ULN2003A on AVRMega168

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#1
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Hi,

I need to drive 6 LEDs with a Mega68, each LED needs 50mA. My plan is to use a ULA2003A as driver. I never used this chip and as hoping someone here has some experience with it:

1) Does ULA2003A work with the 3.3V output from the Mega168? Supply voltage for the connected LEDs is 3.3V also.

2) There is a verison ULA2003AI "with 2.7kOhm resistor for direct TTL logic input". Should they both work?

Thanks a lot for the help,
Tappo

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Some leds take more than 3v to light up. Better check how much they take.

Imagecraft compiler user

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Also, any driver has "forward drop" which you need to add to the LED drop. If the driver is an FET that is characterized by "ON resistance", then simply subtract this resistance from the series current limit resistance.

Jim

 

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And if you are planning on driving the ULN2003 inputs with an AVR powered from 3V3, you will more then likely need a logic level translation between the AVR controller outputs and the ULN2003 inputs, as the ULN2003 is designed for 5 volt logic. The ULN2803 may give better performance, but you'll need to look at it's data-sheet, to be sure.

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