seven segment

i want to use a common cathode 7 segment with decoder ic7447using ULN2003..hw to do that??

You would want to use the ULN2003 as an input for the decoder, which accepts BCD.( each digit of a number is coded in binary rather then the entire number which wouldnt matter for a single digit display) connect the outputs of the decoder to the corresponding inputs of the display. Hope this helps

There is absolutely no reason to use a ULN2003 to drive a 7447 decoder chip. The 2003 is a open collector, high current darlington arrays used for driving things like motors or relays. OP, you need to give more details on what you want to do.

You can't. To drive a common-cathode display you need a high side driver, and the 7447 and 2003 are NPN open collector low side drivers.

To do this you could use a PNP driver for each display segment controlled by the 7447 outputs. Connect the transistor emitters to the plus supply and the bases through a resistor to their respective 7447 outputs. Connect the transistor collectors through a resistor to the respective display segment. Ground the display common-cathode terminal.