The SN74LS390DR is an IC (integrated circuit) component that belongs to the LS (low-power Schottky) family of digital logic devices. It is a dual 4-bit decade and binary counter chip. Here's an overview and key features of the SN74LS390DR:
1. Functionality: The primary function of SN74LS390DR is to count in both decimal (BCD) and binary modes. It can count from 0 to 9 in BCD mode and from 0 to 15 in binary mode.
2. Dual Counter: This IC incorporates two independent counters in a single package. Each counter has a separate clock input, reset input, and a pair of BCD outputs (Q0 and Q1). The clock input determines the counting speed, while the reset input is used to initialize the counters.
3. Counting Modes: The SN74LS390DR includes two counting modes. In the decade (BCD) mode, the counter counts from 0 to 9 and then resets back to 0. In the binary mode, the counter counts from 0 to 15 before restarting from 0.
4. Ripple Carry Output: The IC also features a ripple carry output (RCO) that serves as an overflow indicator. It goes high whenever the counter reaches its maximum value and rolls over to zero. This output can be cascaded to other counters for expanding the counting range
