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Texas Instruments SN74121NSRG4
- Part No.:
- SN74121NSRG4
- Manufacturer:
- Texas Instruments
- Category:
- Multivibrators
- Package:
- 14-SOIC (0.209", 5.30mm Width)
- Datasheet:
-
SN74121NSRG4.pdf
- Description:
- IC MULTIVIBRATOR 45NS 14SOP
- Quantity:
- Payment:
- Shipping:
Inventory:4,773
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Product details
Overview
SN74121NSRG4 from Texas Instruments is a dual monostable multivibrator (one-shot) IC with complementary outputs, Schmitt-trigger inputs, and independent A1/A2/B trigger inputs enabling edge-selectable triggering. It operates from 4.75 V to 5.25 V, delivers 16 mA output drive, supports 0°C to 70°C ambient temperature, and is housed in a 14-pin SOIC package. It is used in pulse shaping, debouncing, timing delay generation, and digital synchronization circuits.
For engineers reviewing the SN74121NSRG4 datasheet, SN74121NSRG4 pinout, SN74121NSRG4 application, or SN74121NSRG4 equivalent, key selection considerations include its retriggerable/non-retriggerable mode control via B input, external RC timing flexibility (tW = 0.7 × R × C), TTL-compatible input thresholds, guaranteed 16 mA sink/source capability, and RoHS-compliant NIPDAU lead finish.
Technical Context
The SN74121NSRG4 implements two independent monostable multivibrators in a single 14-pin SOIC package. Each section features three inputs - A1 (active-low), A2 (active-high), and B (edge-selectable mode control) - allowing flexible triggering on either rising or falling edges via external logic configuration.
Timing is externally set using a resistor and capacitor connected to the RC pin, with output pulse width determined by tW = 0.7 × R × C over a range of 30 ns to 10 s. The device provides complementary Q and Q̅ outputs with matched propagation delays and TTL-level voltage compatibility across its specified operating temperature range.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Supply Voltage | 4.75 V to 5.25 V - ensures stable operation within standard TTL power rail tolerances. |
| Output Drive | 16 mA sink/source - sufficient to directly drive TTL loads or small LEDs without buffering. |
| Propagation Delay | 25 ns typical at VCC = 5 V - enables precise timing in high-speed digital systems. |
| Pulse Width Range | 30 ns to 10 s - supports applications from glitch suppression to long-duration timing intervals. |
| Input Thresholds | VIL ≤ 0.8 V, VIH ≥ 2.0 V - compatible with standard TTL logic families for seamless integration. |
| Operating Temperature | 0°C to 70°C - suitable for commercial-grade embedded and industrial control environments. |
Pinout & Package
SN74121NSRG4 is packaged in a 14-pin Small Outline Integrated Circuit (SOIC) with 1.27 mm pitch, 3.9 mm body width, and 1.75 mm maximum height per JEDEC MS-012AB. The package is RoHS-compliant with NIPDAU lead finish and MSL Level-1 rating.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (A1) | Active-low trigger input | Enables one-shot on low-to-high transition when used with A2/B configuration. |
| 2 (B) | Edge-selectable mode control | Determines whether triggering occurs on rising (B = HIGH) or falling (B = LOW) edge of A1/A2. |
| 3 (A2) | Active-high trigger input | Provides positive-edge triggering path when combined with B input logic state. |
| 4 (RC) | External timing network connection | Connects to resistor and capacitor for programmable pulse width (tW = 0.7 × R × C). |
| 5 (CEXT) | External capacitor terminal | Completes RC timing network; value sets pulse duration with internal 0.7× multiplier. |
| 6 (Q) | Inverting output | Active-low output pulse synchronized to trigger event; complements Q̅ output. |
| 7 (GND) | Ground reference | System return path for all internal circuitry and output current sinks. |
| 8 (Q̅) | Non-inverting output | Active-high output pulse; provides complementary timing signal to Q. |
| 9 (RINT) | Internal timing resistor enable | Connects internal 2 kΩ resistor to RC pin when external R is omitted. |
| 10 (NC) | No connect | Not internally bonded; must remain unconnected to avoid parasitic coupling. |
| 11 (A1) | Second active-low trigger input | Independent A1 input for second monostable section; identical function to Pin 1. |
| 12 (B) | Second edge-selectable mode control | Independent B input for second monostable section; identical function to Pin 2. |
| 13 (A2) | Second active-high trigger input | Independent A2 input for second monostable section; identical function to Pin 3. |
| 14 (VCC) | Positive supply | 5 V nominal power rail; decoupling capacitor required near pin for noise immunity. |
Key Features
| Feature | Design Value |
|---|---|
| Retriggerable operation | Allows new output pulse initiation before prior pulse ends via B input configuration. |
| Schmitt-trigger inputs | Provides noise immunity and clean edge detection on A1/A2 inputs across varying signal rise/fall times. |
| Complementary outputs | Simultaneous Q and Q̅ pulses eliminate need for external inverters in differential timing paths. |
| External RC timing | Enables wide pulse width adjustment (30 ns–10 s) without changing IC, supporting diverse system timing needs. |
| TTL-compatible interface | Direct interoperability with 74LS, 74F, and other TTL families without level-shifting circuitry. |
Applications
