LM5050-1: LM5050 HV Application Circuit Question

Wei-Hao Chen (TW-FAE)

Part Number: LM5050-1

Hi champs,

My customer is interested in the HV circuit we suggested for VCM>80V, but they are not sure about the function of Q2. Would you kindly explain this?

Thanks a lot..

Best Regards,

Wei-Hao

over 5 years ago

0 Karikalan Selvaraj over 5 years ago

TI__Genius 16305 points

Hi Wei-Hao,

This circuit can operated upto 10V-100V nominal range and can handle 200V transients at the input and output.
Q2 is required to protect LM5050-1 during output transient, when the output goes higher during normal operation then Q2 turns off to protect OUT pin from seeing higher voltage (out pin can withstand only 100V absolute maximum voltage).

Regards,
Kari.

0 Karikalan Selvaraj over 5 years ago in reply to Karikalan Selvaraj

TI__Genius 16305 points

Hi Wei-Hao,

Let us know if you have further questions here, otherwise if you think your question is answered please click on "this resolved my issue" button.

Regards,
Kari.

0 Wei-Hao Chen (TW-FAE) over 5 years ago in reply to Karikalan Selvaraj

TI__Expert 3260 points

Thanks Kari, my customer has no further question.

0 Wei-Hao Chen (TW-FAE) over 5 years ago in reply to Karikalan Selvaraj

TI__Expert 3260 points

Hi Kari,

M y customer has one more question, can you please provide the BOM that we used to test this circuit?

Do you any recommendation for Q2? During the normal operation the Q2 gate voltage will be really close to the Q2 source voltage which might not be able to reach th Vth of the Q2 FET, how do we ensure the FET can be turn-on during normal operation? Is Q2 depletion FET?

Thank you.

Best Regards,
Wei-Hao

0 Karikalan Selvaraj over 5 years ago in reply to Wei-Hao Chen (TW-FAE)

TI__Genius 16305 points

Hi Wei-Hao,

Q2 is depletion MOSFET like BSS126.
If you require further questions, can we take this through offline email conversation.

Regards,
Kari.

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LM5050-1: LM5050 HV Application Circuit Question