ZHCSO21 may 2021 BQ25720
PRODUCTION DATA
The charger VSYS_UVP is enabled by POR ( 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, when VSYS is lower than 2.4 V (configurable through VSYS_UVP register bits), there is 2-ms deglitch time, the IIN_DPM is clamped to 0.5 A by the charger itself.
If hiccup mode is enabled with 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 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. The charger only can be enabled again by writing Fault VSYS_UVP bit to 0b.
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. The charger only can be enabled again once the host writes Fault VSYS_UVP bit to 0b.