BQ2052_15 Datasheet, PDF (11/20 Pages) Texas Instruments – Gas Gauge IC

Not Recommended For New Designs
Preliminary bq2052
where
RS = sense resistor value in Ω.
VSRH = high-byte value of current scale
VSRL = low-byte value of current scale
Program Pin Pull-Down Register (PPD)
The PPD register (address = 07h) contains the pull-down
programming pin information for the bq2052. The pro-
gram pins, PROG_1–6, have a corresponding PPD register
location, PPD_1–6. A given location is set if the bq2052
detects a pull-down resistor on its corresponding seg-
ment driver. For example, if PROG₁ and PROG₄ have
pull-down resistors, the contents of PPD are xx001001.
Program Pin Pull-Up Register (PPU)
The PPU register (address = 08h) contains the pull-up
programming pin information for the bq2052. The seg-
ment drivers, PROG_1–6, have a corresponding PPU reg-
ister location, PPU_1–6. A given location is set if a
pull-up resistor has been detected on its corresponding
segment driver. For example, if PROG₃ and PROG₅
have pull-up resistors, the contents of PPU are
xx010100.
Battery Voltage (VSB)
The battery voltage register (address = 0bh) stored the
voltage detected on the SB pin. The bq2052 updates the
VSB register approximately once per second with the
present value of the battery voltage.
V_SB
=
1.2V
∗

VSB
256

temperature. The CAC value is also used in calculating
the LED display pattern relative to PFC.
Program Full Count (PFC)
The PFC register (address = 10h) contains the user se-
lected programmed full count (PFC) setting.
Full Nominal Available Capacity (FNAC)
The FNAC (address = 11h) contains the full capacity
reference of the battery.
Maximum Discharge Rate (MAXRATE)
The MAXRATE register (address = 12h) stores the high-
est discharge rate detected by the bq2052. The bq2052
uses the MAXRATE value to calculate the efficiency
compensation factors.
Discharge Rate (RATE)
The RATE register (address = 13h) provides the current
discharge rate of the battery.
Discharge Count Registers (DCRH/DCRL)
The DCRH high-byte register and the DCRL low-byte
register are the main gas gauging registers for the
bq2052. The DCR registers are incremented during dis-
charge.
Writing to the DCR registers affects the available charge
counts and, therefore, affects the bq2052 gas gauge oper-
ation.
Display
Voltage Threshold Register (VTS)
The end-of-discharge threshold voltages (EDV1 and
EDVF) can be set using the VTS register. The VTS reg-
ister sets the EDV1 trip point. EDVF is set 100mV below
EDV1. The default value in the VTS register is A2h,
representing EDV1 = 0.76V and EDVF = 0.66V.
EDV1
=
1.2V
*

VTS
256
 _.
Relative CAC Register (RCAC)
The RCAC register (address = 0dh) provides the relative
battery state-of-charge by dividing CAC by FNAC.
RCAC varies from 0 to 7dh representing relative
state-of-charge from 0 to 125%.
Compensated Available Capacity (CAC)
The CAC registers (address = 0eh–0fh) contain the
available capacity compensated for discharge rate and
The bq2052 can directly display remaining capacity in-
formation using low-power LEDs. The bq2052 uses the
CAC value in relation to FNAC as the basis for the dis-
play activity. The bq2052 displays the battery’s remain-
ing capacity in either of three modes selected with pro-
gram pin PROG₅. The display is activated using the
DISP input. When DISP is connected to V_CC, the SEG
outputs are OFF. When pulled low, the segment outputs
turn ON for a period of 4 ± 0.5s, depending on the se-
lected mode.
The segment outputs are modulated as two banks, with
segments 1, 3, and 5 alternating with segments 2 and 4.
The segment outputs are modulated at approximately
100Hz with each segment bank active for 30% of the pe-
riod. In incremental and bar graph modes, SEG1 blinks
at a 4Hz rate whenever VSB is below VEDV1 (EDV1
flag bit set in FLGS1), indicating a low-battery condi-
tion. When VSB is below VEDVF (EDVF flag bit set in
FLGS1) the display outputs are disabled in all modes.
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