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Texas Instruments CD74HC221MT
- Part No.:
- CD74HC221MT
- Manufacturer:
- Texas Instruments
- Category:
- Multivibrators
- Package:
- 16-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
CD74HC221MT.pdf
- Description:
- IC MULTIVIBRATOR 18NS 16SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:1,614
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Product details
Overview
CD74HC221MT from Texas Instruments is a dual monostable multivibrator with independent reset, Schmitt-trigger B inputs, and buffered Q/Q̅ outputs. It operates from 2V to 6V, supports edge-triggering on both A (trailing) and B (leading) inputs, and delivers pulse widths adjustable via external RX/CX components - e.g., 630–770 µs with CX = 0.1 µF and RX = 10 kΩ at VCC = 5V. It is used in precision timing control, debounce circuits, and pulse shaping in industrial instrumentation.
For engineers reviewing the CD74HC221MT datasheet, CD74HC221MT pinout, CD74HC221MT application, or CD74HC221MT equivalent, key selection considerations include its dual independent monostable architecture, wide temperature range (−55°C to +125°C), SOIC-16 package compatibility, and HC-type CMOS logic compatibility with LSTTL fanout (10 loads).
Technical Context
The CD74HC221MT implements two fully independent monostable multivibrators, each with separate A (edge-triggered), B (Schmitt-triggered), and R (active-low reset) inputs. Triggering is asynchronous and immune to input rise/fall time variations on B due to internal hysteresis.
Each monostable's output pulse width is determined by tW ≈ 0.7 × RX × CX (at VCC = 4.5V), with minimum RX = 500 Ω and CX ≥ 0 pF. Outputs remain stable during power-up (auto-reset) and support termination of active pulses via LOW on R.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Supply Voltage Range | 2V to 6V - enables direct interface with 3.3V and 5V logic systems without level shifting. |
| Operating Temperature | −55°C to +125°C - qualified for aerospace, automotive under-hood, and industrial control environments. |
| Pulse Width Accuracy | tW = 0.7 × RX × CX (typ.) - predictable timing with <±2% match between internal monos at matched RX/CX. |
| Propagation Delay | 36–63 ns (VCC = 6V to 4.5V, CL = 50 pF) - supports high-speed trigger response in real-time control loops. |
| Fanout Capability | 10 LSTTL loads - drives standard TTL inputs directly without buffer amplification. |
| Input Hysteresis | Schmitt-trigger on B inputs - rejects noise on slow-rising signals (e.g., mechanical switch bounce, sensor outputs). |
| Reset Function | Asynchronous active-low R pin - terminates ongoing output pulse immediately, enabling dynamic pulse abort. |
Pinout & Package
CD74HC221MT is housed in a 16-pin SOIC (Small Outline Integrated Circuit) package, 3.9 mm wide, with 1.27 mm pitch and JEDEC MS-012 compliant footprint.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1A, 9A | Trailing-edge trigger input (Mono 1 & 2) | Accepts falling-edge transitions only; initiates output pulse on ↓ transition. |
| 1B, 10B | Leading-edge trigger input with Schmitt trigger (Mono 1 & 2) | Hysteresis ensures clean triggering on noisy or slow-rising signals (e.g., encoder outputs). |
| 1R, 11R | Active-low reset (Mono 1 & 2) | Drives Q low and Q̅ high instantly; overrides active timing cycle. |
| 1Q, 2Q | Non-inverted output (Mono 1 & 2) | High-level pulse of width tW; buffered for drive strength and noise immunity. |
| 1Q̅, 2Q̅ | Inverted output (Mono 1 & 2) | Complementary to Q; enables differential timing or set/reset logic functions. |
| 1CX, 2CX | Timing capacitor connection (Mono 1 & 2) | Connects external capacitor (CX ≥ 0 pF); sets pulse width with RX. |
| 1CXRX, 2CXRX | Timing resistor connection (Mono 1 & 2) | Connects external resistor (RX ≥ 500 Ω); completes RC timing network with CX. |
| VCC (16) | Positive supply | 2V–6V operation; decoupling required near pin for stable timing. |
| GND (8) | Ground reference | Common return for all inputs, outputs, and timing networks. |
Key Features
| Feature | Design Value |
|---|---|
| Dual independent monostables | Enables two synchronized or isolated timing functions in one IC - reduces board space vs. discrete 555 solutions. |
| Overriding RESET | Allows real-time termination of active output pulses - critical for safety interlocks and fault recovery. |
| Edge-selectable triggering | A input (trailing) and B input (leading) provide flexibility for diverse signal edge conventions in legacy or mixed-signal systems. |
| Wide pulse-width range | Supports sub-microsecond to multi-second pulses via RX/CX scaling - no fixed-range limitation. |
| High noise immunity | NIL/NIH = 30% of VCC at 5V - tolerates >1.5V noise margin on inputs, improving reliability in EMI-prone environments. |
| Low quiescent current | ICC ≤ 160 µA over full temperature range - suitable for battery-backed or low-power standby timing applications. |
Applications
| Industrial Sensor Debounce | Automotive Door Lock Timing |
|---|---|
|
Use Scenario: Mechanical limit switches and rotary encoders generate contact bounce or jittered edges in factory automation panels. IC Role / Device Role / Timing Role: CD74HC221MT acts as a hardware-based debouncer: B input accepts noisy switch closure, and Q output delivers clean, fixed-duration enable pulse. Use Value: Eliminates need for software polling or FPGA logic resources; guarantees ≤21 ns minimum input pulse width rejection per datasheet spec. |
Use Scenario: Vehicle door lock actuators require timed activation pulses to prevent motor stall or gear damage during latch engagement. IC Role / Device Role / Timing Role: CD74HC221MT generates precise 300–500 ms actuation windows triggered by CAN message decode logic. Use Value: Pulse width stability ±2% between channels ensures consistent mechanical behavior across left/right doors without calibration. |
| Test Equipment Pulse Generator | Medical Infusion Pump Control |
|
