BQ2063_15 Datasheet, PDF (53/60 Pages) Texas Instruments – SBS v1.1-COMPLIANT Li-ION GAS-GAUGE IC

Not Recommended For New Designs
bq2063
SBS v1.1ĆCOMPLIANT LiĆION GASĆGAUGE IC
WITH PROTECTOR INTERFACE
SLUS468E− MAY 2001 − REVISED APRIL 2002
PROGRAMMING INFORMATION
measurement calibration
ADC
To describe how the bq2063 calculates reported battery and three individual cell voltages, the following
abbreviations and designations are used:
D VCELL = voltage at the input pin of the bq2063
D VCELLN = reported single-cell voltages (N = 1–4)
D Vn = single cell voltage (n = 1−4)
D VnOffset= single-cell offset voltages (n = 1–4)
D Voltage( ) = reported battery voltage
The bq2063 requests inputs to the VCELL pin. The S-8243 presents either a scaled single-cell voltage or the
offset associated with the voltage, per Table 11. The voltage for each cell, Vn, may be determined by subtracting
the offset measurement from the corresponding cell plus offset measurement.
After subtracting the two ADC readings from each cell voltage, the reported VCELLN voltage is computed as
follows:
ƪ ƫ VCELLN + [ADC(VnOffset
)
0.2 Vn)–ADC(VnOffset)]
ADC Voltage Gain
65536
(27)
ADC(VCELL)
+
VCELL _* 32768
1250
(28)
An ADC Voltage Gain factor of 12500 in EE 0x66−0x67 is the nominal value to correct for the nominal 0.2 (5:1
reduction) gain of the S-8243.
The bq2063 computes the reported voltages as follows:
Voltage( ) = VCELL1 + VCELL2 + VCELL3 + VCELL4
(29)
The bq2063 reports VCELL4 as the most positive cell in the cell stack. Note that this is documented as V1 in
the S-8243 data sheet. The other cell voltages are also in inverse order.
Table 11. bq2063 to S-8243A/B Interface (Cell Voltage Input)
OUTPUT
INPUT
CTL3 CTL4
VCELL (A series)
VCELL (A series)
High High V1 Offset
V1 Offset
High Open V1 Offset +0.2 × V1
V1 Offset + 0.2 × V1
High Low
Don’t care
V2 Offset
Open High Don’t care
V2 Offset + 0.2 × V2
Open Open V2 Offset
V3 Offset
Open Low
V2 Offset + 0.2 × V2
V3 Offset + 0.2 × V3
Low
High V3 Offset
V4 Offset
Low
Open V3 Offset 0.2 × V3
V4 Offset + 0.2 × V4
Low
Low
Don’t care
Don’t care
NOTE: V1 = Cell 1 voltage (positive end of cell stack)
V2 = Cell 2 voltage
V3 = Cell 3 voltage
V4 = Cell 4 voltage (negative end of cell stack)
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