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CSD18533Q5A: How to find 40V and 60V N-MOSFET for minimum heat generated

Part Number: CSD18533Q5A
Other Parts Discussed in Thread: TMS320F28027, DRV8301, CSD18511Q5A, CSD17576Q5B


      Our current platform is TMS320F28027 + IR2101S + AOD4184 FOC sensorless 3 phases DC pump controller, however we find that the heat generated is too much and need quite big heatsink, to reduce size of heatsink & housing we plan to use TI MOSFET SON5x6 because we ever tried BOOSTXL DRV8301 board, the heat generated is what we expected our final product is.

       We have two line of product, one is for 24VDC 6A power supply and the other is 36VDC 5A, carrier frequency is 10kHz, using InstaSPIN solution, we have some questions :

1) Is TI 30V MOSFET is good enough for driving 24VDC pump ? The max. voltage of the DC power can be upto 25.5VDC. What is the typical headroom required to drive a pump safely ?

2) We find there are more than 10 products are tentative but with different parameters and price, is there any formula (or comparsion method) that help to compare N-MOSFET parameters so that we can find the product with least heat generation within our budget, eg. USD 0.5@1k


  • Nikolaus, 

    It is possible to use 30V FET with 24Vin. We see some customers do this, others prefer more headroom at like 40V. It really depends on what the ringing on the FET looks like. 

    You may have to use a snubber if you wish to use 30V devices. For motor control, your losses are going to be dominated by conduction losses, which means the lower resistance, the less power dissipation and increase in temperature. 

    If I limit the search to devices where the 1k price is less than $0.50, the lowest resistance 40V device would be the CSD18511Q5A. 

    The lowest resistance 30V device we have with 1k price under $0.50 would be the CSD17576Q5B.