I have a problem where I would like to have 2 options for powering my board - via multiple LDOs or via a benchtop DC power supply with one output.

The issue is that there are four HPAs each consuming 6V @ 1000mA so they each have their own LDO. I would also like to be able to power them from one of the outputs of a benchtop DC power supply for testing.

Does anyone know how I would go about placing a connector so that the HPAs can pull from either individual power supplies or all from the same power supply?

Note: This is a pretty space-constrained (~2"x3") RF board.

  • \$\begingroup\$ Are all 4 getting power from the same source? Are your ldo on board? Current schematic? \$\endgroup\$
    – Passerby
    Feb 7, 2022 at 21:29
  • \$\begingroup\$ What is an HPA? \$\endgroup\$ Feb 7, 2022 at 22:14
  • \$\begingroup\$ @ScottSeidman it stands for High Power Amplifier. \$\endgroup\$
    – brunerm99
    Feb 7, 2022 at 22:26
  • \$\begingroup\$ @Passerby yes, all the LDOs are powered by the same 7.4V supply and are on-board. I might just end up connecting the benchtop supply to the LDO inputs instead of individually powering each. I just thought it might be useful for minimizing failure points. \$\endgroup\$
    – brunerm99
    Feb 7, 2022 at 22:28

1 Answer 1


You could use something like LTC4414 or some other power selector switch to enable/route the voltage from the LDOs.

I assume you can set the lab supply higher than 6 V to overcome diode forward voltage of the example schematic and it should stay higher than the LDO voltages after the diode too, so the LTC4414 can detect it's precense.

  • \$\begingroup\$ I was not aware of devices like the LTC4414, so thanks for the pointer. I would rather not add any extra components if possible, so I will probably just end up powering the HPAs by connecting the LDO inputs to the benchtop supply rather than powering them separately. I will accept the answer though, because it will most likely work for someone else. \$\endgroup\$
    – brunerm99
    Feb 7, 2022 at 22:35
  • 1
    \$\begingroup\$ Thanks! Some input connectors also have a switch that disconnects when you insert the power input plug. That could be used to disconnect the lab supply, if you happen to have one of those types of connectors in use. \$\endgroup\$
    – Ralph
    Feb 8, 2022 at 6:29

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