TEXAS INSTRUMENTS bq2060A Technical data

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bq2060A

SBS v1.1-Compliant Gas Gauge IC

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 16µV after calibration

Consumes less than 0.5mW operating

Drives a 4- or 5-segment LED display for remaining capacity indication

28-pin 150-mil SSOP

General Description

The bq2060A SBS-Compliant Gas Gauge IC for battery pack or in-system installation maintains an accurate record of available charge in rechargeable batteries. The bq2060A monitors capacity and other critical battery parameters for NiCd, NiMH, Li-Ion, and lead-acid chemistries. The bq2060A uses a V-to-F converter with automatic offset error correction for charge and discharge counting. For voltage, temperature, and current reporting, the bq2060A uses an A-to-D converter. The onboard ADC also monitors individual cell voltages in a Li-Ion battery pack and allows the bq2060A to generate control sig nals that may be used in conjunction with a pack supervisor to enhance pack safety.

The bq2060A 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, current, and remain ing run-time predictions. The

Pin Connections Pin Names

bq2060A provides LED drivers and a push-button input to depict remaining battery capacity from full to empty in 20% or 25% increments witha4or 5-segment display.

The bq2060A works with an external EEPROM. The EEPROM stores the configuration information for the bq2060A, such as the battery’s chem istry, self-discharge rate, rate com pensation factors, measurement cali bration, and design voltage and ca pacity. The bq2060A uses the pro grammable self-discharge rate and other compensation factors stored in the EEPROM to accurately adjust re maining capacity for use and standby conditions based on time, rate, and

temperature. The bq2060A also auto matically calibrates or learns the true battery capacity in the course of a discharge cycle from near-full to near-emptylevels.

The REG output regulates the operating voltage for the bq2060A from the battery cell stack using an external JFET .

HDQ16

ESDA

SLUS500A–OCTOBER 2001–REVISED MAY 2002

ESCL

2 3

RBI

REG

OUT

DISP

LED

28-Pin 150-mil SSOP

SMBC

SMBD

VCELL

25 24 23 22 21 20 19 18 17 16 15

VCELL VCELL SR SR SRC TS THON CVON CFC DFC

28PN2060.eps

3 2

1 1 2

HDQ16 Serial communication

ESCL Serial memory clock ESDA Serial memory data and

RBI Register backup input REG Regulator output V V V DISP LED

LED

input/output

address

EEPROM supply output

OUT

Supply voltage

Ground

Display control input

–

LED displaysegmentoutputs

1 5

DFC Discharge FET control CFC Charge FET control VON Cell voltage divider

control THON Thermistorbias control TS Thermistor voltage input SRC Current sense input

–

SR SR

VCELL VCELL

SMBD SMBus data SMBC SMBus clock

Charge-flow sense resistor

inputs

–

Single-cell voltage inputs

1 4

bq2060A

Pin Descriptions

HDQ16

ESCL

ESDA Serial memory data and address

RBI

REG Regulator output

OUT

DISP

LED1– LED

Serial communication input/output

Open-drain bidirectional communications port

Serial memoryclock

Output to clock the data transfer between the bq2060A and the external nonvolatile configuration memory

Bidirectional pin used to transfer address and data to and from the bq2060A and the external nonvolatile configuration memory

Input that provides backup potential to the bq2060A registers during periods of low operating voltage. RBI accepts a storage capacitor or a battery input.

Output to control an n-JFET for V lation to the bq2060A from the battery potential

Supply output

Output that supplies power to the external EEPROM configuration memory

Supply voltage input Ground Display control input

Input that controls the LED drivers

–LED

LED

LED display segment outputs

Outputs that each may drive an external LED

regu-

DFC

CFC

CVON

THON

SRC

–

VCELL VCELL

SMBD

SMBC

Discharge FET control output

Output to control the discharge FET in the Li-Ion pack protection circuitry

Charge FET control output

Output to control the charge FET in the Li-Ion pack protection circuitry

Cell voltage divider control output

Output control for external FETs to connect the cells to the external voltage dividers during cell voltage measurements

