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CSD18532NQ5B: ID consult for different Vgs

Lin_Charles
Expert 4260 points
Part Number: CSD18532NQ5B
Other Parts Discussed in Thread: CSD18532Q5B

Hi team,

It is nice to know you here. My customer wants to know the ID value when Vgs is 3.8 to 4V during different TA, I cannot find this value from below curve. For example, how can I get ID when VDS=24V, Vgs=3.8V, and TA=-40C? 

BR,

Charles Lin

  • 0
    TI__Mastermind 31995 points

    Hi Charles,

    Thanks for promoting TI FETs at your customer. The transfer characteristics curve in the datasheet is for a single, typical device. The data is collected during product development at 3 temperatures: -55C, 25C and 125C. Unfortunately, we don't have data for 40C. Attached you will find the raw data collected during product development and the curves displayed on a log scale. Can you tell me what the application is and why the data is required? You can contact me on my TI.com email if you do not want to share details about the application on the public e2e forum.

    CSD18532NQ5B Transfer Data.pdf

  • 0 in reply to John Wallace1
    TI__Expert 4260 points

    Hi John,

    Thank you for your help here. My customer used this device to boost topology to converter 9-15VDC to 22V/5A. They have two questions below,

    1. If TA=-40C, VGS=4V, the MOS may not fully turn on when the peak current is 16A and average current is 4A (see waveform below), will MOS break in such condition? 

    2. If the MOS can not turn on fully, the customer wants to use body diode to conduct the current above, will it have any risk if TA=70C?

    Hope to get your professional advice here. Thanks.

    BR,

    CL

  • 0 in reply to Lin_Charles
    TI__Mastermind 31995 points

    Hi Charles,

    Thanks for the follow up. First, TI cannot guarantee rds(on) when VGS < 6V for the CSD18532NQ5B. We can only guarantee what is specified in the datasheet Electrical Characteristics: at VGS = 6V and at VGS =10V. This is where the FETs are tested during production.

    Second, why did they choose the CSD18532NQ5B and not the CSD18532Q5B? This FET has a lower threshold voltage and rds(on) is specified down to VGS = 4.5V. This might work better in their application although we still cannot guarantee rds(on) at VGS = 4V.

    Lastly, in theory the body diode has the same current carrying capability as the MOSFET channel when it is on. However, it is limited by the power dissipation: VF x ID is usually going to be greater than ID x ID x rds(on). The customer needs to take this into account when doing their power loss calculations.