to bq2060 (write) 190 µ s Cycle time, bq2060 to host (read) 190 205 250 µ s Start hold time, host to bq2060 (write) 5 - - ns Start hold time, host to bq2060 (read) 32 - - µ s Data setup time - - 50 µ s Data setup time - - 50 µ s Data hold time 100 - - µ s Data valid time 80 - - µ s Stop setup time - - 145 µ s Stop setup time - - 145 µ s Response time, bq2060 to host 190 - 320 µ s Break time 190 - - µ s Break recovery time 40 - - µ s

= –20 ° C to 70 ° C, unless otherwise noted

OPR

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TD201803.eps

STRH t

DSU

SSU

CYCH

Write ”1” Write ”0”

STRB

DSUB

SSUB

CYCB

Read ”1” Read ”0”

Figure 1. SMBus Timing Data

Figure 2. HDQ16 Break Timing

bq2060

SLUS035E – JANUARY 2000 – REVISED OCTOBER 2005

Figure 3. HDQ16 Host to bq2060

Figure 4. HDQ16 bq2060 to Host

FUNCTIONAL DESCRIPTION

GENERAL OPERATION

The bq2060 determines battery capacity by monitoring the amount of charge input to or removed from a rechargeable battery. In addition to measuring charge and discharge, the bq2060 measures battery voltage, temperature, and current, estimates battery self-discharge, and monitors the battery for low-voltage thresholds. The bq2060 measures charge and discharge activity by monitoring the voltage across a small-value series sense resistor between the battery’s negative terminal and the negative terminal of the battery pack. The available battery charge is determined by monitoring this voltage and correcting the measurement for environmental and operating conditions.

Figure 5 shows a typical bq2060-based battery pack application. The circuit consists of the LED display, voltage

and temperature measurement networks, EEPROM connections, a serial port, and the sense resistor. The EEPROM stores basic battery pack configuration information and measurement calibration values. The EEPROM must be programmed properly for bq2060 operation. Table 10 shows the EEPROM memory map and outlines the programmable functions available in the bq2060.

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bq2060

SLUS035E – JANUARY 2000 – REVISED OCTOBER 2005

FUNCTIONAL DESCRIPTION (continued)

The bq2060 accepts an NTC thermistor (Semitec 103AT) for temperature measurement. The bq2060 uses the thermistor temperature to monitor battery pack temperature, detect a battery full charge condition, and compensate for self-discharge and charge/discharge battery efficiencies.

MEASUREMENTS

The bq2060 uses a fully differential, dynamically balanced voltage-to-frequency converter (VFC) for charge measurement and a sigma delta analog-to-digital converter (ADC) for battery voltage, current, and temperature measurement.

Voltage, current, and temperature measurements are made every 2 to 2.5 seconds, depending on the bq2060 operating mode. Maximum times occur with compensated EDV, mWh mode, and maximum allowable discharge rate. Any AtRate computations requested or scheduled (every 20 seconds) may add up to 0.5 second to the time interval.

Charge And Discharge Counting

The VFC measures the charge and discharge flow of the battery by monitoring a small-value sense resistor between the SR bq2060 detects charge activity when V is negative. The bq2060 continuously integrates the signal over time using an internal counter. The fundamental rate of the counter is 6.25 µVh.

and SR

pins as shown in Figure 5 . The VFC measures bipolar signals up to 250 mV. The

= V

– V

SR2

is positive and discharge activity when V

SR1

= V

SR2

–V

SR1

Offset Calibration

The bq2060 provides an auto-calibration feature to cancel the voltage offset error across SR

and SR

maximum charge measurement accuracy. The calibration routine is initiated by issuing a command to ManufacturerAccess(). The bq2060 is capable of automatic offset calibration down to 6.25 µV. Offset cancellation resolution is less than 1 µV.

Digital Filter

The bq2060 does not measure charge or discharge counts below the digital filter threshold. The digital filter threshold is programmed in the EEPROM and should be set sufficiently high to prevent false signal detection with no charge or discharge flowing through the sense resistor.

Voltage

While monitoring SR and the individual cell voltages through the VCELL

and SR

for charge and discharge currents, the bq2060 monitors the battery-pack potential

–VCELL

pins. The bq2060 measures the pack voltage and

reports the result in the Voltage() register. The bq2060 can also measure the voltage of up to four series elements in a battery pack. The individual cell voltages are stored in the optional Manufacturer Function area.