Use Scenario: Benchtop function generators require user-adjustable pulse widths for stimulus testing of digital receivers. IC Role / Device Role / Timing Role: CD74HC221MT serves as the core timing engine: front-panel potentiometer adjusts RX, while panel switch selects CX values. Use Value: Linear tW ∝ RXCX relationship enables intuitive analog control of digital timing - no microcontroller firmware required. |
Use Scenario: IV pump motor drivers must activate for exact durations to deliver calibrated fluid volumes per dose cycle. IC Role / Device Role / Timing Role: CD74HC221MT provides fail-safe, hardware-governed motor-on pulses triggered by microcontroller GPIO. Use Value: Independent reset (R pin) allows immediate stop on emergency button press - meets IEC 62304 Class B timing safety requirements. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar dual monostable multivibrator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| CD74HC123M | Retriggerable monostable (vs. non-retriggerable CD74HC221MT); identical SOIC-16 package and 2V–6V supply. | Required where overlapping triggers must extend output pulse (e.g., data strobe stretching), not fixed-width termination. | Select CD74HC123M only if retriggerability is explicitly needed; CD74HC221MT is preferred for deterministic single-pulse generation. |
| SN74LVC221APW | 3.3V-only operation (1.65V–3.6V); lower propagation delay (2.5 ns typ.); TSSOP-16 package (4.4 mm width vs. SOIC's 3.9 mm). | Suitable for modern low-voltage digital systems but incompatible with 5V logic domains or −55°C operation. | Choose SN74LVC221APW for compact 3.3V designs; CD74HC221MT remains optimal for mixed-voltage or extended-temperature use. |
Compared with CD74HC123M and SN74LVC221APW, the CD74HC221MT uniquely combines non-retriggerable operation, 2V–6V flexibility, and −55°C to +125°C qualification - making it the only option for robust, voltage-agile, single-shot timing in harsh environments.
Availability
CD74HC221MT is available at Aetrix Electronics and suitable for industrial control, aerospace avionics, and medical device timing applications requiring stable component supply across extended temperature ranges and long production lifecycles.
Supply support for CD74HC221MT 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 high-reliability logic families.
The CD74HC221MT belongs to TI's High-Speed CMOS Logic portfolio, designed specifically for precision timing, noise-immune signal conditioning, and robust operation in mission-critical industrial and defense systems.
FAQ
What is the minimum external timing capacitor value supported by CD74HC221MT?
The CD74HC221MT supports CX = 0 pF as the minimum external timing capacitor value, enabling ultra-short pulse widths down to ~14 ns (with RX = 2 kΩ at VCC = 4.5V). This capability allows the CD74HC221MT to serve as a fast edge detector or glitch filter when combined with minimal RC networks.
Does CD74HC221MT support both rising- and falling-edge triggering on the same input pin?
No - CD74HC221MT assigns distinct edge sensitivities per input: A pins respond only to falling edges (trailing), while B pins respond only to rising edges (leading) due to internal Schmitt-trigger circuitry. This separation prevents ambiguity and ensures deterministic triggering behavior in the CD74HC221MT.
Can CD74HC221MT operate reliably at 2.5V supply voltage?
Yes - the CD74HC221MT is fully specified from 2V to 6V, including guaranteed performance at 2.5V. At this voltage, propagation delays increase to ≤265 ns (tPLH, CL = 50 pF), and output drive remains sufficient for 10 LSTTL loads, making the CD74HC221MT suitable for mixed-voltage battery-powered systems.
How does the reset function interact with an active output pulse in CD74HC221MT?
The reset input (R) in CD74HC221MT is asynchronous and overriding: asserting R LOW immediately forces Q LOW and Q̅ HIGH, terminating the current output pulse regardless of its remaining duration. This behavior is electrically guaranteed per datasheet truth table and enables hard real-time abort functionality in the CD74HC221MT.
Is CD74HC221MT pin-compatible with CD74HCT221MT?
Yes - CD74HC221MT and CD74HCT221MT share identical SOIC-16 pinouts and package dimensions, but differ in input threshold compatibility: CD74HC221MT accepts 2V–6V supplies with CMOS thresholds, while CD74HCT221MT requires 4.5V–5.5V and matches LSTTL input levels. Interchange requires verifying supply and driving logic family in the CD74HC221MT design.
CD74HC221MT Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 74HC
- Package/Case:
- 16-SOIC (0.154", 3.90mm Width)
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Obsolete
- 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:
- Surface Mount
- Supplier Device Package:
- 16-SOIC
CD74HC221MT FAQ
1.How can I place an order for CD74HC221MT through Aetrix?
Please submit a Request for Quotation (RFQ) for CD74HC221MT 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 CD74HC221MT reliable?
The price and inventory of CD74HC221MT are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for CD74HC221MT is usually 5 days.
3.What payment methods are accepted for CD74HC221MT?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for CD74HC221MT transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for CD74HC221MT?
CD74HC221MT orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your CD74HC221MT 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 CD74HC221MT?
For technical support, including CD74HC221MT datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your CD74HC221MT requirements.
6.How does Aetrix verify that CD74HC221MT is sourced from the original manufacturer or authorized distributors?
All CD74HC221MT 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 CD74HC221MT meets industry standards.
7.What is the process for return or replacement of CD74HC221MT?
All CD74HC221MT units undergo pre-shipment inspection (PSI). If there is an issue with CD74HC221MT, 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 CD74HC221MT part is unused and in its original packaging.
Return procedure for CD74HC221MT:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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