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

Texas Instruments CD54HC221F

Name: CD54HC221F
Brand: Texas Instruments
SKU: CD54HC221F
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: CD54HC221F

Manufacturer:: Texas Instruments

Category:: Multivibrators

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

Datasheet:: CD54HC221F.pdf

Description:: HIGH SPEEC CMOS LOGIC DUAL MONOS

Quantity:: RFQ Add To RFQ list

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Product details

Overview

CD54HC221F from Texas Instruments is a military-grade dual monostable multivibrator with independent reset, Schmitt-trigger B inputs, and buffered Q/Q̅ outputs. It operates from 2V to 6V, supports -55°C to +125°C ambient, and delivers pulse widths from nanoseconds to microseconds via external RX/CX networks. It is used in precision timing control for aerospace sensor interface and missile guidance subsystems.

For engineers reviewing the CD54HC221F datasheet, CD54HC221F pinout, CD54HC221F application, or CD54HC221F equivalent, key selection criteria include its CERDIP package for hermetic reliability, dual-edge triggering (A = trailing, B = leading), overriding reset functionality, wide temperature range, and HC logic compatibility with 30% noise margin at 5V.

Technical Context

The CD54HC221F implements two independent monostable circuits, each with separate A (edge-triggered), B (Schmitt-triggered), and R (active-low reset) inputs. Pulse width t_W = 0.7 × R_XC_X at V_CC = 4.5V, with minimum R_X = 500Ω and C_X = 0pF. Outputs remain stable after triggering, unaffected by subsequent A/B transitions.

Its HC logic family ensures CMOS-level power efficiency and high noise immunity (NIL/NIH = 30% of V_CC), while the CERDIP (J) package provides hermetic sealing and MIL-PRF-38535 qualification for defense applications requiring long-term reliability under thermal shock and humidity stress.

Key Specifications

Parameter	Value and Actual Design Meaning
Logic Family	High-speed CMOS (HC), not TTL-compatible; requires 2V–6V supply
Operating Temp Range	-55°C to +125°C - qualified per MIL-PRF-38535 for extended environmental resilience
Pulse Width Range	Configurable from ~140ns (28pF/2kΩ) to >7µs (1000pF/10kΩ) - enables fine-grained timing resolution
Input Trigger Types	A input: trailing-edge sensitive; B input: Schmitt-triggered leading-edge - supports noisy or slow-rising signals
Reset Function	Active-low, overriding reset (R) terminates output pulse immediately - critical for fail-safe timing abort
Output Drive	Standard outputs drive 10 LSTTL loads; bus-driver outputs drive 15 - ensures robust fanout in mixed-logic systems
Propagation Delay	36–63ns (V_CC = 6V–4.5V, CL = 50pF) - enables sub-10MHz reliable retriggering

Pinout & Package

CD54HC221F uses a 16-lead CERDIP (J) package - ceramic dual in-line, hermetically sealed, with 0.3-inch body width and 0.1-inch lead pitch. Designed for high-reliability military/aerospace PCB mounting with solder dip or wave solder compatibility.

Pin/Terminal	Circuit Role	Design Meaning
1A, 9A	Trailing-edge trigger input (Mono 1 & 2)	Accepts clean falling-edge pulses; no Schmitt conditioning - requires fast, low-noise signal source
2B, 10B	Leading-edge Schmitt trigger input (Mono 1 & 2)	Hysteresis rejects noise on slow or degraded edges; enables direct connection to mechanical switches or analog comparators
3R, 11R	Active-low reset input (Mono 1 & 2)	Asynchronous override: forces Q low and Q̅ high regardless of timing state - essential for system-level fault recovery
4Q, 12Q	Inverting output (Mono 1 & 2)	Buffered, rail-to-rail CMOS output; drives downstream logic or discrete gate drivers without level-shifting
5Q̅, 13Q̅	Non-inverting output (Mono 1 & 2)	Complementary to Q; enables differential signaling or dual-signal timing paths in synchronous systems
6, 7, 14, 15	Timing network terminals (1CX, 1CXRX, 2CX, 2CXRX)	Direct connection points for external R_X/C_X; placement minimizes parasitic inductance for stable pulse width accuracy
8	GND	Power ground reference - must be low-impedance, star-connected to avoid timing jitter from ground bounce
16	V_CC	Positive supply (2V–6V); decoupling capacitor (0.1µF ceramic) required within 5mm for transient immunity

Key Features

Feature	Design Value
Overriding RESET	Guarantees immediate pulse termination even mid-output - enables deterministic abort in safety-critical flight control loops
Dual-edge triggering (A/B)	Supports both rising- and falling-edge event capture from same device - reduces component count in dual-signal monitoring systems
Separate resets per mono	Enables independent timing channel management - critical for phased radar pulse generation or multi-stage sequencers
Schmitt trigger on B inputs	Rejects <1.35V noise on 4.5V V_CC - allows direct interfacing with unconditioned sensor outputs or legacy analog comparators
Wide pulse width range	0.7 × R_XC_X formula supports 100:1 timing span with standard components - eliminates need for multiple fixed-timing ICs

