The 4028 CMOS IC not only contains the complete decade counter, but also the 7-segment decoder with current limiting resources. This means that this IC can directly drive a common-cathode display as shown in Figure bellow. The count advances with the positive transition of the clock input. RST becomes “1" to return the count to 0. The output of divide-by-10 [10 OUT] remains "1" for counts from 0 to 4 and "0" for counts from 5 to 9. These outputs can be used when cascading devices to counts above 9.
Driving a 7-Segment Display – 4026
