Question from the customer:
Our question is with regards to the TPS65920 OMAP Companion Chip...
We are trying to understand why we are getting ~1V back onto VBAT when 5V VBUS is applied and main VBAT power is not present. With 5V VBUS applied, we see 1.5V on the VPRECH pin N5, which is to be expected based on Figure 15-11 on page 788 of the TPS65950 TRM, but we are also seeing 3.1V on the VUSB.3P1 pin M8. Why is this? Is the pre-charge circuitry switching the VUSB3V1 LDO input from VBAT to VBUS automatically? Is there a way to prevent this? We do not wish to use the battery charging function of the TPS65920 in our application.