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Original question:

CSD87352Q5D Maximum Switching Frequency

CSD87352Q5D: Does pin4(Vtgr) and pin6/7/8(Vsw) are connected inside the IC?

BX27
Genius 3900 points
Part Number: CSD87352Q5D

Tool/software:

hi we use CSD87352Q5D for buck. 5V to 1V, 10A.

Does pin4(Vtgr) and pin6/7/8(Vsw) are connected inside the IC? from the snapshot of Datasheet, it seems so. Could you pls help confirm?

If so, the layout requirement of Switching Node copper should be applied to both these pins. Right? thanks.

By the way, what does the pin 4 TGR means?

  • 0
    TI__Mastermind 38560 points

    Hello BX27,

    Thanks for your interest in TI power block FETs. The TGR pin is the return path for the top FET gate drive. As indicated in the Layout Guidelines on page 15 of the datasheet, it should be routed separately from the SW node copper back to the driver IC. It is also where the boot strap capacitor should be connected. Please let me know if you have any additional questions.

    Best Regards,

    John Wallace

    TI FET Applications

  • 0 in reply to John Wallace1
    Genius 3900 points

    Hi John,

    1, yes, the datasheet only says The TGR pin is the return path for the top FET gate drive. but not mention how WIDE and how long shoule this trace be , or other requirements, is there any suggestion?  

    For example, for SW pin, the copper area should be minimized and ensure enough width for enough current, and short length.

    2, as I marked with blue rectangle, TGR pin seems connected with SW pin inside the IC ?

  • +1 in reply to BX27
    TI__Mastermind 38560 points

    Hello,

    Yes, TGR is internally connected to the drain of the low side FET (SW) with a bond wire. The length of the trace should be as short as possible to minimize the inductance. TGR carries the same current as TG and the trace width for both should be the same. The recommended layout (see below) in the datasheet shows a trace that is not as wide as the PCB pad (0.650mm nominal). The SW connection to the FET die is made with a copper clip capable of carrying high current. As I mentioned the TGR connection is made with a bond wire. It is not intended to carry the high current like SW.

    Thanks,

    John