TPS2121: Power sources transition issue

Paul Yeh

Genius 16175 points

Part Number: TPS2121

Hi team,

My customer use TPS2121 to do power mux switch, one is 12V, the other is 5V.

But there is long output voltage drop during 12V plug out period. Below is customer's circuit and testing waveform.

Please advise what is possible reason?

CH1: Sout

Ch2: USB_IN

BTW, there is loading in Sout pin and 600ms voltage drop then Sout return back to 5V.

And please also double check below schematic for strange portion.

Thanks

over 4 years ago

0 Shreyas Dmello over 4 years ago

TI__Mastermind 32650 points

Hi Paul,

Your schematic is not showing up online. Feel free to email me directly at s-dmello@ti.com

It is likely that the device is bouncing between the inputs causing the output to drop. This occurs whenever the rails move due to the loading and unloading events especially if fast switchover is used. Is there any hysteresis used on this setup? Please reference this document for more information: https://www.ti.com/lit/ug/tidue50/tidue50.pdf

Section 2.2.2 describes the need for hysteresis.

0 Paul Yeh over 4 years ago in reply to Shreyas Dmello

TI__Genius 16175 points

Shreyas,

Thanks and already add you in mail loop with detail circuit.

BRs

Power management

Power management forum

TPS2121: Power sources transition issue