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Texas Instruments SN74LV221APWR
- Part No.:
- SN74LV221APWR
- Manufacturer:
- Texas Instruments
- Category:
- Multivibrators
- Package:
- 16-TSSOP (0.173", 4.40mm Width)
- Datasheet:
-
SN74LV221APWR.pdf
- Description:
- IC MULTIVIBRATOR 13.2NS 16TSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:2,115
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Product details
Overview
SN74LV221APWR from Texas Instruments is a dual monostable multivibrator IC with Schmitt-trigger inputs, designed for precise pulse generation in 2V–5.5V systems. It features independent A (falling-edge) and B (rising-edge) trigger inputs per channel, overriding clear functionality, programmable output pulse duration via external R/C networks, and glitch-free power-up reset. It is used in timing control, debouncing, and delay generation circuits in industrial control and instrumentation.
For engineers reviewing the SN74LV221APWR datasheet, SN74LV221APWR pinout, SN74LV221APWR application, or SN74LV221APWR equivalent, key selection considerations include its 16-pin TSSOP package, dual-channel retriggerable/non-retriggerable operation, Schmitt-trigger noise immunity on all control inputs, Ioff partial-power-down support, and compatibility with mixed-voltage signal environments.
Technical Context
The SN74LV221APWR implements two independent edge-triggered monostable multivibrators, each with three distinct triggering modes: A-low/B-high transition, B-high/A-low transition, or CLR-high with A-low/B-high preconditioning. Pulse width is externally set by Rext and Cext connected to dedicated pins (e.g., 1Rext/Cext, 1Cext), enabling adjustable durations from ~100 ns to >1 ms.
Schmitt-trigger inputs on A, B, and CLR provide hysteresis for robust operation with slow or noisy signals; the overriding clear input terminates output pulses early. The device supports Ioff, preventing backflow current during partial power-down, and guarantees glitch-free outputs at power-up with Q low and Q high.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VCC Range | 2 V to 5.5 V - Enables direct interface with 2.5V, 3.3V, and 5V logic families without level shifters. |
| Max Propagation Delay | 11 ns at VCC = 5 V - Ensures fast response for timing-critical pulse generation and synchronization. |
| Output Pulse Duration | Programmable via external R/C - Supports wide range (e.g., 90 ns to 1.1 ms) using standard capacitors (28 pF–0.1 µF) and resistors (1 kΩ–5 kΩ). |
| Input Hysteresis | Schmitt-trigger on A, B, CLR - Eliminates false triggering from slow-rising/falling or noisy control signals. |
| Ioff Support | Yes - Allows safe isolation of powered-down sections in mixed-supply systems without damaging current flow. |
| Operating Temperature | −40°C to +85°C - Qualified for industrial-grade embedded applications requiring thermal reliability. |
Pinout & Package
TSSOP-16 (PW) package: 5.00 mm × 6.4 mm body, 0.65 mm pitch, thin-profile surface-mount design optimized for space-constrained PCB layouts.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 A | Falling-edge trigger input (Channel 1) | Active when 1B = high; initiates output pulse on negative transition. |
| 2 1B | Rising-edge trigger input (Channel 1) | Active when 1A = low; initiates output pulse on positive transition. |
| 3 1CLR | Overriding clear input (Channel 1) | Rising-edge triggered; forces 1Q/1Q low and can terminate ongoing pulse. |
| 4 1Q | Inverted output (Channel 1) | Complementary to 1Q; active-low pulse synchronized to trigger event. |
| 5 2Q | Non-inverted output (Channel 2) | Primary output for Channel 2; high pulse duration matches timing components. |
| 6 2Cext | External capacitor negative terminal (Ch2) | Connects to ground side of timing capacitor; sets discharge path for pulse timing. |
| 7 2Rext/Cext | R/C junction node (Channel 2) | Connects external resistor to VCC and capacitor to 2Cext; defines RC time constant. |
| 8 GND | Ground reference | Common return for all internal circuitry and external timing components. |
| 9 2A | Falling-edge trigger input (Channel 2) | Functionally identical to Pin 1; enables independent dual-channel triggering. |
| 10 2B | Rising-edge trigger input (Channel 2) | Functionally identical to Pin 2; supports asynchronous dual-channel operation. |
| 11 2CLR | Overriding clear input (Channel 2) | Functionally identical to Pin 3; provides per-channel pulse termination. |
