SLUSEK7 September 2024 BQ25773
PRODUCTION DATA
Refer to the PDF data sheet for device specific package drawings
The charger VSYS_UVP is enabled by default (VSYS_UVP_ENZ=0b) and can be disabled by writing VSYS_UVP_ENZ=1b. This protection is mainly defined to protect converter from system short circuit under both startup and steady state process. VSYS pin is used to monitor the system voltage, system under voltage lockout threshold is configurable through VSYS_UVP register bits (2.4 V upon POR), there is 2-ms deglitch time and the IIN_DPM is clamped to 0.5 A (VBUS<14.4V)/0.3A(VBUS>14.4V) to limit short circuit current. Detail protection process is slightly different based on whether hiccup mode is enabled:
If hiccup mode is enabled VSYS_UVP_NO_HICCUP = 0b, after 2-ms deglitch time, the charger should shut down for 500 ms.The charger will restart for 10 ms if VSYS is still lower than 2.4 V, the charger should shut down again. This hiccup mode will be tried continuously, if the charger restart is failed for 7 times in 90 second, the charger will be latched off. FAULT_VSYS_UVP bit will be set to 1 to report a system short fault and CHRG_OK pin is pulled accordingly. The charger only can be enabled again by writing FAULT_VSYS_UVP bit to 0b, then CHRG_OK pin can be released. Note as long as system voltage is below VSYS_UVP threshold, then IIN_DPM is also internally clamped to 0.5 A (VBUS<14.4V)/0.3A(VBUS>14.4V) to limit short circuit.
If hiccup mode is disabled VSYS_UVP_NO_HICCUP = 1b. After 2-ms deglitch time, the charger should shut down and latched off. FAULT_VSYS_UVP bit will be set to 1 to report a system short fault and CHRG_OK pin is pulled accordingly. The charger only can be enabled again once the host writes FAULT_VSYS_UVP bit to 0b, then CHRG_OK pin can be released.