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CSD18540Q5B: 100% duty

Shuji Ishiwata
Mastermind 6285 points
Part Number: CSD18540Q5B
Other Parts Discussed in Thread: CSD17382F4

Tool/software:

Hi All,

I have a question about the CSD18540Q5B.

Is it possible for the CSD18540Q5B to have a 100% duty cycle?

If so, is there any documentation to show this?

Best Regards,
Ishiwata

  • +1
    TI__Mastermind 31845 points

    Hello Ishiwata-san,

    Thanks for the inquiry. There is no limitation on the duty cycle that the CSD18540Q5B can be operated at. The limiting factor is power dissipation and junction temperature rise. For a 5x6mm SON package the max power dissipation capability is around 3W and TJmax for this FET is 175°C. The maximum continuous current specified in the datasheet is calculated as shown in the technical article at the link below. Please let me know if you have any additional questions.

    https://www.ti.com/lit/ta/ssztcp0/ssztcp0.pdf

    Best Regards,

    John Wallace

    TI FET Applications

  • 0 in reply to John Wallace1
    Mastermind 6285 points

    Hi John,

    Thank you for your reply.


    I have an additional question.
    Is there any document that meets the following conditions?

    - Vd: 24V
    - Id: 1.8A
    - Vgs: 4.8V
    - Ta=70℃ (25℃ is fine if not available)

    Best Regards,
    Ishiwata

  • 0 in reply to Shuji Ishiwata
    TI__Mastermind 31845 points

    Hi Ishiwata,

    Are you asking if the CSD18540Q5B can meet these requirements? The answer is yes. The calculated I²R loss is very low: ~13mW. The CSD18540Q5B performance is much higher than required and a lower cost FET can be used. For 24V, you should be able to use a lower voltage, 30V FET in a smaller package. For example, the CSD17382F4, 30V N-channel FET in F4 FemtoFET (picostar) package with ~250mW of conduction loss would be a much lower cost and smaller solution. Please let me know what else I can do the assist you.

    Thanks,

    John

  • 0 in reply to John Wallace1
    Mastermind 6285 points

    Hi John,


    Thanks for your reply.

    There is no documentation, but I understand it can be used.

    The customer is considering the CSD18540Q5B to drive the solenoid.


    Best Regards,
    Ishiwata

  • 0 in reply to Shuji Ishiwata
    TI__Mastermind 31845 points

    Hello Ishiwata,

    I'm still not sure what you mean by documentation. The only documentation is the MOSFET datasheet. The CSD18540Q5B is a 60V FET in 5x6mm with max Rds(on) = 3.3mΩ at VGS = 4.5V and it may be over designed and high cost for driving the solenoid driving requirements from your previous post. For 24V input, a 30V FET should work unless there is some overshoot or spikes which require a 40V or 60V FET. TI has many smaller/lower cost options for this application. In the application, is the solenoid being driven at some frequency or is it a static switch, either on or off?

    Thanks,

    John

  • 0 in reply to John Wallace1
    TI__Mastermind 31845 points

    Hello Ishiwata,

    Following up to see if your issue has been resolved. Please let me know.

    Thanks,

    John

  • +1 in reply to John Wallace1
    TI__Mastermind 31845 points

    Hello Ishiwata,

    Since I have not gotten a response from you, I assume your issue has been resolved and will close this thread.

    Best Regards,

    John