Send an Inquiry

To receive a quote for your project, please fill in the following information, and we’ll get back to you promptly.

Submit Inventory List

Please fill in the following information, and we’ll get back to you promptly.

Home > Products > Integrated Circuits (ICs) > Logic > Multivibrators

Texas Instruments SN74221NE4

Name: SN74221NE4
Brand: Texas Instruments
SKU: SN74221NE4
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

Compare

Part No.:: SN74221NE4

Manufacturer:: Texas Instruments

Category:: Multivibrators

Package:: 16-DIP (0.300", 7.62mm)

Datasheet:: SN74221NE4.pdf

Description:: DUAL MONOSTABLE MULTIVIBRATORS W

Quantity:: RFQ Add To RFQ list

Payment:

Shipping:

Inventory:1,845

Please send an inquiry. Send us your inquiry, and we will respond immediately.

Product details

Overview

SN74221NE4 from Texas Instruments is a dual monostable multivibrator IC with TTL-compatible inputs and outputs, designed for precise pulse generation in digital timing circuits. It features two independent one-shot circuits, each with negative- and positive-transition-triggered inputs (A and B), overriding clear (CLR), and external R_ext/C_ext-controlled output pulse width up to 28 µs. Used in debounce, delay generation, and clock conditioning in industrial control and test equipment.

For engineers reviewing the SN74221NE4 datasheet, SN74221NE4 pinout, SN74221NE4 application, or SN74221NE4 equivalent, key selection factors include its 16-pin PDIP package, 0°C to 70°C operating range, Schmitt-trigger B-input for jitter-free triggering down to 1 V/s, TTL-level output drive (16 mA sink), and pulse-width stability ±0.5% unit-to-unit variation with external timing components.

Technical Context

The SN74221NE4 implements two independent retriggerable monostable multivibrators using bipolar TTL logic. Each section uses internal latching circuitry to isolate output pulse duration from input transitions after triggering, ensuring immunity to noise on A/B inputs during active output. The overriding clear (CLR) input forces Q low independently of timing components.

Timing is governed by external R_ext and C_ext, with pulse width defined as t_w ≈ 0.7 × R_ext × C_ext. Pulse stability is internally compensated-variation vs. V_CC and temperature is <±0.5%-and jitter-free operation is maintained across 10 pF–10 µF capacitance and 2 kΩ–40 kΩ resistance ranges.

Key Specifications

Parameter	Value and Actual Design Meaning
Output pulse length	Up to 28 µs maximum; set precisely via external R_ext/C_ext; enables flexible timing from 35 ns to microseconds.
Supply voltage	4.75 V to 5.25 V; compatible with standard 5-V TTL systems without regulation overhead.
Output drive	16 mA sink / −800 µA source; directly interfaces with TTL loads and standard logic gates without buffering.
B-input hysteresis	1.2 V typical; provides jitter-free triggering from slow-rising signals (≥1 V/s), critical for switch debouncing.
Input impedance	A input: 4 kΩ nominal; B/CLR: 2 kΩ nominal; ensures predictable loading in cascaded TTL designs.
Pulse width accuracy	±0.5% unit-to-unit variation at fixed R_ext/C_ext; supports high-repeatability timing in production systems.

Pinout & Package

SN74221NE4 is housed in a 16-pin plastic dual in-line package (PDIP-N), RoHS-compliant with NiPdAu lead finish, rated for 0°C to 70°C operation and suitable for through-hole PCB assembly.

Pin/Terminal	Circuit Role	Design Meaning
1, 2, 3, 4, 5, 6, 7, 9, 10, 11, 12, 13, 14, 15	Functional I/O (A1, B1, CLR1, Q1, Q1̅, A2, B2, CLR2, Q2, Q2̅, R_ext1, C_ext1, R_ext2, C_ext2)	Two fully independent monostable sections; each has dual trigger inputs, clear, complementary outputs, and dedicated timing terminals.
8	GND	Ground reference for all internal logic and output stages; must be low-impedance for stable timing.
16	V_CC	+5 V supply; powers both sections; decoupling capacitor required near pin for noise immunity.