The VCELL maximum input for VCELL

–VCELL

inputs are divided down from the cells using precision resistors, as shown in Figure 5 . The

–VCELL

is 1.25 V with respect to VSS. The voltage dividers for the inputs must be

set so that the voltages at the inputs do not exceed the 1.25 V limit under all operating conditions. Also, the divider ratios on VCELL

–VCELL

must be half of that of VCELL

–VCELL

. To reduce current consumption from

the battery, the CVON output may used to connect the divider to the cells only during measurement period. CVON is high impedance for 250 ms (12.5% duty cycle) when the cells are measured, and driven low otherwise. See Table 1 .

Current

The SRC input of the bq2060 measures battery charge and discharge current. The SRC ADC input converts the current signal from the series sense resistor and stores the result in Current(). The full-scale input range to SBC is limited to ± 250 mV as shown in Table 2 .

for

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bq2060

SMBCTHON

ESDA

ESCL

SRC

RBI

CFC

LED5

LED3

VCELL

LED4

CVON

LED1

REG

OUT

LED2

DFC

DISP

VCELL

SMBD

HDQ16

To Pack

Protection

Circuitry

EEPROM

SDA

SCL

A1 A2 WP

SST113

PACK+

PACK−

SMBC

HDQ

SMBD

Thermistor

FUNCTIONAL DESCRIPTION (continued)

bq2060

SLUS035E – JANUARY 2000 – REVISED OCTOBER 2005

Figure 5. Battery Pack Application Diagram–LED Display and Series Cell Monitoring

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bq2060

SLUS035E – JANUARY 2000 – REVISED OCTOBER 2005

Table 1. Example VCELL1–VCELL4 Divider and Input Range

VOLTAGE INPUT VOLTAGE DIVISION RATIO FULL-SCALE INPUT

VCELL

16 20 16 20

8 10 8 10

Table 2. SRC Input Range

SENSE RESISTOR ( Ω ) FULL-SCALE INPUT

0.02 ± 12.5

0.03 ± 8.3

0.05 ± 5.0

0.10 ± 2.5

(A)

Temperature

The TS input of the bq2060 with an NTC thermistor measures the battery temperature as shown in Figure 5 . The bq2060 reports temperature in Temperature(). THON may be used to connect the bias source to the thermistor when the bq2060 samples the TS input. THON is high impedance for 60 ms when the temperature is measured, and driven low otherwise.

(V)

GAS GAUGE OPERATION

General

The operational overview in Figure 6 illustrates the gas gauge operation of the bq2060. Table 3 describes the bq2060 registers.

The bq2060 accumulates a measure of charge and discharge currents and estimates self-discharge of the battery. The bq2060 compensates the charge current measurement for temperature and state-of-charge of the battery. The bq2060 also adjusts the self-discharge estimation based on temperature.

Figure 6. bq2060 Operational Overview

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FCC(new)  DCR(final) 

 (FCCxBatteryLow%)

DCR(initial) measureddischarge to EDV2

bq2060

SLUS035E – JANUARY 2000 – REVISED OCTOBER 2005

The main counter RemainingCapacity() (RM) represents the available capacity or energy in the battery at any given time. The bq2060 adjusts RM for charge, self-discharge, and leakage compensation factors. The information in the RM register is accessible through the communications ports and is also represented through the LED display.

The FullChargeCapacity() (FCC) register represents the last measured full discharge of the battery. It is used for the battery’s full-charge reference for relative capacity indication. The bq2060 updates FCC when the battery undergoes a qualified discharge from nearly full to a low battery level. FCC is accessible through the serial communications ports.

The Discharge Count Register (DCR) is a non-accessible register that only tracks discharge of the battery. The bq2060 uses the DCR register to update the FCC register if the battery undergoes a qualified discharge from nearly full to a low battery level. In this way, the bq2060 learns the true discharge capacity of the battery under system-use conditions.

Main Gas Gauge Registers

RemainingCapacity() (RM)

RM represents the remaining capacity in the battery. The bq2060 computes RM in either mAh or 10 mWh depending on the selected mode.

On initialization, the bq2060 sets RM to 0. RM counts up during charge to a maximum value of FCC and down during discharge and self-discharge to 0. In addition to charge and self-discharge compensation, the bq2060 calibrates RM at three low-battery-voltage thresholds, EDV2, EDV1, and EDV0 and three programmable midrange thresholds VOC25, VOC50, and VOC75. This provides a voltage-based calibration to the RM counter.

DesignCapacity() (DC)

The DC is the user-specified battery full capacity. It is calculated from Pack Capacity EE 0x3a–0x3b and is represented in mAh or 10 mWh. It also represents the full-battery reference for the absolute display mode.

FullChargeCapacity() (FCC)

FCC is the last measured discharge capacity of the battery. It is represented in either mAh or 10 mWh depending on the selected mode. On initialization, the bq2060 sets FCC to the value stored in Last Measured Discharge EE 0x38–0x39. During subsequent discharges, the bq2060 updates FCC with the last measured discharge capacity of the battery. The last measured discharge of the battery is based on the value in the DCR register after a qualified discharge occurs. Once updated, the bq2060 writes the new FCC value to EEPROM in mAh to Last Measured Discharge. FCC represents the full-battery reference for the relative display mode and relative state of charge calculations.

