i want to drive 12 digit seven segment. i am using common anode (positive) seven segment. i connect segment to directly to pic16f877a's portb. since due to deficiency of pin. i use cd4514 demux to drive common anode of the seven segment. since output current of cd4514 is very much less. seven segment light dull. can anybody suggest me remedy for this.
cd4514 can only provide a few ma (about 3mA) and you expect it to provide up to 80mA to the common display supply, it can't drive the display correctly
No he can't, he is using common anode displays and he wants to use the uln2003 to control the common supply of common anode displays, the segment cathodes are connected to the PIC
i am using common anode (positive) seven segment...
i connect segment to directly to pic16f877a's portb...
Yes it is , ULN2003 can be connected in any load that has the other end connected to the positive supply, in your case the ULN2003 drives the display cathodes and the common anode is connected to the positive supply (directly or through a transistor switch to be able to do multiplexing)
i have a problem with uln2003apg.i connected 5v to common. ground to GND pin. connected 0v to one of input supposing high at output,.but i don't get it.
whether uln work fine with 5v?
may i have to pull up input?
thanks in advance
Your connection is correct but the output will sink current when the input is high.
When the input is 0 the output will be off (floating), if there is any load working as a pullup then the output will be high.