JAJSS91 November 2023 BQ25756E
PRODUCTION DATA
When battery charging is enabled (EN_CHG bit =1 and CE pin is LOW), the device autonomously completes a charging cycle without host involvement. The device charging parameters can be set by hardware through the FB pin to set regulation voltage and the ICHG pin to set charging current. The host can always control the charging operation and optimize the charging parameters by writing to the corresponding registers through I2C.
PARAMETER | VALUE |
---|---|
Charge Stages | Precharge → Fast Charge (CC) → Taper Charge (CV) → Termination → Recharge |
FB Voltage Regulation Target (VFB_REG) | 1.536 V |
Battery Low Voltage (VBAT_LOWV ) | 66.7% x VFB_REG = 1.0245 V |
Recharge Voltage (VRECHG) | 97.6% x VFB_REG =1.4991 V |
Charging Current HW Limit (ICHG pin) | ICHG = KICHG / RICHG |
Pre-Charge Current HW Limit (ICHG pin) | 20% x ICHG |
Termination Current HW Limit (ICHG pin) | 10% x ICHG |
CV Timer | Disabled |
NTC Temperature Profile | JEITA |
Safety Timer | 12 hours |
A new charge cycle starts when the following conditions are valid:
For lithium-ion battery charging, the charger device automatically terminates the charging cycle when the charging current is below termination threshold, charge voltage is above recharge threshold, and device is not in DPM mode. When a full battery voltage is discharged below recharge threshold (threshold selectable via VRECHG[1:0] bits), the device automatically starts a new charging cycle. After the charge is done, toggle either CE pin or EN_CHG bit can initiate a new charging cycle. In addition, the device offers a dedicated CV timer to stop the charging after a programmable period (CV_TMR bits) in CV mode, regardless of the charge current value.
The status register (CHARGE_STAT) indicates the different charging phases as:
When the charger transitions to any of these states, including when charge cycle is completed, an INT pulse is asserted to notify the host.
Supercapacitors do not require Trickle Charge or Pre-charge regions when their voltage is low. For supercapacitor charging, setting the EN_PRECHG bit to 0 can disable both of these charging regions. In this case, the charger outputs ICHG current as long as the feedback voltage (VFB) is below VFB_REG. The following settings are recommended for supercapacitor charging: