I’m trying to use MP28167GQ-A-P without needing I²C. My input voltage varies from 8V~18V. Output spec is 12V+/-10% with up to 1.7A DC load.
Note below the circuit:
My problem is that when I pull ~0.5A the regulation drops and MP28167 gets into hiccup mode. I understood from the datasheet that the default OC level is 3.5A. Can anyone help me identify why my circuit is protecting for such a low load? What is the actual OC default level?
Hi Pedro,
Sorry to hear you are having some issues with the MP28167. According to the datasheet there are 2 reasons why overcurrent protections can occur.
"1. The first is if VOUT exceeds 3V, VFB drops
below 50% of VREF, and VOUT drops below 3V.
The MP28167-A then enters hiccup mode or
latch off mode according to the I2C setting.
2. The second is if VOUT is set below or equal to
3V, and VOUT drops below the under-voltage
(UV) threshold (typically 50% below VREF).
The MP28167-A then enters hiccup mode or
latch-off mode according to the I2C setting.
In hiccup mode, the MP28167-A stops switching
and recovers automatically with 12.5% duty
cycles. In latch-off mode, the MP28167-A stops
switching until the IC restarts (power cycling on
VIN or EN, or EN bit toggling). "
Looking at your schematic, I would add a decoupling capacitor at VCC. Since VCC powers the internal circuitry, not decoupling could result in unexpected behavior. Use 1uF.
Thanks Stephen,
In my case, Vout is >3V (12V). Please confirm the following:
Is Vref constant set to 1V by default?
Is output current limit set 3.5A by default?
In this case, I’m not sure why I can’t put on any load.
Thanks for the suggestion on the decoupling capacitor at VCC. I’ll try that.