Applications

Missile Proximity Fusing	Aerospace Sensor Signal Conditioning
Use Scenario: Detects target proximity via RF return pulse timing and triggers warhead arming sequence within strict microsecond windows. IC Role / Device Role / Timing Role: Dual monostable generates precisely timed enable pulses for RF receiver gating and arming logic activation. Use Value: Overriding reset ensures immediate disarm if target lock is lost; Schmitt B inputs tolerate noisy RF detector outputs.	Use Scenario: Converts analog transducer signals (e.g., accelerometers) into clean digital timing events for inertial measurement unit (IMU) data sampling. IC Role / Device Role / Timing Role: Monostable shapes irregular analog comparator outputs into uniform-width strobes for ADC sampling synchronization. Use Value: -55°C to +125°C operation maintains timing accuracy across launch-to-orbit thermal profiles; CERDIP prevents moisture-induced parameter drift.
Avionics Power Sequencing	Defense Radar Pulse Shaping
Use Scenario: Controls staged turn-on of avionics subsystems (e.g., comms → navigation → mission computer) during aircraft startup. IC Role / Device Role / Timing Role: Each monostable provides programmable delay between power rails using RC networks - replaces discrete RC+transistor timers. Use Value: Separate resets allow manual override of any stage; wide V_CC range accommodates 3.3V and 5V subsystems on same board.	Use Scenario: Generates precise, jitter-free transmit/receive windowing pulses for pulsed Doppler radar front-ends. IC Role / Device Role / Timing Role: Dual monostable produces matched Q/Q̅ pulses for T/R switch control and echo window gating. Use Value: Pulse width match ≤±2% ensures consistent radar range resolution; HC logic minimizes switching noise near RF sections.

Missile Proximity Fusing

Aerospace Sensor Signal Conditioning

Use Scenario: Detects target proximity via RF return pulse timing and triggers warhead arming sequence within strict microsecond windows.

IC Role / Device Role / Timing Role: Dual monostable generates precisely timed enable pulses for RF receiver gating and arming logic activation.

Use Value: Overriding reset ensures immediate disarm if target lock is lost; Schmitt B inputs tolerate noisy RF detector outputs.

Use Scenario: Converts analog transducer signals (e.g., accelerometers) into clean digital timing events for inertial measurement unit (IMU) data sampling.

IC Role / Device Role / Timing Role: Monostable shapes irregular analog comparator outputs into uniform-width strobes for ADC sampling synchronization.

Use Value: -55°C to +125°C operation maintains timing accuracy across launch-to-orbit thermal profiles; CERDIP prevents moisture-induced parameter drift.

Avionics Power Sequencing

Defense Radar Pulse Shaping

Use Scenario: Controls staged turn-on of avionics subsystems (e.g., comms → navigation → mission computer) during aircraft startup.

IC Role / Device Role / Timing Role: Each monostable provides programmable delay between power rails using RC networks - replaces discrete RC+transistor timers.

Use Value: Separate resets allow manual override of any stage; wide V_CC range accommodates 3.3V and 5V subsystems on same board.

Use Scenario: Generates precise, jitter-free transmit/receive windowing pulses for pulsed Doppler radar front-ends.

IC Role / Device Role / Timing Role: Dual monostable produces matched Q/Q̅ pulses for T/R switch control and echo window gating.

Use Value: Pulse width match ≤±2% ensures consistent radar range resolution; HC logic minimizes switching noise near RF sections.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
CD74HC221E	Same logic function and pinout, but PDIP package (non-hermetic, commercial temp: -55°C to +125°C)	Lacks MIL-PRF-38535 qualification; unsuitable for flight hardware or sealed enclosures	Select only for ground-test fixtures or non-mission-critical prototypes where cost and availability outweigh environmental ruggedness
CD74HCT221M	TTL-compatible inputs (VIH = 2V min), SOIC package, same timing behavior but narrower V_CC range (4.5V–5.5V)	Designed for legacy 5V LSTTL systems; incompatible with 3.3V or wide-supply designs	Choose when interfacing directly with 74LS-series logic without level shifters; verify reset timing margins at V_CC = 4.5V

Compared with CD74HC221E and CD74HCT221M, CD54HC221F uniquely combines hermetic CERDIP packaging, full military temperature range, and 2V–6V operation - making it the sole option for space-qualified or high-reliability embedded timing where parameter stability under thermal cycling is non-negotiable.

