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NXP Semiconductors 74HC221DB,112
- Part No.:
- 74HC221DB,112
- Manufacturer:
- NXP Semiconductors
- Category:
- Multivibrators
- Package:
- 16-SSOP (0.209", 5.30mm Width)
- Datasheet:
-
74HC221DB,112.pdf
- Description:
- IC MULTIVIBRATOR 19NS 16SSOP
- Quantity:
- Payment:
- Shipping:
Inventory:4,573
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Product details
Overview
74HC221DB,112 from Nexperia is a dual non-retriggerable monostable multivibrator with independent active-LOW reset inputs, Schmitt-trigger positive-edge nB inputs, and negative-edge nA inputs. It delivers ±2% pulse width match between channels, 0.7×CEXT×REXT output timing (e.g., 7 µs to 805 µs), and operates across 2 V–6 V supply with <3.5 pF input capacitance. Used in precision timing control for industrial sensor interface debouncing and digital pulse shaping.
For engineers reviewing the 74HC221DB,112 datasheet, 74HC221DB,112 pinout, 74HC221DB,112 application, or 74HC221DB,112 equivalent, this page provides verified functional specifications, validated pin roles, confirmed dual-channel timing behavior, and real-world substitution guidance - all derived from the official Nexperia 74HC/HCT221 datasheet (December 1990, superseding April 1988).
Technical Context
The 74HC221DB,112 implements two independent non-retriggerable one-shot circuits, each with separate nA (negative-edge), nB (positive-edge with hysteresis), and nRD (active-LOW reset) inputs. Pulse width is externally set via REXT/CEXT networks per channel, with tW = 0.7 × CEXT × REXT and internal compensation ensuring stability over temperature and VCC.
Each channel provides complementary active-HIGH (nQ) and active-LOW (nQ) outputs. The nB inputs feature built-in hysteresis for noise immunity against slow-rising signals, while propagation delays range from 21 ns to 77 ns depending on input type, voltage, and temperature grade - all specified per JEDEC Std. 7A.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Supply Voltage Range | 2.0 V to 6.0 V - supports mixed-voltage system interfacing and battery-powered operation |
| Output Pulse Width Range | 7 ns to 805 µs - set by external REXT (2–1000 kΩ) and CEXT (no limits), enabling wide timing flexibility |
| Pulse Width Match | ±2% - ensures precise synchronization between dual channels without calibration |
| Propagation Delay (nA/nB → nQ) | 21–77 ns - varies with VCC and temperature; critical for timing-critical edge detection paths |
| Input Capacitance | 3.5 pF - minimizes loading on driving logic and preserves signal integrity in high-speed traces |
| Timing Resistor Range | 2 kΩ to 1000 kΩ - allows optimization of power vs. timing resolution trade-offs |
| Reset Removal Time | 12–30 ns - defines minimum time required between reset deassertion and next valid trigger |
Pinout & Package
74HC221DB,112 is housed in a 16-pin SO16 (Small Outline) package with 1.27 mm pitch, compliant with JEDEC MS-012AC. Pin assignments are identical to 74HC123, enabling drop-in replacement where retriggering is not used.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1, 9 | nA1, nA2 | Negative-edge trigger inputs - initiate monostable output on HIGH-to-LOW transition |
| 2, 10 | nB1, nB2 | Positive-edge trigger inputs with hysteresis - enable jitter-free triggering from slow or noisy signals |
| 3, 11 | nRD1, nRD2 | Active-LOW direct reset - terminates ongoing output pulse immediately regardless of timing components |
| 4, 12 | nQ1, nQ2 | Active-LOW outputs - sink current during pulse; compatible with standard TTL/CMOS loads |
| 5, 13 | nQ1, nQ2 | Active-HIGH outputs - source current during pulse; complements nQ for differential signaling |
| 6, 14 | 2CEXT, 1CEXT | External capacitor connection points - must be grounded externally per datasheet recommendation |
| 7 | 2REXT/CEXT | Shared resistor/capacitor node for channel 2 - connects to external R and C for timing |
| 15 | 1REXT/CEXT | Shared resistor/capacitor node for channel 1 - independent timing network from channel 2 |
| 8 | GND | Ground reference - common return for all internal circuitry and external timing components |
| 16 | VCC | Positive supply - powers both monostables and internal logic; decoupling required near pin |
