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CSD17577Q3A: Question about ID limit

Austin Do
Expert 3315 points
Part Number: CSD17577Q3A

Hi Team,

My customer is using CSD17577Q3A, but there is a design change of battery current limit. The changed the limit to 19A from 16.

Can you explain what are package limited(35A) and silicon limited(83A) and current limit(19A)? In this case, which one the customer need to consider?

Best Regards,

Austin

  • +1
    TI__Mastermind 38330 points

    Hello Austin,

    Thanks for promoting TI FETs at your customer. I am including two links below. The first is an app note that includes links to all of TI's web based technical for our FETs. The second link which is included in the app note, is to a blog on how TI specs continuous current ratings for our FETs. Briefly, the package limit is based on the internal connections between the die and package/lead frame. The other two limits are calculated as explained the blog. These are useful specs when comparing parts. However, the best method is to estimate the power losses in the FET, Depending on the application, we have many FET selection tools (links in the app note) that can be used to estimate the power loss to see if the FET package can dissipate the heat. What is the application? Is this for a switching charger or for the battery charge/discharge FETs? The sync buck or sync boost tool can be used for a switching charger and the load switch tool can be used for battery charge/discharge FETs.

    https://www.ti.com/lit/an/slvafg3b/slvafg3b.pdf

    https://e2e.ti.com/blogs_/b/powerhouse/posts/understanding-mosfet-data-sheets-part-3

    Best Regards,

    John Wallace

    TI FET Applications

  • 0 in reply to John Wallace1
    TI__Expert 3315 points

    Hi John,

    Thanks for reply.

    The application is ultrasound scanner and it is used for battery charge/discharge. The battery current limit is 19A, which means 19A is not nominal current, so it seems that it could be okay to use. What load switch tool can be utilize?

    Best Regards,

    Austin

  • +1 in reply to Austin Do
    TI__Mastermind 38330 points

    Hi Austin,

    You can download the load switch FET selection tool at the link below. You will need to input your conditions and then click on the big blue CLICK HERE button to start the FET selection. Then you can sort by price, power loss or package for up to 3 different TI solutions. I input the following: N channel, low side switch, Vin = 12V, Vg = 10V, Iload = 19A and TJ = 75°C. At these conditions, the CSD17577Q3A calculated conduction loss is 2.149W. This is close to the maximum power this package can dissipate. This will be less if the normal charge and discharge current are lower than 19A. Let me know if you have any questions.

    https://www.ti.com/tool/LOAD-SWITCH-FET-LOSS-CALC

    Thanks,

    John