BQ76PL536APAPR datasheet(17/74 Pages) TI1

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SLUSAD3B – JUNE 2011 – REVISED JANUARY 2016

7.3 Feature Description

7.3.1 Analog-to-Digital Conversion (ADC)

7.3.1.1 General Features

The integrated 14-bit (unsigned) high-speed successive approximation register (SAR) analog-to-digital converter

uses an integrated band-gap reference voltage (VREF) for the cell and brick measurements. The ADC has a front-

end multiplexer for nine inputs – six cells, two temperature sensors, and one general-purpose analog input

(GPAI). The GPAI input can further be multiplexed to measure the brick voltage between the BATx pin and VSS

or the voltage between the GPAI+ and GPAI– pins.

The ADC and reference are factory trimmed to compensate for gain, offset, and temperature-induced errors for

all inputs. The measurement result is not allowed to roll over due to offset error at the top and bottom of the

range. For example, a reading near zero does not underflow to 0x03ff due to offset error, and vice-versa.

The converter returns 14 valid unsigned magnitude bits in the following format:

<00xxxxxx xxxxxxxx>

Each word is returned in big-endian format in a register pair consisting of two adjacent 8-bit registers. The MSB

of the word is located in the lower-address register of the pair, that is, data for cell 1 is returned in registers 0x03

and 0x04 as 00xxxxxx xxxxxxxxb.

7.3.1.2 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 Typical Application section. Unused VCx inputs

should be connected to the next VCx input down until an input connected to a cell is reached – that is, in a four

cell stack, VC6 connects to VC5, which connects to VC4 (Figure 13).

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 13. Connecting < 6 Cells (4 Shown)

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