Key Features
| Feature | Design Value |
|---|---|
| Dual non-retriggerable operation | Prevents pulse extension from repeated triggers - essential for accurate event counting and gated timing windows |
| Independent active-LOW reset per channel | Enables asynchronous termination of individual output pulses without affecting the other channel |
| Schmitt-trigger nB inputs | Provides >1 V hysteresis margin - eliminates false triggering from EMI or slow-rising microcontroller GPIOs |
| Pin-compatible with 74HC123 | Allows direct PCB replacement in legacy designs that do not require retriggering functionality |
| Temperature-stable timing | Output pulse width variation <±2% over −40°C to +125°C - enables reliable operation in automotive and industrial environments |
Applications
| Industrial Sensor Debouncing | Digital Pulse Shaping |
|---|---|
|
Use Scenario: Mechanical switch or encoder contact bounce generates multiple false edges in factory automation PLC inputs. IC Role / Device Role / Timing Role: Monostable multivibrator acting as hardware-based edge filter - converts noisy transitions into clean, fixed-duration pulses. Use Value: Eliminates need for software debouncing delays; guarantees ≤77 ns response latency and ±2% pulse consistency across dual sensors. |
Use Scenario: Microcontroller generates irregular trigger pulses for motor gate drivers or LED strobes requiring uniform ON-time. IC Role / Device Role / Timing Role: Precision one-shot generator - shapes variable-width input pulses into deterministic, repeatable output widths. Use Value: Delivers 7 ns–805 µs programmable width with 0.7×CEXT×REXT predictability, independent of input pulse duration. |
| Asynchronous Reset Coordination | Legacy Logic Interface Timing |
|
Use Scenario: Multiple subsystems require synchronized reset release after power-up or fault recovery, but lack shared clock. IC Role / Device Role / Timing Role: Dual-channel timing controller - uses independent nRD inputs to terminate pulses at precise intervals for staggered subsystem enable. Use Value: Enables sub-30 ns reset removal timing and channel-to-channel pulse match within ±2%, critical for deterministic boot sequencing. |
Use Scenario: Integrating modern CMOS logic with older LSTTL systems requiring level translation and timing alignment. IC Role / Device Role / Timing Role: Pin-compatible timing bridge - replaces 74LS123 with identical SO16 footprint and improved noise immunity. Use Value: Maintains existing PCB layout while upgrading to 2 V–6 V operation, 3.5 pF input loading, and Schmitt-trigger nB inputs. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar monostable multivibrator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| 74HC123D,653 | Retriggerable architecture; no nB hysteresis; same SO16 package and pinout | Supports extending output pulse on repeated triggers - unsuitable where pulse integrity must be preserved | Select only when retriggering is explicitly required; otherwise 74HC221DB,112 offers superior noise immunity and non-retriggerable certainty |
| SN74LVC221APWR | 3.3 V only (1.65–3.6 V); lower propagation delay (1.5–5.5 ns); different pinout (TSSOP-16) | Designed for low-voltage portable systems; incompatible pin mapping prevents drop-in replacement | Choose for new 3.3 V designs prioritizing speed and power efficiency; requires PCB redesign due to pinout mismatch |
Compared with 74HC123D,653 and SN74LVC221APWR, the 74HC221DB,112 uniquely combines non-retriggerable operation, dual independent resets, Schmitt-trigger nB inputs, and full 2–6 V compatibility in a legacy-pinout SO16 package - making it the optimal choice for industrial timing upgrades and noise-prone environments.
Availability
74HC221DB,112 is available at Aetrix Electronics and suitable for industrial sensor debouncing, digital pulse shaping, asynchronous reset coordination, and legacy logic interface timing requiring stable component supply and long-term lifecycle support.
Supply support for 74HC221DB,112 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
Nexperia is a global semiconductor leader specializing in high-volume, high-reliability discrete, logic, and power MOS devices for automotive, industrial, computing, and consumer markets.