| 12 2Q | Inverted output (Channel 2) | Complementary to 2Q; ensures matched timing and polarity control per channel. |
| 13 1Q | Non-inverted output (Channel 1) | Primary output for Channel 1; high pulse duration determined by Rext/Cext values. |
| 14 1Cext | External capacitor negative terminal (Ch1) | Ground-side connection for Channel 1 timing capacitor; critical for accurate pulse width. |
| 15 1Rext/Cext | R/C junction node (Channel 1) | Shared node for Channel 1 resistor-to-VCC and capacitor-to-1Cext connections. |
| 16 VCC | Positive supply | Supplies core logic and output drivers; requires local 0.1 µF bypass capacitor. |
Key Features
| Feature | Design Value |
|---|---|
| Dual independent monostables | Enables two separate, non-interfering timing functions on one IC - reduces board area and component count vs discrete solutions. |
| Schmitt-trigger inputs on A/B/CLR | Provides ≥0.3×VCC hysteresis - eliminates chatter and false triggers from mechanical switch bounce or EMI-prone traces. |
| Overriding clear with pulse truncation | Allows real-time termination of active output pulses - essential for safety interlocks and dynamic timing adjustments. |
| Glitch-free power-up reset | Guarantees known initial state (1Q/2Q low, 1Q/2Q high) without external reset circuitry - simplifies system initialization. |
| Ioff partial-power-down support | Blocks current flow when VCC = 0 V - prevents back-driving of powered-down buses in hot-swap or multi-rail systems. |
Applications
| Switch Debounce Circuit | Pulse Width Modulation (PWM) Timing |
|---|---|
Use Scenario: Mechanical pushbutton or relay contact interfacing with microcontroller GPIO, where contact bounce causes multiple unintended interrupts. IC Role / Device Role / Timing Role: SN74LV221APWR acts as hardware-level debounce filter, generating clean single-pulse outputs per button press using Schmitt-triggered A/B inputs. Use Value: Eliminates need for software debouncing delays or complex firmware logic; supports reliable operation across −40°C to +85°C industrial environments. | Use Scenario: Generating fixed-duration gate drive pulses for MOSFETs in DC-DC converter feedback loops or motor control timing stages. IC Role / Device Role / Timing Role: SN74LV221APWR serves as programmable one-shot timer, with pulse width set by precision R/C network on 1Rext/Cext and 1Cext pins. Use Value: Provides stable, temperature-compensated pulse widths (±1% variation) independent of MCU clock jitter or software latency. |
| Asynchronous Event Synchronization | Power Sequencing Control |
Use Scenario: Aligning asynchronous external interrupt signals (e.g., sensor wake-up) to a synchronous system clock domain without metastability risk. IC Role / Device Role / Timing Role: SN74LV221APWR converts unsynchronized edges into deterministic-width strobes, leveraging its dual-channel capability for parallel event capture. Use Value: Reduces FPGA or ASIC logic resources needed for synchronizer chains; Schmitt inputs tolerate slow-rising wake-up signals from battery-powered sensors. | Use Scenario: Controlling sequential power-up of multiple voltage rails (e.g., core, I/O, analog) in FPGA or processor-based systems. IC Role / Device Role / Timing Role: SN74LV221APWR generates staggered enable pulses using cascaded channels - e.g., Channel 1 triggers Channel 2 via 1Q→2B connection. Use Value: Replaces discrete RC-delay networks and comparators; ensures repeatable, jitter-free sequencing with no firmware dependency. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar monostable multivibrator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SN74AHC123ADTR | Higher VCC max (5.5 V), but no Schmitt-trigger inputs on CLR; propagation delay ~7.5 ns at 5 V. | Lacks inherent noise immunity on clear line; requires external filtering for noisy environments. | Prefer SN74LV221APWR when CLR signal integrity is uncontrolled or layout-limited. |
| MC74LVX123DR2G | Same 2V–3.6V VCC range; lower ICC (10 µA typical), but no Ioff support and narrower temp range (−40°C to +85°C same). | Not suitable for partial-power-down systems; lacks overriding clear pulse truncation feature. | Choose SN74LV221APWR for designs requiring safe hot-swap or multi-rail isolation. |
Compared with SN74AHC123ADTR and MC74LVX123DR2G, the SN74LV221APWR uniquely combines Schmitt-triggered CLR, Ioff, and guaranteed pulse truncation - making it the only option among the three qualified for robust industrial timing in electrically noisy or thermally variable conditions.