Discharge Count Register (DCR)

The DCR register counts up during discharge, independent of RM. DCR can continue to count even after RM has counted down to 0. Prior to RM = 0, discharge activity, light discharge estimation and self-discharge increment DCR. After RM = 0, only discharge activity increments DCR. The bq2060 initializes DCR to FCC – RM when RM is within twice the programmed value in Near Full EE 0x55. The DCR initial value of FCC – RM is reduced by FCC/128 if SC = 0 (bit 2 in Control Mode) and is not reduced if SC = 1. DCR stops counting when the battery voltage reaches the EDV2 threshold on discharge.

Capacity Learning (FCC Update) And Qualified Discharge

The bq2060 updates FCC with an amount based on the value in DCR if a qualified discharge occurs. The new value for FCC equals the DCR value plus the programmable nearly full- and low-battery levels, according to the following equation:

where:

BatteryLow% = (value stored in EE 0x54) ÷ 2.56

(1)

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bq2060

SLUS035E – JANUARY 2000 – REVISED OCTOBER 2005

A qualified discharge occurs if the battery discharges from RM ≥ FCC – Near Full * 2 to the EDV2 voltage threshold with the following conditions:

• No valid charge activity occurs during the discharge period. A valid charge is defined as an input 10 mAh into the battery.

• No more than 256 mAh of self-discharge and/or light discharge estimation occurs during the discharge period.

• The temperature does not drop below 5 ° C during the discharge period.

• The battery voltage reaches the EDV2 threshold during the discharge period and the voltage was less than

the EDV2 threshold minus 256 mV when bq2060 detected EDV2.

• No midrange voltage correction occurs during the discharge period.

FCC cannot be reduced by more than 256 mAh or increased by more than 512 mAh during any single update cycle. The bq2060 saves the new FCC value to the EEPROM within 4 s of being updated.

Table 3. bq2060 Register Functions

FUNCTION SMBus ACCESS UNITS

ManufacturerAccess 0x00 0x00 read/write n/a

RemainingCapacityAlarm 0x01 0x01 read/write mAh, 10 mWh

RemainingTimeAlarm 0x02 0x02 read/write minutes

BatteryMode 0x03 0x03 read/write n/a

AtRate 0x04 0x04 read/write mAh, 10 mWh

AtRateTimeToFull 0x05 0x05 read minutes

AtRateTimeToEmpty 0x06 0x06 read minutes

AtRateOK 0x07 0x07 read Boolean

Temperature 0x08 0x08 read 0.1 ° K

Voltage 0x09 0x09 read mV Current 0x0a 0x0a read mA

AverageCurrent 0x0b 0x0b read mA

MaxError 0X0c 0X0c read percent

RelativeStateOfCharge 0x0d 0x0d read percent

AbsoluteStateOfCharge 0x0e 0x0e read percent

RemainingCapacity 0x0f 0x0f read mAh, 10 mWh

FullChargeCapacity 0x10 0x10 read mAh, 10 mWh

RunTimeToEmpty 0x11 0x11 read minutes

AverageTimeToEmpty 0x12 0x12 read minutes

AverageTimeToFull 0x13 0x13 read minutes

ChargingCurrent 0x14 0x14 read mA

ChargingVoltage 0x15 0x15 read mV

Battery Status 0x16 0x16 read n/a

CycleCount 0x17 0x17 read cycles

DesignCapacity 0x18 0x18 read mAh, 10 mWh

DesignVoltage 0x19 0x19 read mV

SpecificationInfo 0x1a 0x1a read n/a

ManufactureDate 0x1b 0x1b read n/a

SerialNumber 0x1c 0x1c read Integer

Reserved 0x1d-0x1f 0x1d-0x1f - -

ManufacturerName 0x20 0x20-0x25 read string

DeviceName 0x21 0x28-0x2b read string

DeviceChemistry 0x22 0x30-0x32 read string

ManufacturerData 0x23 0x38-0x3b read string

COMMAND CODE

SMBus HDQ16

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bq2060

SLUS035E – JANUARY 2000 – REVISED OCTOBER 2005

Table 3. bq2060 Register Functions (continued)

FUNCTION SMBus ACCESS UNITS

Pack Status 0x2f (LSB) 0x2f (LSB) read/write n/a

Pack Configuration 0x2f (MSB) 0x2f (MSB) read/write n/a

VCELL4 0x3c 0x3c read/write mV VCELL3 0x3d 0x3d read/write mV VCELL2 0x3e 0x3e read/write mV VCELL1 0x3f 0x3f read/write mV

