Ocv Timing And Ocv_Cmd Use Recommendations; Active Mode (Fuel Gauge Is Not In Sleep Mode); Sleep Mode; Initial Ocv - Por - Texas Instruments BQ27220 Technical Reference Manual

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7.2 OCV Timing and OCV_CMD Use Recommendations

The VIT measurement used for the OCV calculation is the last VIT measured before the OCV_CMD was

received. The VIT value used for the OCV calculation needs to be a stable, not transient value. Before sending

the OCV_CMD, the current must be stable and < C/20 for at least one second. The recommendations for the

OCV_CMD used for ACTIVE mode is that the VIT remains stable from two seconds before the OCV_CMD is

sent until the end of SOC_INT (see

In SLEEP mode, the fuel gauge measures VIT every 20 s, instead of 1 s. The VIT measurement used for the

OCV calculation is the last VIT measured before the OCV_CMD was received. Sleep current is usually below the

OCV current-fail threshold. So, the recommendations for the OCV_CMD sent during SLEEP mode is that the VIT

remains stable and below the sleep threshold from the time OCV_CMD is sent until the end of SOC_INT.

7.2.3 Initial OCV – POR

During POR, the VIT measurement used for the OCV calculation and qualification takes place between about

300 ms after POR until the end of SOC_INT. To achieve a good initial OCV measurement after POR, the

recommendation is to keep VIT stable from POR until the end of SOC_INT (see

SLUUBD4A – APRIL 2016 – REVISED NOVEMBER 2022

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Figure

7-2).

Figure 7-2. OCV Calculation Based on OCV Command

Open-Circuit Voltage Measurement Background

Figure

7-3).

BQ27220

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