bq2060A
SLUS500D – OCTOBER 2001 – REVISED OCTOBER 2011
www.ti.com
SBS v1.1-Compliant Gas Gauge IC
Check for Samples: bq2060A
FEATURES
1
•
•
•
•
•
•
•
•
•
•
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 (3,8-mm) SSOP
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
voltage-to-frequency 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 signals that may be used 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
remaining battery capacity, temperature, voltage,
current, and remaining run-time predictions. The
bq2060A provides LED drivers and a pushbutton
input to depict remaining battery capacity from full to
empty in 20% or 25% increments with a 4- or
5-segment display.
The bq2060A works with an external EEPROM. The
EEPROM stores the configuration information for the
bq2060A, such as battery chemistry, self-discharge
rate, rate compensation factors, measurement
calibration, and design voltage and capacity. The
bq2060A 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 bq2060A 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 bq2060A from the battery cell stack using an
external JFET.
PIN CONNECTIONS
150-Mil (3,8-mm) SSOP
28-Pin
1
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.
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.
Copyright © 2001–2011, Texas Instruments Incorporated
bq2060A
SLUS500D – OCTOBER 2001 – REVISED OCTOBER 2011
www.ti.com
This integrated circuit can be damaged by ESD. Texas Instruments recommends that all integrated circuits be handled with
appropriate precautions. Failure to observe proper handling and installation procedures can cause damage.
ESD damage can range from subtle performance degradation to complete device failure. Precision integrated circuits may be more
susceptible to damage because very small parametric changes could cause the device not to meet its published specifications.
Pin Descriptions
PIN
NAME
DESCRIPTION
NUMBER
HDQ16
1
Serial communication input/output. Open-drain bidirectional communications port
ESCL
2
Serial memory clock. Output to clock the data transfer between the bq2060A and the external nonvolatile
configuration memory
ESDA
3
Serial memory data and address. Bidirectional pin used to transfer address and data to and from the bq2060A
and the external nonvolatile configuration memory.
RBI
4
Register backup input. Input that provides backup potential to the bq2060A registers during periods of low
operating voltage. RBI accepts a storage capacitor or a battery input.
5
Regulator output. Output to control an n-JFET for VCC regulation to the bq2060A from the battery potential
6
EEPROM supply output. Output that supplies power to the external EEPROM configuration memory
7
Supply voltage input
8
Ground
9
Display control input. Input that controls the LED drivers LED1–LED5
REG
VOUT
(1)
(1)
VCC
VSS
DISP
LED1–LED5
10–14
LED display segment outputs. Outputs that each may drive an external LED
DFC
15
Discharge FET control. Output to control the discharge FET in the Li-ion pack protection circuitry
CFC
16
Charge FET control output. Output to control the charge FET in the Li-ion pack protection circuitry
CVON
17
Cell voltage divider control output. Output control for external FETs to connect the cells to the external voltage
dividers during cell voltage measurements
THON
18
Thermistor bias control. Output control for external FETs to connect the thermistor bias resistor during a
temperature measurement
TS
19
Thermistor voltage input. Input connection for a thermistor to monitor temperature
SRC
20
Current sense input. Input to monitor instantaneous current
SR1– SR2
21–22
Charge-flow sense resistor inputs. Input connections for a small value sense resistor to monitor the battery
charge and discharge current flow
VCELL1–VC
ELL4
23–26
Single-cell voltage inputs. Inputs that monitor the series element cell voltages
SMBD
27
SMBus data. Open-drain bidirectional pin used to transfer address and data to and from the bq2060A
SMBC
28
SMBus clock. Open-drain bidirectional pin used to clock the data transfer to and from the bq2060A
(1)
CAUTION: Recent changes to some EEPROM ICs have made the timing of the VOUT pin unreliable. It is strongly recommended that the
EEPROM is powered from the VCC pin (pin 7). Also, it is acceptable to short pins 6 and 7, if needed.
