MPM54304 - Hardware termination and software guidelines for disabling an unused VOUT4 channel

Integrated Inductor Power Modules
1

Hi Team,

We are using the MPM54304 for a power supply application where we only require 3 output channels.

Since we are not using Channel 4 (VOUT4), we have a few hardware and software implementation questions:

  1. Software/MTP Configuration: Is setting the EN4 bit to 0 sufficient to permanently disable VOUT4 at boot? Also, could you clarify whether we should configure this change in the runtime register address 0x0C or if there is a direct MTP mirror address we must target?
  2. Hardware Termination: What is the recommended hardware connection for the unused pins? Should VOUT4 (Pins 22, 23) be left floating, and should the feedback pin FB4 (Pin 24) be left floating or tied directly to Signal Ground (SGND)?

Kindly provide us with the correct hardware layout and software configuration guidelines for this scenario.

Thank you!

2

Hello Girish,

What is the input voltage, load currents, and output voltages that you have for the 3 channels you are using? The reason I ask is because you could connect channel 4 in parallel with one of the other channels to provide headroom to one of the channels to increase efficiency, therefore improving thermals and IC reliability.

We have configurations of this module where channels 1 and 2 are paralleled by default or channels 3 and 4 are paralleled by default. See this configurations on page 42 of the MP54304 datasheet.

To answer your questions though, setting the EN4 bit to 0 should sufficiently disable VOUT4 at boot. You’ll want to save this setting to NVM such that this continues to be the case by default. Floating or pulling this unused pin to GND should also be ok.

Please let me know if you have any additional questions.

Best,

Krishan

3

Hello Krishan,

Thank you for your explanation.

Our output requirements are:

Buck1: 5.0V ,150mA

Buck2: 1.8V,20mA

Buck3: 3.3V,100mA

Since all three channels operate at very light load compared to the available output current

capability of each buck, we believe paralleling channel 4 is not necessary for our application.

We will proceed with disabling Buck4 by setting EN4=0 and programming the setting into

the device’s MTP so that it remains disabled after power-up.

Thank you for confirming that the unused VOUT4 and FB4 pins can be left floating.

Thanks again for your support.

Best Regards,

Girish K