Modify the output voltage on a PWM controller to fall within LED driver range

Question

I'm trying to use a simple PWM controller (this) as a dimmer for a Meanwell LED driver (this).

The driver accepts PWM dimming but needs a voltage range of ~2-8V, and the PWM controller outputs 7-12V when powered by the 12V input I'll be using.

Is there an easy way I can modify the controller to get the voltage down to this range?

Would lowering the input voltage lower the output range too? Or could I simply change the value of the pot/add in a resistor or two, or would that destroy the PWM signal?

I will be repositioning the potentiometer from the controller as space is very limited in my use case, so some soldering is required anyway. However the theory on this is a bit beyond my skill level.

Many thanks for any help on this

Answer 1

The easiest way would be to use a transistor to pull the PWM-Dim pin down to PWM-.

The PWM-Dim is also the on/off signal for the power supply. Open (no connected, floating) is on. Connected to PWM- is off. That means it has a pull up connected internally. All you have to do is pull down PWM-Dim.

Your PWM controller provides up to 5A of current, and is complete overkill. You can still use it.

Here's how I'd go about it:

^{simulate this circuit – Schematic created using CircuitLab}

It has the disadvantage that the dimmer knob on your PWM controller will work backwards. This circuit inverts the PWM signal. When the PWM controller generates a 1% duty cycle, the LDH45 will receive a 99% duty cycle. When the PWM controller generates a 90% duty cycle, the LDH45 will receive a 10% duty cycle.