AN4324 datasheet(9/31 Pages) STMICROELECTRONICS

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AN4324

Battery parameters

DocID024963 Rev 2.0

9/31

3.2

Battery open circuit voltage (OCV) curve measurement and

calculation

The default OCV curve selected by the STC3115 version can be adjusted to fit the battery

REG_OCVTAB model. The TAB registers can be filled to define the OCV curve as in the

equation: OCV[x] = OCVinit[x] + OCVTAB[x].

The battery OCV curve can be characterized and evaluated by measuring the relaxed

voltage of the battery at a given state of charge (SOC). In the table below, column 2,

"Battery OCV (V)", should be measured using the relaxed voltages of the corresponding

"SOC (%)" values in column 1. These measured points can then be used to define the

REG_OCVTAB(0.55mV) "Value" in column 6 using the equation: REG_OCVTAB[x] =

(Battocv[x] - OCVinit[x]) / 0.55.

Table 3: OCV offset calculation table

SOC

(%)

Battery OCV in volts

(battery measurement

data)

OCV-init(V)

REG_OCVTAB(0.55mV)

STC3115AIJT /

STC3115AIQT

STC3115IJT /

STC3115IQT

Address

Value

100

4.176

4.313

0x3F

4.076

4.197

0x3E

3.991

4.088

0x3D

3.929

3.990

0x3C

3.899

3.953

0x3B

3.863

3.914

0x3A

3.802

3.825

0x39

3.778

3.790

0x38

3.761

3.770

0x37

3.747

3.761

0x36

3.721

3.743

0x35

3.695

3.710

0x34

3.658

3.675

0x33

3.618

3.651

0x32

3.541

3.571

0x31

3.300

0x30

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