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TPS2662: Problem with Hotplug

Part Number: TPS2662

Hi Team

We use TPS26623 VSON10. We have the following schematic:

RTN is not connected to GND. PowerPAD ist connected to GND.

A relais ist placed after the OUT Pin. After the relais ia a capacitor (22µF) and optocouplers.

When the Relais is switched on, and everything works fine, the signals look like this:

Yellow: FLT (Pullup to 3V3)

Green: Out Voltage TPS

Violette: Current

Blue: Don't care

But sometimes when we switch the Relais, the TPS goes into fault state and never recovers (You have to switch the 24V in). Here's a picture of the signals:

Yellow: FLT

Green: OutPut Voltage TPS

Violette: Current

Blue: RTN

Can you please help me why the TPS is going to fault state and doesn't recover?

Why does it sometimes work and sometimes not? Where is the difference?

What have we made wrong?


Thank you for your help




  • Hi Christoph,

    I will get back by early next week on this.


    Kunal Goel

  • Hi Christoph,

    Please see two recommendations from my side to improve your design:

    1. You have shorted thermal pad directly to GND pin, which is not correct. Please short thermal pad to RTN pin.

    2. When you are switching cap it will draw high current from eFuse, which will be like a short circuit event for eFuse device. So eFuse device will turn off . Since you have large inductance in path because of relay, when current through inductance suddenly goes zero it will develop a EMF across it due to which voltage at VOUT pin of efuse device can go negative and cross abs min rating of pin and cause device to misbehave. 

    So we recommend using a schottky diode like placed close to device VOUT pin for suppressing these negative transients.

    3. Also can you tell why are you using relay? You can use eFuse only to switch power to cap. You can use EN pin of eFuse to turn on and off .


    Kunal Goel