LM5575-Q1: Automotive temperature Grade 0

Hello Rick,

Your confusion makes sense to me as I am confused as well

I will clarify with the team...it may be typo.

If it is, we may have to consider alternative device such as

LM5164-Q1 if 1A is enough. Some products in the pipeline also may service this application.

Allow me to follow up.

What is your applications' max vin and max load current requirement?

I assume you do need grade 0?

Hello Rick,

I believe the non-Qgrade datasheet was referenced.

The Qgrade datasheet contains the AEC-Q100 Grade 0 orderable. It is rated, both ambient and junction for Grade 0.

ie: LM5575Q0MH/NOPB

Hi Marshall, thanks for the replies.  I am referring to the Q-grade datasheet, however.  I did see the ordering code, but the only way it makes sense is if the Q0 version has a maximum junction temperature that is higher (quite a bit) than 150°C.  Is that the case, and it's just an error on the datasheet?

Hello Rick,

I am no expert in auto qualifcation standards, but I referenced the specification and it states it requires device ambient temperature to support up to 150degC and device junction to support up to 150degC.

There could be applications in which output power is derated at higher ambient temperature or device only needs to be in standby perhaps, thus little to no rise.

The datasheet has no error.

If this is not satisfactory per your application requirements please let me know what the max vin and max load requirement is.

For example,  we have LM5163H-Q1 with 165degC junction rating.

Thanks again.

Is there any way of finding out the test conditions for the Grade 0 tests?  They may well have been conducted with the device in shutdown mode, but if that's the case, it seems misleading to omit that information.  It would have to be shutdown mode, not just de-rated active mode.

Also, is there definitely no physical difference between the Q0 and the Q1?  Is it just that the tests for the former were done at 150 ambient and shutdown mode and the latter were done at 125 ambient, presumably with some load?

I appreciate your help and understand that you might not have these answers. 

The 1.5A is at the low end really, so the LM5163H-Q1 won't be suitable, unfortunately.  I'm pretty sure I've exhausted all other options.

I see. I will see how grade 0 is characterized as I would think the TSD threshold would be exceeded unless grade 0 variant has different trim.

The thermal shutdown is 180degC. 

The qualifcation would be done to ensure the 150degC ambient and 150degC junction requirement per grade 0

Hi Marshall, I didn't see this reply.  Thanks anyway, but your last sentence doesn't make sense.  You're adding to the confusion!  You originally stated that you understood the confusion, but your last sentence implies that you don't.  There's no point in replying - we're just not going anywhere.