MPM3620 with 24V input

DC-DC Power Converters
1

Hello,

We are using a buck converter MPM3620 in multiple projects. So far is working as expected in our projects, for this projects we used input voltages from 9V to 12V. The problem started when we wanted to use it in a new project which has a 24V power supply.

When doing some testing we found that it works the first time we turn it ON and the output is stable at the desired output 3.44V in this case. The problem is that when we turn it OFF it wont give any output voltage when we turn it ON again.

Is there any special consideration to take when the input voltage is 24V?

I’m attaching the schematic of our circuit. We have tried it with load and without load and the results is the same.

Thanks

MPM3620 schematic
MPM3620 schematic711×295 27.8 KB

2

This is the 24V power supply we are using.

Power supply
Power supply1920×2560 464 KB

3

Well what is the Vin when the part is disabled? Does it go past 28V. Myself I would be more suspicious of the Vbat. That implies the output is powered. Can you try it with a resistive load first

4

Hi,

Vbat is just the output of the converter, there is no other power source after the buck output. I have tried with no load attached as well as with the microcontroller pcb attached. Both cases same result.

Regarding Vin, it is 24V stable. Have checked on the scope with no signs of over voltage on power on but will double check again.

Thanks

5

Hey @jrubio.g.4 ,

Apologies for the late reply. There should not be a special considering to consider with a Vin of 24V. When you say turn off and turn on, do you mean disconnecting the input power supply and connecting it back on? Try capturing the waveform EN and the SW node are seeing. Make sure EN gets no more than 6V for proper operation.

Best,
Jonathan