Availability
SN74LV221APWR is available at Aetrix Electronics and suitable for industrial control panels, test equipment interfaces, and embedded timing modules requiring stable component supply across extended temperature ranges and long production lifecycles.
Supply support for SN74LV221APWR 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, with over 90 years of innovation in logic, timing, and interface technologies.
The SN74LV221APWR belongs to TI's LV family of low-voltage CMOS logic devices, engineered specifically for interoperability across mixed-voltage systems while maintaining TTL-compatible speed and drive strength.
FAQ
What is the maximum operating frequency or minimum pulse width supported by the SN74LV221APWR?
The SN74LV221APWR does not operate at a fixed frequency but generates single pulses with programmable width. Minimum achievable pulse width is ~90 ns (with Cext = 28 pF, Rext = 2 kΩ at VCC = 5 V), limited by internal propagation delay and external component parasitics. It is not intended for continuous oscillation or clock generation.
Can the SN74LV221APWR be used in retriggerable mode, and how is it configured?
Yes, the SN74LV221APWR supports retriggerable operation. To enable retriggering, hold CLR high and apply successive A or B triggers before the current output pulse ends - each new trigger extends the output pulse duration. This behavior is confirmed in the function table and timing diagrams of the official datasheet.
Does the SN74LV221APWR require external pull-up or pull-down resistors on unused inputs?
Yes. Per TI's recommended operating conditions, all unused inputs (A, B, CLR) of the SN74LV221APWR must be tied to either VCC or GND to prevent floating states that could cause excessive ICC, erratic triggering, or increased EMI susceptibility. Schmitt-trigger inputs do not eliminate this requirement.
How does the Ioff feature of the SN74LV221APWR protect the device during partial power-down?
The Ioff feature in the SN74LV221APWR disables output drivers when VCC = 0 V, blocking current flow from powered I/O lines into the unpowered IC. This prevents damage from back-current through protection diodes and maintains signal integrity in multi-rail systems - a critical safeguard not present in legacy 74-series variants.
What is the purpose of the 1Rext/Cext and 1Cext pins on the SN74LV221APWR, and how are they connected?
The 1Rext/Cext and 1Cext pins define the RC timing network for Channel 1: connect an external resistor between 1Rext/Cext and VCC, and an external capacitor between 1Rext/Cext and 1Cext (which is grounded). This configuration sets the output pulse width according to tw ≈ K × Rext × Cext, where K depends on Cext value and VCC.
SN74LV221APWR Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 74LV
- Package/Case:
- 16-TSSOP (0.173", 4.40mm Width)
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Logic Type:
- Monostable
- Independent Circuits:
- 2
- Schmitt Trigger Input:
- Yes
- Propagation Delay:
- 13.2 ns
- Current - Output High, Low:
- 12mA, 12mA
- Voltage - Supply:
- 2 V ~ 5.5 V
- Operating Temperature:
- -40°C ~ 85°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 16-TSSOP
SN74LV221APWR FAQ
1.How can I place an order for SN74LV221APWR through Aetrix?
Please submit a Request for Quotation (RFQ) for SN74LV221APWR 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 SN74LV221APWR reliable?
The price and inventory of SN74LV221APWR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74LV221APWR is usually 5 days.
3.What payment methods are accepted for SN74LV221APWR?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SN74LV221APWR transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SN74LV221APWR?
SN74LV221APWR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SN74LV221APWR 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 SN74LV221APWR?
For technical support, including SN74LV221APWR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74LV221APWR requirements.
6.How does Aetrix verify that SN74LV221APWR is sourced from the original manufacturer or authorized distributors?
All SN74LV221APWR 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 SN74LV221APWR meets industry standards.
7.What is the process for return or replacement of SN74LV221APWR?
All SN74LV221APWR units undergo pre-shipment inspection (PSI). If there is an issue with SN74LV221APWR, 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 SN74LV221APWR part is unused and in its original packaging.
Return procedure for SN74LV221APWR:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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