dimming led driver

Question

I know the basics of powering LEDs and am pretty sure I have found a suitable driver for most of them. The LEDs I have are :

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4 x White Foreward voltage: 9-11v Foreward current: 900 - 1050 mA

4 x Blue Forward voltage: 9-11v Forward current: 900 - 1050 mA

1 x Violet Forward voltage: 9.5-10v Forward current: 900 - 1050 mA

1 x Green Forward voltage: 9-12v Forward current: 900 - 1000 mA

1 x Red Forward voltage: 6-8v Forward current: 900 mA

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I will be powering the white and blue LEDs on 2 x dimable 50-watt drivers with these specs:

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Input Voltage: AC 100V-240V, 50Hz/60Hz

Output Voltage: 30V-36VDC

Output Current: 0-1.5A

Power Factor (PF): 85%

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What I am unsure of is for the rest of the LEDs could I use a driver with these specs:

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Input Voltage: AC 85~265V 50/60Hz Output Voltage: DC 7V~12V Output Current: 900mA~1000mA

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I'm worried about the red LED specifically.

If I can use that driver could I just hook up PWM to the output to achieve dimming?

Answer 1

From those specifications, it is not obvious that these drivers are actually constant current (CC) drivers. Let's suppose, they are. Then you can drive your LEDs with them directly. If you want dimming as well, you can probably do that only if these CC drivers have PWM control input. Normally, you cannot put a PWM dimming circuit after a CC driver, you have to implement dimming within (with the help of) the driver. That's because an average CC driver might not tolerate fast switching of the load on/off. If the documentation of the CC driver states its ability to cope with a PWM-switched load, then it's fine, otherwise probably not.