TPS61193: Only one of the multiple sets has Fault pin Low when EN pin Low

Hi Hardy could u help in this case

Hi Wakasugi-san,

Could you help to share your schematic? Fault pin is open-drain structure so that there need a pull high resistor for normal operation. If there is no fault detected, this pin would keep high. When EN disabled, the fault pin should not open and fault pin should still keep high.

Is Fault pin for this set always low, or high originally but became low after work a while? What I suspect is here may some connection issue on the pull-high resistor, could you help to re-solder it?

I share the schematic.

Fault pin is pull up 10k resistor of  the 1.8V voltage. This pin keep the 1.8V ether VDDIO/EN is Hi or Low.

Fault pin is Hi originally but became low after work a while?

I re-solder the pull up resistor, but reproduce it.

best regards,

wakasugi

Hi Wakasugi-san,

The Fault signal should be released and back to high level by toggling VDDIO/EN pin low for a short period of 2 µs to 20 µs. It is really strange that you said 'Fault pin may be Low when EN pin Low'. Maybe this IC is somehow damaged during transportation or operation? Have you tried replace this IC to another good set's IC to see if this abnormal behavior follow IC or board?

If the failure follows the board, it means there are actually faults detected in board. What happened for the LEDs when the fault detected? The fault LED string should be disabled when fault detected.

Thank you for your help.

I haven't tried replacing this IC yet.

However  I tried replacing the good LED(LCD panel), but this fault didn't happened.

So I don't think it's the LED issue.

Hi Hardy, please keep following this case.