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Home > Products > Integrated Circuits (ICs) > Logic > Multivibrators

Renesas 74LS221FP-E

Name: 74LS221FP-E
Brand: Renesas
SKU: 74LS221FP-E
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: 74LS221FP-E

Manufacturer:: Renesas

Category:: Multivibrators

Package:: -

Datasheet:: 74LS221FP-E.pdf

Description:: IC MULTIVIBRATOR

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Product details

Overview

74LS221FP-E from Renesas Electronics is a dual monostable multivibrator IC with independent negative- and positive-edge-triggered inputs per section, Schmitt-trigger B-input for jitter-free triggering down to 1 V/s, TTL-compatible outputs, and external RC timing (tw = C_ext × R_ext × ln2). It operates from 4.75–5.25 V over –20°C to +75°C and is used in pulse shaping, debouncing, and timing control circuits.

For engineers reviewing the 74LS221FP-E datasheet, 74LS221FP-E pinout, 74LS221FP-E application, or 74LS221FP-E equivalent, key selection considerations include its dual independent monostable architecture, Schmitt-trigger noise immunity (1.2 V), clear override functionality, and compatibility with standard LS-TTL logic families in industrial control and instrumentation systems.

Technical Context

The 74LS221FP-E integrates two identical monostable multivibrators on a single chip, each with separate A (negative-edge), B (positive-edge/Schmitt), and CLR (active-low asynchronous clear) inputs. Each section generates a single output pulse whose width is determined solely by external R_ext and C_ext components - not internal propagation delays.

Its Schmitt-trigger B input provides hysteresis (V_T+ ≈ 1.0–2.0 V, V_T− ≈ 0.8–1.0 V at V_CC = 4.75 V), enabling reliable triggering from slow-rising or noisy signals. Internal latching ensures output stability against V_CC noise (1.5 V typical) and eliminates retriggering during the output pulse.

Key Specifications

Parameter	Value and Actual Design Meaning
Supply Voltage	4.75–5.25 V - Ensures stable operation within standard TTL power rail tolerances; supports direct interface with 5 V logic systems.
Output Pulse Width Range	6.7 ns to 7.5 ms - Achieved via external R_ext (1.4–100 kΩ) and C_ext (0–1000 µF); enables precise timing across six decades of capacitance (10 pF–10 µF).
Propagation Delay (t_PLH/t_PHL)	35–80 ns - Guarantees predictable edge-to-output timing for synchronization-critical applications like clock gating or event capture.
B Input Noise Immunity	1.2 V typical - Schmitt-trigger hysteresis rejects low-amplitude noise on slow-rising trigger lines, eliminating false triggers in industrial environments.
V_CC Noise Immunity	1.5 V typical - Internal latching prevents spurious output changes due to supply ripple, critical for reliability in shared-power-rail systems.
Operating Temperature	–20°C to +75°C - Qualified for commercial/industrial ambient conditions without derating; suitable for non-automotive embedded equipment.
Output Drive	I_OL = 8 mA / I_OH = –400 µA - Directly drives standard TTL loads (e.g., 74LS inputs) without buffering; supports fan-out ≥20.

Pinout & Package

DIP-16 package (JEDEC MS-001, Renesas code PRDP0016AE-B, package abbreviation P), 19.2 mm × 6.3 mm body, 2.54 mm lead pitch, through-hole mounting.

Pin/Terminal	Circuit Role	Design Meaning
1, 15	1A / 2A	Negative-edge-trigger input for Section 1 / Section 2 - Initiates output pulse on falling edge; no hysteresis.
2, 14	1B / 2B	Positive-edge-trigger/Schmitt input for Section 1 / Section 2 - Triggers on rising edge with 1.2 V hysteresis for noise immunity.
3, 13	1CLR / 2CLR	Active-low asynchronous clear for Section 1 / Section 2 - Forces Q low and Q high immediately, overriding ongoing timing.
4, 12	1Q / 2Q	True output for Section 1 / Section 2 - Active-high pulse with TTL-compatible VOH ≥2.7 V and VOL ≤0.4 V @ 4 mA.
5, 11	1Q / 2Q	Inverted output for Section 1 / Section 2 - Complementary to Q; supports differential timing or reset logic.
6, 10	1R_ext/C_ext / 2R_ext/C_ext	Timing resistor/capacitor node for Section 1 / Section 2 - Connects external R and C to set pulse width per tw = R × C × ln2.
7, 9	1C_ext / 2C_ext	Timing capacitor connection for Section 1 / Section 2 - Provides timing reference node; accepts 0–1000 µF capacitors.
8	GND	Ground reference - Must be connected to system common; decoupling capacitor recommended near pin.
16	V_CC	+5 V supply - Requires local 0.1 µF ceramic bypass capacitor between V_CC and GND to suppress switching noise.

