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CSD17506Q5A: Continuous Drain Current

Part Number: CSD17506Q5A
Other Parts Discussed in Thread: CSD17577Q5A,


Customer is confused. Can you please specify which maximum current rating customer should take? 100 or 23A? And what is the difference? Thank you.

Best regards,


  • Hello Randy,

    Thanks for promoting TI FETs at your customer. The maximum drain current ratings in the datasheet are calculated as explained in the blog at the link below. The 100A continuous current rating assumes the case temperature can be held at 25°C which in theory would require an "infinite" heat sink to maintain. The 23A continuous current rating is calculated using RθJA as measured on a single layer PCB as explained in Note (1) and shown in the figure on the left below the note in the datasheet. Actual performance in the customer's application will depend on PCB layout & stackup and ambient temperature and airflow. With a good layout on a multilayer PCB, RθJA can be reduced to 15°C/W to 20°C/W. Why is the customer using the CSD17506Q5A in their application? It is an older, higher cost FET. We have a newer, lower cost, pin-to-pin replacement, CSD17577Q5A, with slightly higher on resistance (4.2mΩ vs. 4.0mΩ max at VGS = 10V). I'm including a second link below to all of our FET web-based technical information. In includes links to documentation, app notes, tech articles and FET power loss and selection tools.

    Best Regards,

    John Wallace

    TI FET Applications