LMR14010A: LMR14010A Vin disconnection trouble

juan carlos salido gómez

Part Number: LMR14010A
Other Parts Discussed in Thread: LMR54410, LM5158

Hi all,

I've been testing LMR14010AEVM Evaluation board and I have a trouble. I've modified PCB for VIN=35V, Vout=27V/750mA, Cout = 4.7uF x2 + 100nF

With Resistive Load is working out up to 750mA , but DC-DC has broken when I disconnect and connect VIN positive wire with a Switch and maximum load, the VIN power is a PSU Lab with Current limit 1A.

I've made the test with the same PCB and LMR54410 PN(So the Vout = 28V/800mA ) and the effect was the same, IC was broken as well.

Thanks in advance.

Juan Carlos

over 2 years ago

0 Marshall_Beck over 2 years ago

TI__Mastermind 31830 points

Hello Juan,

An inductive ring will be present in a test your conducting and you could overstress the device.

MY suggestion is, if you are to conduct a test like this, implement a damping network and also, have a protection circuit such as a TVS clamp on the input to ensure no voltage overstress.

0 juan carlos salido gómez over 2 years ago in reply to Marshall_Beck

Prodigy 50 points

Hi Marshall,

Which LC filter would you suggest and bandwidth? The Input for this Buck is the Output of a Boost made with LM5158/7, 28,5Vin , Out = 35V/750mA, 900MHz fsw

Thanks.

Juan Carlos.

0 juan carlos salido gómez over 2 years ago in reply to Marshall_Beck

Prodigy 50 points

Hi Marshall,

Which LC filter would you suggest and bandwidth? The Input for this Buck is the Output of a Boost made with LM5158/7, 28,5Vin , Out = 35V/750mA, 900MHz fsw

Thanks.

Juan Carlos.

0 Marshall_Beck over 2 years ago in reply to juan carlos salido gómez

TI__Mastermind 31830 points

Hello Juan,

I am assuming you are still talking about the hotplug testing you are doing. A LC filter will not prevent electrical overstress on the device. I was advice a damping capacitor to be present on the input (reference) and a TVS to clamp the voltage.

For a LC filter for the buck for compliance testing, I often recommend the corner frequency to be at least a decade below the switching frequency.

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LMR14010A: LMR14010A Vin disconnection trouble