Help with a led matrix 8x8 problem

[Vinay_Ganatra]

when m connecting led matrix to micro controller(PIC18F4520) ,voltage on port pins of controller get reduced and i dont get required pattern on matrix. but when m connecting single LED on that port pin m getting led glowing properly. can any one help me where m going wrong??

 

[vijay satija]

i got it when u connect led matrix led get dim
...becoz led are current operated component .......
when u connect power supply to ur ckt all the current used by controller there is no enough current in ur ckt for drive led matrix .......
there is only two solution u have to use 5A power supply .....
or use ULN 2803 this ic can sink 500ma current and provide to led matrix i am also working on this same project with 8051
if u think this data is helpdul for u
plz press helped ...tjis is ma first one

 

[Vinay_Ganatra]

but m not glowing more than single led at a time, and controller can sink or source current up to 25mA and that is enough for led to glow properly.
and m using power supply of 5V/3A.

 

[vijay satija]

then use a resisitor across a led .....
a voltage drop across resistor will help led to glow.....