ORDERING INFORMATION
(1)
2
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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ABSOLUTE MAXIMUM RATINGS
Supply voltage, VCC
MIN
MAX
–0.3
6
V
–0.3
6
V
VSS – 0.3
V + 0.3
to CC
V
Relative to VSS
HDQ16, SMBC, SMBD relative to VSS
Input Voltage, VIN
All other pins
UNIT
Operating temperature, TOPR
–20
70
°C
Junction temperature, TJ
–40
125
°C
NOTES
Commercial
DC ELECTRICAL CHARACTERISTICS
VCC = 2.7 V to 3.7 V, TOPR = –20°C to 70°C, unless otherwise noted
SYMBOL
PARAMETER
TEST CONDITIONS
MIN
TYP
MAX
2.7
3.3
3.7
UNIT
V
180
235
µA
5
10
µA
0.2
µA
VCC
Supply voltage
ICC
Operating current
VOUT inactive
ISLP
Low-power storage mode current
1.5 V < VCC < 3.7 V
ILVOUT
VOUT leakage current
VOUT inactive
VOUT source current
VOUT active,
VCC – 0.6 V
Output voltage low: LED1–LED5, CFC,DFC
IOLS = 5 mA
0.4
V
Output voltage low: THON, CVON
IOLS = 5 mA
0.36
V
–0.3
0.8
V
2
VCC + 0.3
V
0.4
V
0.8
V
1.7
6.0
V
VSS – 0.3
1.25
V
50
nA
IVOUT
VOLS
VIL
Input voltage low DISP
VIH
Input voltage high DISP
VOL
Output voltage low SMBC, SMBD, HDQ16, ESCL, ESDA
VILS
Input voltage low SMBC, SMBD, HDQ16, ESCL, ESDA
VIHS
Input voltage high SMBC, SMBD, HDQ16, ESCL, ESDA
VAI
Input voltage range VCELL1–4, TS, SRC
–0.2
–5
mA
IOL = 1 mA
–0.3
VRBI > 3 V,
VCC < 2 V
IRB
RBI data-retention input current
10
VRBI
RBI data-retention voltage
1.3
V
ZAI1
Input impedance: SR1, SR2
0–1.25 V
10
MΩ
ZAI2
Input impedance: VCELL1–4, TS, SRC
0–1.25 V
5
MΩ
VFC CHARACTERISTICS
VCC = 3.1 to 3.5 V, TOPR = –0°C to 70°C, unless otherwise noted
SYMBOL
PARAMETER
TEST CONDITIONS
MIN
VSR
Input voltage range, VSR2 and VSR1
VSR = VSR2– VSR1
–0.25
VSROS
VSR input offset
VSR2 = VSR1, auto-correction disabled
–250
VSRCOS
Calibrated offset
RMVCO
Supply voltage gain coefficient (1)
Temperature gain coefficient (1)
INL
Integral nonlinearity error
VCC = 3.3 V
Total deviation TOPR = –20°C to 70°C
Slope for TOPR = –0°C to 50°C
Total deviation TOPR = –0°C to 50°C
(1)
–50
–16
Slope for TOPR = –20°C to 70°C
RMTCO
TYP
TOPR = 0°C–50°C
0.8
MAX
UNIT
+0.25
V
250
µV
+16
µV
1.2
%/V
%/°C
–0.09
+0.09
–1.6%
0.1%
–0.05
+0.05
–0.6%
%/°C
0.1%
0.21%
RM(TCO) total deviation is from the nominal gain at 25°C.
