Stellarcore
New Member
Hello folks,
I've got a bunch of RGB Leds that I've purchased, and I'm planning on pulse width modulating the colours while multiplexing between 5 of them. So each LED will have a time slice during which the colours are PWM'd for a couple of cycles before moving on to the next LED.
I've tested this on the breadboard, and it seems to work quite well. My question, however, relates to the forward current that the LEDs can handle. Each colour is rated at 20mA constant current, but since I am pulsing them, I should be able to run them at a higher rate.
I've attached a chart from the LED data sheet. In my display, I plan on having at most 5 LEDs on at the same time, so if I set each colour to full (ie 100% pwm), then my duty cycle is 1/5 (or 0.2) and according to the attached chart, I should be able to run them at a peak current of about 200mA if my pulse is on for 100uS or less. I'll likely play it safe and try closer to 100mA or lower for 100uS pulses, lowering the current until it no longer is bright enough for my purposes.
Am I interpreting this chart correctly?
I've got a bunch of RGB Leds that I've purchased, and I'm planning on pulse width modulating the colours while multiplexing between 5 of them. So each LED will have a time slice during which the colours are PWM'd for a couple of cycles before moving on to the next LED.
I've tested this on the breadboard, and it seems to work quite well. My question, however, relates to the forward current that the LEDs can handle. Each colour is rated at 20mA constant current, but since I am pulsing them, I should be able to run them at a higher rate.
I've attached a chart from the LED data sheet. In my display, I plan on having at most 5 LEDs on at the same time, so if I set each colour to full (ie 100% pwm), then my duty cycle is 1/5 (or 0.2) and according to the attached chart, I should be able to run them at a peak current of about 200mA if my pulse is on for 100uS or less. I'll likely play it safe and try closer to 100mA or lower for 100uS pulses, lowering the current until it no longer is bright enough for my purposes.
Am I interpreting this chart correctly?