Key Features

Feature	Design Value
Dual independent monostables	Enables two synchronized or isolated timing functions in one package-reduces board space and component count vs. discrete solutions.
Overriding clear (CLR)	Terminates output pulse immediately regardless of timing capacitor charge state-critical for emergency reset or fault recovery.
Schmitt-trigger B input	Eliminates false triggering from noisy or slow-rising signals (e.g., mechanical switches), enabling robust debounce without external RC filters.
Complementary Q/Q̅ outputs	Provides both true and inverted timing pulses simultaneously-simplifies interface to differential receivers or latch enable logic.
DC-triggered reset capability	With C_ext = 0 and R_ext = 2 kΩ, delivers ~30 ns pulse-usable as synchronous reset signal in TTL state machines.

Applications

Switch Debounce Circuit	Programmable Delay Generator
Use Scenario: Mechanical push-button or relay contact interfacing with digital logic where contact bounce causes multiple unintended edges. IC Role / Device Role / Timing Role: Monostable section acts as hardware-based edge filter; triggered on first contact closure, ignoring subsequent bounces until output pulse completes. Use Value: Eliminates need for software debouncing or external RC+Schmitt circuits; guarantees single clean edge per press with <30 ns minimum pulse width.	Use Scenario: Generating precise, adjustable delays between control signals in test instrumentation or sequencer logic. IC Role / Device Role / Timing Role: One-shot configured with user-selected R_ext/C_ext to produce deterministic delay (e.g., 100 µs–10 ms) between trigger and output assertion. Use Value: Achieves sub-microsecond repeatability (±0.5%) across units; avoids microcontroller timing drift or interrupt latency issues.
Asynchronous Reset Synchronizer	Edge-Detector Pulse Extender
Use Scenario: Converting asynchronous system reset signals into clean, width-controlled pulses for clock-domain crossing in multi-clock systems. IC Role / Device Role / Timing Role: Triggered by falling edge on asynchronous reset line; generates fixed-duration active-low pulse aligned to local clock domain. Use Value: Ensures reset pulse meets minimum width requirements of downstream flip-flops while preventing metastability propagation.	Use Scenario: Converting narrow logic pulses (e.g., from comparators or zero-crossing detectors) into wider, logic-compatible strobes for sampling or gating. IC Role / Device Role / Timing Role: Negative-edge-triggered A input captures transient events; output pulse width extended to match system timing margins (e.g., 500 ns). Use Value: Converts sub-20 ns glitches into reliable 35 ns–28 µs pulses-compatible with TTL input setup/hold times and bus arbitration logic.

Switch Debounce Circuit

Programmable Delay Generator

Use Scenario: Mechanical push-button or relay contact interfacing with digital logic where contact bounce causes multiple unintended edges.

IC Role / Device Role / Timing Role: Monostable section acts as hardware-based edge filter; triggered on first contact closure, ignoring subsequent bounces until output pulse completes.

Use Value: Eliminates need for software debouncing or external RC+Schmitt circuits; guarantees single clean edge per press with <30 ns minimum pulse width.

Use Scenario: Generating precise, adjustable delays between control signals in test instrumentation or sequencer logic.

IC Role / Device Role / Timing Role: One-shot configured with user-selected R_ext/C_ext to produce deterministic delay (e.g., 100 µs–10 ms) between trigger and output assertion.

Use Value: Achieves sub-microsecond repeatability (±0.5%) across units; avoids microcontroller timing drift or interrupt latency issues.

Asynchronous Reset Synchronizer

Edge-Detector Pulse Extender

Use Scenario: Converting asynchronous system reset signals into clean, width-controlled pulses for clock-domain crossing in multi-clock systems.

IC Role / Device Role / Timing Role: Triggered by falling edge on asynchronous reset line; generates fixed-duration active-low pulse aligned to local clock domain.

Use Value: Ensures reset pulse meets minimum width requirements of downstream flip-flops while preventing metastability propagation.

Use Scenario: Converting narrow logic pulses (e.g., from comparators or zero-crossing detectors) into wider, logic-compatible strobes for sampling or gating.

IC Role / Device Role / Timing Role: Negative-edge-triggered A input captures transient events; output pulse width extended to match system timing margins (e.g., 500 ns).

Use Value: Converts sub-20 ns glitches into reliable 35 ns–28 µs pulses-compatible with TTL input setup/hold times and bus arbitration logic.

Equivalent & Alternatives

The following parts are listed as comparable options for similar monostable multivibrator applications.