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REG CHARACTERISTICS
TOPR = –20°C to 70°C
SYMBOL
VRO
IREG
4
PARAMETER
Normal mode: REG controlled
output voltage
Sleep mode: REG controlled
output voltage
TEST CONDITIONS
MIN
TYP
MAX
3.1
3.3
3.5
JFET: Rds(on) < 150 Ω, Vgs(off) < –3 V at 10 µA
UNIT
V
4
REG output current
1
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µA
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SLUS500D – OCTOBER 2001 – REVISED OCTOBER 2011
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SMBus AC SPECIFICATIONS
VCC = 2.7 V to 3.7 V, TOPR = –20°C to 70°C, unless otherwise noted
SYMBOL
PARAMETER
TEST CONDITIONS
fSMB
SMBus operating frequency
Slave mode, SMBC 50% duty cycle
fMAS
SMBus master clock frequency
Master mode, no clock low slave
extend
tBUF
Bus free time between start and stop
tHD:STA
Hold time after (repeated) start
tSU:STA
Repeated start setup time
tSU:STO
Stop setup time
tHD:DAT
Data hold time
tSU:DAT
Data setup time
tTIMEOUT
Error signal/detect
tLOW
Clock low period
tHIGH
10
MAX
UNIT
100
kHz
51.2
kHz
4.7
µs
4
µs
µs
4
µs
Receive mode
0
ns
Transmit mode
300
ns
250
(1)
Clock high period
See
(2)
tLOW:SEXT
Cumulative clock low slave extend time
See
tLOW:MEXT
Cumulative clock low master extend time
See
(4)
TYP
4.7
See
(1)
(2)
(3)
MIN
ns
25
35
ms
µs
4.7
50
µs
(3)
25
ms
(4)
10
ms
4
The bq2060A times out when any clock low exceeds TTIMEOUT.
THIGH Max. is minimum bus idle time. SMBC = 1 for t > 50 ms causes reset of any transaction involving bq2060A that is in progress.
TLOW:SEXT is the cumulative time a slave device is allowed to extend the clock cycles in one message from initial start to the stop.
The bq2060A typically extends the clock only 20 ms as a slave in the read byte or write byte protocol.
TLOW:MEXT is the cumulative time a master device is allowed to extend the clock cycles in one message from initial start to the stop.
The bq2060A typically extends the clock only 20 ms as a master in the read byte or write byte protocol.
HDQ16 AC SPECIFICATIONS
VCC = 2.7 V to 3.7 V, TOPR = –20°C to 70°C, unless otherwise noted
SYMBOL
PARAMETER
TEST CONDITIONS
MIN
TYP
MAX
190
205
250
µs
Start hold time, host to bq2060A(write)
5
—
—
ns
Start hold time, bq2060A to host (read)
32
—
—
µs
DSU
Data setup time
—
—
50
µs
tDSUB
Data setup time
—
—
50
µs
tDH
Data hold time
100
—
—
µs
tDV
Data valid time
80
—
—
µs
tSSU
Stop setup time
—
—
145
µs
tSSUB
Stop setup time
—
—
145
µs
tRSPS
Response time, bq2060A to host
190
—
320
µs
t]
Break time
190
—
—
µs
tBR
Break recovery time
40
—
—
µs
tCYCH
Cycle time, host to bq2060A (write)
190
tCYCB
Cycle time, bq2060A to host (read)
tSTRH
tSTRB
UNIT
µs
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THIGH
SMBC
THD:STA
TLOW
TSU:STA
TSU:STO
SMBD
THD:DAT
TSU:DAT
TBUF
Figure 1. SMBus Timing Data
Figure 2. HDQ16 Break Timing
Figure 3. HDQ16 Host to bq2060A
Figure 4. HDQ16 bq2060A to Host
FUNCTIONAL DESCRIPTION
General Operation
The bq2060A determines battery capacity by monitoring the amount of charge input or removed from a
rechargeable battery. In addition to measuring charge and discharge, the bq2060A measures battery voltage,
temperature, 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 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.
6
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Figure 5 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 resistor.
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 condition, and
compensate for self-discharge and charge/discharge battery efficiencies.
Measurements
The bq2060A 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 2–2.5 seconds, depending on the bq2060A
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 SR1 and SR2 pins as shown in Figure 5. The VFC measures bipolar signals up to 250 mV. The
bq2060A detects charge activity when VSR = VSR2 – VSR1 is positive and discharge activity when VSR =
VSR2 – VSR1 is negative. The bq2060A continuously integrates the signal over time using an internal counter. The
fundamental rate of the counter is 6.25 µVh.
