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  • Inquire: Call 0086-755-23203480, or reach out via the form below/your sales contact to discuss our design, manufacturing, and assembly capabilities.
  • Quote: Email your PCB files to Sales@pcbsync.com (Preferred for large files) or submit online. We will contact you promptly. Please ensure your email is correct.
Drag & Drop Files, Choose Files to Upload You can upload up to 3 files.

Notes:
For PCB fabrication, we require PCB design file in Gerber RS-274X format (most preferred), *.PCB/DDB (Protel, inform your program version) format or *.BRD (Eagle) format. For PCB assembly, we require PCB design file in above mentioned format, drilling file and BOM. Click to download BOM template To avoid file missing, please include all files into one folder and compress it into .zip or .rar format.

SN74HC595DR – 8-Bit SIPO Shift Register, SOIC-16 T&R | PCBSync
🔴 Texas Instruments ● Active Production ✓ RoHS Compliant SOIC-16 T&R 2500/reel
SNx4HC595 Family · Part No. SN74HC595DR

SN74HC595DR
8-Bit SIPO Shift Register

8-bit serial-in, parallel-out shift register with 3-state output registers. Separate shift and storage clocks, direct clear, cascadable serial output. The industry workhorse for GPIO expansion in LED, display, and embedded control applications.

Supply Voltage
2–6V
Max Clock
25MHz
Output Drive
±6mA
Propagation Delay
13ns typ
Quiescent ICC
80µA max
Operating Temp
−40–85°C
💬 Get a Quote — PCBSync 📄 Official Datasheet (TI) 🛒 Check Stock & Price
Package
SOIC-16
9.9 × 3.9 mm / 1.27mm pitch
Interface
SPI
Serial-in, 8-bit parallel-out
Logic Family
HC-CMOS
High-speed CMOS
Output Type
3-State
Hi-Z when OE = HIGH
ESD Rating
2 kV
HBM — 1 kV CDM
Tape & Reel
2500
pcs / reel (330mm)
🔌 Interactive Pinout Diagram
Hover over any pin to see its function, type, and design notes. SOIC-16 top view.

SN74HC595DR · SOIC-16 · Top View

Pin 1 marker at top-left notch ◁  |  Hover pins to explore

QB1
QC2
QD3
QE4
QF5
QG6
QH7
GND8
SN74HC595
Texas Instruments
SOIC-16 · DR variant
16VCC
15QA
14SER
13/OE
12RCLK
11SRCLK
10/SRCLR
9QH'
PIN — — —
—
Parallel Output Control / Data Input Serial Cascade VCC GND
🔧 Functional Block Diagram
Data flow: SER input → 8-stage shift register → 8-bit storage latch → 3-state parallel outputs
8-BIT SHIFT REGISTER D D D D D D D D SRCLK ↑ · SRCLR ‾ 8-BIT STORAGE REGISTER D D D D D D D D RCLK ↑ · OE ‾ data SER SRCLK SRCLR RCLK OE QA QB QC QD QE QF QG QH QH'

🔗 Daisy-Chaining Multiple 74HC595s

Connect QH' (pin 9) of the first chip to SER (pin 14) of the next. All chips share SRCLK, RCLK, and OE. Send 16 bits for 2 chips, 24 for 3, etc. Only one SPI interface needed regardless of chain length.

