Sn74Hc164N

Overview

SN74HC164N 8-Bit Serial-In Parallel-Out (SIPO) Shift Register by Texas Instruments. A high-speed CMOS logic IC used for serial-to-parallel data conversion in digital electronics, LED matrix control, 7-segment displays, port expansion, and embedded systems. Compatible with Arduino, ESP32, STM32, Raspberry Pi, and all 5V/3.3V logic systems.

Specifications

Parameter	Value
Model	SN74HC164N
Type	8-bit SIPO Shift Register
Manufacturer	Texas Instruments
Supply Voltage	2V – 6V
Logic Family	HC (High-Speed CMOS)
Clock Frequency	Up to 25MHz @ 5V
Output Type	Push-Pull (Totem-Pole)
Inputs	Serial Data (A, B) + Clock + Clear
Outputs	8 parallel outputs (QA–QH)
Package	DIP-14 (Through-hole)
Propagation Delay	~15ns @ 5V
Operating Temperature	-40°C to +125°C
Output Current	±25mA per pin

Pin Configuration

Pin	Name	Description
1	A	Serial data input A
2	B	Serial data input B
3	QA	Parallel output bit 0
4	QB	Parallel output bit 1
5	QC	Parallel output bit 2
6	QD	Parallel output bit 3
7	GND	Ground
8	CLK	Clock input
9	CLR	Clear (active LOW)
10	QE	Parallel output bit 4
11	QF	Parallel output bit 5
12	QG	Parallel output bit 6
13	QH	Parallel output bit 7
14	VCC	Power supply (2V–6V)

Features

• 8-bit serial to parallel conversion — expand GPIO with just 3 pins
• High-speed CMOS — up to 25MHz clock frequency
• AND-gated serial inputs — data = A AND B (tie together for single input)
• Synchronous clear — CLR pin resets all outputs low
• Wide voltage range — 2V to 6V operation
• DIP-14 package — breadboard and PCB friendly
• Cascadable — chain multiple ICs for 16, 24, 32-bit expansion
• Low power consumption
• TTL compatible inputs

Wiring (Arduino)

SN74HC164N	Arduino
VCC (pin 14)	5V
GND (pin 7)	GND
A (pin 1)	Data pin (e.g. pin 11)
B (pin 2)	Data pin (tie to A)
CLK (pin 8)	Clock pin (e.g. pin 13)
CLR (pin 9)	5V (or GPIO for reset)
QA–QH	LEDs / Load

Wiring (ESP32)

SN74HC164N	ESP32
VCC (pin 14)	3.3V
GND (pin 7)	GND
A (pin 1)	GPIO23 (DATA)
B (pin 2)	GPIO23 (tie to A)
CLK (pin 8)	GPIO18 (CLK)
CLR (pin 9)	3.3V

Arduino Code Example

int dataPin = 11;
int clockPin = 13;

void setup() {
  pinMode(dataPin, OUTPUT);
  pinMode(clockPin, OUTPUT);
}

void shiftOut(byte data) {
  for (int i = 7; i >= 0; i--) {
    digitalWrite(dataPin, (data >> i) & 1);
    digitalWrite(clockPin, HIGH);
    delayMicroseconds(1);
    digitalWrite(clockPin, LOW);
  }
}

void loop() {
  shiftOut(0b10101010); // Alternating pattern
  delay(500);
  shiftOut(0b11110000);
  delay(500);
}

Cascading Multiple ICs

Connect QH (pin 13) of first IC to A (pin 1) of second IC. Share the same CLK and CLR signals. Result: 16-bit output with only 3 microcontroller pins.

⚠️ Notes

• Tie A and B together for single data line input
• Keep CLR HIGH during normal operation
• Add 100nF decoupling capacitor between VCC and GND near IC
• For 3.3V systems (ESP32) — operates correctly at 3.3V
• Do NOT exceed 25mA per output pin

Applications

• LED bar graph and matrix control
• 7-segment display driving
• GPIO port expansion
• Serial communication protocols
• Data latching and buffering
• Light chaser / sequencer circuits
• Relay bank control
• Arduino / ESP32 output expansion