Welcome to EDAboard.com

Welcome to our site! EDAboard.com is an international Electronics Discussion Forum focused on EDA software, circuits, schematics, books, theory, papers, asic, pld, 8051, DSP, Network, RF, Analog Design, PCB, Service Manuals... and a whole lot more! To participate you need to register. Registration is free. Click here to register now.

Sinking/sourcing current for LED Matrix.

Status
Not open for further replies.

mouzid

Full Member level 5
Joined
Jun 22, 2007
Messages
249
Helped
9
Reputation
18
Reaction score
0
Trophy points
1,296
Activity points
2,876
current sinking and sourcing

Hi edaboarders,
I do not really understand how to use the ULN2003a for my dot matrix project. The matrix led that I have is common anode, I connect the PORT B of my PIC to the ULN2003. The output of the ULN goes to the row of the matrix, the PIN 9, of the ULN is connected to +5V and the PIN 8 to GND.
Unfortunately leds seems to be not receiving power supply and I see no leds blinking. I used another ULN but the problem persisted.
What's wrong with my circuits ?
Do you know a better circuit that the ULN to source current to led ?

Thanks in advance for you replies.
 

mouzid

Full Member level 5
Joined
Jun 22, 2007
Messages
249
Helped
9
Reputation
18
Reaction score
0
Trophy points
1,296
Activity points
2,876
blueroomelectronics said:
Post your full schematic. Also how are you driving the columns? You need an anode drive circuit.

Hi all,
Schematic is simple. The ULN2003 drives the Rows and the other pins of the dot matrix goes to GND.

Reading the datasheet I realised that the ULN2003 is for sinking current.
Could you please tell me guys the equivalent circuit of the ULN2003 for sourcing current and capable of delivering 500ma ?
 

Status
Not open for further replies.

Part and Inventory Search

Welcome to EDABoard.com

Sponsor

Top