Dual non-retriggerable monostable multivibrator with reset

The 74HCT221 is a dual non-retriggerable monostable multivibrator. Each multivibrator features edge-triggered inputs (nA and nB), either of which can be used as an enable input. Pulse triggering occurs at a particular voltage level and is not directly related to the transition time of the input pulse. Schmitt-trigger input circuitry for the nB inputs allow jitter-free triggering from inputs with slow transition rates, providing the circuit with excellent noise immunity. Once triggered, the outputs (nQ, nQ) are independent of further transitions of nA and nB inputs. The output pulse width is defined by the following relationship:

  • tW = 0.7 × CEXTREXT

The output pulses can be terminated by the active LOW reset inputs (nRD). Pulse width stability is achieved through internal compensation and is virtually independent of VCC and temperature. In most applications pulse stability will only be limited by the accuracy of the external timing components . This device features reduced input threshold levels to allow interfacing to TTL logic levels. Inputs also include clamp diodes, this enables the use of current limiting resistors to interface inputs to voltages in excess of VCC.

Features and benefits

  • Supply voltage range from 4.5 V to 5.5 V

  • CMOS low power dissipation

  • High noise immunity

  • Input levels:

    • For 74HCT221: TTL level

  • Pulse width variance is typically less than ±5%

  • Direct reset terminates output pulse

  • Schmitt-trigger action on nB inputs

  • Latch-up performance exceeds 100 mA per JESD 78 Class II Level B

  • ESD protection:
    • HBM: ANSI/ESDA/JEDEC JS-001 class 2 exceeds 2000 V

    • CDM: ANSI/ESDA/JEDEC JS-002 class C3 exceeds 1000 V

  • Specified from -40 °C to +85 °C and from -40 °C to +125 °C


Type numberProduct statusVCC (V)Logic switching levelsOutput drive capability (mA)tpd (ns)Power dissipation considerationsTamb (°C)Rth(j-a) (K/W)Ψth(j-top) (K/W)Rth(j-c) (K/W)Package name
74HCT221DProduction4.5 - 5.5TTL± 432low-40~125621.019SO16


Type numberPackagePackage informationReflow-/Wave solderingPackingStatusMarkingOrderable part number, (Ordering code (12NC))
( 9337 151 10118 )

Discontinuation information

Type numberOrderable part number, (Ordering code (12NC))Last time buy dateLast time delivery dateReplacement productStatusComments

    Environmental information

    Type numberOrderable part numberChemical contentRoHSRHF-indicatorLeadfree conversion date
    74HCT221D74HCT221D,11874HCT221Dweek 4, 2004
    Quality and reliability disclaimer

    Documentation (6)

    File nameTitleTypeDate
    74HCT221Dual non-retriggerable monostable multivibrator with resetData sheet2024-04-04
    74HCT221D_Nexperia_Product_Reliability74HCT221D Nexperia Product ReliabilityQuality document2024-06-17
    SO-SOJ-WAVEFootprint for wave solderingWave soldering2009-10-08
    SO-SOJ-REFLOWFootprint for reflow solderingReflow soldering2009-10-08
    WAVE_BG-BD-1Wave soldering profileWave soldering2021-09-08
    SOT109-1plastic, small outline package; 16 leads; 1.27 mm pitch; 9.9 mm x 3.9 mm x 1.75 mm bodyPackage information2023-11-07


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