I'm designing a circuit that should be able to connect to two active radio antennas. The antennas are phantom powered, 12V, and has a current consumption of 25mA each. It should be possible to turn phantom power off with 3.3V logic in case a passive antenna is connected.

The power supply section of the circuit consists of the following: 12V from the car battery -> TVS-diodes -> smart diode ic (LM74610) -> EMI filter before it is distributed to consumers through separate 3.3V and 1.8V converters.

My question is how to best provide power to the active antennas?

  1. Take 12V directly after the EMI filter and use a high side switch with embedded protection circuitry. Like this from Infineon
  2. Use a separate voltage regulator with ON/OFF and embedded protection circuitry. Like this from Semtech.
  3. Something completely different?

Automobile DC is notoriously badly regulated, has a ton of variable frequency ripple, and is noisy as all heck. You need a well regulated supply for this, or you will just be creating a wonderful noise transmitter.


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