Thermistor bias control output

Output control for external FETs to connect the thermistor bias resistor during a tempera ture measurement

Thermistor voltage input

Input connection for a thermistor to monitor temperature

Current sense voltageinput

Input to monitor instantaneous current

Sense resistor inputs

Input connections for a small value sense resistor to monitor the battery charge and discharge current flow

Single-cell voltage inputs

–

1 4

Inputs that monitor the series element cell voltages

SMBus data

Open-drain bidirectional pin used to trans fer address and data to and from the bq2060A

SMBus clock

Open drain bidirectional pin used to clock the data transfer to and from the bq2060A

bq2060A

Functional Description

General Operation

The bq2060A determines battery capacity by monitoring the amount of charge input or removed from a recharge able battery. In addition to measuring charge and dis charge, the bq2060A measures battery voltage, tempera ture, and current, estimates battery self-discharge, and monitors the battery for low-voltage thresholds. The bq2060A 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 1 shows a typical bq2060A-based battery-pack application. The circuit consists of the LED display, voltage and temperature measurement networks, EEPROM connections, a serial port, and the sense resis tor. The EEPROM stores basic battery-pack configuration information and measurement-calibration values. The EEPROM must be programmed properly for bq2060A operation. Table 9 shows the EEPROM memory map and outlines the programmable functions available in the bq2060A.

The bq2060A accepts an NTC thermistor (Semitec 103AT) for temperature measurement. The bq2060A uses the thermistor temperature to monitor battery-pack temperature, detect a battery full-charge con dition, and compensate for self-discharge and charge/dis charge battery efficiencies.

Measurements

The bq2060A uses a fully differential, dynamically bal anced voltage-to-frequency converter (VFC) for charge measurement and a sigma delta analog-to-digital con verter (ADC) for battery voltage, current, and tempera ture measurement.

Voltage, current, and temperature measurements are made every 2–2.5 seconds, depending on the bq2060A operating mode. Maximum times occur with compen sated EDV, mWh mode, and maximum allowable dis charge rate. Any AtRate computations requested or scheduled (every 20 seconds) may add up to 0.5 seconds 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

and SR2pins as shown in Figure 1.

The VFC measures bipolar signals up to 250mV. The bq2060A detects charge activity when V V

is positive and discharge activity when VSR=V

SR1

–V integrates the signal over time using an internal counter. The fundamental rate of the counter is

6.25µVh.

Offset Calibration

The bq2060A provides an auto-calibration feature to can cel the voltage offset error across SR mum charge measurement accuracy. The calibration rou tine is initiated by issuing a command to ManufacturerAccess(). The bq2060A is capable of auto matic offset calibration down to 6.25µV.Offset cancellation resolution is less than 1µV.

is negative. The bq2060A continuously

SR1

SR=VSR2

and SR2for maxi

Digital Filter

The bq2060A does not measure charge or discharge counts below the digital filter threshold. The digital fil

ter 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 SR1and SR2for charge and discharge currents, the bq2060A monitors the battery-pack potential and the individual cell voltages through the VCELL

voltage and reports the result in Voltage(). The bq2060A

can also measure the voltage of up to four series ele ments in a battery pack. The individual cell voltages are stored in the optional Manufacturer Function area.

The VCELL cells using precision resistors, as shown in Figure 1. The

maximum input for VCELL

spect to V

set so that the voltages at the inputs do not exceed the

1.25V limit under all operating conditions. Also, the di vider ratios on VCELL VCELL the battery, the CVON output may used to connect the

divider to the cells only during measurement period.

CVON is high impedance for 250ms (12.5% duty cycle) when the cells are measured, and driven low otherwise. (See Table1.)

The SRC input of the bq2060A 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 ±250mV as shown in Table2.

