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TPS22953: Vout drop issue of TPS22953?

Jason Chien42
Expert 1180 points
Part Number: TPS22953
Other Parts Discussed in Thread: TPS2121

Dear Sir:

               We follow datasheet page 32 , Figure 63. to design our circuit as below picture, We have a issue as when U4 IN1 turn off and Vout have drop as below picture 2 , Does TI have suggest to us? such as increase output capacitance?

CH1=>+3.8V

CH2=>+VBAT

CH3=>SW1_PG

CH4=>SW2_EN

  • 0
    TI__Genius 10855 points

    Hi Jason, 

    Thanks for reaching out on E2E!

    The TPS22953 power mux configuration is intended to work in a "break-before-make" configuration. This ensures that one power supply is completely disconnected before the other power supply is connected. This prevents any fast reverse current from damaging upstream components, such as your VBAT_S or 3.8V supply. There are a few recommendations to minimize VOUT dip:

    1. As you mentioned, you could increase your output capacitance to reduce the voltage dip as the supplies switchover
    2. Take a look at our Power MUXing using Load Switches and eFuses app note. Page 11 shows a configuration using 2 eFuses in ideal diode mode that creates a "make-before-break" configuration, minimizing output voltage dip. 
    3. We just released a new integrated power mux device, the TPS2121. This device can switchover between supplies in 5us using fast switchover, minimizing output voltage dip. 

    Please let me know if you have any questions!

    Thanks,

    Arthur Huang