Availability

CD54HC221F is available at Aetrix Electronics and suitable for missile fusing, avionics sequencing, and radar pulse shaping requiring stable component supply across extended temperature extremes and long product lifecycles.

Supply support for CD54HC221F 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 delivering analog and embedded processing solutions for industrial, automotive, and defense markets.

The CD54HC221F belongs to TI's military-grade HC logic family, engineered specifically for high-reliability timing applications where hermetic sealing, radiation tolerance, and guaranteed parametric performance over extreme temperatures are mandatory.

FAQ

What is the minimum external timing capacitor value supported by the CD54HC221F?

The CD54HC221F supports C_X = 0pF as the minimum external timing capacitance, enabling nanosecond-scale pulse widths when paired with low-value R_X resistors. This capability is confirmed in the datasheet's "Description" section and validated by test conditions for t_W = 140ns (28pF/2kΩ) and t_W = 1.5µs (1000pF/2kΩ). The CD54HC221F achieves this via internal current-source-based timing architecture that does not require minimum capacitive loading for stability.

Does the CD54HC221F support simultaneous triggering of both monostables?

Yes, the CD54HC221F supports independent and simultaneous triggering of both monostables - Mono 1 (pins 1A/2B/3R) and Mono 2 (pins 9A/10B/11R) operate autonomously. Their timing networks (1CX/1CXRX and 2CX/2CXRX) are fully isolated, and propagation delays (t_PLH/t_PHL) are matched to ±2% per datasheet. This enables synchronized dual-pulse generation in radar T/R switching or dual-channel sensor timestamping without cross-talk.

What is the maximum recommended V_CC for continuous operation of the CD54HC221F?

The CD54HC221F has an absolute maximum V_CC rating of 7V, but the recommended operating range is 2V to 6V per the "Operating Conditions" table. Continuous operation above 6V risks exceeding internal oxide breakdown limits and is not characterized for timing accuracy, propagation delay, or quiescent current. The CD54HC221F's typical t_W = 0.7 × R_XC_X formula and noise immunity specs are only guaranteed within 2V–6V.

How does the Schmitt trigger on the B input improve noise immunity for the CD54HC221F?

The Schmitt trigger on each B input (pins 2B and 10B) provides hysteresis - with VIH ≈ 3.15V and VIL ≈ 1.35V at V_CC = 4.5V - giving a 1.8V noise margin. This rejects sub-threshold glitches and slow-rising signals common in sensor interfaces or relay outputs. Unlike standard CMOS inputs, the CD54HC221F's B inputs prevent false triggering from EMI or contact bounce, ensuring single-event reliability in harsh electromagnetic environments.

Is the CD54HC221F pin-compatible with the CD74HC221 series?

Yes, the CD54HC221F is pin-compatible with the CD74HC221E, CD74HC221M, and CD74HCT221 variants - all share identical 16-pin CERDIP/PDIP/SOIC footprints and identical pin functions (e.g., pin 1 = 1A, pin 3 = 1R, pin 16 = V_CC). However, the CD54HC221F's CERDIP package has different mechanical dimensions and soldering requirements than plastic packages, so PCB land patterns must match the J-outline drawing, not the N- or D-outline.

CD54HC221F Specifications

Product attributes: Attribute value

Manufacturer:: Texas Instruments

Series:: 54HC

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

Packaging:: Tube

Product Status:: Active

Logic Type:: Monostable

Independent Circuits:: 2

Schmitt Trigger Input:: Yes

Propagation Delay:: 18 ns

Current - Output High, Low:: 5.2mA, 5.2mA

Voltage - Supply:: 2 V ~ 6 V

Operating Temperature:: -55°C ~ 125°C

Grade:: -

Qualification:: -

Mounting Type:: Through Hole

Supplier Device Package:: 16-CDIP

CD54HC221F FAQ

1.How can I place an order for CD54HC221F through Aetrix?

Please submit a Request for Quotation (RFQ) for CD54HC221F 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 CD54HC221F reliable?

The price and inventory of CD54HC221F are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for CD54HC221F is usually 5 days.

3.What payment methods are accepted for CD54HC221F?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for CD54HC221F transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for CD54HC221F?

CD54HC221F orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your CD54HC221F 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 CD54HC221F?

For technical support, including CD54HC221F datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your CD54HC221F requirements.

6.How does Aetrix verify that CD54HC221F is sourced from the original manufacturer or authorized distributors?

All CD54HC221F 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 CD54HC221F meets industry standards.

7.What is the process for return or replacement of CD54HC221F?

All CD54HC221F units undergo pre-shipment inspection (PSI). If there is an issue with CD54HC221F, 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 CD54HC221F part is unused and in its original packaging.

Return procedure for CD54HC221F:

1.Submit a request within 90 days.

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

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