Offset Calibration
The bq2060A provides an auto-calibration feature to cancel the voltage offset error across SR1 and SR2 for
maximum charge measurement accuracy. The calibration routine is initiated by issuing a command to
Manufacturer Access(). The bq2060A is capable of automatic offset calibration down to 6.25 µV. Offset
cancellation resolution is less than 1 µV.
Digital Filter
The bq2060A 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 SR1 and SR2 for charge and discharge currents, the bq2060A monitors the battery-pack
potential and the individual cell voltages through the VCELL1 – VCELL4 pins. The bq2060A measures the pack
voltage and reports the result in Voltage(). The bq2060A 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 VCELL1 – VCELL4 inputs are divided down from the cells using precision resistors, as shown in Figure 5.
The maximum input for VCELL1 – VCELL4 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 VCELL1 – VCELL2 must be half of that of VCELL3 – VCELL4. To reduce current consumption
from the battery, the CVON output may be 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).
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 ±250 mV as shown in Table 2.
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VCC
bq2060
LED1
LED2
To Pack
VCC Protection
Circuitry
A0
VCC
VCC
LED3
CVON
LED4
VCELL4
LED5
VCELL3
CFC
VCELL2
DFC
VCELL1
G
S
D
SST113
PACK+
RBI
DISP
EEPROM
REG
VCC
VCC
SRC
A1
A2
ESCL
SCL
SR2
R5
WP
VSS
SDA
VCC
ESDA
SR1
PACK-
THON
SMBC
SMBC
TS
SMBD
SMBD
VSS
HDQ16
Thermistor
HDQ
Figure 5. Battery Pack Application Diagram – LED Display and Series Cell Monitoring
8
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Table 1. Example VCELL1–VCELL4 Divider and
Input Range
Table 2. SRC Input Range
SENSE RESISTOR
(Ω)
FULL-SCALE INPUT
(A)
0.02
± 12.5
0.03
± 8.3
VOLTAGE
INPUT
VOLTAGE
DIVISION RATIO
FULL-SCALE
INPUT (V)
VCELL4
16
20
VCELL3
16
20
0.05
±5
VCELL2
8
10
0.1
± 2.5
VCELL1
8
10
Current
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 ±250 mV, as shown in Table 2.
Temperature
The TS input of the bq2060A along with an NTC thermistor measures the battery temperature as shown in
Figure 5. The bq2060A reports 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 60 ms when the
temperature is measured, and driven low otherwise.
GAS GAUGE OPERATION
General
The operational overview in Figure 6 illustrates the gas gauge operation of the bq2060A. Table 3 and
subsequent text describes the bq2060A registers.
The bq2060A accumulates a measure of charge and discharge currents and estimates self-discharge of the
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 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
communications 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 register 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.
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Inputs
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Charge
Current
Battery Electronics
Load Estimate
Discharge
Current
Self-Discharge
Timer
Charge
Efficiency
Compensation
Temperature
Compensation
−
+
Main Counters and
Capacity Reference (FCC)
−
−
Remaining
Capacity
(RM)
+
Full
Charge
Capacity
(FCC)
≤
+
+
Discharge
Count
Qualified Register
(DCR)
Transfer
Temperature, Other Data
Outputs
Chip-Controlled
Available Charge
LED Display
Two-Wire
Serial Port
Figure 6. bq2060A Operational Overview
Table 3. bq2060A Register Functions
FUNCTION
10
COMMAND CODE
SMBus
HDQ16
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
mA, 10 mW
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
percent
RelativeStateOfCharge
0x0d
0x0d
read
AbsoluteStateOfCharge
0x0e
0x0e
read
percent
RemainingCapacity
0x0f
0x0f
read
mAh, 10 mWh
FullChargeCapacity
0x10
0x10
read
mAh, 10 mWh
RunTimeToEmpty
0x11
0x11
read
minutes
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Table 3. bq2060A Register Functions (continued)
COMMAND CODE
SMBus
HDQ16
SMBus
ACCESS
UNITS
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
integer
FUNCTION
SerialNumber
0x1c
0x1c
read
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
n/a
Pack Status
0x2f (LSB)
0x2f (LSB)
read/write
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
MAIN GAS GAUGE REGISTERS
RemainingCapacity() (RM)
RM represents the remaining capacity in the battery. The bq2060A computes RM in either mAh or 10 mWh,
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 CapacityEE 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 bq2060A sets FCC to the value stored in Last Measured Discharge
EE 0x38–0x39. During subsequent discharges, the bq2060A 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 bq2060A 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.
