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I'm designing a power distribution system, for connection an auxiliary battery to my system.

The idea is to use a power distribution mux, similar to TPS2124 from TI. I want to be able to control the switch-over from my uController:

enter image description here

The problems I have is the following:

  1. Vsupply can range between 5-36V, which the TPS2124 cannot handle.
  2. Current output of the power mux should be up to 5A
  3. I want to control the switch over, but if Vsupply is removed, then the system should automatically switch over to the auxiliary battery

I'm unsure if this is the best solution or if there is a single chip solution that can handle the charging requirements as well as the option to switch over from the uController.

Looking for inputs on the design.

Thanks!

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1 Answer 1

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If you use a micro-controller make sure your software is able to react pretty fast in order to switch from mains to battery.

I did that in the past and I never had problems.

Bulk capacitors on the +3V supply bus are able to keep alive your micro-controller for a minimum of 10 ms, depending on the board design.

As a power mux you may use two pnp 60V MOSFET's in parallel. In this case you will have to use 2 output pins of your micro-controller to turn selectively on the 2 MOSFET's.

https://www.digikey.com/en/products/detail/vishay-siliconix/SIHFR9024TR-GE3/10641179

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  • \$\begingroup\$ It should be possible with the MOSFET in parallel, but is it possible to get the same solution in a dedicated IC, like with the TPS2124? And how do you handle the automatic switch over if the Vsupply is removed? \$\endgroup\$
    – stackman82
    Commented Mar 22, 2021 at 13:11
  • \$\begingroup\$ Texas Instruments' power muxes products have a maximum ratings of 22 Volt. The switch over in case of MOSFET's is handled this way: every 10 ms fire an interrupt and measure the value of your power supply. If it's below a certain threshold, than do the swtich over. \$\endgroup\$ Commented Mar 22, 2021 at 13:33

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