Posts Tagged ‘theory’

[theory] How does a boost converter behave when it receives input voltage above the target output voltage?

Friday, September 1st, 2017

What is the boost converter doing when it receives input voltage above the target output voltage?

I have a homemade TV remote that I designed with a NCP1402 boost converter so I could power with a single AA and have a 3.3V board voltage. Worked fine in testing, but I wanted more range. So I swapped out the standard 1.5 volt alkaline AA for a 3.7 volt 14500 Li-Ion. The board components can handle the extra voltage. Not worried there. I was curious what the boost converter thinks about the situation.

Example schematic:

Datasheet: https://www.onsemi.com/pub/Collateral/NCP1402-D.PDF

My observations and theory: When I input 3.7 volts and probe the boost converter’s normally 3.3V output, I see the 3.7V input voltage instead. Using block diagram in the datasheet, I imagine the boost converter gets stuck in a voltage feedback loop. Never engaging the oscillator.

See reddit for responses.