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Author Topic: Shift registers? Display Drivers? Comparison  (Read 895 times)
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Is there a good comparison chart of information that can explain the differences in shift registers or LED display drivers.  I have been using the Max7221, but I an curious to know differences or reasons for using other things that seem to pop up.

Ex.  max7219, max7221, 74HC164, TLC5940, 4021?   ????

Thank you in advance for your help.
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Sounds like a good challenge for you. Put a chart together comparing ease of use, # of LEDs, voltages that can be directly supported, ease of PWM capability, ease of use with LED matrix, RGB LED, single LEDs, multiplex support needed, etc.
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Yeah, I was hoping someone had already done this.  I do not know enough yet.  Is there a explanation/comparison chart or article?

Cheers,
Dan
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Not that I know.
Start with the part you are familiar with, the MAX7221, and come up with a summary of what you know as a starting point:
64 LEDs, 5V, SPI interface, etc. Come up with a table format to put the characteristics into,  and go from there.
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You can probably compile a more comprehensive list, however, my take:

1) max7221 / 7219 are practically the same.
2) minor differences between hc164 and hc595.

leds to drive: max7221 / 7219 / 5940 can drive a lot of leds. in the case of those first two, up to 64 leds. hc164/595 can drive up to 8 leds.
types of leds to drive: max7221/7219 only common cathode. hc164/595 can drive any leds.
driving mechanism: max7221/7219/5940 are constant current type drives. hc164/595 requires an external part to achieve that.
brightness control: 5940 can control individual led's brightness. 7221/7219 can control only the brightness of all leds. hc595 offers pwm capabilities but the user has to drive it. hc164 has no pwm capabilities.
working voltage: max7221/7219 cannot work reliably at 3.3v or lower (I think the datasheet suggests 4.xv minimum) - you may not be able to reliably initialize it. 5940 works down to 3.3v, as does hc164/595. 4021 works to 15v (per datasheet) or 18v (my experience).
signaling: 7221 follows spi convention (with a cs pin). Others don't.
latching: hc164 is transparent: the output sees the transmission. others offer output latching.
speed: I have driven hc164/595 to 32Mbps without any problem. I doubt others can.

That's what I can think of now. Others may add more.
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7219 & HC595 work just fine with SPI as well.
Common cathode vs common anode - there is no difference, they can be used interchangebly with a little thought.
Look at the attached - one is advertised as common cathode, one as common anode - where is the difference?
5940 is common anode only for sure as it only sinks current.


* CommonCathode_vs_CommonAnode.jpg (80.57 KB, 960x720 - viewed 24 times.)
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Designing & building electrical circuits for over 25 years. Check out the ATMega1284P based Bobuino and other '328P & '1284P creations & offerings at  www.crossroadsfencing.com/BobuinoRev17.
Arduino for Teens available at Amazon.com.

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