LM7480-Q1: Inrush current limiting

Andriy Tkachuk

Part Number: LM7480-Q1

Hi,

can I use the CdVdT capacitor for inrush current limiting when the LM7480-Q1 setup is "Unsuppressed Load Dump 200 V - Output Clamp"?

Thank you.

over 4 years ago

0 Praveen GD over 4 years ago

TI__Guru 57737 points

Hi Andriy,

Can you let us know how much Cdvdt cap you are planning to use on the HGate.

0 Andriy Tkachuk over 4 years ago in reply to Praveen GD

Prodigy 180 points

Hi Praveen,

thank you for your quick reply.

I am intending to limit inrush current within 30 and 40 A when the output capacitance is 1500uF. According to the equation from the datasheet, the CdV/dt should be around 2.2nF.

The design nominal output current is around 30A, and the output power is around 0.5kW.

Thank you.

0 Praveen GD over 4 years ago in reply to Andriy Tkachuk

TI__Guru 57737 points

Hi Andriy,

Thanks for providing more information.

There should be no problem in using Cgate if you choose to cut-off the HGATE (like shown below) when there is an over-voltage event including Load Dump.

It is not recommended to use Output Clamp option as during clamping the Voltage across the FET can be as high as 140V (as shown below) and the load current in your case is around 30A. The power across the FET is too high for the FET cannot withstand it for longer durations due to SOA limitations.

0 Andriy Tkachuk over 4 years ago in reply to Praveen GD

Prodigy 180 points

Praveen,

thank you. That was very helpful.

Best regards.

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LM7480-Q1: Inrush current limiting