Hello,
I have a problem with MPM3612-33, it outputs 0.6V instead of 3.3.
My board design is based on EVM3612-33-LQ-00A.
I can’t find a solution could you please help me ?
My schematic
Bottom layer
Top layer
Mid layer 1 (power)
Mid layer 2 (GND)
Hi julien,
Welcome to MPS technical forums!
MPM3612 has two versions, ‘-33’ is a dedicated fixed 3.3V output voltage and there is one with adjustable one.
Looking at the schematic it looks OK overall except the R5 = 220k resistor. You need to remove that resistor, as this part has internal FB resistor dividers built in.
Removing R5 should give you the required output. Please refer to EVB schematic.
Regards,
Adhish
I removed R5, and the problem is still there.
Hi julien,
That is very strange to happen.
What is the input voltage and load current you are applying? Did you try checking if this is happening at various load?
Regards,
Adhish
Hi Adhish,
Yes I have tried with my cheap current load tester, with load from 100mA to 1A and still the same problem.
I have also tried with input voltage from 5VDC to 22VDC.
Hi again Adhish,
Upon reviewing the datasheet, I realized that the marking on the component installed on my board starts with BNR (adjustable output) and not BNT (3.3V output). I think the manufacturer made a mistake.
So if I replace R4 with a 976K resistor and a 220K resistor for R4, it should output 3.3VDC.
Are you okay with my diagnosis?
Hi julien,
That could be the possible reason for the Vout being 0.6V.
Yes, having R4=976K and R5=220K should give you the required output voltage of 3.3V
Regards,
Adhish
Can you confirm that the BNR marking corresponds to the MPM3612 adjustable output version, and BNT to the 3.3 V fixed output version ?
I need a confirmation so I can tell the PCB manufacturer that they made a mistake.
Hi julien,
Yes, after checking our internal database for top marking;
the BNR corresponds to adjustable output version and BNT is for fixed 3.3 Vout, which is given in the datasheet as well.
Regards,
Adhish
Hi Adhish,
Thank you for your reply. The PCBA manufacturer made a mistake.
After changing R4 and R5 with correct values, I now get 3.3V at the output.
Thanks for your help.
This topic can be closed.
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