LM5060: TIMER pin question

Patrick Chen

Part Number: LM5060

Hello,

Below are normal chip and abnormal chip on the same board testing. For abnormal chip, Voltage of TIMER pin exceed 2V threshold condition. Could I know what is the issue root cause of this abnormal chip to cause this phenomenon ？ LM5060 already run 4K pcs normal chip but happen this one abnormal chip. Thank you.

Normal chip

Abnormal chip

Patrick

over 6 years ago

0 Brian Daugherty over 6 years ago

TI__Expert 5940 points

Patrick

Most likely a fault is present on the board and the timer has timed out, shutting down the gate. Look at the timer at power up along with current.

Brian

0 Ann_Lien over 6 years ago in reply to Brian Daugherty

TI__Genius 10640 points

Hi Brian,

Have you seen this issue before? We know TIMER behavior is abnormal but TIMER pin is output pin and we want to know if this is due to IC internal damage or TIMER pin damage. Thanks!

Best regards,
Ann Lien

0 Brian Daugherty over 5 years ago in reply to Ann_Lien

TI__Expert 5940 points

Timer looks to have just timed out. you need to look at current, Vin, Vout, Vtimer, Vgate at power up to know what is happening.

Brian

0 Ann_Lien over 5 years ago in reply to Brian Daugherty

TI__Genius 10640 points

Hi Brian,

Thanks for reply!

I looked into it and found out Vgate will not go up (keeps zero always) and VTIMER pin rises in the beginning with no fault occur(no VDS or start up fault). For the same board, we tested with a new and good LM5060 and it could turn on normally. So we believe this issue is because of IC itself. We measured every pin impedance(versus GND and also gate to source and drain to source) and there is no previous short/open in result. We want to know if there is anything we can try to find the root cause.

Thanks a lot!!!!

Best regards,
Ann Lien

0 Brian Daugherty over 5 years ago in reply to Ann_Lien

TI__Expert 5940 points

Ann,

Would need to see start up waveforms requested to help further. Email these as easier to diagnose. You may have a damaged IC.

Brian

0 Ann_Lien over 5 years ago in reply to Brian Daugherty

TI__Genius 10640 points

Hi Brian,

Thanks a lot!! I will send you start up waveform by mail, thanks!

Best regards,

Ann Lien

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LM5060: TIMER pin question