–VCELL4pins. The bq2060Ameasures the pack

–VCELL4inputs are divided down from the

–VCELL4is 1.25V with re

. The voltage dividers for the inputs must be

–VCELL4. To reduce current consumption from

–VCELL2must be half of that of

–

SR2

bq2060A

Figure 1. Battery Pack Application Diagram–LED Display and Series Cell Monitoring

bq2060A

Table 1. Example VCELL1–VCELL4Divider

and Input Range

Voltage Input

VCELL

Voltage Division

Ratio

16 20.0 16 20.0

8 10.0 8 10.0

Full-Scale Input

(V)

Table 2. SRC Input Range

Sense Resistor (W) Full-Scale Input

0.02

0.03

0.05

0.10

(A)

±12.5

±8.3 ±5.0 ±2.5

Current

Temperature

The TS input of the bq2060A in conjunction with an NTC thermistor measures the battery temperature as shown in Figure 1. The bq2060Areports temperature in Temperature(). THON may be used to connect the bias source to the thermistor when the bq2060A samples the TS input. THON is high impedance for 60ms when the temperature is measured, and driven low otherwise.

Gas Gauge Operation

General

The operational overview in Figure 2 illustrates the gas gauge operation of the bq2060A. Table 3 describes the bq2060Aregisters.

The bq2060A accumulates a measure of charge and discharge currents and estimates self-discharge of the

Figure 2. bq2060A Operational Overview

bq2060A

Table 3. bq2060A Register Functions

Function

ManufacturerAccess 0x00 0x00 read/write n/a

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

RemainingTimeAlarm 0x02 0x02 read/write minutes

BatteryMode 0x03 0x03 read/write n/a

AtRate 0x04 0x04 read/write mA, 10mW

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, 10mWh

FullChargeCapacity 0x10 0x10 read mAh, 10mWh

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, 10mWh

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

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

Command Code SMBus

SMBus HDQ16

Access Units

bq2060A

battery. The bq2060A compensates the charge current measurement for temperature and state-of-charge of the battery. It also adjusts the self-discharge estimation based on temperature.

The main counter RemainingCapacity() (RM) represents the available capacity or energy in the battery at any given time. The bq2060A 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 as the battery’s full-charge reference for relative capacity indication. The bq2060A updates FCC when the battery undergoes a qualified discharge from nearly full to a low battery level. FCC is accessible through the serial com munications ports.

The Discharge Count Register (DCR) is a non-accessible register that only tracks discharge of the battery. The bq2060A uses the DCR register to update the FCC regis ter if the battery undergoes a qualified discharge from nearly full to a low battery level. In this way, the bq2060A 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 bq2060A computes RM in either mAh or 10mWh depending on the selected mode.

On initialization, the bq2060A 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 bq2060A 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 rep resented in mAh or 10mWh. It also represents the full-battery reference for the absolute display mode.

FullChargeCapacity() (FCC)

FCC is the last measured discharge capacity of the bat tery. It is represented in either mAh or 10mWh depend ing on the selected mode. On initialization, the bq2060A sets FCC to the value stored in Last Measured Dis charge EE 0x38–0x39. During subsequent discharges, the bq2060A updates FCC with the last measured dis

charge capacity of the battery. The last measured dis charge of the battery is based on the value in the DCR register after a qualified discharge occurs. Once up dated, the bq2060A writes the new FCC value to EEPROM in mAh to Last Measured Discharge. FCC represents the full battery reference for the relative dis play mode and relative state of charge calculations.

Discharge Count Register (DCR)

The DCR register counts up during discharge, independ ent 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 bq2060A 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 bq2060A 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:

FCC(new) DCR(final) DCR(initial) measured dischar

(FCC Battery Low%+´ )

where

Battery Low % (value stored in EE 0x54)=¸256.

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 of 10mAh into the battery.

No more than 256mAh 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 256mV when the bq2060A detected EDV2.

No midrange voltage correction occurs during the discharge period.

There is no overload condition when voltage ≤ EDV2 threshold

+ ge to EDV2

(1)

bq2060A

FCC cannot be reduced by more than 256mAh or in creased by more than 512mAh during any single update cycle. The bq2060A saves the new FCC value to the EEPROM within 4s of being updated.

