SN74121NG4 Texas Instruments Integrated Circuit (Dual-In-Line Packages) In Stock
The SN74121NG4 is a monostable multivibrator (one-shot) IC from Texas Instruments featuring Schmitt-trigger inputs and internally compensated timing for stable pulse generation. It generates a single output pulse of programmable width using external RC timing, operates from 5 V supply, and is packaged in a 14-pin PDIP for timing and pulse-shaping applications.
- Manufacturer
- Texas Instruments
- Package
- Dual-In-Line Packages
- Pin Count
- 14
- Lifecycle
- ACTIVE
- Datasheet
- SN74121NG4 Datasheet PDF
- Category
- Integrated Circuit
- RoHS
- Compliant
- Lead Time
- 3–7 business days
- Shipping
- DHL Express · Worldwide
Key Features
- Monostable multivibrator (one-shot) with stable retriggerable-free pulse generation
- Schmitt-trigger inputs for reliable triggering from noisy or slow-rise signal edges
- Programmable pulse width using external resistor and capacitor for 40 ns to several seconds range
- Internal timing resistor option for minimum external component count designs
- Standard 5 V TTL compatible operation in a 14-pin PDIP through-hole package
Applications
The SN74121NG4 is used in digital timing circuits, debounce circuits, and pulse-width extension applications where a clean, precise output pulse must be generated from a noisy or asynchronous input trigger. It is commonly found in legacy industrial control systems, power supply sequencing circuits, and educational electronics prototypes for generating fixed-duration reset or enable pulses.
Compliance & Regulatory
| RoHS Status | Compliant |
| Lead-Free | Yes (Pb-Free) |
Alternate & Equivalent Parts
Compatible alternatives and drop-in replacements for SN74121NG4:
Frequently Asked Questions
What is a monostable multivibrator and what does the SN74121NG4 do?
A monostable multivibrator (one-shot) has one stable state and one quasi-stable state. The SN74121NG4 generates a single output pulse of programmable width each time it is triggered, then returns to its stable state. The pulse width is set by external R and C components connected to the timing pins.
How do you set the output pulse width of the SN74121NG4?
The output pulse width is determined by the external timing resistor (Rext, 2 kΩ to 40 kΩ) and capacitor (Cext) connected to the REXT/CEXT and CEXT pins, with pulse width approximately equal to 0.7 × R × C. The internal 2 kΩ resistor can also be used for short pulse widths without external components.
What are the Schmitt-trigger inputs used for on the SN74121NG4?
The SN74121NG4 has Schmitt-trigger trigger inputs (A1, A2) which provide hysteresis to reliably trigger from slow-rising, noisy, or mechanical switch signals without producing multiple false triggers, making it suitable for debounce circuits and conditioning slow analog-derived signals.
What package does the SN74121NG4 come in and is it still in production?
The SN74121NG4 is packaged in a 14-pin PDIP (plastic dual in-line package) through-hole format. The G4 suffix indicates RoHS-compliant, lead-free construction. Availability should be confirmed with distributors as classic 74121 devices may have limited production runs compared to modern CMOS equivalents.
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About Texas Instruments
Texas Instruments (TI) is a global semiconductor company headquartered in Dallas, Texas. TI designs and manufactures analog and embedded processing chips used in industrial, automotive, consumer, communications, and enterprise systems.
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