Alternative Part	Technical Difference	Application Difference	Selection Advice
SN74LS221N	Lower power (ICC = 4.7–11 mA vs. 26–50 mA), slower max R_ext (100 kΩ vs. 40 kΩ), LS-TTL output levels (V_OH min = 2.7 V).	Better suited for low-power, noise-sensitive systems; requires level-shifting when interfacing with legacy TTL loads.	Select SN74LS221N when power budget is constrained and timing range >28 µs is not required.
SN74121N	No Schmitt-trigger B input; no overriding clear; single-trigger-only (no A/B dual input); shorter max pulse (13 µs).	Limited to basic one-shot use cases without noise immunity or forced termination; incompatible with debounce or fail-safe reset designs.	Choose SN74121N only for cost-sensitive, non-critical timing where external filtering and manual clear handling are acceptable.

Compared with SN74LS221N and SN74121N, the SN74221NE4 delivers superior noise immunity via Schmitt-trigger inputs, deterministic pulse termination via overriding clear, and higher drive strength-making it optimal for industrial-grade timing integrity where reliability outweighs power savings.

Availability

SN74221NE4 is available at Aetrix Electronics and suitable for industrial control panels, test equipment design, and legacy TTL system upgrades requiring stable component supply and long-term obsolescence management.

Supply support for SN74221NE4 includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

Texas Instruments is a global semiconductor leader specializing in analog, embedded processing, and logic ICs, with decades of heritage in TTL and advanced timing solutions.

The SN74xx221 family was engineered for high-stability, retriggerable monostable operation in mission-critical industrial and military systems-emphasizing pulse repeatability, noise immunity, and compatibility with legacy 5-V TTL infrastructure.

FAQ

What is the maximum output pulse width achievable with SN74221NE4?

The SN74221NE4 supports a maximum output pulse width of 28 µs, achieved using the recommended external timing components-specifically R_ext = 40 kΩ and C_ext = 1000 µF. This value is specified under recommended operating conditions (V_CC = 4.75–5.25 V, T_A = 0–70°C) and reflects the upper limit of its jitter-free timing range. Shorter pulses down to 35 ns are also supported with appropriate R/C values.

Does SN74221NE4 support retriggering during an active output pulse?

Yes, the SN74221NE4 is retriggerable: a new trigger on either A or B input during an active output pulse will restart the timing cycle, extending the total output duration. This behavior is inherent to its monostable architecture and is confirmed in the function table and switching characteristics. Retriggering occurs regardless of whether the input is negative- or positive-going, provided the input meets setup time and voltage threshold requirements.

Can SN74221NE4 be used with a 3.3-V supply?

No, SN74221NE4 is not rated for 3.3-V operation. Its absolute maximum supply voltage is 7 V, but the recommended operating range is strictly 4.75 V to 5.25 V. Operation below 4.75 V risks failure to meet TTL logic thresholds (e.g., V_IH min = 2 V, V_IL max = 0.8 V) and may cause erratic triggering or reduced noise margin. For 3.3-V systems, consider modern CMOS monostables like the CD74HC221 or SN74LVC1G123.

How does the overriding clear (CLR) function interact with the timing capacitor?

The overriding clear (CLR) input on SN74221NE4 forces Q low immediately and discharges the internal timing capacitor, terminating the output pulse regardless of its current state. This action is independent of R_ext/C_ext values and occurs within 20 ns (t_w min for CLR). Once CLR returns high, the device remains in a quiescent state until the next valid trigger-no automatic retriggering occurs. This makes CLR ideal for emergency stop or fault-clear sequences.

Is SN74221NE4 pin-compatible with SN74123N?

Yes, SN74221NE4 has identical pinout to SN74123N and SN74LS123N, as explicitly stated in the datasheet: "Pin assignments for these devices are identical to those of the SN54123/SN74123 or SN54LS123/SN74LS123." However, functional substitution requires adjusting R_ext and C_ext values and reversing capacitor polarity due to internal circuit differences-direct drop-in replacement is not guaranteed without validation of timing and noise performance.

SN74221NE4 Specifications

Product attributes: Attribute value

Manufacturer:: Texas Instruments

Series:: 7400

Package/Case:: 16-DIP (0.300", 7.62mm)

Packaging:: Tube

Product Status:: Active

Logic Type:: Monostable

Independent Circuits:: 2

Schmitt Trigger Input:: Yes

Propagation Delay:: 50 ns

Current - Output High, Low:: 16mA, 800µA

Voltage - Supply:: 4.75 V ~ 5.25 V

Operating Temperature:: 0°C ~ 70°C

Grade:: -

Qualification:: -

Mounting Type:: Through Hole

Supplier Device Package:: 16-PDIP

SN74221NE4 FAQ

1.How can I place an order for SN74221NE4 through Aetrix?

