Designing an 8x8 RGB Led array + controller

Thread Starter

melillo

Joined Nov 15, 2010
2
Hi everybody,

I want to design an 8x8 RGB Led array and it's corresponding controller. I did this schematic, but because the Leds and some components are surface mount, I cannot test it easily before sending it to a PCB manufacturer. My question is: do you see any errors or flaws in this circuit? To simplify, the schematic I show you is for a 4x4 array. As you can see, there is one PCA9634 per color (R, G, B), and each PCA9634 feed a row of four Leds simultaneously. The intensity of each Leds is controlled by PWM inside the PCA9634. The rows are activated one after the other by the CD4051 at a rate defined by the PIC18F4550 microcontroller.

If you have any comments or questions, I will gladly answer!
Thank you in advance and have a nice day,
Marc
 

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Sensacell

Joined Jun 19, 2012
3,432
The CD4051 is not suitable for the high-side driver, it cannot handle much current.

At Vdd 5v Ron is 470 ohms typical- it's not a power switching device, it's for low power signals.
 

Thread Starter

melillo

Joined Nov 15, 2010
2
Thnak you very much Sensacell, I overlooked that parameter. A search a bit and came up with this new design, where I replaced the CD4051 by a 74HC138 and some PNP transistors. Does it make more sense?

Thanks a lot and have a nice day!
Marc
 

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