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Topic: Selecting the right IC chips? (Read 114 times) previous topic - next topic

drafski89

Oct 29, 2014, 05:10 pm Last Edit: Oct 29, 2014, 05:12 pm by drafski89
Hi everybody -

I am working on a project that involves lighting up several blue LED bar graphs (seen here). I wired each of the LEDs in pairs (so there are 5 sections to control) then wired up three of the bars together in series. According to the data sheet, each LED takes 20 mA of power, meaning that each pair would take 40 mA. Additionally, each set takes 3V, so the total voltage drop would be 9V.

My question is this: If I want to use shift registers to dump into the LED display, what would the best IC chips to use? I was thinking the 595 to receive the output from the Arduino. The outputs on the 595 would be connected to a ULN2803 (seen here), which has 8 Darlington pairs. According to the datasheet, the max voltage is 50V at 500 mA. Is there a better solution for me? This seems like overkill (which I am more than happy with), but is there a more elegant solution I'm missing?

Thanks so much for your help in advance :)
Andrew

Quick Edit: I have also looked at the NDP6060L MOSFET, but I would like a single chip that would have a few sets of I/Os contained in one.

Grumpy_Mike

Yes that sounds fine. However you might want to look at the TPIC6B595, that has a FET driver built in and you would not need the ULN2803.

Quote
According to the datasheet, the max voltage is 50V at 500 mA.
Yes but that does not mean that you can use all 8 drivers running 500mA at the same time. Total for all combined is only about 650mA.

drafski89

Thanks so much for your input. At any time, the light array should be drawing 40mA with a 9V drop, so either chip would work fine. I appreciate your offering of another chip. I knew there had to be one out there; I just didn't know where to look.

Thanks again,
Andrew

Paul__B

You said "several".  A (single) MAX7219 would be a good idea to drive six at a time.


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