End-of-Discharge Thresholds And Capacity Correction

The bq2060 monitors the battery for three low-voltage thresholds, EDV0, EDV1, and EDV2. The EDV thresholds are programmed in EDVF/EDV0 EE 0x72–0x73, EMF/EDV1 EE 0x74–0x75, and EDV C1/C0 Factor/ EDV2 EE 0x78–0x79. If the CEDV bit in Pack Configuration is set, automatic EDV compensation is enabled and the bq2060 computes the EDV0, EDV1, and EDV2 thresholds based on the values in EE 0x72–0x7d, 0x06, and the battery’s current discharge rate, temperature, capacity, and cycle count. The bq2060 disables EDV detection if Current() exceeds the Overload Current threshold programmed in EE 0x46 - EE 0x47. The bq2060 resumes EDV threshold detection after Current() drops below the overload current threshold. Any EDV threshold detected is reset after a 10-mAh charge is applied.

The bq2060 uses the thresholds to apply voltage-based corrections to the RM register according to Table 4 . The bq2060 adjusts RM as it detects each threshold. If the voltage threshold is reached before the corresponding

capacity on discharge, the bq2060 reduces RM to the appropriate amount as shown in Table 4 . If RM reaches the capacity level before the voltage threshold is reached on discharge, the bq2060 prevents RM from decreasing until the battery voltage reaches the corresponding threshold.

COMMAND CODE

SMBus HDQ16

Table 4. State of Charge Based on Low Battery Voltage

THRESHOLD STATE OF CHARGE IN RM

EDV0 0% EDV1 3% EDV2 Battery Low %

Self-Discharge

The bq2060 estimates the self-discharge of the battery to maintain an accurate measure of the battery capacity during periods of inactivity. The algorithm for self-discharge estimation takes a programmed estimate for the expected self-discharge rate at 25 ° C stored in EEPROM and makes a fixed reduction to RM of an amount equal to RemainingCapacity()/256. The bq2060 makes the fixed reduction at a varying time interval that is adjusted to achieve the desired self-discharge rate. This method maintains a constant granularity of 0.39% for each self-discharge adjustment, which may be performed multiple times per day, instead of once per day with a potentially large reduction.

The self-discharge estimation rate for 25 ° C is doubled for each 10 degrees above 25 ° C or halved for each 10 degrees below 25 ° C. The following table shows the relation of the self-discharge estimation at a given temperature to the rate programmed for 25 ° C (Y% per day):

TEMPERATURE (C) SELF-DISCHARGE RATE

Temp < 10 ¼Y% per day 10 ≤ Temp <20 ½Y% per day 20 ≤ Temp <30 Y% per day 30 ≤ Temp <40 2Y% per day 40 ≤ Temp <50 4Y% per day 50 ≤ Temp <60 8Y% per day 60 ≤ Temp <70 16Y% per day

70 ≤ Temp 32Y% per day

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Self−DischargeUpdateTime 

640 13500

256 n  (Y% per day)

seconds

640 13500

256 n  (Y% per day)

 6750 seconds

bq2060

SLUS035E – JANUARY 2000 – REVISED OCTOBER 2005

The interval at which RM is reduced is given by the following equation, where n is the appropriate factor of 2 n = ¼ , ½ , 1, 2, . . . ):

The timer that keeps track of the self-discharge update time is halted whenever charge activity is detected. The timer is reset to zero if the bq2060 reaches the RemainingCapacity()=FullChargeCapacity() condition while charging.

Example: If T = 35 ° C (n = 2) and programmed self-discharge rate Y is 2.5 (2.5% per day at 25 ° C), the bq2060 reduces RM by RM/256 (0.39%) every

(2)

(3)

Figure 7. Self-Discharge at 2.5%/Day @25 ° C

This means that a 0.39% reduction of RM is made 12.8 times per day to achieve the desired 5% per day reduction at 35 ° C.

Figure 7 illustrates how the self-discharge estimate algorithm adjusts RemainingCapacity() versus temperature.

Light Discharge Or Suspend Current Compensation

The bq2060 can be configured in two ways to compensate for small discharge currents that produce a signal below the digital filter. First, the bq2060 can decrement RM and DCR at a rate determined by the value stored in

Light Discharge Current EE 0x2b when it detects no discharge activity and the SMBC and SMBD lines are high. Light Discharge Current has a range of 44 µA to 11.2 mA.

Alternatively, the bq2060 can be configured to disable the digital filter for discharge when the SMBC and SMBD lines are high. In this way, the digital filter does not mask the leakage current signal. The bq2060 is configured in this mode by setting the NDF bit in Control Mode.