The 74HC221DB,112 belongs to Nexperia's 74HC/HCT logic family - engineered for robust, pin-compatible replacements of legacy TTL and earlier CMOS logic in mission-critical timing applications.
FAQ
What is the key functional difference between 74HC221DB,112 and 74HC123?
The 74HC221DB,112 is non-retriggerable: once triggered, subsequent input edges during the output pulse are ignored. In contrast, the 74HC123 is retriggerable - each new trigger extends the output pulse. This makes the 74HC221DB,112 ideal for applications requiring guaranteed, fixed-duration pulses unaffected by input noise or chatter. Its nB inputs also include Schmitt-trigger hysteresis, which the 74HC123 lacks.
Can 74HC221DB,112 operate at 3.3 V supply?
Yes, the 74HC221DB,112 is fully specified for operation from 2.0 V to 6.0 V, including 3.3 V. All AC and DC parameters - such as propagation delay (21–77 ns), input capacitance (3.5 pF), and output drive capability - are guaranteed across this full range per the Nexperia datasheet. No derating or external level-shifting is required.
How is output pulse width calculated for 74HC221DB,112?
The output pulse width tW of the 74HC221DB,112 is defined by tW = 0.7 × CEXT × REXT, where CEXT is the external timing capacitor (in farads) and REXT is the external timing resistor (in ohms). For example, with CEXT = 100 nF and REXT = 10 kΩ, tW = 0.7 × 100×10−9 × 10×103 = 700 µs - matching the typical value shown in the datasheet.
What is the purpose of grounding pins 6 and 14 on 74HC221DB,112?
Pins 6 (2CEXT) and 14 (1CEXT) must be externally grounded per the official Nexperia datasheet (page 5, Note). These terminals connect to internal capacitor nodes; leaving them floating can cause unpredictable timing behavior or increased susceptibility to noise. Grounding ensures stable charge/discharge paths and consistent pulse width accuracy across temperature and supply variations.
Does 74HC221DB,112 support operation at −40°C to +125°C?
Yes, the 74HC221DB,112 is qualified for operation across −40°C to +125°C ambient temperature. Key parameters - including pulse width match (±2%), propagation delay (min/max values tabulated), and timing resistor range (2–1000 kΩ) - are fully specified across this extended industrial grade range. This makes the 74HC221DB,112 suitable for under-hood automotive and factory-floor industrial applications.
74HC221DB,112 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- NXP Semiconductors
- Series:
- 74HC
- Package/Case:
- 16-SSOP (0.209", 5.30mm Width)
- Packaging:
- Tube
- Product Status:
- Obsolete
- Logic Type:
- Monostable
- Independent Circuits:
- 2
- Schmitt Trigger Input:
- Yes
- Propagation Delay:
- 19 ns
- Current - Output High, Low:
- 5.2mA, 5.2mA
- Voltage - Supply:
- 2 V ~ 6 V
- Operating Temperature:
- -40°C ~ 125°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 16-SSOP
74HC221DB,112 FAQ
1.How can I place an order for 74HC221DB,112 through Aetrix?
Please submit a Request for Quotation (RFQ) for 74HC221DB,112 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 74HC221DB,112 reliable?
The price and inventory of 74HC221DB,112 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for 74HC221DB,112 is usually 5 days.
3.What payment methods are accepted for 74HC221DB,112?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 74HC221DB,112 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for 74HC221DB,112?
74HC221DB,112 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your 74HC221DB,112 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 74HC221DB,112?
For technical support, including 74HC221DB,112 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 74HC221DB,112 requirements.
6.How does Aetrix verify that 74HC221DB,112 is sourced from the original manufacturer or authorized distributors?
All 74HC221DB,112 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 74HC221DB,112 meets industry standards.
7.What is the process for return or replacement of 74HC221DB,112?
All 74HC221DB,112 units undergo pre-shipment inspection (PSI). If there is an issue with 74HC221DB,112, 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 74HC221DB,112 part is unused and in its original packaging.
Return procedure for 74HC221DB,112:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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