This anomaly applies to IC Rev. Revision 1, build codes CAAA-C00.
BUCK converter shuts off unexpectedly during mode change.
Mode is changed from PWM to hysteretic automatically, manually, or due to a VSYS voltage transient when, for example, removing a USB cable.
BUCK converter shuts off, and VOUTB is discharged to ground.
Avoid BUCK converter mode change from PWM to hysteretic by always keeping BUCK in forced PWM mode by setting MODE pin to HIGH. This increases quiescent current by several mA compared to hysteretic mode.
If BUCK converter shuts off, it can be recovered by pulling MODE pin HIGH.