End-of-Discharge Thresholds and Capacity Cor rection

The bq2060A monitors the battery for three low-voltage thresholds, EDV0, EDV1, and EDV2. The EDV thresh olds are programmed in EDVF/EDV0 EE 0x72–0x73,

EMF/EDV1 EE 0x74–0x75, and EDV C1/C0 Fac tor/EDV2 EE 0x78–0x79. If the CEDV bit in Pack Con figuration is set, automatic EDV compensation is en

abled and the bq2060A computes the EDV0, EDV1, and EDV2 thresholds based on the values in EE 0x72–0x7d, 0x06, and the battery’s current discharge rate, tempera ture, capacity, and cycle count. The bq2060A disables EDV detection if Current() exceeds the Overload Current threshold programmed in EE 0x46 - EE 0x47. The bq2060A resumes EDV threshold detection after Cur rent() drops below the overload current threshold. Any EDV threshold detected will be reset after 10mAh of charge are applied.

The bq2060A uses the thresholds to apply voltage-based corrections to the RM register according to Table4.

Table 4. State of Charge Based

on Low Battery Voltage

Threshold State of Charge in RM

EDV0 0% EDV1 3% EDV2 Battery Low %

The bq2060A adjusts RM as it detects each threshold. If the voltage threshold is reached before the correspond ing capacity on discharge, the bq2060A 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 bq2060A prevents RM from decreasing until the battery voltage reaches the corre sponding threshold, but only on a full learning-cycle dis charge (VDQ = 1). The EDV1 threshold is ignored if Mis cellaneous Options bit7=1.

Self-Discharge

The bq2060A 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 bq2060A 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 de grees 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)

Temp < 10

10 ≤ Temp <20

20 ≤ Temp <30 30 ≤ Temp <40 40 ≤ Temp <50

50 ≤ Temp <60 60 ≤ Temp <70

70 ≤ Temp

Self-Discharge Rate

Y% per day

4 1

Y% per day

Y% per day 2Y% per day 4Y% per day 8Y% per day

16Y% per day 32Y% per day

The interval at which RM is reduced is given by the following equation, where n is the appropriate factor of 2

(n =

,1,2,...):

Self Disch e Update Time

arg

640 13500

n Y per day

··

256 ( % )

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 bq2060A reaches the RemainingCapacity()=FullChargeCapacity() condition while charging.

Example: IfT=35°C (n = 2) and programmed

self-discharge rate Y is 2.5 (2.5% per day at 25°C), the bq2060Areduces RM by RM/256 (0.39%) every

640 13500

256

··=n Y per day

(% )

6750

econds

This means that a 0.39% reduction of RM will be made

12.8 times per day to achieve the desired 5% per day re duction at 35°C.

Figure 3 illustrates how the self-discharge estimate al gorithm adjusts RemainingCapacity() vs. temperature.

Light Discharge or Suspend Current Compensation

The bq2060A can be configured in two ways to compen sate for small discharge currents that produce a signal

(2)

seconds

(3)

Figure 3. Self-Discharge at 2.5%/Day @25C

below the digital filter. First, the bq2060A can decrement RM and DCR at a rate determined by the value stored in Light Discharge Current EE 0x2b when it detects no dis charge activity and the SMBC and SMBD lines are high. Light Discharge Current has a range of 44µA to 11.2mA.

Alternatively, the bq2060A can be configured to disable the digital filter for discharge when the SMBC and SMBD lines are high. In this way, the digital filter will not mask the leakage current signal. The bq2060A is configured in this mode by setting the NDF bit in Con- trol Mode.

Midrange Capacity Corrections

The bq2060A applies midrange capacity corrections when the VCOR bit is set in Pack Configuration. The bq2060A adjusts RM to the associated percentage at three different voltage levels VOC25, VOC50, and VOC75. The VOC values represent the open circuit bat tery voltage at which RM corresponds to the associated state of charge for each threshold.

bq2060A

Threshold Associated State of Charge

VOC25 25% VOC50 50% VOC75 75%

For the midrange corrections to occur, the temperature must be in the range of 19°Cto31°C inclusive and the Current() and AverageCurrent() must both be between –64mA and 0. For a correction to occur, the bq2060A must also detect the need for correction during two adja cent measurements separated by 20s. The second mea surement is not required if the first measurement is im mediately after a device reset. The bq2060A makes midrange corrections as shown in Table5.