Midrange Capacity Corrections

The bq2060 applies midrange capacity corrections when the VCOR bit is set in Pack Configuration. The bq2060 adjusts RM to the associated percentage at three different voltage levels: VOC25, VOC50, and VOC75. The VOC values represent the open-circuit battery voltage which RM corresponds to the associated state of charge for each threshold.

THRESHOLD ASSOCIATED STATE OF CHARGE

VOC25 25% VOC50 50% VOC75 75%

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For the midrange corrections to occur, the temperature must be in the range of 19 ° C to 31 ° C inclusive and the Current() and AverageCurrent() must both be between –64 mA and 0. The bq2060 makes midrange corrections as shown in Table 5 .

Table 5. Midrange Corrections

CONDITION RESULT

≥ VOC75 and RelativeStateOfCharge() ≤ 63% RelativeStateOfCharge() set to 75% < VOC75 and RelativeStateOfCharge() ≥ 87% RelativeStateOfCharge() set to 75%

Voltage()

Charge Control

Charging Voltage and Current Broadcasts

The bq2060 supports SBS charge control by broadcasting the ChargingCurrent() and ChargingVoltage() to the Smart Charger address. The bq2060 broadcasts the requests every 10 s. The bq2060 updates the values used the charging current and voltage broadcasts based on the battery’s state of charge, voltage, and temperature. The fast-charge rate is programmed in Fast-Charging Current EE 0x1a - 0x1b while the charge voltage is programmed in Charging Voltage EE 0x0a-0x0b.

The bq2060 internal charge control is compatible with popular rechargeable chemistries. The primary charge-termination techniques include a change in temperature over a change in time ( ∆ T/ ∆ t) and current taper, for nickel-based and Li-ion chemistries, respectively. The bq2060 also provides pre-charge qualification and a number of safety charge suspensions based on current, voltage, temperature, and state of charge.

≥ VOC50 and RelativeStateOfCharge() ≤ 38% RelativeStateOfCharge() set to 50% < VOC50 and RelativeStateOfCharge() ≥ 62% RelativeStateOfCharge() set to 50% ≥ VOC25 and RelativeStateOfCharge() ≤ 13% RelativeStateOfCharge() set to 25% < VOC25 and RelativeStateOfCharge() ≥ 37% RelativeStateOfCharge() set to 25%

Alarm Broadcasts to Smart Charger and Host

If any of the bits 8–15 in BatteryStatus() is set, the bq2060 broadcasts an AlarmWarning() message to the Host address. If any of the bits 12–15 in BatteryStatus() are set, the bq2060 also sends an AlarmWarning() message to the Smart Charger address. The bq2060 repeats the AlarmWarning() message every 10 s until the bits are cleared.

Pre-Charge Qualification

The bq2060 sets ChargingCurrent() to the pre-charge rate as programmed in Pre-Charge Current EE 0x1e-0x1f under the following conditions:

• Voltage: The bq2060 requests the pre-charge charge rate when Voltage() drops below the EDV0 threshold (compensated or fixed EDVs). Once requested, a pre-charge rate remains until Voltage() increases above the EDVF threshold. The bq2060 also broadcasts the pre-charge value immediately after a device reset until Voltage() is above the EDVF threshold. This threshold is programmed in EDVF/EDV0 EE 0x72-0x73.

• Temperature: The bq2060 requests the pre-charge rate when Temperature() is between 0 ° C and 5 ° C. Temperature() must rise above 5 ° C before the bq2060 requests the fast-charge rate.

Charge Suspension

The bq2060 may temporarily suspend charge if it detects a charging fault. A charging fault includes the following conditions.

• Overcurrent: An overcurrent condition exists when the bq2060 measures the charge current to be more than the Overcurrent Margin above the ChargingCurrent(). Overcurrent Margin is programmed in EE 0x49. On detecting an overcurrent condition, the bq2060 sets the ChargingCurrent() to zero and sets the TERMINATE_CHARGE_ALARM bit in Battery Status(). The overcurrent condition and TERMINATE_ CHARGE_ALARM are cleared when the measured current drops below the ChargingCurrent plus the Overcurrent Margin.

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• Overvoltage: An overvoltage condition exists when the bq2060 measures the battery voltage to be more than the Overvoltage Margin above the ChargingVoltage() or a Li-ion cell voltage has exceeded the overvoltage limit programmed in Cell Under-/Overvoltage. Overvoltage Margin is programmed in EE 0x48 and Cell Under-/Overvoltage in EE 0x4a (least significant nibble). On detecting an overvoltage condition, the bq2060 sets the ChargingCurrent() to zero and sets the TERMINATE_CHARGE_ALARM bit in BatteryStatus(). The bq2060 clears the TERMINATE_ CHARGE_ALARM bit when it detects that the battery is no longer being charged (DISCHARGING bit set in BatteryStatus()). The bq2060 continues to broadcast zero charging current until the overvoltage condition is cleared. The overvoltage condition is cleared when the measured battery voltage drops below the ChargingVoltage() plus the Overvoltage Margin or when the CVOV bit is reset.

