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For big numbers of LEDs i'd be tempted to use shift registers direct, ie 8 LEDs per 8bit shift reg. You save all the multiplexing etc and you can just concentrate on basic driving and PWM.
That would work too. You'd only need about 42 shift registers for 330 LEDs (140 left + 140 right + 50 transom) but you might be able to use a similar modular daisy-chain topology.
Years ago I designed a LED advertising sign with about 800 LEDs. I used a shift register. Multiplexed the LEDs. Which brings me to a question about the design so far. If you use 20mA LEDs and 8x multiplex them then the LED current may be 160mA at 1/8 duty cycle.
I think I ran the LED current at 0.5 amp peak at a very low duty cycle. Will your design run the LEDs at 150mA and low duty cycle? Can the drivers handle that? If LED current is 150mA and a column driver handles 8 LEDs then the total is 1.2 Amps.
One of the companies I design for uses 5,000,000 LEDs a year. Yes I am looking for more work.
The 5.6 amp figure I mentioned was for all 56 LEDs in a single row (spanning 7 driver boards) lighted at the same time (unlikely) at 100-ma or approximately 12.5-ma "average" current with the 1/8th duty cycle. The Vishay Si2312BDS is rated at 5.0 amps (5 seconds) and up to 15.0 amps in "pulsed" mode with the usual junction temperature and heat sink disclaimers. Now even though most of these LEDs have a max' 100-ma "peak" current spec', I suspect they would work just fine at higher "peak" current levels at a 12.5% duty cycle, yes, no? Each N-FET row driver is on 1/8th of the time. The MIC5891 column drivers have 500-ma outputs which only drive one LED at a time so they should do fine sourcing 100-ma or even 150-ma to each LED, yes, no?
Now I see the 5A FET drivers. OK
I looked at a number of data sheets and see the "100mA max". I know I have used 20mA LEDs at higher levels but those were different parts. Probably 100mA at 12.5% will give good light.
Use 2 oz copper and heavy traces to carry away heat. If you keep the PCB about 90% copper the LEDs will be cooler.
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