CD4021 belongs to the 4000 Series CMOS Logic Family of Integrated Circuits (IC’s) constructed with N- and P-channel enhancement mode transistors. CD4021 has 8-stage Static Shift Register
CD4021 has a supply voltage range of 5V to 20V, which is much higher than any contemporary logic family. It has buffered output which improves transfer characteristics by providing very high gain. All inputs are protected against static discharge with diodes to VDD and VSS.

CD4021 Features
- High Voltage Types (20V Rating)
- Medium Speed Operation 12MHz (Typ.) Clock Rate at VDD-VSS = 10V
- Fully Static Operation
- 8 Master-Slave Flip-Flops Plus Output Buffering and Control Gating
- 100% Tested for Quiescent Current at 20V
- Maximum Input Current of 1µA at 18V Over Full Package Temperature Range; 100nA at 18V and +25oC
- Noise Margin (Full Package Temperature Range)
- 1V at VDD = 5V
- 2V at VDD = 10V
- 2.5V at VDD = 15V
CD4021 Specifications
Absolute Maximum Ratings
- DC Supply Voltage Range, (VDD): -0.5V to +20V (Voltage Referenced to VSS Terminals)
- Input Voltage Range, All Inputs: -0.5V to VDD +0.5V
- DC Input Current, Any One Input: ±10mA
- Operating Temperature Range: -55oC to +125oC Package Types D, F, K, H
- Storage Temperature Range (TSTG): -65oC to +150oC
- Lead Temperature (During Soldering): +265oC
- At Distance 1/16 ± 1/32 Inch (1.59mm ± 0.79mm) from case for 10s Maximum
CD4021 Pinout Diagram

CD4021 Pin Description
Pin No | Pin Name | Description |
---|---|---|
1 | PI-8 | Parallel Input 8 of Shift Register |
2 | Q6 | The output of Shift Register 6 |
3 | Q8 | The output of Shift Register 8 |
4 | PI-4 | Parallel Input 4 of Shift Register |
5 | PI-3 | Parallel Input 3 of Shift Register |
6 | PI-2 | Parallel Input 2 of Shift Register |
7 | PI-1 | Parallel Input 1 of Shift Register |
8 | GND | ground |
9 | LATCH | Latch Input |
10 | CLK | Clock Signal Input |
11 | SERIAL | Serial Input |
12 | Q7 | The output of Shift Register 7 |
13 | PI-5 | Parallel Input 5 of Shift Register |
14 | PI-6 | Parallel Input 6 of Shift Register |
15 | PI-7 | Parallel Input 7 of Shift Register |
16 | VDD | Drain Supply |
CD4021 Circuit
Applications
- Parallel Input/Serial Output Data Queueing
- Parallel to Serial Data Conversion
- General Purpose Register
CD4021 Alternative Equivalent
CD4006, CD4015
Download CD4021 8-stage Static Shift Register Datasheet from the link given below.