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LM5060-Q1: Maximum VIN

Part Number: LM5060-Q1

Dear, Sir.

My customer is applying LM5060-Q1 for their system.

At this time, RMA(device failure) was happened on the system, so they are asking following

points. Sorry to ask you about this kind of matter, but hoping to get your your advice.

1. VIN = 75V, Absolute Max Rating.

   I think it was related to silicon process and it would be a kinf of design spec(not tested

   in manufacturing process).  I wonder my understanding is correct?

2. VIN = 65V, Operating Max.

   They are asking this paramemter is tested in manufacturing process & its frequency(sampling or 100% tested).

   Please give your advice against this kind of question.

3. Diode Clamping on VIN pin.

   If the over-voltage exceed VIN = 75V, What kind of internal component possible to be broken, first?

  

PS) I already proposed to add TVS on VIN line because VIN is appying using long cable from external

      Super-CAP. When LM5060-Q1 was OFF, Higher voltage could be concerned due to BEMF.

Best Regards,

H. Sakai

  • Hideyuki,

    1) Yes, this is silicon process, not production tested. It was thoroughly tested during IC design and validation. 

    2) 65v is where the DS functional specifications are guaranteed. It is not production tested, but was done so during IC evaluation during production release and we work with these all the time in the lab on a regular basis so we are 100% confident in the rating.  Between 65v and 75v, full functional parameters can not be guaranteed, but there should be no damage to the IC as long as no current fault have occurred.  Keep in mind that current protection is very basic on this device, only a time out, not current or power limit.  See section 8.1.5 of the DS.  This device only provides basic protection, not full feature set as with our other HSC devices.  It is the only Q1 HSC part we offer however.

    3) Could be a number of things, including ESD structures.  If the design lacks a front end TVS, Vin can certainly rise above 75v when current fault occurs due to long cable inductance.  Add a TVS on the input to protect against OVP and a power Schottky on the output to keep Vout from going below -0.3v.  Both need to be rated to full short circuit current as it will be dumped into both when the FET shuts off fast.

    Brian