// Arduino: drive 16 LEDs with 2× 74HC595 chained SPI.begin(); digitalWrite(RCLK_PIN, LOW); SPI.transfer(0b10110001); // data for 2nd chip (QA–QH of chip 2) SPI.transfer(0b11001010); // data for 1st chip (QA–QH of chip 1) digitalWrite(RCLK_PIN, HIGH); // latch — both chips update simultaneously
📊 Full Electrical Specifications
Key parameters from TI datasheet SCLS041J. All values for SN74HC595 (industrial temp range).
Absolute Maximum Ratings
Supply Voltage (VCC)−0.5 to 7 V
Input Clamp Current (IIK)±20 mA
Output Clamp Current (IOK)±20 mA
Continuous Output Current (IO)±35 mA
Total VCC or GND Current±70 mA
Junction Temperature (TJ)150 °C
Storage Temperature−65 to 150 °C
ESD — Human Body Model2000 V
ESD — Charged Device Model1000 V
Recommended Operating Conditions
VCC Supply Voltage2 V to 6 V
VIH (High Input) @ 4.5V≥ 3.15 V
VIL (Low Input) @ 4.5V≤ 1.35 V
VIH @ 5V nominal≥ 3.15 V
VIH @ 3.3V nominal≥ 2.31 V
Input Voltage Range0 to VCC
Output Voltage Range0 to VCC
Operating Temp (SN74HC)−40 to 85 °C
Input Rise / Fall Time @ 4.5V≤ 500 ns
DC Electrical Characteristics (VCC = 4.5V, TA = 25°C)
VOH (IOH = −6mA, QA–QH)≥ 3.84 V
VOH (IOH = −20µA)≥ 4.4 V
VOL (IOL = 6mA, QA–QH)≤ 0.33 V
VOL (IOL = 20µA)≤ 0.1 V
IOZ (Hi-Z output leakage)≤ ±5 µA
II (Input leakage)≤ ±1 µA
ICC (Quiescent current)≤ 80 µA max
Input Capacitance (Ci)≤ 10 pF
Output Drive @ 5V±6 mA
Switching / Timing (VCC = 4.5V, CL = 50pF)
Max Clock Frequency25 MHz
tpd RCLK → QA–QH37 ns max
tpd SRCLK → QH'40 ns max
tsu SER before SRCLK↑25 ns min
th SER after SRCLK↑0 ns
tw SRCLK/RCLK pulse width20 ns min
tsu SRCLK↑ before RCLK↑19 ns min
ten OE → outputs active37 ns max
tdis OE → outputs Hi-Z50 ns max
Thermal Information (SN74HC595DR — SOIC-16)
PackageSOIC-16 (D)
θJA Junction-to-Ambient73 °C/W
Max Power Dissipation (TA = 85°C)≈ 890 mW (derated)
Power Dissipation Capacitance (Cpd)400 pF typ
Body Size9.90 × 3.90 mm
Land PatternSOIC-16 per IPC-7351
MSL RatingLevel-1 — Unlimited @ 260°C reflow
💡 Where Can You Use This Chip?
The 74HC595 is one of the most versatile logic ICs in embedded design. Here's where engineers reach for it:
💡
LED Matrix & Displays
Drive 8-segment displays, LED bars, dot-matrix panels, and scrolling message boards. Each 595 controls one digit or row.
7-Segment LED Matrix Score Boards
🔌
GPIO Expansion
Expand a microcontroller from 3 SPI pins to 8, 16, 24+ digital outputs. Essential for resource-constrained designs.
Arduino ESP32 STM32 RP2040
🏭
Relay & Solenoid Banks
Control multiple relay modules, SSRs, or solenoid valves in industrial PLC-replacement and automation boards.
Relay Boards SSR Banks Valve Control
🎵
VU Meters & Spectrum
Drive LED bar-graph VU meters and audio spectrum analyzers. Use OE pin with PWM for smooth brightness scaling.
VU Meter LED Spectrum Music Visualizer
⌨️
Keyboard Scanning
Drive rows of key matrix keyboards and button arrays. Sequentially assert rows, read columns to detect key press position.
Matrix Keyboard Button Array
🌈
RGB LED Control
Control discrete RGB LED banks (not addressable strips). Combine with PWM on OE for dimming without extra hardware.
RGB Arrays Indicator Panels
🌐
Network Status Panels
Drive port status LEDs, activity indicators, and link indicators on network switches and routers.
Network Switches Port Indicators
🚗
Dashboard & Automotive
Warning light panels and indicator clusters in automotive applications at 5V bus (with appropriate decoupling).
Warning Lights Instrument Cluster
🔊
Server & Rack Systems
Front-panel LED status indicators, drive failure lights, and alarm output boards in server and rack infrastructure.
Rack Indicators Power LED
🛠️ Expert Design Tips
Curated engineering guidance — not just datasheet regurgitation. These are the things that matter in real designs.
🔋 Always place a decoupling capacitor right at VCC ▼

Place a 100nF ceramic capacitor (X5R or X7R, 0402 or 0603) between pin 16 (VCC) and pin 8 (GND) as close to the IC body as possible — ideally within 2mm. This suppresses the switching noise spikes generated when outputs toggle simultaneously.

In noisy environments or when driving inductive loads, add a secondary 10µF bulk capacitor nearby. If you're using multiple 595s on the same board, each needs its own 100nF cap.

⚠️ Omitting decoupling on a toggling shift register is one of the most common causes of erratic behavior in beginner designs.
⏱️ Tie SRCLK and RCLK together — with care ▼

If your MCU doesn't have a spare pin for a separate RCLK, you can tie SRCLK and RCLK together. The datasheet explicitly supports this: the shift register will always be one clock pulse ahead of the storage register.

The trade-off: the outputs will show intermediate states (glitching) during shifting because RCLK fires simultaneously with each SRCLK. This is fine for LED driving (the flicker is imperceptible), but problematic for logic control signals where glitches could trigger unintended actions downstream.

⚠️ Use separate SRCLK and RCLK lines whenever driving logic signals, relay coils, or anything that shouldn't pulse mid-transfer.
💡 LED current limiting: 560Ω or calculate properly ▼

The typical application schematic uses 560Ω resistors per LED at 5V. Use the formula: R = (VCC − VLED − VOL) / ILED

For a standard red LED at 5V: R = (5V − 2V − 0.33V) / 10mA = 267Ω → use 270Ω

For 3.3V logic: R = (3.3V − 2V − 0.33V) / 5mA = 194Ω → use 200Ω

Critical: The maximum continuous output current is ±35mA per pin, but the total package current across all 8 outputs is ±70mA. With 8 LEDs at 10mA each = 80mA — this exceeds the package limit. Design for max 8mA per pin or use a dedicated LED driver IC for higher currents.

🌟 Use /OE for flicker-free PWM brightness control ▼

The Output Enable pin is rarely used to its full potential. Connect /OE to an MCU PWM output. Now you get global brightness control of all connected LEDs without touching SPI data.

