Hi TI Team,
We encounter an issue that the BQ25883 sometimes didn't power up the REGN LDO and converter when the 5V VBUS (thru Type-C female receptacle, from the wall charger or laptop's USB-C port) was inserted without the battery pack presence, the VSYS was not generated at all; however the REGN LDO and VSYS probably were turned on at other moments (still no battery but 5V VBUS inserted only);
You can refer to our schematic & layout (Allegro 17.2), we left BQ25883's D+&D- as N.C., besides we didn't put a small decoupling capacitor for PMID.
The datasheet indicates:
The REGN LDO supplies internal bias circuits as well as the QHS and QLS gate drive. The LDO also provides
bias rail to TS external resistors. The pull-up rail of STAT and PG can be connected to REGN as well. The
REGN is enabled when all the below conditions are valid.
1. VBUS above VVBUS_UVLO_RISING in boost mode or VBUS below VVBUS_UVLO_RISING in buck mode
2. Poor Source Qualification detects a valid input source
3. Input Source Type Detection completes and sets appropriate input current limit
I'm wondering if our design goes wrong or some specific conditions cause REGN not be turned on?
Sincerely,
