TPS2116: If Vinx is floating, will it damage the device? How to design the circuit to force RCB?

Hi Patrick,

If the IFW current is 150m, is that acceptable? The device seems to have some thermal issue and the RCB does not activate.

Is there any tolerance between the TPS2116 that cause some devices doesn't perform RCB and others do in same condition?

Thanks,

Leo

Hi Leo,

By IFW, do you mean the current from OUT to INx?

What thermal issue does the device have - does it enter thermal shutdown? Or does the device keep INx active?

There is some variation in TPS2116 specifications as in all ICs, but in this case it looks to be more system/condition-dependent.

Thanks,

Patrick

Hi Patrick
I'm John, RD from WNC.
The problem I am encountering now is that no matter I supply power from VIN1 or VIN2 or at the same time, when OUT is not loaded, there will be a current consumption of 5V 150mA, and it will get hot very quickly. If the components after OUT are turned on , it can be powered normally, but current consumption and heating will continue to occur. And when 5V is powered from VIN1 alone and VIN2 is floating, VIN2 will have a 5V reverse voltage.
I tried to connect VIN2 to ground with a resistor of 301K, but it seems that the situation will not recover. What is the reason why TPS2116 continues to be hot? Does it mean it is damaged?

Hi John,

Thanks for the updated information. Unfortunately, it looks like the device has been damaged. Do you know if at any point there was > 0.5A from VOUT to VIN for a significant amount of time? If there was, I believe that could have damaged the device, but it is hard to diagnose from here.

Can you replace this damaged device with a new one?

Thanks,

Patrick

Hi Patrick:

In our design, there is no >0.5A current flow from Vout to Vin.

VIN1 comes from BUCK output, VIN2 comes from the battery and the battery is charged by BQ25171.

The battery is often not connected during testing.

And I have done ABA swap and the situation follows NG TPS2116.

Thanks, John

Hi John,

Have you seen multiple TPS2116 units failing? Or just the one?

Can you send a schematic via Leo?

Thanks,

Patrick

Hi Patrick:
3 out of 20 boards I own have had TPS2116 issues.
I sent the schematic to Leo for reference. Is there anything that needs to be modified?
At the same time, I have applied for "Product Return: CPR241095705" and attached the circuit diagram. Please help follow up.

Thanks, John

Hi John,

I don't see any issues with the schematic, but this brings to my memory previous failures due to negative voltage on the inputs - even a very short negative pulse <100ns will damage the device. Is there any chance during fabrication or testing that a negative voltage was applied to the battery connector? Or could the battery have been inserted backwards?

Also, overvoltage due to ringing during switchover could damage the device - but, if these failures were found before board power-up/on first board power-up, then I think we can rule this out.

Thanks,

Patrick

Hi Patrick:

According to our testing process, there will be no negative voltage to the input, but we cannot guarantee that there is any possibility that negative voltage will be accidentally generated during the test, so please suggest how to modify the circuit to avoid the generation of negative voltage.
Can you please explain what overvoltage means? Can you also suggest how to modify the circuit to avoid overvoltage?
These conditions occur after some tests and are not the first time the device is powered on.

Thanks,
John

Hi Patrick,

Thanks for help. Will 6V Zener be good to use as well?

Leo