Key Features

Feature	Design Value
Dual independent monostables	Enables two separate timing functions (e.g., delay + pulse stretch) on one IC, reducing board space and component count.
Schmitt-trigger B input	Supports clean triggering from slow or noisy sources (≥1 V/s rise/fall), eliminating need for external signal conditioning.
Asynchronous clear override	Allows immediate termination of active output pulses - essential for emergency stop, fault recovery, or dynamic pulse width adjustment.
RC timing with wide range	R_ext = 1.4–100 kΩ and C_ext = 0–1000 µF support pulse widths from nanoseconds to milliseconds using low-cost passive components.
TTL-compatible I/O	Direct interface with 74LS, 74S, and other TTL families without level-shifting; VOH/VOL meet LS-TTL voltage thresholds.

Applications

Keyboard Debounce Circuit	Pulse Width Modulator Trigger
Use Scenario: Mechanical keyboard matrix with contact bounce causing multiple unintended key scans. IC Role / Device Role / Timing Role: Monostable section acts as hardware debounce timer - triggered by key press edge and generating a clean, fixed-duration strobe. Use Value: Eliminates software polling or firmware debounce delays; guarantees single scan per key press using 10–20 ms RC timing.	Use Scenario: Generating variable-width gate pulses for PWM-driven motor control based on analog feedback. IC Role / Device Role / Timing Role: One section triggered by error comparator output; pulse width set by R/C to define duty cycle baseline. Use Value: Provides analog-settable, jitter-free timing reference independent of microcontroller clock jitter or load variations.
Serial Data Framing	Test Equipment Timing Generator
Use Scenario: Isolating start/stop bits in asynchronous serial communication where clock recovery is unavailable. IC Role / Device Role / Timing Role: Monostable triggered by falling edge of start bit; output pulse defines guaranteed minimum frame window. Use Value: Prevents false framing from noise spikes; ensures consistent bit sampling window regardless of baud rate drift.	Use Scenario: Bench-level generation of calibrated delay pulses for oscilloscope trigger alignment or logic analyzer calibration. IC Role / Device Role / Timing Role: Dual sections generate precisely timed, non-overlapping strobes (e.g., delay + width) using matched R/C networks. Use Value: Delivers sub-100 ns timing accuracy with minimal component variation; avoids microcontroller timing resolution limits.

Keyboard Debounce Circuit

Pulse Width Modulator Trigger

Use Scenario: Mechanical keyboard matrix with contact bounce causing multiple unintended key scans.

IC Role / Device Role / Timing Role: Monostable section acts as hardware debounce timer - triggered by key press edge and generating a clean, fixed-duration strobe.

Use Value: Eliminates software polling or firmware debounce delays; guarantees single scan per key press using 10–20 ms RC timing.

Use Scenario: Generating variable-width gate pulses for PWM-driven motor control based on analog feedback.

IC Role / Device Role / Timing Role: One section triggered by error comparator output; pulse width set by R/C to define duty cycle baseline.

Use Value: Provides analog-settable, jitter-free timing reference independent of microcontroller clock jitter or load variations.

Serial Data Framing

Test Equipment Timing Generator

Use Scenario: Isolating start/stop bits in asynchronous serial communication where clock recovery is unavailable.

IC Role / Device Role / Timing Role: Monostable triggered by falling edge of start bit; output pulse defines guaranteed minimum frame window.

Use Value: Prevents false framing from noise spikes; ensures consistent bit sampling window regardless of baud rate drift.

Use Scenario: Bench-level generation of calibrated delay pulses for oscilloscope trigger alignment or logic analyzer calibration.

IC Role / Device Role / Timing Role: Dual sections generate precisely timed, non-overlapping strobes (e.g., delay + width) using matched R/C networks.

Use Value: Delivers sub-100 ns timing accuracy with minimal component variation; avoids microcontroller timing resolution limits.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
SN74LS221N	Same logic function, pinout, and electrical specs; manufactured by Texas Instruments; DIP-16 package identical to 74LS221FP-E.	No functional difference; fully interchangeable in legacy 74LS designs requiring through-hole mounting.	Select SN74LS221N when TI-sourced parts are required for supply chain diversification or qualification continuity.
74HC221D	CMOS version (74HC family); higher V_CC range (2–6 V), lower I_CC, but no Schmitt B-input - requires clean digital edges.	Lacks 1.2 V noise immunity on B input; unsuitable for slow/noisy trigger sources unless externally conditioned.	Choose 74HC221D only for low-power, 3.3 V–5 V mixed-voltage systems with clean clock or logic edges; not drop-in for noise-prone environments.