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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 bq2060A initializes DCR to FCC –
RM when FCC-RM is less than 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 discharge to EDV2 + (FCCxBatteryLow%)
(1)
Where:
BatteryLow% = (value stored in EE 0x54) + 2.56
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 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 between
the EDV2 threshold and [EDV2 threshold – 256 mV] when the bq2060A detected EDV2.
• No midrange voltage correction occurs during the discharge period.
• No overload condition occurs when voltage ≤ EDV2 threshold
FCC cannot be reduced by more than 256 mAh or increased by more than 512 mAh during any single update
cycle. FCC becomes invalid if it is initialized or updated to a value less then 256 mAH. FCC becomes invalid if it
is initialized or updated to a value less than 256 mAH. The bq2060A saves the new FCC value to the EEPROM
within 4 s of being updated.
End-of-Discharge Thresholds and Capacity Correction
The bq2060A monitors the battery for three low-voltage thresholds, EDV0, EDV1, and EDV2. The EDV
thresholds are programmed in EDVF/EDV0 EE 0x72–0x73, EMF/EDV1EE 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 bq2060A computes the EDV0, EDV1, and EDV2 thresholds based on the values in EE 0x72–0x7d, 0x06,
and the battery load current, temperature, 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 the Current() drops below the overload current threshold. Any EDV threshold
detected is reset after 10 mAh of charge is applied.
The bq2060A uses the thresholds to apply voltage-based corrections to the RM register according to Table 4.
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
corresponding 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 corresponding threshold, but only on a full learning-cycle
discharge (VDQ = 1). The EDV1 threshold is ignored if Miscellaneous Options bit 7 = 1.
12
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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
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
1/4Y% per day
10 ≤ Temp < 20
½ Y% 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
The interval at which RM is reduced is given by the following equation, where n is the appropriate factor of 2 (n =
1/ 4, 1/ 2, 1, 2 . . . ):
Self-DischargeUpdateTime =
640 x 13500
seconds
256 x n x (Y% per day)
(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 bq2060A 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 bq2060A
reduces RM by RM/256 (0.39%) every
256
640
n
135000
+ 6750 seconds
(Y% per day)
(3)
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() vs. temperature.
Light Discharge or Suspend Current Compensation
The bq2060A can be configured in two ways to compensate for small discharge currents that produce a signal
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 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 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 does not mask the leakage current signal. The bq2060A is configured
in this mode by setting the NDF bit in Control Mode.
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1200
Capacity − mAh
1000
15°C
800
600
25°C
400
35°C
200
45°C
0
0
10
20
30
40
50
60
70
t − Time − days
Figure 7. Self-Discharge at 2.5%/Day at 25°C
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 battery voltage at which RM corresponds to the associated state of
charge for each threshold.
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°C to 31°C inclusive and the
Current() and AverageCurrent() must both be between –64 mA and 0. For a correction to occur, the bq2060A
must also detect the need for correction during two adjacent measurements separated by 20 s. The second
measurement is not required if the first measurement occurs immediately after a device reset. The bq2060A
makes midrange corrections as shown in Table 5.
Charge Control
Charging Voltage and Current Broadcasts
The bq2060A supports SBS charge control by broadcasting the ChargingCurrent() and ChargingVoltage() to the
Smart Charger address. The bq2060A broadcasts the requests every 10 s. The bq2060A updates the values
used in the charging current and voltage broadcasts based on the battery 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 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 (ΔT/Δt) and current taper,
for nickel-based and Li-ion chemistries, respectively. The bq2060A also provides pre-charge qualification and a
number of safety charge suspensions based on current, voltage, temperature, and state of charge.
