I am building an array of LEDs that I plan to power up with an LED driver. Here is the one I chose - Mean Well LCM-60U
I have been using it and it works great. However, I have one thing I am trying to optimize on it and that is turning it on and off consistently. That datasheet explains that the turn-on time is about 1 second from cold start and that the turn-on time can vary the more it is turned on and off. I am using PWM control for dimming, but it is not possible to dim all the way to zero current. Turning on and off the AC line works, but I plan to have other controllers working in parallel and I would like them to turn on and off pretty close to the same time (100ms or so of each other).
I have two ideas to go about it, but I am not sure if this will harm the driver in any way. My first idea (that I tried) was to place a relay contact and a few regular diodes in parallel with the LED string. When I click the relay on, the diode absorbs all the current leaving the LED string off. When I want to turn on the LED string again, I open up the relay and the driver goes back to power the LEDs. Since I am cycling between a lower voltage (2V) and a higher voltage (27V), my LED string never gets overvoltaged so I am happy with the result. I just hate that there is wasted energy. My hunch is that no harm is caused to the driver, but I am not sure if this yields more consistent on/off times. Side note: I guess I do not have to use a diode to direct away the current, but a resistor would probably work okay too.
The second idea was to simply have a relay contact in series with the LED string. Thing is, the maximum open circuit voltage can reach 102V. When I close the relay to power the LEDs, I am afraid that the initial 102V will damage my LED string before the current regulates the string and it goes down to 27V.
Any comments on what I have tried so far or other ideas?