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Texas Instruments CD54HC221F3A
- Part No.:
- CD54HC221F3A
- Manufacturer:
- Texas Instruments
- Category:
- Multivibrators
- Package:
- 16-CDIP (0.300", 7.62mm)
- Datasheet:
-
CD54HC221F3A.pdf
- Description:
- HIGH SPEEC CMOS LOGIC DUAL MONOS
- Quantity:
- Payment:
- Shipping:
Inventory:243
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Product details
Overview
CD54HC221F3A 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 ~140ns to >770µs via external RX/CX networks. It is used in precision timing control for aerospace sequencers and radiation-hardened test instrumentation.
For engineers reviewing the CD54HC221F3A datasheet, CD54HC221F3A pinout, CD54HC221F3A application, or CD54HC221F3A equivalent, key selection criteria include its CERDIP-16 package, dual-edge triggering (A = trailing, B = leading), overriding reset functionality, wide temperature range, and HC-series CMOS logic compatibility with LSTTL fanout.
Technical Context
The CD54HC221F3A implements two independent monostable circuits, each with separate A (edge-triggered), B (Schmitt-triggered), and R (active-low reset) inputs. Timing is externally set by resistor–capacitor networks connected to dedicated CX and CXRX pins per channel, enabling precise pulse width tuning per circuit.
Its HC logic family ensures 2V–6V operation, high noise immunity (NIL/NIH = 30% of VCC at 5V), and low quiescent current (≤160 µA over full temperature range). Propagation delays are specified down to 36 ns (tPLH, VCC = 6V, CL = 50pF), with matched pulse width tolerance of ±2% between internal monostables.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Logic Family | High-speed CMOS (HC), not TTL-compatible - requires 2V–6V supply and delivers CMOS-level outputs. |
| Operating Temperature | -55°C to +125°C - qualified for military/aerospace applications per MIL-PRF-38535. |
| Pulse Width Range | 140 ns to 805 µs - adjustable via external RX (≥500Ω) and CX (0 pF min) per channel. |
| Input Triggering | A input: trailing-edge only; B input: leading-edge only with Schmitt trigger - eliminates sensitivity to slow/ringing edges. |
| Reset Function | Active-low, overriding reset (R) terminates output pulse immediately - enables synchronous abort in timing sequences. |
| Output Drive | Standard outputs drive 10 LSTTL loads; bus-driver outputs drive 15 LSTTL loads - supports direct interface to legacy TTL systems. |
| Propagation Delay | 36 ns max (tPLH, VCC = 6V, CL = 50pF) - enables sub-20 MHz reliable retriggering in high-speed digital systems. |
Pinout & Package
CD54HC221F3A uses a 16-lead Ceramic Dual In-line Package (CERDIP, J package), hermetically sealed for high-reliability environments. Pin 1 index is marked by a notch or dot; leads are tin-lead (SNPB) finished.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1A, 9A | Trigger A input (Mono 1 & 2) | Trailing-edge sensitive input - initiates pulse on falling edge; no Schmitt action. |
| 2B, 10B | Trigger B input (Mono 1 & 2) | Leading-edge sensitive input with Schmitt trigger - rejects noise and accepts slow-rising signals. |
| 3R, 11R | Reset input (Mono 1 & 2) | Active-low asynchronous reset - forces Q low and Q̅ high regardless of ongoing pulse. |
| 4Q, 12Q | True output (Mono 1 & 2) | Buffered, non-inverted output - provides rail-to-rail CMOS swing and fanout capability. |
| 5Q̅, 13Q̅ | Inverted output (Mono 1 & 2) | Buffered, inverted output - complements Q; both outputs available simultaneously. |
| 6GND | Ground reference | Common return path for all logic and timing functions - must be low-inductance connection. |
| 7VCC | Positive supply | 2V–6V DC supply - decoupling capacitor (0.1 µF ceramic) required near pin. |
| 8, 141CX, 2CX | Timing capacitor connection | Connect external timing capacitor (CX) - 0 pF minimum; determines pulse width baseline. |
| 15, 161CXRX, 2CXRX | Timing resistor connection | Connect external timing resistor (RX ≥500Ω) - sets pulse width scaling factor (tW ≈ 0.7·RX·CX). |
Key Features
| Feature | Design Value |
|---|---|
| Dual independent monostables | Enables two synchronized or isolated timing functions in one IC - reduces board space vs discrete solutions. |
| Overriding active-low reset | Allows real-time termination of any active output pulse - critical for safety-critical abort logic. |
| Separate A/B triggering modes | Supports mixed-edge detection in same system - e.g., A triggers on clock fall, B on sensor rise. |
| Schmitt-trigger B inputs | Rejects noise and slow transitions on B lines - eliminates need for external conditioning circuitry. |
| Wide pulse width range (140 ns – 805 µs) | Configurable timing across 4+ decades - suitable for debounce, delay, strobe, and gating applications. |
Applications
| Avionics Timing Sequencer | Spacecraft Power-Up Controller |
|---|---|
Use Scenario: Generating precisely timed enable pulses for sequential activation of flight computer subsystems during cold-start. IC Role / Device Role / Timing Role: Dual monostable provides staggered power-on reset intervals and watchdog-triggered recovery windows. Use Value: Guaranteed -55°C to +125°C operation and CERDIP packaging ensure reliability under thermal cycling and radiation exposure. | Use Scenario: Controlling staged power delivery to payload instruments after launch vibration settles. IC Role / Device Role / Timing Role: Monostable #1 triggers primary regulator enable; Monostable #2 gates secondary sequencing based on first output. Use Value: Independent resets allow mid-sequence abort if voltage monitoring detects fault - prevents cascading failures. |
| Nuclear Instrumentation Pulse Shaper | Military Test Equipment Debounce Circuit |
