Converting 21 inputs into 8 inputs for EEPROM address pins

Question

I am just diving into the world of multiplexers, so my knowledge of them is not the greatest. I am trying to develop a circuit that can control 10 RGB LEDS (30 total LEDs) via 2 inputs per LED and one input that affects all LEDs (21 total inputs). I would like to achieve this with an EEPROM, so I was going to try a LED multiplexer on the output pin, but I am unsure if there exists a multiplexer that can pull in 21 inputs and condense them down to 8 inputs so that they are addressable on the input side.

I would like to avoid a microcontroller, because I want to see if it can be done with an EEPROM. Thanks for the help ahead of time!

Truth Table utilizing 7 EEPROM ICs:

I am sure that this is super inefficient cost-wise and space-wise, since it uses 7 EEPROMS for 13 RGB LEDs (39 total LEDs). The left table is the input into the 15 Address pins on the EEPROM, and the right table is the I/O output pins to the LEDs. The table with Blocks 1-8 control 12 RGB LEDs (36 LEDs), and the bottom table is a single EEPROM that controls a single RGB LED (3 LEDs). Let me know if this all makes since or if I can clarify anything.

Answer 1

If you only require the visual appearance of the LEDs being controlled, you could use (say) the lower 3 address inputs on the EEPROM and clock them at a relatively high frequency (kHz), then multiplex the LEDs in 8 banks, giving you up to 64 outputs.

If you have RGB LEDs with common anodes you would likely want to drive them in 5 pairs of 2 with two EEPROM outputs unused and 3 bytes of EEPROM unused (you could count to 5 rather than 8 to improve the duty cycle).

So you have a 3 bit counter and a 1 of 8 decoder, a clock oscillator and 6 sink drivers (eg. ULN2003A) and 5 high-side source drivers (could be a few dual MOSFETS) for the 10 LEDs. Plus 6 resistors. You might need to add a one-shot multivibrator to reduce ghosting.

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Edit:

^{simulate this circuit – Schematic created using CircuitLab}