tdenson
Posts: 153
Joined: Tue May 13, 2014 1:51 pm

IC for driving LEDs

Wed May 24, 2017 8:21 am

I want to drive 6 LEDs from GPIO pins for a project of mine. Obviously I can wire up the LEDs with 6 transistors and resistors, but I thought there would be an IC that does the job for me. However, I have searched all the usual sources (Farnell, RS, eBay etc) in vain. It seems a simple enough requirement.

scotty101
Posts: 3784
Joined: Fri Jun 08, 2012 6:03 pm

Re: IC for driving LEDs

Wed May 24, 2017 8:31 am

If you just want simple on/off control but need to drive LEDs that require more than the Pi can supply, you could look at something like the ULN2803A, it is a darlington pair array which contains 8 pairs of transistors.Its capable of driving up to 50V and 500mA.

There are obviously similar packages out there with higher ratings.
Electronic and Computer Engineer
Pi Interests: Home Automation, IOT, Python and Tkinter

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joan
Posts: 14607
Joined: Thu Jul 05, 2012 5:09 pm
Location: UK

Re: IC for driving LEDs

Wed May 24, 2017 8:49 am

Have a look at the PCA9685. It is an I2C device and provides 16 channels.

It usually comes bundled in a convenient module, generally marketed as a servo driver but it's intended usage is as a PWM LED driver.

E.g. have a look on eBay for PCA9685 and PWM.

tdenson
Posts: 153
Joined: Tue May 13, 2014 1:51 pm

Re: IC for driving LEDs

Wed May 24, 2017 12:20 pm

scotty101 wrote:If you just want simple on/off control but need to drive LEDs that require more than the Pi can supply, you could look at something like the ULN2803A, it is a darlington pair array which contains 8 pairs of transistors.Its capable of driving up to 50V and 500mA.

There are obviously similar packages out there with higher ratings.
Perfect, thanks very much

tdenson
Posts: 153
Joined: Tue May 13, 2014 1:51 pm

Re: IC for driving LEDs

Wed May 24, 2017 12:21 pm

joan wrote:Have a look at the PCA9685. It is an I2C device and provides 16 channels.

It usually comes bundled in a convenient module, generally marketed as a servo driver but it's intended usage is as a PWM LED driver.

E.g. have a look on eBay for PCA9685 and PWM.
Thanks, but more sophisticated than I need

pcmanbob
Posts: 7743
Joined: Fri May 31, 2013 9:28 pm
Location: Mansfield UK

Re: IC for driving LEDs

Wed May 24, 2017 8:17 pm

tdenson wrote:
scotty101 wrote:If you just want simple on/off control but need to drive LEDs that require more than the Pi can supply, you could look at something like the ULN2803A, it is a darlington pair array which contains 8 pairs of transistors.Its capable of driving up to 50V and 500mA.

There are obviously similar packages out there with higher ratings.
Perfect, thanks very much
Even if you use a ULN2803A you will still need current limiting resistors in series with your LEDs.
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tdenson
Posts: 153
Joined: Tue May 13, 2014 1:51 pm

Re: IC for driving LEDs

Wed May 24, 2017 9:54 pm

pcmanbob wrote:
tdenson wrote:
scotty101 wrote:If you just want simple on/off control but need to drive LEDs that require more than the Pi can supply, you could look at something like the ULN2803A, it is a darlington pair array which contains 8 pairs of transistors.Its capable of driving up to 50V and 500mA.

There are obviously similar packages out there with higher ratings.
Perfect, thanks very much
Even if you use a ULN2803A you will still need current limiting resistors in series with your LEDs.
Yes, I had assumed that

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