Renesas 74HC221FP-E

Overview

74HC221FP-E from Renesas is a dual non-retriggerable monostable multivibrator with Schmitt-trigger inputs, operating from 2–6 V supply, delivering pulse widths from 14 ns to >1 ms via external R_ext/C_ext, and used in precision timing, debounce, and pulse shaping circuits in industrial control and instrumentation.

For engineers reviewing the 74HC221FP-E datasheet, 74HC221FP-E pinout, 74HC221FP-E application, or 74HC221FP-E equivalent, this page provides verified functional behavior, exact package mapping (SOP-16), confirmed non-retriggerable operation, output propagation delays down to 29 ns, and real-world timing design constraints including C_ext/R_ext layout sensitivity.

Technical Context

The 74HC221FP-E implements two independent monostable circuits, each with dual-edge trigger capability (A = negative edge, B = positive edge), clear-synchronized triggering, and inherent Schmitt-trigger hysteresis on all inputs for noise immunity. Each section features separate R_ext/C_ext pins enabling independent pulse width tuning per channel.

It operates as a non-retriggerable one-shot: once triggered, the output pulse (Q) remains active for t_W = 0.7·R_ext·C_ext regardless of subsequent input transitions, and the clear input resets Q asynchronously while preserving timing independence between sections.

Key Specifications

Pinout & Package

SOP-16 (JEITA PRSP0016DH-B / FP-16DAV), 1.27 mm pitch, 5.5 mm × 10.06 mm body, Ni/Pd/Au-plated leads, 0.24 g typical mass.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74LS221N and MC74HC221ADTR2G, the 74HC221FP-E offers wider supply range (2–6 V), lower quiescent current, and JEITA-standard SOP-16 packaging optimized for reflow compatibility-making it preferred for modern industrial and portable designs requiring voltage flexibility and thermal reliability.

Availability

74HC221FP-E is available at Aetrix Electronics and suitable for industrial control panels, test equipment timing modules, and embedded sensor interface circuits requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for 74HC221FP-E 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

Renesas Electronics Corporation is a global semiconductor leader specializing in microcontrollers, analog, power, and timing solutions for automotive, industrial, and infrastructure markets.

The HD74HC221 product line delivers robust, low-power monostable timing functions for noise-prone environments-designed specifically for reliable edge detection, switch conditioning, and pulse-width-controlled actuation in factory automation and instrumentation.

FAQ

What is the maximum recommended value for R_ext when using the 74HC221FP-E?

The 74HC221FP-E datasheet does not specify an absolute maximum R_ext, but practical limits arise from leakage current and timing accuracy. At V_CC = 6 V, input leakage ≤ ±1.0 µA implies R_ext should remain below 10 MΩ to avoid >10% pulse width error due to current injection into C_ext. For stable operation across –40°C to +85°C, Renesas recommends R_ext ≤ 2.2 MΩ with standard film resistors. The 74HC221FP-E's internal structure requires R_ext to sink sufficient current to discharge C_ext reliably during reset.

Can the 74HC221FP-E be triggered simultaneously on both A and B inputs?

No-the 74HC221FP-E does not support simultaneous dual-edge triggering. Its function table defines A as negative-edge sensitive and B as positive-edge sensitive, but only one input per section may initiate a pulse. If both A and B transition within the input rise/fall time window (≤400 ns at V_CC = 6 V), the device behavior is undefined per datasheet caution. The 74HC221FP-E is designed for exclusive use of either A or B per monostable section; using both concurrently risks metastable output states or missed triggers.

Is the 74HC221FP-E pin-compatible with the older HD74HC221P DIP-16 version?

No-the 74HC221FP-E (SOP-16) and HD74HC221P (DIP-16) share identical logic functionality and pin numbering sequence, but their physical pinouts differ due to package geometry: SOP-16 has gull-wing leads with 1.27 mm pitch and staggered corner pins, while DIP-16 uses through-hole leads with 2.54 mm pitch. The 74HC221FP-E cannot be substituted into a DIP socket without adapter hardware. Both packages map Pin 1 (1A) to top-left corner, but mechanical mounting and solder reflow requirements are incompatible.

Does the 74HC221FP-E support retriggering during an active output pulse?

No-the 74HC221FP-E is explicitly defined as a non-retriggerable monostable multivibrator. Once triggered, the output pulse duration t_W = 0.7·R_ext·C_ext proceeds to completion regardless of additional A, B, or clear transitions. Subsequent triggers are ignored until Q returns low and the internal state fully resets. This behavior is confirmed in the device description ("non-retriggerable, and therefore cannot be retriggered until the output pulse times out") and distinguishes the 74HC221FP-E from retriggerable alternatives like the 74HC4538.

What is the minimum C_ext value supported by the 74HC221FP-E for stable operation?

The 74HC221FP-E requires C_ext ≥ 28 pF for guaranteed minimum pulse width compliance, as validated in the "Minimum output pulse width t_WQ(min)" specification (380 ns at V_CC = 6 V, R_ext = 2 kΩ). Using C_ext < 20 pF risks failure to achieve specified t_W due to internal node capacitance dominating timing. For sub-100 ns pulses, Renesas specifies t_W ≥ 14 ns at V_CC = 6 V-but this assumes C_ext ≥ 28 pF and R_ext ≥ 0.5 kΩ. The 74HC221FP-E's internal timing circuitry relies on measurable RC charge/discharge; values below 28 pF yield unpredictable jitter and duty cycle drift.