Datasheet
0.1 Fm
0.1 Fm
64 63
BAT
BAT
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
VC6
CB6
VC5
CB5
VC4
CB4
VC3
CB3
VC2
CB2
VC1
CB1
VC0
VSS
AGND
VREF
11
1 kW
1 kW1 kW 1 kW 1 kW
1 kW 1
0.1 Fm 0.1 Fm 0.1 Fm
10 Fm
bq76PL536A
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SLUSAD3A –JUNE 2011–REVISED AUGUST 2012
3 to 6 Series Cell Configuration
When fewer than 6 cells are used, the most-positive cell voltage of the series string should be connected to the
BAT1/BAT2 pins, through the RC input network shown in the Reference Schematic section. Unused VCx inputs
should be connected to the next VCx input down until an input connected to a cell is reached – i.e., in a four cell
stack, VC6 connects to VC5, which connects to VC4.
The internal multiplexer control can be set to scan only the inputs which are connected to cells, thereby speeding
up conversions slightly. The multiplexer is controlled by the ADC_CONTROL[CN2:0] bits.
Figure 4. Connecting < 6 Cells (4 Shown)
Cell Voltage Measurements
Converting the returned cell measurement value to a dc voltage (in mV) is done using the following formula (all
values are in decimal).
mV = (REG
MSB
× 256 + REG
LSB
) × 6250 / 16383
Example:
Cell_1 == 3.35 V (3350 mV);
After conversion, REG_03 == 0x22; REG_04 == 0x4d
0x22 × 0x100 + 0x4d = 0x224d (8781.)
8781 × 6250 / 16,383 = 3349.89 mV ≈ 3.35 V
GPAI or V
BAT
Measurements
The bq76PL536A features a differential input to the ADC from two external pins, GPAI+ and GPAI–. The ADC
GPAI result register can be configured (via the FUNCTION_CONFIG[GPAI_SRC] to provide a measurement of
the voltage on these two pins, or of the brick voltage present between the BATx pins and VC0.
In the bq76PL536A device, the V
BAT
measurement is taken from the BATx pin to the VC0 pin, and is a separate
input to the ADC mux. Because this is a separate input to the ADC, certain common system faults, such as a
broken cell wire, can be easily detected using the bq76PL536A and simple firmware techniques.
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