ADP5350ACBZ-1-R7 datasheet(28/63 Pages) AD

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ADP5350

Data Sheet

Rev. B | Page 28 of 63

For some batteries, the internal resistance is different when the

battery is in charge vs. discharge mode. Use the K_RBAT_

CHARGE bits to program the battery internal resistance

coefficient when charging.

State of Charge Limit Filter

To avoid impacting SOC accuracy caused by the effects of a

battery discharge and the instantaneous interference on the

battery current sense, the ADP5350 uses filter limitation for

delta SOC calculation of each step. The filter limitation can be

selected from a 0.125 C rate to a 3 C rate via I2C programming,

which is equal to or greater than real system current consumption

(the C rate is the battery charge or discharge current rate over

the battery capacity). For example, when the full system load is

60 mA with 300 mAh, and the discharge current rate is 0.2 C,

the filter limitation can be programmed to 0.25 C using the

FILTER_DISCHARGE bits.

When the fuel gauge is enabled, the SOC value is reset based on

the current battery voltage and internal resister compensation,

without any initial filter effects. Repeatedly disabling and

enabling the fuel gauge or setting Register 0x25, Bit 7 to reset

the SOC value during a battery discharge increases errors in

SOC calculation. It is recommended that the SOC be reset only

when there is no discharge current and the battery voltage is in

a completely relaxed state; that is, the battery voltage is stable.

During sleep mode, the filter limitation is reduced because the

ADP5350 outputs a low discharge current.

FLOWCHART OF SOC CALCULATION

See Figure 47 for a flowchart of the SOC calculation. Down_Lim is

the delta SOC in each step when the SOC reduces. Up_Lim is

the delta SOC in each step when the SOC increases.

Figure 47. ADP5350 SOC Calculation Flowchart

READ VBAT (12-BIT)

ENABLE FUEL GAUGE

first_start = True

CALCULATE IBAT

FILTER LIMITS

Up_Lim = FILT_CHARGE

Down_Lim = 0

COMPENSATE

VBAT TO VOCV

MULTIPLY RBAT

WITH CHARGING

COEFFICIENT

FILTER LIMITS

Down_Lim = FILT_IDLE

Up_Lim = 0

FILTER LIMITS

Down_Lim = FILT_DISCHARGE

Up_Lim = 0

IDLE

–25mA < IBAT < 25mA

DISCHARGE

IBAT < –25mA

CHARGE

IBAT > 25mA

New_SOC

Old_SOC

New_SOC

Old_SoC +

Up_lim

New_SOC

Old_SOC –

Down_lim

New_SOC =

Old_SOC

New_SOC =

Old_SOC +

Up_Lim

New_SOC =

Old_SOC –

Down_Lim

UPDATE New_SOC

TO SOC REGISTER

first_start

YES

first_start = False

CALCULATE SOC

BASED ON VOCV

SAMPLE

TIMER OUT?

CALCULATE THE RBAT

COMPENSATE

VBAT TO VOCV

COMPENSATE

VBAT TO VOCV

NO NO

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