d123
Advanced Member level 5
Hu,
I'm posting separate threads about one circuit to prevent too many questions making it complicated and messy to understand and answer. I'm trying to break a problem into manageable parts.
If I want three paralled LEDs to carry e.g. maximum 25mA each with a stable DC voltage and current, then make the DC signal/source 100Hz with a 10% ON duty cycle, the LEDs are very dim compared to the constant current.
The maximum LED current is controlled by an op amp constant current and NMOS block, the op amp voltage reference is variable but clamped at 1V to prevent blowing the LEDs with too much current.
Do I need to pass/pulse e.g. 10 times more current through the LEDs for the equivalent brightness achieved with constant DC as the duty cycle is only 10%? That makes no sense to me... Is the duty cycle too low: 1ms on, 9 ms off?
Thanks.
I'm posting separate threads about one circuit to prevent too many questions making it complicated and messy to understand and answer. I'm trying to break a problem into manageable parts.
If I want three paralled LEDs to carry e.g. maximum 25mA each with a stable DC voltage and current, then make the DC signal/source 100Hz with a 10% ON duty cycle, the LEDs are very dim compared to the constant current.
The maximum LED current is controlled by an op amp constant current and NMOS block, the op amp voltage reference is variable but clamped at 1V to prevent blowing the LEDs with too much current.
Do I need to pass/pulse e.g. 10 times more current through the LEDs for the equivalent brightness achieved with constant DC as the duty cycle is only 10%? That makes no sense to me... Is the duty cycle too low: 1ms on, 9 ms off?
Thanks.