Please submit a Request for Quotation (RFQ) for SN74221NE4 on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.

2.Are the price and stock information for SN74221NE4 reliable?

The price and inventory of SN74221NE4 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74221NE4 is usually 5 days.

3.What payment methods are accepted for SN74221NE4?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SN74221NE4 transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for SN74221NE4?

SN74221NE4 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your SN74221NE4 order is processed, you will receive an email with the shipment details and tracking number.

Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.

5.How can I obtain technical support or documentation for SN74221NE4?

For technical support, including SN74221NE4 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74221NE4 requirements.

6.How does Aetrix verify that SN74221NE4 is sourced from the original manufacturer or authorized distributors?

All SN74221NE4 products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that SN74221NE4 meets industry standards.

7.What is the process for return or replacement of SN74221NE4?

All SN74221NE4 units undergo pre-shipment inspection (PSI). If there is an issue with SN74221NE4, returns or replacements are accepted under the following conditions:

1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.

2.The issue is reported within 90 days of delivery.

3.The SN74221NE4 part is unused and in its original packaging.

Return procedure for SN74221NE4:

1.Submit a request within 90 days.

2.Obtain a Return Material Authorization (RMA) from Aetrix.

Tech Hub

2026-09-03 Logic Level Shifter: How to Connect 3.3V and 5V Logic Safely

A practical engineering guide to 3.3V and 5V logic compatibility, input thresholds, resistor dividers, translator ICs, MOSFET level shifting, I2C pull-ups, timing limits and power-sequencing risks.

2026-09-03 74HC595 vs TPIC6B595: Output Drive, Pinout, Current, and Load Selection

The 74HC595 uses push-pull logic outputs, while the TPIC6B595 uses 50 V open-drain DMOS sinks for higher-power loads. This guide compares timing, current limits, 3.3 V interfacing, load wiring, thermal…

2026-09-01 74HC595 Pinout, Timing, Output Current, and Applications

The 74HC595 converts serial data into eight stable parallel outputs. This guide covers pin functions, shift and storage timing, OE and MR behavior, drive-current limits, cascading, voltage compatibilit…

2026-09-01 Latch vs Flip-Flop: Timing, Differences and Design Choices

A technical comparison of level-sensitive latches and edge-triggered flip-flops, covering timing windows, setup and hold limits, master–slave operation, time borrowing, race-through, HDL inference and…

2026-08-30 D Latch Circuit: Truth Table, Timing, ICs and Applications

A D latch stores one bit while Enable controls when data can pass. This reference covers gate-level operation, truth tables, transparency, setup and hold timing, LE versus OE, common ICs and practical …

2026-08-28 SR Latch Explained: NOR and NAND Circuits, Truth Tables, and Applications

An SR latch stores one bit through cross-coupled feedback. This engineering reference covers NOR and NAND implementations, truth tables, forbidden-state recovery, gated operation, switch debouncing, fa…

2026-08-27 Latch Circuit: SR and D Latches, Truth Tables, Timing, and Applications

Latch circuits retain one bit through feedback. This technical reference covers SR and D latches, truth tables, transparency, timing limits, latch-versus-flip-flop behavior, applications and common log…

2026-08-21 What Is an LED Driver? Types, Circuits, Dimming, and Selection

An engineering guide to LED driver operation, constant-current and constant-voltage outputs, linear and switching topologies, dimming, IC selection, calculations, replacement compatibility, and fault c…

2026-08-18 Operational Amplifier (Op Amp): Basics, Configurations, Feedback and Applications

Operational amplifier guide covering op amp basics, feedback, ideal vs real op amps, common configurations, buffer circuits, offset, bias current, gain-bandwidth, slew rate, rail-to-rail limits and sel…

2026-08-14 Jumper Cables: How to Use, Connect and Choose Them Safely

Jumper cables guide covering safe connection order, red and black clamp placement, final ground connection, cable gauge, length, clamp quality, copper vs CCA cables, jump starter comparison and battery…