Hello
(This is a follow up question to this thread.)
Could you confirm DC/DC circuit is stable if the pull-up resistor is changed from 1kΩ to 10kΩ?
Summary
1. Power sequence - 3.3V_B is always turned on first, and 3.3V_A is turned on when power button is pressed.
2. When 3.3V_B is ON, 3.3V_A is OFF:
- 3.3V_A is about 1.2V level even though TPS53015 is off state.
- Reverse current is about 900mA via 1kΩ pull-up resistor from 3.3V_B.
3. 3.3V_B doesn't start properly when the power button is pressed. It still stay about 1.2V.
4. If a diode is connected between VREG5 and the bootstrap capacitor C4, it always started normally. Unfortunately this change cannot be applied because Board-A is not our product, and there's no space to rework in the board.
5. We changed the pull-up resistor from 240Ω to 10kΩ with various temperatures, and found it works very well with 10kΩ as on below table.
Could you confirm DC/DC circuit is stable if the pull-up resistor is changed from 1kΩ to 10kΩ?
Best regards,
Choon
Board-A and Board-B configuration
Pull-up resistor and temperature sweep for DC/DC start-up
TPS53015 DC/DC circuit in Board-A