Drive at >100Hz PWM frequency to avoid visible flicker. At 1kHz+ it becomes completely imperceptible. This technique is used in professional LED signage controllers to achieve smooth brightness curves.

Additionally, during an SPI transaction, you can pull /OE HIGH to blank outputs, preventing any glitch from being displayed until the latch pulse finalizes the new data. This gives truly glitch-free updates on RCLK-tied designs.

🔗 Cascading: get n×8 outputs for n chips ▼

Connect QH' (pin 9) of chip 1 → SER (pin 14) of chip 2. Chain as many as needed. All chips share SRCLK, RCLK, and OE signals.

When you clock in bits, they ripple from chip 1 into chip 2, 3, etc. After sending n × 8 bits, pulse RCLK once — all chips latch simultaneously. This is how large LED panels and relay banks are driven efficiently.

At 25MHz max clock, a chain of 8 chips (64 bits) can be refreshed in 64 / 25,000,000 = 2.56µs — far faster than any visible flicker.

⚡ 3.3V MCU with 5V 595: level shift or choose correctly ▼

The 74HC595 supports VCC from 2V to 6V. If your system is 3.3V, simply power the 595 at 3.3V. The SPI signals from your MCU at 3.3V are perfectly valid. Outputs will swing 0–3.3V.

If you need 5V outputs (to drive 5V relays, or interface with 5V logic), power the 595 at 5V. Your 3.3V MCU output (VIH threshold at 4.5V VCC = 3.15V) will still exceed the threshold. This is a compatible level shift for the INPUTS.

Do not connect a 5V-powered 595's outputs back into 3.3V-powered MCU inputs without clamping — 5V will exceed the MCU's absolute maximum voltage.

🔒 Tie /SRCLR high — don't leave it floating ▼

If you don't need to clear the shift register in firmware, tie /SRCLR (pin 10) to VCC through a 10kΩ pull-up resistor. Never leave it floating — floating CMOS inputs can trigger parasitic states and cause unpredictable behavior.

If you do want software-controlled clear, connect it to a GPIO. Assert LOW to clear: all shift register bits go to 0. The storage register (and thus the outputs) are unaffected by SRCLR — you must still pulse RCLK to transfer the cleared state to the outputs.

⚠️ TI explicitly requires all unused inputs to be tied to VCC or GND. A floating SRCLR is one of the top causes of "ghost" output behavior on breadboard projects.
📐 Layout: minimize loop area between VCC and GND ▼

VCC (pin 16) and GND (pin 8) are on opposite sides of the chip. Place the decoupling capacitor between these two pins on the same side as pin 16 — routing from pin 16 to cap to nearby via to ground plane. Keep total trace length under 5mm.

For the SRCLK and SER signal traces, keep them short and matched in length for high-speed designs. At ≤1MHz (Arduino SPI default), trace length is inconsequential. Above 10MHz, use ground fill and matched impedance if trace lengths exceed 10cm.

If driving LED loads, route output traces away from clock lines to prevent capacitive coupling interference at high scan rates.

💰 Price Comparison by Quantity
Approximate unit prices (USD) across major distributors. Updated indicatively — verify on supplier sites before ordering.
SN74HC595DR — Unit Price (USD)
⚠ Indicative market prices. Actual prices vary by date, region, and availability. Always confirm on supplier's website before purchasing.
DigiKey
$0.295
→ DigiKey
Mouser
$0.310
→ Mouser
Newark
$0.420
→ Newark
Arrow
$0.285
→ Arrow
PCBSync
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⏱ Timing Requirements Summary
Key timing parameters at VCC = 4.5V for SN74HC595 (industrial). Compare with your MCU SPI peripheral spec.
Parameter Min Typ Max Unit
Clock Frequency (fclock)——25MHz
SRCLK / RCLK pulse width (high or low)20——ns
Setup: SER before SRCLK↑ (tsu)25——ns
Hold: SER after SRCLK↑ (th)0——ns
Setup: SRCLK↑ before RCLK↑19——ns
Propagation: SRCLK → QH'173240ns
Propagation: RCLK → QA–QH173037ns
Output enable: OE↓ → active—3037ns
Output disable: OE↑ → Hi-Z—4050ns
SRCLR low → QH' low (tPHL)—3544ns
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Contact Sales & After-Sales Service

Contact & Quotation

  • Inquire: Call 0086-755-23203480, or reach out via the form below/your sales contact to discuss our design, manufacturing, and assembly capabilities.

  • Quote: Email your PCB files to Sales@pcbsync.com (Preferred for large files) or submit online. We will contact you promptly. Please ensure your email is correct.

Drag & Drop Files, Choose Files to Upload You can upload up to 3 files.

Notes:
For PCB fabrication, we require PCB design file in Gerber RS-274X format (most preferred), *.PCB/DDB (Protel, inform your program version) format or *.BRD (Eagle) format. For PCB assembly, we require PCB design file in above mentioned format, drilling file and BOM. Click to download BOM template To avoid file missing, please include all files into one folder and compress it into .zip or .rar format.