• Over-Temperature: An over-temperature condition exists when Temperature() is greater than or equal to the Max T value programmed in EE 0x45 (most significant nibble). On detecting an over-temperature condition, the bq2060 sets the ChargingCurrent() to zero and sets the OVER_TEMP_ALARM and TERMINATE_CHARGE_ ALARM bit in BatteryStatus() and the CVOV bit in Pack Status. The over-temperature condition is cleared when Temperature() is equal to or below ( Max T– 5 ° C).

• Overcharge: An overcharge condition exists if the battery is charged more than the Maxmum Overcharge value after RM = FCC. Maximum Overcharge is programmed in EE 0x2e–0x2f. On detecting an overcharge condition, the bq2060 sets the ChargingCurrent() to zero and sets the OVER_CHARGED_ALARM, TERMINATE_CHARGE_ ALARM, and FULLY_CHARGED bits in BatteryStatus(). The bq2060 clears the OVER_ CHARGED_ALARM and TERMINATE_CHARGE_ ALARM when it detects that the battery is no longer being charged. The FULLY_CHARGED bit remains set and the bq2060 continues to broadcast zero charging current until RelativeStateOfCharge() is less than Fully Charged Clear% programmed in EE 0x4c.The counter used to track overcharge capacity is reset with 2mAh of discharge.

• Under-Temperature: An under-temperature condition exists if Temperature() < 0 ° C. On detecting an under-temperature condition, the bq2060 sets ChargingCurrent() to zero. The bq2060 sets ChargingCurrent() to the appropriate pre-charge rate or fast-charge rate when Temperature() ≥ 0 ° C.

Primary Charge Termination

The bq2060 terminates charge if it detects a charge-termination condition. A charge-termination condition includes the following.

• ∆ T/ ∆ t: For ∆ T/ ∆ t, the bq2060 detects a change in temperature over many seconds. The ∆ T/ ∆ t setting is programmable in both the temperature step, DeltaT (1.6 ° C – 4.6 ° C), and the time step, DeltaT Time (20 s–320 s). Typical settings for 1 ° C/minute include 2 ° C/120 s and 3 ° C/180 s. Longer times are required for increased slope resolution. The DeltaT value is programmed in EE 0x45 (least significant nibble) and the Delta T Time in EE 0x4e.

In addition to the ∆ T/ ∆ t timer, a holdoff timer starts when the battery is being charged at more than 255 mA and the temperature is above 25 ° C. Until this timer expires, ∆ T/ ∆ t detection is suspended. If Current() drops below 256 mA or Temperature() below 25 ° C, the hold-off timer resets and restarts only when the current and temperature conditions are met again. The holdoff timer is programmable (20 s–320 s) with Holdoff Time value in EE 0x4f.

• Current Taper: For current taper, ChargingVoltage() must be set to the pack voltage desired during the constant-voltage phase of charging. The bq2060 detects a current taper termination when the pack voltage is greater than the voltage determined by Current Taper Qual Voltage in EE 0x4f and the charging current is below a threshold determined by Current Taper Threshold in EE 0x4e, for at least 40 s. The bq2060 uses the VFC to measure current for current taper termination. The current polarity must remain positive as measured by the VFC during this time.

Once the bq2060 detects a primary charge termination, the bq2060 sets the TERMINATE_CHARGE_ALARM and FULLY_CHARGED bits in BatteryStatus(), and sets the ChargingCurrent() to the maintenance charge rate as programmed in Maintenance Charging Current EE 0x1c–0x1d. On termination, the bq2060 also sets RM to a programmed percentage of FCC, provided that RelativeStateOfCharge() is below the desired percentage of FCC and the CSYNC bit in Pack Configuration EE 0x3f is set. If the CSYNC bit is not set and RelativeStateOfCharge() is less than the programmed percentage of FCC, the bq2060 clears the FULLY_CHARGED bit in BatteryStatus(). The programmed percentage of FCC, Fast Charge Termination %, is set in EE 0x4b. The

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bq2060 clears the FULLY_CHARGED bit when RelativeStateOfCharge() is less than the programmed Fully Charged Clear %. The bq2060 broadcasts the fast-charge rate when the FULLY_CHARGED bit is cleared and voltage and temperature permit. The bq2060 clears the TERMINATE_CHARGE_ALARM when it no longer detects that the battery is being charged or it no longer detects the termination condition. See Table 6 for a summary of BatteryStatus() alarm and status bit operation.

