SLUSEK7 September 2024 BQ25773
PRODUCTION DATA
Refer to the PDF data sheet for device specific package drawings
The device charges the battery in four phases: trickle charge, pre-charge, constant current, constant voltage. At the beginning of a charging cycle, the device checks the battery voltage and regulates current/voltage accordingly. If autonomous charging is enabled, automatic termination can be achieved and automatic recharge will begin when VBAT drops below certain value of CHARGE_VOLTAGE(), user registers VRECHG bits are used to configure battery re-charge threshold.
When charger is in trickle charge status (VBAT<VBAT_SHORT) and EN_LDO=1b, charge current is upper limited by IBAT_SHORT to prevent battery from overcurrent charge and wake up battery pack. The practical charge current should be the lower value of CHARGE_CURRENT() and IBAT_SHORT to provide EC flexibility to program trickle charge current following battery package request. Note when EN_LDO=0b, IBAT_SHORT current clamp is not effective and provide EC flexibility to program charge current through CHARGE_CURRENT() register.
When charger is in pre-charge status (VBAT_SHORT<VBAT<VSYS_MIN()) and EN_LDO=1b, charge current is the lower value of IPRECHG() and CHARGE_CURRENT() setting; and the maximum charge current is limited by maximum setting of IPRECHG() which is 2048mA to prevent overheat generated on BATFET. Under this condition larger VSYS_MIN() minus VBAT delta and larger charge current should generate more thermal dissipation at BATFET which should be properly limited to ensure safe operation. Therefore the device has additional two levels current clamp to ensure the maximum BATFET dissipation loss below 2W based on the relationship between VBAT and VSYS_MIN() setting referring to Table 7-9. Note when EN_LDO=0b, pre-charge current limit (IPRECHG()) is not effective and provide EC flexibility to program charge current through CHARGE_CURRENT() register.
VBAT CONDITION | CHARGING CURRENT | DEFAULT SETTING | CHRG_STAT |
---|---|---|---|
VBAT< VBAT_SHORT | IBAT_SHORT | 128mA | 001 |
VBAT_SHORT<VBAT< VSYS_MIN() | IPRECHG | 384mA | 010 |
VSYS_MIN()<VBAT<CHARGE_VOLTAGE() | CHARGE_CURRENT() | 0A (need host to configure based on battery request) | 011 |
If the charger device is in DPM regulation during charging, the actual charging current will be less than the programmed value. In this case, termination is temporarily disabled and the charging safety timer is counted at half the clock rate, as detailed in Charging Safety Timer section.