Charge Control

Charging Voltageand CurrentBroadcasts

The bq2060A supports SBS charge control by broadcasting the ChargingCurrent() and ChargingVoltage() to the Smart Charger address. The bq2060A broadcasts the requests every 10s. The bq2060A updates the values used in 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 VoltageEE 0x0a-0x0b.

The bq2060A 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, respec tively. The bq2060A also provides pre-charge qualifica tion and a number of safety charge suspensions based on current, voltage, temperature, and state of charge.

Voltage()

Table 5. Midrange Corrections

Condition Result

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

≥VOC50 and RelativeStateOfCharge() ≤ 38% RelativeStateOfCharge()→50%

<VOC50 and RelativeStateOfCharge() ≥ 62% RelativeStateOfCharge()→50% ≥ VOC25 and RelativeStateOfCharge() ≤ 13% RelativeStateOfCharge()→25% < VOC25 and RelativeStateOfCharge() ≥ 37% RelativeStateOfCharge()→25%

bq2060A

Alarm Broadcasts to SmartCharger andHost

If any of the bits 8–15 in BatteryStatus() is set, the bq2060A broadcasts an AlarmWarning() message to the Host address. If any of the bits 12–15 in BatteryStatus() is set, the bq2060A also sends an AlarmWarning() message to the Smart Charger address. The bq2060A repeats the AlarmWarning() message every 10s until the bits are cleared.

Pre-Charge Qualification

The bq2060A sets ChargingCurrent() to the pre-charge rate as programmed in Pre-Charge Current EE 0x1e-0x1f under the following conditions:

Voltage: The bq2060A 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 bq2060A 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 bq2060A requests the

pre-charge rate when Temperature() is between 0°C and 5°C. Temperature() must rise above 5°C before the bq2060A requests the fast-charge rate.

Charge Suspension

The bq2060A may temporarily suspend charge if it detects a charging fault. A charging fault includes the following conditions.

Overcurrent: An overcurrent condition exists when the bq2060A 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 bq2060A 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.

Overvoltage: An overvoltage condition exists when the bq2060A 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-/Overoltage. Overvoltage

Margin is programmed in EE 0x48 and Cell Under/Over Voltage in EE 0x4a (least significant nibble). On

detecting an overvoltage condition, the bq2060A sets the ChargingCurrent() to zero and sets the TERMINATE_CHARGE_ALARM bit in BatteryStatus(). The bq2060A clears the TERMINATE_ CHARGE_ALARM bit when it detects that the battery

is no longer being charged (DISCHARGING bit set in BatteryStatus()). The bq2060A 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 bq2060A 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). The temperature set by MaxT is increased by 16°Cif bit5inMiscellaneous Options is set.

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 bq2060A sets the ChargingCurrent() to zero and sets the OVER_CHARGED_ALARM, TERMINATE_CHARGE_ ALARM, and FULLY_CHARGED bits in BatteryStatus(). The bq2060A 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 bq2060A 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 bq2060A sets ChargingCurrent() to zero. The bq2060A sets ChargingCurrent() to the appropriate pre-charge rate or fast-charge rate when Temperature() ≥ 0°C.

Primary Charge Termination

The bq2060A terminates charge if it detects a charge-termination condition. A charge-termination condition includes the following.

∆T/∆t: For ∆T/∆t, the bq2060A 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 (20s-320s). Typical settings for 1°C/minute

include 2°C/120s and 3°C/180s. 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.

bq2060A

In addition to the ∆T/∆t timer, a hold-off timer starts when the battery is being charged at more than 255mA and the temperature is above 25°C. Until this timer expires, ∆T/∆t detection is suspended. If Current() drops below 256mA or Temperature() below 25°C, the hold-off timer resets and restarts only when the current and temperature conditions are met again. The hold-off timer is programmable (20s – 320s) 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 bq2060A 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 80s. The bq2060A uses the VFC to measure current for current taper termination. The current must also remain above

0.5625/R

Once the bq2060A detects a primary charge termination, it 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 bq2060A 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 Configu- ration EE 0x3f is set. If the CSYNC bit is not set and RelativeStateOfCharge() is less than the programmed percentage of FCC, the bq2060A clears the FULLY_CHARGED bit in BatteryStatus(). The programmed percentage of FCC, Fast Charge Termination %, is set in EE 0x4b. The bq2060A clears the FULLY_CHARGED bit when RelativeStateOfCharge() is less than the programmed Fully Charged Clear %. The bq2060A broadcasts the fast-charge rate when the FULLY_CHARGED bit is cleared and voltage and tem perature permit. The bq2060A clears the TERMI NATE_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.

mA to qualify the termination condition.

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 put. The bq2060A 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 bq2060A uses FCC as the full-battery reference; in abso lute mode, it uses DC.

The DMODE bit in Pack Configuration programs the bq2060A for the absolute or relative display mode. The

LED bit in Control Mode programs the 4 or 5 LED op tion. A 5th LED can be used with the 4 LED display op tion 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 accomplished with a pullup resistor and a pushbutton switch. Detection of the transition activates the dis

and starts a four-second display timer. The timer

play expires and turns off the display whether

brought low momentarily or held low indefinitely. Reac tivation of the display requires that the DISP turn to a logic-high state and then transition low again. The second high-to-low transition must occur after the display timer expires. The bq2060A requires the DISP input to remain stable for a minimum of 250ms to detect the logic state.

If the EDV0 bit is set, the bq2060A disables the LED display. The display is also disabled during a VFC cali bration and should be turned off before entering low-power storage mode.

input. This is usually

DISP

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. Tables 7A and 7B show the display operation.

In either mode, the bq2060A blinks the LED display if RemainingCapacity() is less than Remaining CapacityAlarm(). The display is disabled if EDV0= 1.

Secondary Protection for Li-Ion

The bq2060A has two pins, CFC and DFC, that can be

used for secondary override control of a Li-Ion protector

or for blowing a fuse to disable the battery pack. The

CFC pin is the Charge FET Control pin for secondary protector control or for blowing a fuse. The DFC pin is the Discharge FET Control pin for secondary protector control. Discharge current can cause an override of the CFC control, and charge current can cause an override of the DFC control. Pack Status can read the CVOV and CVUV status flags and can also read the true logic state of theCFC and DFC pins.

The CVOV status flag is set if Voltage() ≥ Charging Voltage() + Overvoltage Margin, any VCELL voltage ≥ Cell Overvoltage threshold, or if Temperature() ≥ MaxT. When CVOV=1 and Miscellaneous Options bit6=0,the CFC pin is pulled low unless DISCHARGING bit in

BatteryStatus() is set or Temperature() > Safety Overtemperature threshold. If Miscellaneous Options bit 6 = 1, the CPC pin is pulled low only if Temperature() >Safety Overtemperature threshold.