Display Port

General

The display port drives a 4- or 5-LED, bar-graph display. The display is activated by a logic signal on the DISP input. The bq2060 can display RM in either a relative or absolute mode with each LED representing a percentage of the full-battery reference. In relative mode, the bq2060 uses FCC as the full-battery reference; in absolute mode, it uses DC.

The DMODE bit in Pack Configuration programs bq2060 for the absolute or relative display mode. The LED bit in Control Mode programs the 4-or 5-LED option. A 5th LED can be used with the 4-LED display option to show when the battery capacity is ≥ to 100%.

Activation

The display may be activated at any time by a high-to-low transition on the DISP input. This is usually accomplished with a pullup resistor and a pushbutton switch. Detection of the transition activates the display and starts a 4-s display timer. The timer expires and turns off the display whether DISP was brought low momentarily or held low indefinitely. Reactivation of the display requires that the DISP input return to a logic-high state and then transition low again. The second high-to-low transition must occur after the display timer expires. The bq2060 requires the DISP input to remain stable for a minimum of 250ms to detect the logic state.

If the EDV0 bit is set, the bq2060 disables the LED display. The display is also disabled during a VFC calibration and should be turned off before entering the low-power storage mode.

Display Modes

In relative mode, each LED output represents 20% or 25% of the RelativeStateOfCharge() value. In absolute mode, each LED output represents 20% or 25% of the AbsoluteStateOfCharge() value. Table 7 shows the display operation.

In either mode, the bq2060 blinks the LED display if RemainingCapacity() is less than Remaining CapacityAlarm(). The display is disabled if EDV0 = 1.

Secondary Protection for Li-Ion

Undervoltage and overvoltage thresholds may be programmed in the byte value Cell Under/Over Voltage EE 0x4a to set a secondary level of protection for Lithium ion cells. The bq2060 checks individual cell voltages for undervoltage and overvoltage conditions. The bq2060 displays the results in the Pack Status register and controls the state of the FET control outputs CFC and DFC. any cell voltage is less than the V

threshold, the bq2060 sets the CVUV bit in Pack Status and pulls the DFC pin to a logic low. If any cell voltage is greater than the V

threshold, the bq2060 sets the CVOV bit in Pack Status and pulls the CFC pin to a logic low.

Low-Power Storage Mode

The bq2060 enters low-power mode 5 to 8 s after receiving the Enable Low-Power command. In this mode the bq2060 consumes less than 10 µA. A rising edge on SMBC, SMBD, or HDQ16 restores the bq2060 to the full operating mode. The bq2060 does not perform any gas gauge functions during low-power storage mode.

Device Reset

The bq2060 can be reset with commands over the HDQ16 or SMBus. On reset, the bq2060 initializes its internal registers with the information contained in the configuration EEPROM. The following command sequence initiates a full bq2060 reset:

Write 0x4f to 0xff5a Write 0x7d to 0x0000 Write 0x7d to 0x0080

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Table 6. Alarm and Status Bit Summary

BATTERY STATE CONDITIONS CC() STATE AND CC() = FAST OR PRE-CHARGE CURRENT

Overcurrent C() ≥ CC() + CC() = 0, TCA = 1 C() < CC() + Overcurrent Margin

Overvoltage VCELL1, 2, 3, or 4 > Cell Over

Over temperature T() ≥ Max T CC() = 0, OTA= 1, T() ≤ Max T - 5 ° C or T() ≤ 43 ° C

Overcharge ≥

Under temperature T() < 0 ° C CC() = 0 0 ° C ≤ T() < 5 ° C, CC() = Pre-Charge Current

Fast charge termination ∆ T/ ∆ t or Current Taper

Fully discharged V() ≤ EDV2 FD = 1 RSOC() > 20%

Overdischarged

Low capacity RM() < RCA() RCA = 1 RM() ≥ RCA() Low run-time ATTE() < RTA() RTA = 1 ATTE() ≥ RTA()

(1) C() = Current(), CV() = ChargingVoltage(), CC() = ChargingCurrent(), V() = Voltage(), T() = Temperature(),

TCA = TERMINATE_CHARGE_ALARM, OTA = OVER_TEMPERATURE_ALARM, OCA = OVER_CHARGED_ALARM, TDA = TERMINATE_DISCHARGE_ALARM, FC = FULLY_CHARGED, FD = FULLY_DISCHARGED, RSOC() = RelativeStateOfCharge(). RM() = RemainingCapacity(), RCA = REMAINING_CAPACITY_ALARM, RTA = REMAINING_TIME_ALARM, ATTE() = AverageTimeToEmpty(), RTA() = RemainingTimeAlarm(), RCA() = RemainingCapacityAlarm(), FCC() = FullChargeCapacity.

