BQ27210 Datasheet, PDF (22/30 Pages) Texas Instruments – Li-Ion AND Li-Pol BATTERY GAS GAUGE IC FOR PORTABLE APPLICATIONS (bqJUNIOR)

bq27010, bq27210
SLUS707B – APRIL 2006 – REVISED JANUARY 2007
Discharge Rate Compensation Threshold
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DCOFF[2:0]
0
1
2
3
4
5
6
7
DCOFF Threshold⁽¹⁾
0
(DCGN / 256) * 1C / 8
(DCGN / 256) * 2C / 8
(DCGN / 256) * 3C / 8
(DCGN / 256) * 4C / 8
(DCGN / 256) * 5C / 8
(DCGN / 256) * 6C / 8
(DCGN / 256) * 7C / 8
(1) C = ILMD * 256
The discharge compensation capacity reduction (DCMP) is a function of discharge rate, temperature, and age
(cycle count). There is no compensation if the DCGN factor increased for age and temperature times AI is less
than the DCOFF threshold (DCMP ≥ 0). The following is the combined equation for the DCMP reduction:
DCMP = AI * (ADCGN / 256) * (1 + TCGN * (273 + TOFF – T) / 32) – DCGN * DCOFF * ILMD / 8
ADCGN = DCGN * (1 + TCGN * (CYCT / 16) * GAF / 32)
If PKCFG[1] = 1, the bqJUNIOR assumes a fixed value of 0x6C for DCOMP, giving a discharge rate
compensation gain of 5.08% with a compensation offset threshold of C/2. This frees the EEPROM location of
0x7E for use as a programmable identification byte. If DCOMP is updated using the UPCOMP host command
(see Device Control section), the value written by the host for DCOMP will be used regardless of the bit 1 value
in PKCFG.
Temperature Compensation Coefficients (TCOMP) – Address 0x7F
This register is used to set the compensation coefficients for temperature. These coefficients are used to scale
the aged discharge rate compensation for improved accuracy of predicted available capacity at cold
temperatures.
NAME
BIT 7
TCGN[4]
BIT 6
TCGN[3]
BIT 5
TCGN[2]
BIT 4
TCGN[1]
BIT 3
TCGN[0]
BIT 2
TOFF[2]
BIT 1
TOFF[1]
BIT 0
TOFF[0]
TCGN[4:0] The temperature compensation gain coefficient is used to scale DCGN when temperature drops
below the T_off threshold. TCGN will increase the ADCGN value in increments of 3.125% (TCGN /
32) for each degree that temperature is below the T_off threshold.
TOFF[2:0]
The temperature compensation offset threshold sets the temperature above which there is no
temperature compensation applied to DCGN. This threshold is also used as the threshold for
application of cold temperature compensation of EDV1 (see GAF/EDVT section) and the threshold
to allow the NAC = LMD capacity adjustment to be made at IMIN detection (see Functional
Description section). The T_off threshold in degrees Celsius is equal to 2 * TOFF.
If PKCFG[0] = 1, the bqJUNIOR assumes a fixed value of 0x46 for TCOMP. This will increase the DCGN factor
by 25% per degree below T_off of 12°C. This frees the EEPROM location of 0x7F for use as a programmable
identification byte. If TCOMP is updated using the UPCOMP host command (see Device Control section), the
value written by the host for TCOMP will be used regardless of the bit 0 value in PKCFG.
Power Modes
The bqJUNIOR has five power modes: Active, Sleep, Ship, Hibernate, and Data Retention (RBI). Figure 5
shows the flow that moves the device between the Active, Sleep, and Ship modes. Hibernate and Data
Retention are special modes not included in the flow. Detailed explanations of each mode follow the diagram in
Figure 5.
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