MPM3630 output voltage shifts to high level voltage under no load condition

DC-DC Power Converters
1

Hi MPS guy，
I select MPM3630 to convert 12V voltage to 0.8V voltage, but I test the output voltage with multi-meter, and find that output voltage floats to high level 1.3V voltage at static load, can you help to explain this problem? thanks.

2

Hello there,

Can you provide a schematic of how you are setting the output voltage? Please clearly show the value of all the components used.

Thanks,
Cindy

3

MPM3630_12V_to_0.8V_sch
MPM3630_12V_to_0.8V_sch1133×239 49.3 KB

Hi Cindy, Please refer to the attached schematic, and the value uesd is complianced with the PCBA BOM installed, thanks.

4

Thanks for providing your schematic.
Does your output ever reach 0.8V? How exactly are you measuring the output? Can you point out where you are probing?

Thanks,
Cindy

5

Hi cindy,
Does your output ever reach 0.8V? ==>yes, if having more than 12mA load(my dc electronic load’s minimized output)
How exactly are you measuring the output?==>if no load, I measure the voltage can increase from 0.8V to 1.3V in some minutes after powering up.
Can you point out where you are probing?==>the point is C420

6

Hi,

Can you probe your Vin and Vout at the same time you power on the part?
Let me know what you see.

Cindy

7

Screenshot_2022-07-18_0_055557
Screenshot_2022-07-18_0_0555571280×800 37.2 KB
Screenshot_2022-07-18_1_055704
Screenshot_2022-07-18_1_0557041280×800 37.9 KB

Hi Cindy, please help to check the images. Thanks.

8

That’s really strange. Exactly how long after powering up does the part go to 1.3V? Does it stay at that voltage if you leave it running?
I’ll test this in the lab and see if I can duplicate what you’re seeing.

Cindy

9

Exactly how long after powering up does the part go to 1.3V? ==》it rises to 1.3V in less than 2 munites.
Does it stay at that voltage if you leave it running?==》yes, if no load, it will saty at 1.3V after powering up.

10

Hi bekogong,

Can you try adding a third 22uF capacitor on the output?
For lower output voltages, it’s recommended to have 3 output caps.

image

Thanks,
Cindy

11

Hi Cindy,
I have installed one 22uF CAP in parrelle with C417, and test the voltage still increase to 1.3V after powering up, thanks.

12

Thanks for trying it. I’ll get this setup in the lab and see if I get the same result.
You aren’t using the EVB correct?

13

I don’t have the MPM3630 EVB :slightly_smiling_face:

14

Hi Cindy,
Any update for this issue? Thanks~~~ :slightly_smiling_face:

15

Hi bekogong,

Apologies for the delay. Have been unable to get into the lab to perform the testing on the EVB.
Could you submit your request directly to MPSNow here: MPS NOW Technical Support - Contact
We will be able to assist faster.

Thanks,
Cindy