Mosaic
Well-Known Member
Hi:
I want to drive a string of 6 Piranha type LEDs, (2.1Vfwd) but my source voltage varies from around 11.5 thru 14.5V. Max continuous current is about 30mA each.
Placing a resistor alone inline to limit the current will cause brightness changes as the drive voltage changes.
Can I approach this by trying to place a FET in linear mode and control it via PWM and a gate RC DAC? I can sample the Vfwd drop across the FET to provide the ADC feedback for the PWM.
Perhaps there's a better approach?
thanks!!
I want to drive a string of 6 Piranha type LEDs, (2.1Vfwd) but my source voltage varies from around 11.5 thru 14.5V. Max continuous current is about 30mA each.
Placing a resistor alone inline to limit the current will cause brightness changes as the drive voltage changes.
Can I approach this by trying to place a FET in linear mode and control it via PWM and a gate RC DAC? I can sample the Vfwd drop across the FET to provide the ADC feedback for the PWM.
Perhaps there's a better approach?
thanks!!