5x7 matrix display...

[simrantogether]

hi nigel and everyone..

i need to make a 5x7 matrix display..
for this i am using max 6952 but i was not able to get the full data on this..

can you help me.. in some way..

simran..

 

[Gayan Soyza]

To run a 5X7 display you don't need an additional MAX 6952 IC.
It’s designed to limit I/O pins in a micro or to control through serial interface up to 4 digits.

Directly driving from a MICROCONTROLLER will be easy than you expect.
A 18 pin PIC is enough for the job. The circuits are all over the internet.

 

[joeyla]

I'm currently using this device for the first time in a project. They are very straightforward to use, just follow datasheet recommendations.

I do wish to power higher current/voltage LED matrix with it and I'm struggling to find a suitable circuit. Anyone any suggestions.

 

[simrantogether]

for high power.. add uln 2803

hi joela...

for any circuit you design.. and you want to add high power...

just interface ULN 2803 or ULN 2003 with it..

the circuit diagram is easy...

just add it between the microcontroller and the device you want...

remember,

the output you get in uln2803 is inverted hence add not gate before uln2803...

just make the picture of this reply...

regards

simran..

 

[joeyla]

The MAX6952 has supply pins for the LED anode and sinking pins for the LED catode. I can see who the ULN2803 could be used for the sinking but will it also work for sourcing, or vice versa?

 

[simrantogether]

current sinking...

hi,

since it is used for current sinking hence.. i asked you to add one not gate before uln2803..

it is a very common ic..

 

[joeyla]

So what can I use for the sourcing side of the LEDs (Anode) ? Will a standard high current BJT work. Should I use NPN or PNP. I never really know when it is appropiate to use NPN or PNP, is there a general rule for this, likewise for N-FET or P-FET.

 

[simrantogether]

hey.. dont worry...

dont worry...

just you have to do is if it is common anode then directly interface it with uln 2803

if it is common cathode then add and gate...

ok, if getting confused then read the following titles on this page...

dont worry if your microcontroller doesnt match.. just refer this site..

www.freewebs.com/maheshwankhede

read the following titles:

1. interfacing led's switches with 8051... in this you not will use uln
2. interfacing seven segment with 8051... in this also you will not use uln
3. interfacing stepper motor... in this you shall be using uln...

simran

 

[simrantogether]

sorry.. by mistake

if it is common cathode then use 'not gate'..

 

[justDIY]

this may be of some use to you, controlling a 5x7 matrix using a micro controller

https://projects.dimension-x.net/archives/101

no special purpose driver chips were used or needed, just PFets to drive the anode columns, and internal drivers of the uc to sink the cathode rows.

 

[joeyla]

I can see what your saying but the MAX6952 has multiplexed outputs so the sourcing and the sinking needs to be switched on/off. The ULN2803 is Ok for the sinking part but the sourcing, which will be 24V in my case is not permanently connected, it needs to be switched on and off also, so a sourcing element similar to the ULN2803 does for sinking is needed.

 

[joeyla]

Hi all. I think I may have found a solution to my sourcing problem. I've found a device, UDN2981A which seems to be what I'm looking for. Has anyone any experience of this device? Do you think this will solve my sourcing issue. I can then use the ULN2803 inverted for sinking the current.

I think I should have been searching for "High Side Switching" all along.

 

[simrantogether]

udn2981

hi joyela,

to find the function of an IC is simple like udn...

go to google.com... then click to images.... the enter these of similar keywords..

"udn2981 projects"

the image you find important.. visit that website...

i think this may help you....

simran.