I make small LED lamps for craft projects, powered by USB chargers. I recently started making my own aluminium PCBs with 3.3V SMD LEDs. (Total current in the range of 0.5-1.0A)
Problem: Too much heat generated from resistors to drop the voltage from 5V to 3.3V. So I ditched the resistors, and tried using a buck converter to drop the 5V from the USB charger, but the LEDs starting flickering extremely badly. I then tried with a 'low ripple' buck converter, which didn't work either. The combination which did work was 5V from bench power (or random 5V wall adapter) and the 'low ripple' converter.
I'd like to understand the relevant technical difference between the USB charger and the 5V wall adapter, if there is any way I can still use my stock of USB chargers, or if not, how I can make sure that any 5V wallwart I buy is not going to have the same problem.
Thanks!
Problem: Too much heat generated from resistors to drop the voltage from 5V to 3.3V. So I ditched the resistors, and tried using a buck converter to drop the 5V from the USB charger, but the LEDs starting flickering extremely badly. I then tried with a 'low ripple' buck converter, which didn't work either. The combination which did work was 5V from bench power (or random 5V wall adapter) and the 'low ripple' converter.
I'd like to understand the relevant technical difference between the USB charger and the 5V wall adapter, if there is any way I can still use my stock of USB chargers, or if not, how I can make sure that any 5V wallwart I buy is not going to have the same problem.
Thanks!