was

input re

bq2060A

Table 6. Alarm and Status Bit Summary

Battery State Conditions

Overcurrent

Overvoltage

Overtemperature

Overcharge

Undertemperature

Fast charge termination

Fully discharged

Overdischarged

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

C() ≥ CC() + Overcurrent

Margin

V() ≥ CV() + Overvoltage

Margin

VCELL1, 2, 3, or 4 > Cell

Over Voltage

T() ≥ Max T

Capacity added after

RM() = FCC() ≥

Maximum Overcharge

T()<0°C

∆T/∆t or Current Taper

V() ≤ EDV2

RM() < FCC()*Battery

Low%

V() ≤ EDV0

VCELL1, 2, 3 or 4 < Cell

Under Voltage

RM() = 0 TDA = 1

CC() State and

BatteryStatus Bits Set

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

CC()=0,CVOV=1

CC()=0,OTA=1,

TCA = 1, CVOV = 1

CC() = 0, FC = 1 RSOC() < Fully Charged Cleared %

OCA = 1, TCA= 1 DISCHARGING = 1

CC() = Maintenance

Charging Current,

TDA = 1, CVUV = 1

CC() = Fast or Pre-charge Current

and/or Bits Cleared

TCA = 1 DISCHARGING = 1

V() < CV() + Overvoltage Margin

Li-Ion cell voltage ≤ Cell Over Voltage

T() ≤ Max T -5°CorT()≤ 43°C

CC() = 0

FC=1

TCA = 1

FD = 1 RSOC() > 20%

TDA = 1 V() > EDV0

0°C ≤ Τ() < 5°C, CC() = Pre-Charge

Current

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

RSOC() < Fully Charged Cleared %

DISCHARGING=1ortermination

condition is no longer valid.

VCELL1, 2, 3, or 4 ≥ Cell Under Voltage

RM() > 0

RM() ≥ RCA()

ATTE() ≥ RTA()

Note: C() = Current(), CV() = ChargingVoltage(), CC() = ChargingCurrent(), V() = Voltage(), T() = Tempera

ture(), 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.

bq2060A

Table 7A. Display Mode

Condition

Relative or

Absolute

StateOfCharge()

EDV0 = 1 OFF OFF OFF OFF OFF

<20% ≥20%, <40% ≥40%, <60% ≥60%, <80%

≥80%

The CVUV status flag is set if any VCELL voltage < Cell Undervoltage threshold. When CVUV = 1, the DVC pin

is pulled low unless DISCHARGING bit in BatteryStatus() is set or Temperature() is not set.

Cell Undervoltage and Cell Overvoltage limits may be programmed in the upper and lower nibbles of EE 0x4a. Safety Overtemperature threshold may be programmed in EE 0x09, and Miscellaneous Options is programmed in EE 0x08.

5 LED Display Option

LED1 LED2 LED3 LED4 LED5

ON OFF OFF OFF OFF ON ON OFF OFF OFF ON ON ON OFF OFF ON ON ON ON OFF ON ON ON ON ON

Low-Power Storage Mode

The bq2060A enters low-power mode 5– 8s after receiving the Enable Low-Power command. In this mode the bq2060A consumes less than 10µA. A rising edge on SMBC, SMBD, or HDQ16 restores the bq2060A to the full operating mode. The bq2060A does not perform any gas gauge functions during low-power storage mode.

Device Reset

The bq2060A can be reset when power is applied or by commands over the HDQ16 or SMBus. Upon reset, the bq2060A initializes its internal registers with the infor mation contained in the configuration EEPROM. The following command sequence initiates a full bq2060A re set:

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

A partial reset of the bq2060A occurs if step 1 is omitted and all check-byte values previously loaded into RAM are still correct. All initial RAM values are read from EEPROM for both full and partial resets. A full reset initializes MaxError = 100%, sets RELEARN_FLAG (bit

7)=1inBattery Mode, and initializes RM from EE 0x2c–2d (should be zero for rechargeable batteries). A

Table 7B. Display Mode

Condition

Relative or

Absolute

StateOfCharge()

EDV0 = 1 OFF OFF OFF OFF

<25% ≥25%, <50% ≥50%, <75%

≥75%

partial reset leaves MaxError, RELEARN_FLAG, and RM unchanged. The bq2060A delays reading the EEPROM for 700ms after all resets to allow settling time for V

4 LED Display Option

LED1 LED2 LED3 LED4

ON OFF OFF OFF ON ON OFF OFF ON ON ON OFF ON ON ON ON

Communication

The bq2060A 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 pull these lines low if V should be pulled down with a 100KΩ 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 bq2060A. In this way a sys tem can efficiently monitor and manage the battery.

