LED stepdown power supply


Posted on Apr 25, 2012

Below is a proof of concept circuit which needs improvement. The part values shown will run a high efficiency red LED with a Vf of 1.9V from only 2 nicads, right down to 2 volts. For a white LED you will need more batteries and you must increase the 1.0K resistor to a higher value. Current sensing at a mere 18mV over 1ohm makes this stepdown switcher efficient, but efficiency can be increased by using a larger inductor, improving transistor switching speed, or by increasing the value of the 1.0K resistor. Positive feedback from the driver transistor back into the current mirror through the 47K hysterisys resistor ensures that this circuit behaves as a switching power supply, however it could be used in linear mode if this resistor and the inductor were removed.


LED stepdown power supply
Click here to download the full size of the above Circuit.




Leave Comment

characters left:

New Circuits

.

 


Popular Circuits

A Talking Fish using PIC16F819
Wien bridge oscillator circuit
The anti exciting type switching power supply based on FSDM0565R is designed
Current to voltage converter proofing
pulse width modulation
hygrometer
Some interesting Projects
Pipe Descaler
Effective output 50W distortion rate of 0.003% thick film hybrid amplifier



Top