Mods: please move to Hardware/Interfacing, I guess it fits better there! Thanks!
I want to drive high power LEDs (18 LEDs, up to 350mA each) using a driver chip that can only sink up to 20mA per channel. My thought: A circuit/IC that linearly converts the current/voltage on each channel into a PWM signal, which can then drive a transistor controlling the LED, as follows:
Is this the best approach? What other possibility do I have to be able to sink 350mA from a driver that sinks 20mA? While preserving the proportionality? (i.e. sinking 10mA at the driver means sinking 175mA at the LED) Feel free to fill out the magic cloud below :)
Requirements: Circuit must SINK current, because the LEDs are common-anode RGBs. Assume there is no alternative for the driver chip, unless you know an I2C compatible PWM driver with at least 18 channels!
Any hints and suggestions appreciated!!