I am attempting to recreate the EV172A-S-00A circuit which uses MP172A to get an output of 5V, 120mA.
The changes I made to the reference design for my circuit:
- I added a 1A fuse (Littlefuse 37411000410) before the fusible resistor on my design.
- Used ON-SEMI RGF1M diode instead of SRGC10MH
- Used SMC ES1J diode instead of STTH1R06A
The issue I initially faced was that that the output voltage was 5.764V instead of 5V. I adjusted the values of R1 and R2 and got ~5.3V. It is still not 5V but it is acceptable for now.
The next issue that I faced was that the voltage would sag significantly as soon as there is any load connected to it. I recorded a large voltage drop with just 10mA draw.
EV172A-S-00A circuit: 5.171V at 0mA, 5.012V at 10mA
My original circuit: 5.764V at 0mA, 4.913 at 10mA
My circuit with modified resistor values: 5.368V at 0mA, 4.202 at 10mA
I am looking for some assistance with this issue. I don’t understand why the voltage is falling so greatly on my circuit, but does not drop as significantly on the EV172A-S-00A. The circuit is rated to handle up to 120mA and my current draw is not even close to its limit. Please let me know if there is something obvious that I am overlooking.