Use Scenario: Converting fast, noisy detector pulses into clean, uniform-width logic pulses for counting and time-of-flight analysis. IC Role / Device Role / Timing Role: B-input Schmitt trigger cleans analog pulse edge; monostable generates fixed-width gate for ADC sampling window. Use Value: Input hysteresis and wide temp range ensure consistent pulse shaping despite EMI and thermal drift in shielded enclosures. | Use Scenario: Eliminating mechanical switch bounce in ruggedized field-test panels with tactile pushbuttons. IC Role / Device Role / Timing Role: Each monostable debounces one switch channel; A-input triggered by contact closure, reset by microcontroller. Use Value: Adjustable pulse width (via RX/CX) allows fine-tuning for different switch types without firmware change. |
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-16 plastic package; rated -55°C to +125°C, RoHS-compliant NiPdAu finish. | Not qualified for military/aerospace use; lacks hermetic seal and MIL-PRF-38535 certification. | Select for commercial/industrial prototypes where cost and RoHS compliance outweigh radiation/thermal robustness needs. |
| CD74HCT221M | HCT variant: TTL-compatible inputs (VIH = 2V min, VIL = 0.8V max); SOIC-16 package; same temperature range. | Requires 4.5V–5.5V supply only; interfaces directly to legacy 5V TTL logic without level shifters. | Select when integrating with older 5V TTL systems and board space constraints favor SOIC over CERDIP. |
Compared with CD74HC221E and CD74HCT221M, the CD54HC221F3A uniquely combines hermetic CERDIP packaging, SNPB leads, and full MIL-PRF-38535 qualification - making it the only choice for deployed defense and space systems requiring guaranteed long-term reliability under extreme environmental stress.
Availability
CD54HC221F3A is available at Aetrix Electronics and suitable for avionics timing sequencers, spacecraft power-up controllers, nuclear instrumentation pulse shapers, and military test equipment requiring stable component supply across extended temperature ranges and long production lifecycles.
Supply support for CD54HC221F3A 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 high-reliability logic solutions for industrial, automotive, aerospace, and defense markets.
The CD54HC221F3A belongs to TI's military-grade HC logic family, designed specifically for high-stability timing applications in harsh environments where extended temperature operation, radiation tolerance, and hermetic packaging are mandatory.
FAQ
What is the minimum external timing resistor value supported by the CD54HC221F3A?
The CD54HC221F3A specifies a minimum external timing resistor (RX) value of 500 Ω per monostable channel. Using lower values may cause excessive current draw, timing inaccuracies, or potential damage to internal timing circuitry. The recommended range is 500 Ω to 10 MΩ, with typical designs using 2 kΩ to 100 kΩ for predictable pulse widths.
Can the CD54HC221F3A operate reliably at 2.0V supply voltage?
Yes, the CD54HC221F3A is fully specified for operation at 2.0V supply voltage across its full -55°C to +125°C temperature range. At 2V, propagation delays increase (e.g., tPLH up to 315 ns), and output drive strength decreases, but all logic thresholds, pulse width accuracy, and triggering behavior remain functional and guaranteed per datasheet limits.
Does the CD54HC221F3A support retriggering during an active output pulse?
No - once triggered, the CD54HC221F3A outputs are immune to further A or B input transitions until the current pulse completes or is terminated by the active-low reset (R) input. This non-retriggerable behavior ensures deterministic pulse width and prevents accumulation of spurious triggers in noisy environments.
How does the Schmitt trigger on the B input improve noise immunity for the CD54HC221F3A?
The Schmitt trigger on each B input of the CD54HC221F3A provides hysteresis (~0.8V at VCC = 5V), meaning the rising-edge threshold (VIH) and falling-edge threshold (VIL) differ significantly. This prevents multiple false triggers from slowly rising/falling or noisy signals - a critical advantage in high-EMI avionics or industrial settings where signal integrity cannot be guaranteed.
Is the CD54HC221F3A pin-compatible with the CD74HC221 series?
Yes, the CD54HC221F3A is functionally and pinout-compatible with the CD74HC221E (PDIP), CD74HC221M (SOIC), and CD74HC221NSR (SOP) variants. All share identical pin assignments, electrical behavior, and timing architecture - differing only in package type, material, and qualification level. However, CERDIP packaging and military screening make CD54HC221F3A unsuitable for automated SMT assembly.
CD54HC221F3A 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
CD54HC221F3A FAQ
1.How can I place an order for CD54HC221F3A through Aetrix?
Please submit a Request for Quotation (RFQ) for CD54HC221F3A 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 CD54HC221F3A reliable?
The price and inventory of CD54HC221F3A are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for CD54HC221F3A is usually 5 days.
3.What payment methods are accepted for CD54HC221F3A?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for CD54HC221F3A transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for CD54HC221F3A?
CD54HC221F3A orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your CD54HC221F3A 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 CD54HC221F3A?
For technical support, including CD54HC221F3A datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your CD54HC221F3A requirements.
6.How does Aetrix verify that CD54HC221F3A is sourced from the original manufacturer or authorized distributors?
All CD54HC221F3A 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 CD54HC221F3A meets industry standards.
7.What is the process for return or replacement of CD54HC221F3A?
All CD54HC221F3A units undergo pre-shipment inspection (PSI). If there is an issue with CD54HC221F3A, 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 CD54HC221F3A part is unused and in its original packaging.
Return procedure for CD54HC221F3A:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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