Compared with SN74LS221N, the 74LS221FP-E offers identical timing behavior and pin compatibility but originates from Renesas' qualified LS-TTL line; versus 74HC221D, it provides superior noise immunity and guaranteed TTL drive strength at the cost of higher static current.

Availability

74LS221FP-E is available at Aetrix Electronics and suitable for industrial control panels, test instrumentation, and legacy TTL-based embedded systems requiring stable component supply and long-term obsolescence management.

Supply support for 74LS221FP-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 industrial, automotive, and infrastructure markets.

The 74LS221FP-E belongs to Renesas' legacy LS-TTL logic family, designed for robust, noise-immune timing and waveform shaping in industrial control, instrumentation, and legacy system upgrades.

FAQ

What is the maximum external timing capacitance supported by the 74LS221FP-E?

The 74LS221FP-E supports external timing capacitance up to 1000 µF, as specified in the Recommended Operating Conditions table. This enables output pulse widths extending into the millisecond range (e.g., 7.5 ms with R_ext = 10 kΩ and C_ext = 1 µF). Larger capacitors may degrade accuracy due to leakage or ESR effects, so values above 100 µF should use low-leakage electrolytics or tantalums with verified stability.

Does the 74LS221FP-E have built-in hysteresis on both A and B inputs?

No - only the B input features Schmitt-trigger hysteresis (V_T+ ≈ 1.0–2.0 V, V_T− ≈ 0.8–1.0 V), providing 1.2 V typical noise immunity. The A input is a standard negative-edge-triggered TTL input with no hysteresis; it responds to fast falling edges but lacks noise rejection for slow or noisy signals. Use B input for noisy environments and A input for clean clock or logic transitions.

Can the 74LS221FP-E operate reliably at 4.75 V supply voltage?

Yes - the 74LS221FP-E is fully specified down to 4.75 V V_CC, with all electrical characteristics (VOH, VOL, t_PLH, t_PHL, threshold voltages) guaranteed across this minimum supply. Its internal latching circuitry maintains 1.5 V typical immunity to V_CC noise even at this lower rail, ensuring stable operation in systems with marginal or ripple-prone 5 V supplies.

Is the 74LS221FP-E pin-compatible with the SN74LS221N?

Yes - the 74LS221FP-E and SN74LS221N share identical DIP-16 pinouts, logic functions, timing equations, and DC/AC electrical specifications. Both devices use the same HD74LS221 internal die design and are functionally interchangeable in existing PCB layouts without modification.

What is the minimum input pulse width required to trigger the 74LS221FP-E?

The minimum input pulse width for reliable triggering is 40 ns for both A/B inputs and the CLR input, as defined in the Recommended Operating Conditions. Pulses shorter than this may fail to register due to internal setup time (t_su = 15 ns) and propagation constraints. For robust operation, maintain input pulses ≥60 ns, especially under temperature extremes or supply variations.

74LS221FP-E Specifications

Product attributes: Attribute value

Manufacturer:: Renesas

Series:: *

Package/Case:: -

Packaging:: Bulk

Product Status:: Active

Logic Type:: -

Independent Circuits:: -

Schmitt Trigger Input:: -

Propagation Delay:: -

Current - Output High, Low:: -

Voltage - Supply:: -

Operating Temperature:: -

Grade:: -

Qualification:: -

Mounting Type:: -

Supplier Device Package:: -

74LS221FP-E FAQ

1.How can I place an order for 74LS221FP-E through Aetrix?

Please submit a Request for Quotation (RFQ) for 74LS221FP-E 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 74LS221FP-E reliable?

The price and inventory of 74LS221FP-E are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for 74LS221FP-E is usually 5 days.

3.What payment methods are accepted for 74LS221FP-E?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 74LS221FP-E transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for 74LS221FP-E?

74LS221FP-E orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your 74LS221FP-E 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 74LS221FP-E?

For technical support, including 74LS221FP-E datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 74LS221FP-E requirements.

6.How does Aetrix verify that 74LS221FP-E is sourced from the original manufacturer or authorized distributors?

All 74LS221FP-E 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 74LS221FP-E meets industry standards.

7.What is the process for return or replacement of 74LS221FP-E?

All 74LS221FP-E units undergo pre-shipment inspection (PSI). If there is an issue with 74LS221FP-E, 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 74LS221FP-E part is unused and in its original packaging.

Return procedure for 74LS221FP-E:

1.Submit a request within 90 days.

2.Obtain a Return Material Authorization (RMA) from Aetrix.

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