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TPD3S716-Q1: Why the VBUS_SYS input capcacitor is 100uF

cao yumei
Prodigy 40 points
Part Number: TPD3S716-Q1

Hi TI Support  Team 

 I notice that the TPD3S716 datasheet shows that the input capacitor for VBUS_SYS pin is 100uF. I know that the maxim value of the current is 2.4A , so when the hotplug happens , the load transient response need be took into consideration, so we need choose a big capacitance capacitor.

I want to know if we really need choose 100uF  capacitance ,  I think it is big , so could you help guide me how to calculate its value ? 

By the way , if we set the output current value is 0.9A via the Radj value setting, 100uF is still needed?

  • 0
    TI__Mastermind 36045 points

    您好

    关于这个部分的配置官方给与的建议是100uf，至于原因请看下面datasheet原文说明

    The VBUS_SYS pins provide power to the chip and supply current through the load switch to VBUS_CON. A 100-µF
    bulk capacitor is recommended on VBUS_SYS to supply the USB port and maintain compliance. A 1-µF capacitor
    is recommended on the VBUS_CON pin with adequate voltage rating to tolerate short-to-battery conditions. A
    supply voltage above the UVLO threshold for VBUS_SYS must be supplied for the device to power on.

    cao yumei 说：
    By the way , if we set the output current value is 0.9A via the Radj value setting, 100uF is still needed?

    https://www.ti.com.cn/cn/lit/zip/slvmbj4

    结合您的实际情况，通过官方仿真模型辅助您验证您实际应用那个电容值为最佳。