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TPS92411 working down to -45C?

Paul Schoenke
Expert 1375 points
Other Parts Discussed in Thread: TPS92411

Hello!

I have a project for which the TPS92411 would be a great fit, but I need the temperature range to work down to -45C.  Would this part be able to work at that temperature or would there be something else in the TI portfolio that would work here?

Any feedback or input is welcomed and appreciated!

Thanks!

Paul

  • 0
    TI__Intellectual 2540 points

    Hi Paul -

    Sorry for the delay.  Of course, we can only "guarantee" the IC down to -40C as per datasheet; however, I spoke to our applications team and no IC related problems were noted at -40 during system evaluation meaning we don't expect issues at -45C, but again have no official supporting data for TPS92411 operation at this temperature.  In summary, the IC is likely to be fine, but the customer should perform their own testing.

    A different, but related concern has to do with the choice of capacitors to use across the LED strings connected to the TPS92411's.  To achieve low current ripple we suggest using properly derated electrolytic capacitors.  They are the most cost effective option for significant energy storage and need to be sizable to achieve low LED current ripple.  The trouble is that electrolytic caps can freeze at extremely low temperatures.  If so, the LED current ripple will increase considerably until the system warms up (assuming it can do so based on the environment it is working in).  Many LED power supplies, including SMPS based ones, use electrolytic caps to decrease LED current ripple.  Customers don’t like them and they often have concerns about using them, but avoiding them is costly and it seems cost wins over lifetime in most cases.  So, using a different IC or drive technique (buck, flyback, etc) may not allay the concerns with low temperature operation if low LED ripple current performance is expected.  Something to consider.   

    The TPS92411 is generally indifferent to the type of capacitance connected.  It does need some minimum amount to bias the IC and operate correctly, but it can be pretty small.  The tradeoff is high current ripple.  Electrolytic caps, as mentioned, have the best energy density and are the lowest cost option.  If sustained operation at cold temperature is expected, the some other suitable capacitor type and size will have to be determined.

     

    John