Texas Instruments SN74LV221ADGVR

Overview

SN74LV221ADGVR 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 SN74LV221ADGVR datasheet, SN74LV221ADGVR pinout, SN74LV221ADGVR application, or SN74LV221ADGVR equivalent, key selection considerations include its 16-pin TVSOP package, 11ns max propagation delay at 5V, Schmitt-trigger input hysteresis for noise immunity, Ioff support for partial-power-down operation, and compatibility with mixed-voltage signal interfaces.

Technical Context

The SN74LV221ADGVR implements two independent edge-triggered monostable multivibrators, each with dual trigger inputs (A and B) and an overriding clear (CLR). Triggering is determined by logic state transitions: A triggers on falling edge when B = H; B triggers on rising edge when A = L; CLR triggers on rising edge when A = L and B = H. Output pulse width is externally set via Rext and Cext connected to dedicated pins (e.g., 1Rext/Cext, 1Cext), enabling adjustable durations from nanoseconds to milliseconds.

Each channel delivers complementary Q and Q̅ outputs with TTL-compatible rise/fall times. Schmitt-trigger inputs on A, B, and CLR ensure jitter-free response to slow or noisy signals. The device includes Ioff circuitry to disable outputs during power-down, preventing backflow current, and guarantees glitch-free initialization with Q low and Q̅ high at power-up.

Key Specifications

Pinout & Package

SN74LV221ADGVR uses a 16-pin TVSOP (DGV) package measuring 3.6 mm × 6.4 mm (body: 3.6 mm × 4.4 mm), optimized for high-density PCB layouts and automated assembly.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74AHC123DR and MC74LVX123DT, the SN74LV221ADGVR uniquely combines Schmitt-trigger inputs, Ioff, and guaranteed glitch-free power-up - making it optimal for industrial edge-node timing where signal integrity and power sequencing matter.

Availability

SN74LV221ADGVR is available at Aetrix Electronics and suitable for industrial control, test equipment, and embedded timing applications requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.

Supply support for SN74LV221ADGVR 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 solutions, with decades of expertise in high-reliability timing and interface ICs.

The SN74LV221ADGVR belongs to TI's LV family of low-voltage logic devices, engineered for robust operation across wide supply ranges and demanding industrial environments - emphasizing noise immunity, power efficiency, and interoperability.

FAQ

What is the maximum output pulse duration achievable with SN74LV221ADGVR?

The SN74LV221ADGVR supports output pulse durations from nanoseconds up to several milliseconds, depending on external R/C values. With Rext = 10 kΩ and Cext = 0.1 µF, typical pulse width is 0.9–1.1 ms. Larger capacitances (e.g., 1 µF) and resistances (e.g., 100 kΩ) extend duration further, though practical limits arise from leakage and timing accuracy degradation. The SN74LV221ADGVR datasheet confirms no hard upper bound, but recommends Cext ≤ 1 µF for stability.

Does SN74LV221ADGVR support retriggering during an active output pulse?

No, the SN74LV221ADGVR does not support retriggering while an output pulse is active. Once triggered, the output remains active for the full duration set by Rext and Cext, regardless of subsequent A or B input transitions. This non-retriggerable behavior is inherent to its monostable architecture and is explicitly documented in the function table and timing diagrams of the SN74LV221ADGVR datasheet.

Can SN74LV221ADGVR operate with VCC = 2.3 V and still drive 5V-tolerant inputs?

Yes, the SN74LV221ADGVR supports mixed-mode voltage operation: it can operate at VCC = 2.3 V while accepting input signals up to 5.5 V (per absolute max ratings), and its outputs swing rail-to-rail (0 V to VCC). However, its outputs will only reach 2.3 V high-level - so driving true 5V logic requires level shifting. The SN74LV221ADGVR itself is safe, but system-level interfacing must account for output voltage compliance.

How does the overriding clear (CLR) function interact with ongoing timing in SN74LV221ADGVR?

In the SN74LV221ADGVR, asserting CLR (driving it high) terminates the current output pulse immediately - forcing Q low and Q̅ high regardless of remaining timing capacitor charge. This override works at any point during the pulse and is synchronized to the internal logic, ensuring deterministic early termination. The SN74LV221ADGVR datasheet specifies that CLR is a rising-edge-triggered input with priority over A/B triggers.

Is SN74LV221ADGVR pin-compatible with older 74-series monostables like SN74LS123?

No, SN74LV221ADGVR is not pin-compatible with SN74LS123. While both are dual monostables, their pin assignments differ significantly - e.g., SN74LV221ADGVR places CLR on pins 3/11 and uses dedicated Rext/Cext pins (6/7/14/15), whereas SN74LS123 uses different pinouts and lacks Schmitt-trigger inputs. The SN74LV221ADGVR datasheet notes pin compatibility only with 'AHC123A and 'AHCT123A, not LS-family devices.