Arduino Forum

Using Arduino => LEDs and Multiplexing => Topic started by: 8rmfyj5U3Qk on Feb 02, 2013, 10:21 pm

Title: Sinking current on a 8x8 matrix
Post by: 8rmfyj5U3Qk on Feb 02, 2013, 10:21 pm
Hello,

I have a 8x8 LED Matrix. I control the output with a 74HC595 chip, this basically controls the line for the display (given a particular column it controls which LED will be displayed). In this configuration 1 of 8 pins get connected to +5V. This works.

Now I need to controller the column and it depends on which pin is connected to the GND. In this configuration 1 of 8 pins get connected to 0V. This need to be done.

What inexpensive chip exist to do that?

Searching on the forum I saw the PCF8574 but it's not clear to me if it's right and the simplest inexpensive solution for me.

Thanks in advance!

EDIT: or should I use a ULN2803 ??
Title: Re: Sinking current on a 8x8 matrix
Post by: fungus on Feb 02, 2013, 10:36 pm
The TLC5916.

It's just like your 74HC595 but it has eight current controlled inputs.
Title: Re: Sinking current on a 8x8 matrix
Post by: 8rmfyj5U3Qk on Feb 03, 2013, 12:13 am
It does not seem to be in the catalog of my current vendor. Are there any other alternatives?
Title: Re: Sinking current on a 8x8 matrix
Post by: CrossRoads on Feb 03, 2013, 01:30 am
ULN2803, one output low at a time. Buffer arduino outputs with it, or outputs of 74CH595.
Even better, use a TCIP6B595 open drain shift register with high current sinking capability.

Who's your current vendor?
Title: Re: Sinking current on a 8x8 matrix
Post by: 8rmfyj5U3Qk on Feb 03, 2013, 12:21 pm
It seems the ULN2803 needs 8 pins to be controlled, is that right? It's a bit extreme.

I can't find the other ships on http://www.reichelt.de/

EDIT: I found the TPIC6B595,  thank you. (it's TPIC not TCIP)