The IC 4520 is a Dual Binary Up Counter with two synchronous 4-stage up counters using D-type flip flops. It allows for easy incrementing on either the positive or negative transition by interchanging CLOCK and ENABLE lines.

For single-unit operation, the ENABLE input is held high, and the counter advances on each positive-going CLOCK transition. On their RESET lines, these counters can be reset from their high levels. The IC also has several advantages, such as low thermal dissipation and strong noise immunity. The IC is always accessible in a hermetically sealed 16-pin package and can be directly interfaced with any TTL, CMOS, or NMOS device.