SLUSEK7 September 2024 BQ25773
PRODUCTION DATA
Refer to the PDF data sheet for device specific package drawings
The charger monitors total system power. During forward mode, the input adapter powers the system. During reverse OTG mode and battery only discharge scenario, the battery powers the system and VBUS output. The ratio of PSYS pin output current and total system power, KPSYS, can be programmed in PSYS_RATIO register bit with default 1 μA/W. The input and charge sense resistors (RAC and RSR) are selected in RSNS_RAC bit and RSNS_RSR bit. If PSYS_CONFIG=00b then PSYS voltage can be calculated with Equation 2, where IIN_A/IIN_B >0 when the charger is in forward charging and IIN_A/IIN_B <0 when charger is in OTG operation; where IBAT<0 when the battery is in charging and IBAT>0 when battery is discharging.
For proper PSYS functionality, RAC practical value is limited to 10 mΩ or 5 mΩ and should be consistent with RSNS_RAC register setting; RSR practical value is limited to 5 mΩ or 2 mΩ and should be consistent with RSNS_RSR register setting.
Charger can block IBAT contribution to above equation by setting PSYS_CONFIG =01b in forward mode and block IBUS contribution to above equation by setting PSYS_OTG_IDCHG=1b.
To minimize the quiescent current, the PSYS function is disabled by default PSYS_CONFIG = 11b.
CASE # | PSYS_CONFIG BITS | PSYS_OTG_IDCHG BITS | FORWARD MODE PSYS CONFIGURATION | OTG MODE PSYS CONFIGURATION |
---|---|---|---|---|
1 | 00b | 0b | PSYS=PBUS+PBAT | PSYS=PBUS+PBAT |
2 | 00b | 1b | PSYS=PBUS+PBAT | PSYS=PBAT |
3 | 01b | 0b | PSYS=PBUS | PSYS=0 |
4 | 01b | 1b | PSYS=PBUS | PSYS=0 |
5 | 11b | Xb | PSYS=0(Disabled) | PSYS=0(Disabled) |