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TPS92641: TPS92641 design confirm

Guangyan Liu
Intellectual 2130 points
Part Number: TPS92641
Other Parts Discussed in Thread: CSD19534Q5A

Dear Team

Good day

My customer want to use the TPS92641 in their application , their design requirement is 

Vin=55V , Vout =45V , Led current =10A  , digital dimming and analog dimming .

I had check the datasheet ,most of requirements can be met , I am worried about the power consumption ,it is 450W , from your experience , could you help me to confirm whether TPS92641  can be used in this application . could you suggest some mosfet part number for me ?

If the TPS92641 is not suitable , could you provide some other devices which are suitable.

Best regards,

 Leon.liu

  • 0
    TI__Mastermind 28655 points

    Hello Leon,

    The TPS92641 will work however this design is more about the power stage design at this power level.

    As for MOSFET choice.  The approximate conduction loss will be RDSon*I^2.  If 20 mohm MOSFETs are used that would be approximately 2 watts for both MOSFETs.  Since the duty cycle is high the upper MOSFET will get the most conduction loss.  The switching loss will probably be the largest loss, this will have to be calculated based on what you want your design to do.  Switching frequency choice is a big part of this design.

    CSD19534Q5A is a part that could work depending on how you heatsink the MOSFETs (metal core board in this case), it may require two in parallel on the top position since duty cycle will be above 80%.  If FR4 board is used TO-220 packaged MOSFETs tied to a heatsink may make more sense.  Choosing MOSFETs is related to switching frequency choice, heatsinking capability and method as well as ambient temperature and other design criteria.  Again, this is a power stage design that needs to be able to operate from the TPS92641 gate drive capability.  If you assume 95% efficiency you will have to dissipate 24 watts in the power stage which will be the MOSFETs, current sense resistor, inductor and other losses.

    Best Regards,