RGB strip driver – 12V/150W

[Vermes]

It is a design of RGB strip driver. The device can be used as a lighting driver in a room. This driver allows the control over single compounds of the color (R-G-B) and the brightness of the whole.

This device is equipped with 9 buttons RESET, R: + and -, G: + and -, B: + and – and Brightness: + and -. When the user changes the color of diodes light, the circuit detects the change and then waits for several seconds and stores these new values to the EEPROM. After the restart, the circuit returns the value stored in the memory.

The device is based on microprocessor Atmega8 with 12MHz clock. The system of buttons is the matrix 4x2. Control is carried out via 3-channel PWM. All the channels are set the same: Fast-PWM, 8-bit, Clear Ocxx on Compare Match, without prescaler. The higher frequency, the better.

During normal operation, green diode blinks once a second. When a change of color is detected, the diode indicates counting down the time to store via blinking rapidly. When the blinking goes back to normal one, this means the storing was implemented.

Power stage was made on three Field Effect Transistors IRFR4105 and six bipolar transistors. Using transistors with a low RDS(on)-0,045ohm, provides very low losses, and thus the transistors do not heat up. It is easy to calculate that even if you load a single transistor with a current of 4A, these losses will be only 0,72W on a control element – such power will be spread in laminate without any problems. Bipolar transistors (BC817) ensure more rapid switching of the FET.

The circuit can be also used for direct control form the switch by galvanically isolated input.

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Link to original thread - Sterownik taśm RGB - 12V/150W