• Welcome to our site! Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.

Shift Register Issue

Suraj143

Active Member
I'm doing a 8x8 LED matrix design.Rows driving via B562 & columns driving directly from 74HC595 (via a resistor). Doing a 1/8th scanning method.

The problem is only NXP brand 74HC595 is surviving & cheap Aliexpress SN74HC595 ICs are heating (only working few minutes) & getting stuck & heating too much.

How to avoid above situation?
 

Attachments

rjenkinsgb

Well-Known Member
Most Helpful Member

ChrisP58

Well-Known Member
The 74HC series can only source or sink very low currents and are not at all suitable for direct driving a LED matrix.

Looks at the MIC5841YN - that is a combination of a shift register plus high current darlington driver transistors:
http://ww1.microchip.com/downloads/en/DeviceDoc/mic5841.pdf

There is also a 5891, which is a "high side" version, switching its loads to a positive supply (anything up to 50V) rather than ground.
http://ww1.microchip.com/downloads/en/devicedoc/20005638a.pdf
Nice parts. But the ~2.3 V saturation voltage on the MIC5891 might make it a no-go for use on 5V rails.
 

rjenkinsgb

Well-Known Member
Most Helpful Member
But the ~2.3 V saturation voltage on the MIC5891 might make it a no-go for use on 5V rails.
We use them for 24V system outputs, I'd not consider them for as low as 45V.

The 5841 outputs are fine for things at 5V etc., no different to any other general darlington driver output.
 

Latest threads

EE World Online Articles

Loading

 
Top