SMBus

The SMBus interface is a command-based protocol. A

processor acting as the bus master initiates communica tion to the bq2060A by generating a START condition. A START condition consists of a high-to-low transition of the SMBD line while the SMBC is high. The processor then sends the bq2060A device address of 0001011 (bits 7–1) plus a R/W mand code. The R/W the bq2060A to either store the forthcoming data to a register specified by the SMBus command code or out put 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 SMBus, the most significant bit ofa data byte is transmitted first.

bit (bit 0) followed by an SMBus com

. Also, the bq2060A will not

to the part is zero . HDQ16

bit and the command code instruct

and may be

bq2060A

In some instances, the bq2060A acts as the bus master. This occurs when the bq2060A broadcasts charging re quirements and alarm conditions to device addresses 0x12 (SBS Smart Charger) and 0x10 (SBS Host Control ler.)

SMBus Protocol

The bq2060Asupports the following SMBus protocols:

Read Word

Write Word

Read Block

A processor acting as the bus master uses the three pro tocols to communicate with the bq2060A. The bq2060A acting as the bus master uses the WriteWordprotocol.

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

SMBus Packet Error Checking

The bq2060A 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 bq2060A can receive or transmit data with or with out PEC. Figure 4 shows the communication protocol for the Read Word, Write Word, and Read Block mes sages without PEC. Figure 5 includes PEC.

In the Write Word protocol, the bq2060A receives the PEC after the last byte of data from the host. If the host does not support PEC, the last byte of data is followed by a STOP condition. After receipt of the PEC, the bq2060A compares the value to its calculation. If the PEC is correct, the bq2060A responds with an AC KNOWLEDGE. If it is not correct, the bq2060A re sponds with a NOT ACKNOWLEDGE and sets an error code.

In the Read Word and Block Read, the host generates an ACKNOWLEDGE after the last byte of data sent by the bq2060A. The bq2060A then sends the PEC and the host acting as a master-receiver generates a NOT AC KNOWLEDGE and a STOPcondition.

PEC Calculation

The basis of the PEC calculation is an 8-bit Cyclic Re dundancy Check (CRC-8) based on the polynomial C(X)

8+X2+X1

bytes in the transmission, including address, command, and data. The PEC calculation does not include AC

KNOWLEDGE, NOT ACKNOWLEDGE, START, STOP,

+ 1. The PEC calculation includes all

and Repeated START bits. For example, the host requests RemainingCapacity()

from the bq2060A. This includes the host following the Read Word protocol. The bq2060A calculates the PEC based on the following 5 bytes of data, assuming the re maining capacity of the battery is 1001mAh.

Battery Address with R/W = 0: 0x16

Command Code for RemainingCapacity(): 0x0f

Battery Address with R/W = 1: 0x17

RemainingCapacity(): 0x03e9

For 0x160f17e903, the bq2060A transmits a PEC of 0xe8 to the host.

PEC Enable in Master Mode

PEC for master mode broadcasts to the charger, host, or both can be enabled/disabled with the combination of the bits HPE and CPE in Control Mode.

SMBus On and Off State

The bq2060A detects whether the SMBus enters the Off State” by monitoring the SMBC and SMBD lines. When both signals are continually low for at least 2.5s, the bq2060A detects the Off State. When the SMBC and SMBD lines go high, the bq2060A detects the On State and can begin communication within 1ms. One-MΩ pulldown resistors on SMBC and SMBD are recom mended for reliable Off State detection.

HDQ16

The HDQ16 interface is a command-based protocol. (See

Figure 6.) A processor sends the command code to the bq2060A. The 8-bit command code consists of two fields, the 7-bit HDQ16 command code (bits 0–6) and the 1-bit R

/W field. The R/W field directs the bq2060Aeither to

Store the next 16 bits of data to a specified register or

Output 16 bits of data from the specified register

With HDQ16, the least significant bit of a data byte

(command) or word (data) is transmitted first. A bit transmission consists of three distinct sections. The

first section starts the transmission by either the host or the bq2060A taking the HDQ16 pin to a logic-low state

for a period t data-transmission, where the data bit is valid by the time, t nication. The data bit is held for a period t the host processor or bq2060Ato sample the data bit.

after the negative edge used to start commu

DSU;B

. The next section is the actual

STRH;B

DH;DV

to allow

+ 32 hidden pages

TEXAS INSTRUMENTS bq2060A Technical data

Specifications and Main Features

Frequently Asked Questions

User Manual