Questions:
1. Why do switching regulator ICs have dedicated PWM inputs pins?
2. Can you use PWM on a low side switch at the output of a constant voltage buck regulator module? For instance Remcom Power's R-78E5.0-1.0. My concern is that dedicated PWM inputs operate differently than using an external low side switch on the output of a module. Concerns include:
a) Would the buck regulator module be able to switch completely on and off quickly enough?
b) Would buck regulator module have inductor current oscillation issues from turning on and off so quickly?
Context:
I have a single high power RGBW LED with each channel requiring between 2.7 and 3.5 Vdc at 150mA per channel.
I have an Bluetooth RGBW controller that outputs 12 Vdc.
I want to be able to connect the two together but I do not want to step down the voltage by using linear regulation (resistors or voltage regulator) because it gets way too hot: 12V - 2.7V = 9.3V -> *0.150A = 1.4W (similar calculations for other channels).
Instead, I'd like to use some kind of switching regulator to step down the voltage.
My potential solutions include:
1. Finding a 4 channel constant current buck regulator with 4 PWM inputs that control each channel independently. I'd use a highly resistive voltage divider on the output of the RGBW controller to control the 4 PWM inputs of the 4 channels. I do not know if a chip like this exists? Anyone?
2. Could I get a way with using a 1-channel constant voltage buck regulator + four low side switches for PWM on the output of each RGBW channel of the LED? My concerns with controlling a buck regulator module (that doesn't have a PWM pin) are listed at the top of my thread.
What do you guys think about this?
1. Why do switching regulator ICs have dedicated PWM inputs pins?
2. Can you use PWM on a low side switch at the output of a constant voltage buck regulator module? For instance Remcom Power's R-78E5.0-1.0. My concern is that dedicated PWM inputs operate differently than using an external low side switch on the output of a module. Concerns include:
a) Would the buck regulator module be able to switch completely on and off quickly enough?
b) Would buck regulator module have inductor current oscillation issues from turning on and off so quickly?
Context:
I have a single high power RGBW LED with each channel requiring between 2.7 and 3.5 Vdc at 150mA per channel.
I have an Bluetooth RGBW controller that outputs 12 Vdc.
I want to be able to connect the two together but I do not want to step down the voltage by using linear regulation (resistors or voltage regulator) because it gets way too hot: 12V - 2.7V = 9.3V -> *0.150A = 1.4W (similar calculations for other channels).
Instead, I'd like to use some kind of switching regulator to step down the voltage.
My potential solutions include:
1. Finding a 4 channel constant current buck regulator with 4 PWM inputs that control each channel independently. I'd use a highly resistive voltage divider on the output of the RGBW controller to control the 4 PWM inputs of the 4 channels. I do not know if a chip like this exists? Anyone?
2. Could I get a way with using a 1-channel constant voltage buck regulator + four low side switches for PWM on the output of each RGBW channel of the LED? My concerns with controlling a buck regulator module (that doesn't have a PWM pin) are listed at the top of my thread.
What do you guys think about this?