TPS25940-Q1: Multiplexing Power Supplies - eFuse Reverse Current issue

Yassine Damoh

Part Number: TPS25940-Q1
Other Parts Discussed in Thread: TPS25947

Hello all,

I'm using two TPS25940-Q1 in the below matter to switch between two power supplies.

It seems that when both input are present at the same time, then one of them is disconnected, its corresponding e-Fuse stays latched and the output voltage from the second supply is then transferred to the input.

Similar results of this simulation were observed during testing.

Note : IN#1)= 12V < V(IN#2) + 66mV = 12.15V

- Is there a way around this issue by implementing minimum change to the above circuit ?

Thanks in advance for the support.

Yassine

over 1 year ago

0 Kunal Goel over 1 year ago

TI__Guru* 79071 points

Hi Yassine,

Sorry but I could not understand your concern. Can you help explain again?

Regards

Kunal Goel

0 Yassine Damoh over 1 year ago in reply to Kunal Goel

Prodigy 205 points

Hi Kunal,

For example, if both of IN#1 and IN#2 were present at the same time, then IN#1 is disconnected, we can still measure the voltage IN#2 at IN#1.

meaning that there's a reverse current flow from output to input.

I believe it's the same issue described in this thread : TPS25940-Q1: [TPS25940AQRVCRQ1] Reverse voltage related inquiry - Power management forum - Power management - TI E2E support forums

So if there's no 1.57A flow from the output to input, the eFuse is not detecting reverse current.

Thanks,

Yassine

0 Kunal Goel over 1 year ago in reply to Yassine Damoh

TI__Guru* 79071 points

Hi Yassine,

That is true. Device will need around 1.57A reverse current to start reverse current blocking.

Other option is using TPS25942 which has lower current threshold of 238mA.

We have device like TPS25947 that has linear ORing also to block DC reverse current. It will eventually block the reverse current even if comparator threshold is missed.

You can try playing with input cap also to see if helps in increasing reverse current and thus cross the threshold.

Regards

Kunal Goel