MP5031 Circuit Topology

DC-DC Power Converters
1

Hi,

I’m planning to create a circuit as shown in the attached image. In the reference circuits for the MP5031, I’ve noticed that a buck-boost converter is typically used. However, in my design, I intend to use a step-down converter to provide a 5V output that powers both the USB Type-C port and the MP5031.

To prevent current backflow and manage inrush current, I’ve incorporated a load switch between the 5V source and the Type-C connector. The VDRV pin of the MP5031 will drive this load switch. When a USB device with a battery is plugged into the USB port, the MP5031 will enable the load switch and manage the PD (Power Delivery) negotiations.

My questions are:

  1. Is there any issue with this design approach?
  2. Where should I connect the VBUS_P pin of the MP5031—before or after the load switch? Since the VBUS_P pin has a discharge function, and I’m connecting it to the 5V system power, I want to prevent any unwanted discharge. How should I handle this?

Thanks

MP5031_TOPOLOGY
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2

Thanks for any insight

3

Hello again,

I don’t see any issues with this design approach. However, for your application, I would just defer to the following typical application where VBUS_P is connected to the output of the DC/DC converter.

image
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Typically, VBUS_P would be directly interfaced with the DC/DC converter. Since you have the load switch to protect from backflow and to protect from inrush current, then connecting this at the VOUT of the load switch appears to be the best move here. Test for functionality when doing this to see if you get the desired behavior.

Best,
Krishan