Overcurrent Margin

V() ≥ CV() + Overvoltage Margin

Voltage

Capacity added after RM() = FCC() CC() = 0, FC = 1 RSOC() < Fully Charged Cleared %

Maximum Overcharge

V() ≤ EDV0 TDA = 1 V() > EDV0

VCELL1, 2, 3 or 4 < Cell Under TDA = 1, CVUV = 1 VCELL1, 2, 3, or 4 ≥ Cell Under Voltage

Voltage

BatteryStatus BITS SET AND/OR BITS CLEARED

TCA = 1 DISCHARGING = 1

CC() = 0, CVOV = 1 V() < CV() + Overvoltage Margin

TCA = 1, CVOV = 1

OCA = 1, TCA = 1 DISCHARGING = 1

CC() = Maintenance RSOC() < Fully Charged Cleared %

Charging Current,

FC = 1

TCA = 1 DISCHARGING = 1 or termination condition is

(1)

Li-ion cell voltage ≤ Cell Over Voltage

T() ≥ 5 ° C, CC() = Fast-Charging Current

no longer valid.

Table 7. DISPLAY MODE (5 LED)

CONDITION 5 LED DISPLAY OPTION

RELATIVE OR

ABSOLUTE

STATEOFCHARGE

()

EDV0 = 1 OFF OFF OFF OFF OFF

<20% ON OFF OFF OFF OFF

≥ 20%, <40% ON ON OFF OFF OFF ≥ 40%, <60% ON ON ON OFF OFF ≥ 60%, <80% ON ON ON ON OFF

≥ 80% ON ON ON ON ON

LED1 LED2 LED3 LED4 LED5

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Table 8. DISPLAY MODE (4 LED)

CONDITION 4 LED DISPLAY OPTION

RELATIVE OR

ABSOLUTE

STATEOFCHARGE()

EDV0 = 1 OFF OFF OFF OFF

<25% ON OFF OFF OFF

≥ 25%, <50% ON ON OFF OFF ≥ 50%, <75% ON ON ON OFF

≥ 75% ON ON ON ON

Communication

The bq2060 includes two types of communication ports: SMBus and HDQ16. The SMBus interface is a 2-wire bidirectional protocol using the SMBC (clock) and SMBD (data) pins. The HDQ16 interface is a 1-wire bidirectional protocol using the HDQ16 pin. All three communication lines are isolated from V pulled up higher than V

. Also, the bq2060 does not pull these lines low if V

should be pulled down with a 100-k Ω resistor if not used. The communication ports allow a host controller, an SMBus-compatible device, or other processor to access the

memory registers of the bq2060. In this way a system can efficiently monitor and manage the battery.

SMBus

The SMBus interface is a command-based protocol processor acting as the bus master initiates communication to the bq2060 by generating a START condition. The START condition consists of a high-to-low transition of the SMBD line while the SMBC is high. The processor then sends the bq2060 device address of 0001011 (bits 7–1) plus a R/ W bit (bit 0) followed by an SMBus command code. The R/ W bit and the command code instruct the bq2060 to either store the forthcoming data to a register specified by the SMBus command code or output the data from the specified register. The processor completes the access with a STOP condition. A STOP condition consists of a low-to-high transition of the SMBD line while the SMBC is high. With the SMBus protocol, the most significant bit of a data byte is transmitted first.

In some instances, the bq2060 acts as the bus master. This occurs when the bq2060 broadcasts charging requirements and alarm conditions to device addresses 0x12 (SBS Smart Charger) and 0x10 (SBS Host Controller.)

LED1 LED2 LED3 LED4

to the part is zero. HDQ16

and may be

SMBus Protocol

The bq2060 supports the following SMBus protocols:

• Read Word

• Write Word

• Read Block

A processor acting as the bus master uses the three protocols to communicate with the bq2060. The bq2060 acting as the bus master uses the WriteWord protocol.

The SMBD and SMBC pins are open drain and require external pullup resistors.

SMBus Packet Error Checking

The bq2060 supports Packet Error Checking as a mechanism to confirm proper communication between it and another SMBus device. Packet Error Checking requires that both the transmitter and receiver calculate a Packet Error Code (PEC) for each communication message. The device that supplies the last byte in the communication message appends the PEC to the message. The receiver compares the transmitted PEC to its PEC result to determine if there is a communication error.

PEC Protocol

The bq2060 can receive or transmit data with or without PEC. Figure 8 shows the communication protocol for the Read Word, Write Word, and Read Block messages without PEC. Figure 9 includes PEC.

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