4015 IC ‎Dual 4-Bit Shift Register (SIPO)

The CD4015 is a CMOS IC with two 4-bit shift registers. Each shift register has serial input and parallel output pins. It’s commonly used to give you more output pins from a microcontroller, such as Arduino.

You’ll see an example of this further down.

Pin Overview

What is a 4-Stage Shift Register?

A shift register is a simple memory circuit that can store a number of bits. You can build one using a series of flip-flops. Each flip-flop can store one bit. A 4-bit shift register like the ones in the CD4015 chip has 4 flip-flops and is often called a 4-stage shift register:

After the first clock pulse, whatever is on the Data In pin will be stored in the first flip-flop. What was on the first flip-flop from before is stored on the second flip-flop. What was one the second flip-flop from before is stored on the third… And so on.

The bit that was stored on the last flip-flop will be overwritten. So on every clock pulse, the data is shifted one flip-flop, or one position, to the right. Hence the name shift register.

How To Use The CD4015

First of all, you need to connect the VDD pin to your positive supply terminal and the GND pin to your negative supply terminal. You can use a power supply voltage between 3V and 15V. Although, some versions of the 4015 IC support up to 20V. Check your datasheet for exact values.

Each of the two shift registers in the chip has an independent Clock, Reset, and Data pins. Use the clock and data pins to load data into the registers like this: On each rising edge of the CLK pin, whatever is on the D pin is shifted into the register.

Set the RST pin HIGH to reset the four bits of the register back to 0000. Otherwise, keep it LOW.

At any point in time, you can read the state of the shift registers from the Q_xx pins.

Technical Specifications

CD4015B Datasheet