Alarm Broadcasts to Smart Charger and Host
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 10 s until the bits are
cleared.
14
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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 BatteryStatus(). 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-/Overvoltage. Overvoltage Margin is programmed in EE 0x48 and
Cell Under-/Overvoltage in EE 0x4a. 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.
• Overtemperature: An overtemperature condition exists when Temperature() is greater than or equal to the
MaxT value programmed in EE 0x45 (most significant nibble). On detecting an overtemperature 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
overtemperature condition is cleared when Temperature() is equal to or below (MaxT – 5°C). The
temperature set by MaxT is increased by 16°C if bit 5 in Miscellaneous Options is set.
• Overcharge: An overcharge condition exists if the battery is charged more than the Maximum 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 2 mAh of discharge.
• Undertemperature: An undertemperature 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.
Table 5. Midrange Corrections
CONDITION
Voltage()
RESULT
≥ VOC75 and RelativeStateOfCharge() ≤ 63%
RelativeStateOfCharge()→75%
< VOC75 and RelativeStateOfCharge() ≥ 87%
RelativeStateOfCharge()→75%
≥VOC50 and RelativeStateOfCharge() ≤ 38%
RelativeStateOfCharge()→50%
Safety
Overtemperature threshold, then it is pulled low even if the Discharging bit in BatteryStatus() is set.
The formula for this description is:
CFC = SOT
or
CVOV + DSG + MISC OPTION BIT 6
If Miscellaneous Options bit 6 = 1, the CFC pin is pulled low only if Temperature() > Safety Overtemperature
threshold.
Table 6. Alarm and Status Bit Summary (1)
BATTERY STATE
CONDITIONS
CC() STATE AND
BatteryStatus BIT SET
CC() = FAST OR PRECHARGE
CURRENT AND/OR
BITS CLEARED
Overcurrent
C() ≥ CC() +Overcurrent Margin
CC() = 0, TCA = 1
C() < CC() + Overcurrent Margin
TCA = 1
DISCHARGING = 1
CC() = 0, CVOV = 1
V() < CV() + Overvoltage Margin
Li-ion cell voltage ≤ Cell Over Voltage
CC() = 0, OTA = 1,
TCA = 1, CVOV = 1
T() ≤MaxT – 5°C or T() ≤ 43°C
CC() = 0, FC = 1
RSOC() < Fully Charged Cleared %
OCA = 1, TCA = 1
DISCHARGING = 1
T() < 0°C
CC() = 0
0°C ≤ T() < 5°C,
CC() = Pre-Charge Current;
T() ≥ 5°C,
CC() = Fast-Charging Current
RSOC() < Fully Charged Cleared %
ΔT/Δt or Current Taper
CC() = Maintenance
Charging Current,
FC = 1
TCA = 1
DISCHARGING = 1 or termination
condition is no longer valid.
V() ≤ EDV2 or
RM() < FCC() *Battery Low%
FD = 1
RSOC() > 20%
V() ≤ EDV0
TDA = 1
V() > EDV0
Overdischarged
VCELL1, 2, 3 or 4 < Cell
Under Voltage
TDA = 1, CVUV = 1
VCELL1, 2, 3, or 4 ≥ Cell Under Voltage
RM() = 0
TDA = 1
RM() > 0
Low capacity
RM() < RCA()
RCA = 1
RM() ≥ RCA()
Low run-time
ATTE() < RTA()
RTA = 1
ATTE() ≥ RTA()
Overvoltage
V() ≥ CV() + Overvoltage Margin
VCELL1, 2, 3, or 4 > Cell Over Voltage
Over temperature
T() ≥ MaxT
Overcharge
Capacity added after
RM() = FCC() ≥
Maximum Overcharge
Undertemperature
Fast-charge
termination
Fully discharged
(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().
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Table 7. 5-LED Display Mode
5-LED Display Option
Condition Relative or Absolute
StateOfCharge()
LED1
LED2
LED3
LED4
LED5
EDV0 = 1
OFF
OFF
OFF
OFF
OFF
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