Bipolar transistors


ESD protection, TVS, filtering and signal conditioning





Analog & Logic ICs

Automotive qualified products (AEC-Q100/Q101)


74HC221; 74HCT221

Dual non-retriggerable monostable multivibrator with reset

The 74HC/74HCT221 are high-speed Si-gate CMOS devices and are pin compatible with low power Schottky TTL (LSTTL). They are specified in compliance with JEDEC standard no. 7A.

The 74HC/HCT221 are dual non-retriggerable monostable multivibrators. Each multivibrator features an active LOW-going edge input (nA) and an active HIGH-going edge input (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 and are a function of the timing components. The output pulses can be terminated by the overriding active LOW reset inputs (nR D ). Input pulses may be of any duration relative to the output pulse.

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.

The output pulse width is defined by the following relationship:



Pin assignments for the '221' are identical to those of the '123' so that the '221' can be substituted for those products in systems not using the retrigger by merely changing the value of REXT and/or CEXT.

Features and benefits

  • Pulse width variance is typically less than ± 5%

  • Pin-out identical to '123'

  • Overriding reset terminates output pulse

  • nB inputs have hysteresis for improved noise immunity

  • Output capability: standard (except for nREXT /CEXT)

  • ICC category: MSI



Type number VCC (V) Logic switching levels Output drive capability (mA) tpd (ns) Power dissipation considerations Tamb (°C) Package name
74HCT221D 4.5 - 5.5 TTL ± 4 32 low -40~125 SO16


Type number Orderable part number, (Ordering code (12NC)) Status Marking Package Package information Reflow-/Wave soldering Packing
74HCT221D 74HCT221D,118
Active 74HCT221D SOT109-1

Environmental information

Type number Orderable part number Chemical content RoHS RHF-indicator
74HCT221D 74HCT221D,118 74HCT221D rohs rhf rhf
Quality and reliability disclaimer

Documentation (11)

File name Title Type Date
74HCT221 Dual non-retriggerable monostable multivibrator with reset Data sheet 2024-04-04
AN11044 Pin FMEA 74HC/74HCT family Application note 2019-01-09
SOT109-1 3D model for products with SOT109-1 package Design support 2020-01-22
Nexperia_package_poster Nexperia package poster Leaflet 2020-05-15
SO16_SOT109-1_mk plastic, small outline package; 16 leads; 1.27 mm pitch; 9.9 mm x 3.9 mm x 1.35 mm body Marcom graphics 2017-01-28
SOT109-1 plastic, small outline package; 16 leads; 1.27 mm pitch; 9.9 mm x 3.9 mm x 1.75 mm body Package information 2023-11-07
74HCT221D_Nexperia_Product_Reliability 74HCT221D Nexperia Product Reliability Quality document 2024-06-16
SO-SOJ-REFLOW Footprint for reflow soldering Reflow soldering 2009-10-08
HCT_USER_GUIDE HC/T User Guide User manual 1997-10-31
SO-SOJ-WAVE Footprint for wave soldering Wave soldering 2009-10-08
WAVE_BG-BD-1 Wave soldering profile Wave soldering 2021-09-08


If you are in need of design/technical support, let us know and fill in the answer form we'll get back to you shortly.


File name Title Type Date
SOT109-1 3D model for products with SOT109-1 package Design support 2020-01-22

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