LM5116: Reverse Input Polarity

Aidan Phillips

Part Number: LM5116

Hello,

I am in a situation where i'd like to check that the LM5116 will not be damaged due to an input condition. The situation is as follows:

Upstream of the LM5116 there is a unidirectional TVS from VIN to GND. If there is a negative transient, then the voltage from Vin to GND is clamped to about -0.7V. This breaks the datasheet specification of -0.3V.

If a diode is added from the power positive line to the Vin pin, will this protect against the reverse current situation from the negative transient described above?

Aidan

over 4 years ago

0 EricLee over 4 years ago

TI__Guru 68581 points

Hello Aidan

Yes, the device can be damaged if the negative spike exceeds its Abs Max ratings.

Usually, the negative spike at the device input does not exceed its Abs Max by placing the TVS as close to the connector/source of ESD events as possible.
If the reverse surge is long and can cause an excessive negative spike at the device pin, a reverse voltage protection diode is used in general.

- Eric Lee

0 Aidan Phillips over 4 years ago in reply to EricLee

Prodigy 140 points

Thanks Eric, where is the best place for the reverse voltage protection diode. To the input, or from pin ground to circuit ground?

0 EricLee over 4 years ago in reply to Aidan Phillips

TI__Guru 68581 points

Hello Aidan

It should be at the input side between TVS and the converter. Please refer https://www.ti.com/lit/an/slva139/slva139.pdf

- Eric Lee

0 EricLee over 4 years ago in reply to EricLee

TI__Guru 68581 points

Hello
I am closing this thread since I have not heard from you for sometime.
If you are still trying to resolve the issue, please feel free to open a new thread or reopen this thread. Thanks
- Eric Lee (Applications Engineering)

Power management

Power management forum

LM5116: Reverse Input Polarity