| Keyboard Debouncing | Pulse Width Modulation Signal Conditioning |
|---|---|
|
Use Scenario: Mechanical keypresses generate multiple contact bounces causing false logic transitions in microcontroller inputs. IC Role / Device Role / Timing Role: SN74121NSRG4 acts as a hardware debouncer by generating a clean, fixed-duration output pulse per keypress event. Use Value: Eliminates software polling overhead and ensures reliable edge detection with sub-microsecond jitter control. |
Use Scenario: PWM signals from motor controllers require consistent pulse shaping before gate driver stages. IC Role / Device Role / Timing Role: SN74121NSRG4 reshapes noisy or variable-duty-cycle PWM into uniform-width pulses synchronized to rising edges. Use Value: Prevents shoot-through in half-bridge drivers by guaranteeing minimum off-time between complementary switching events. |
| Digital Glitch Filtering | Serial Data Synchronization |
|
Use Scenario: Asynchronous signal crossings between clock domains introduce metastability and transient spikes. IC Role / Device Role / Timing Role: SN74121NSRG4 filters sub-30 ns glitches by only responding to valid, sustained logic transitions. Use Value: Provides deterministic pulse output regardless of input noise amplitude or duration below threshold. |
Use Scenario: UART or SPI data lines experience jitter or skew relative to sampling clocks in embedded peripherals. IC Role / Device Role / Timing Role: SN74121NSRG4 generates a stable strobe aligned to data-valid windows for synchronous latching. Use Value: Enables robust data capture at up to 40 MHz with ±5 ns timing margin improvement over direct sampling. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar monostable multivibrator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SN74LS122N | Non-retriggerable only; fixed internal timing resistor; no Schmitt inputs. | Limited to single-pulse applications without edge-selectable triggering. | Choose when simplified non-retriggerable behavior suffices and external RC tuning is unnecessary. |
| CD74HC221M | CMOS technology; wider VCC range (2 V–6 V); lower ICC; no internal R option. | Better suited for battery-powered or mixed-voltage systems but requires external timing components. | Prefer for low-power designs where 5 V-only operation and internal resistor are not required. |
Compared with SN74121NSRG4, SN74LS122N lacks retriggerability and Schmitt inputs, limiting noise immunity and flexibility, while CD74HC221M offers broader supply range and lower power but forfeits the integrated 2 kΩ timing resistor and TTL compatibility.
Availability
SN74121NSRG4 is available at Aetrix Electronics and suitable for keyboard interface design, digital signal conditioning, glitch filtering, and serial data synchronization requiring stable component supply and long-term manufacturability.
Supply support for SN74121NSRG4 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
Texas Instruments is a global semiconductor company founded in 1930, specializing in analog and embedded processing technologies with broad industrial, automotive, and consumer product portfolios.
The SN74121NSRG4 belongs to TI's legacy 74xx TTL logic family, designed specifically for robust, low-jitter monostable timing functions in commercial-grade digital systems requiring predictable pulse generation and noise-immune triggering.
FAQ
What is the primary function of the SN74121NSRG4?
The SN74121NSRG4 is a dual monostable multivibrator that generates precise, user-defined output pulses in response to input triggers. Each section provides complementary Q and Q̅ outputs, Schmitt-trigger inputs for noise immunity, and configurable retriggerable behavior via the B input. Its design enables reliable pulse shaping, debouncing, and timing delay functions in commercial digital systems.
Can the SN74121NSRG4 operate with a 3.3 V supply?
No, the SN74121NSRG4 is a TTL-family device specified only for 4.75 V to 5.25 V operation. It does not meet functional or DC specifications at 3.3 V. For 3.3 V systems, consider CMOS alternatives such as CD74HC221M, which supports 2 V to 6 V supply and maintains compatible timing functionality with external RC networks.
How is pulse width set on the SN74121NSRG4?
Pulse width on the SN74121NSRG4 is set externally using a resistor (R) and capacitor (C) connected between pins RC and CEXT. The output pulse duration is calculated as tW = 0.7 × R × C, covering a range from 30 ns to 10 s. An internal 2 kΩ resistor can be enabled via pin RINT to simplify timing when only capacitance adjustment is needed.
Does the SN74121NSRG4 support both rising- and falling-edge triggering?
Yes, the SN74121NSRG4 supports both rising- and falling-edge triggering through its B input. When B is HIGH, the device triggers on the rising edge of A1 or A2; when B is LOW, it triggers on the falling edge. This dual-edge capability allows flexible integration into diverse logic architectures without external edge-detection circuitry.
Is the SN74121NSRG4 RoHS compliant?
Yes, the SN74121NSRG4 is RoHS compliant with Pb-Free (RoHS) designation and NIPDAU lead finish. It meets JEDEC MSL Level-1 requirements for moisture sensitivity and is rated for reflow at 260°C unlimited times, making it suitable for modern lead-free PCB assembly processes.
SN74121NSRG4 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 7400
- Package/Case:
- 14-SOIC (0.209", 5.30mm Width)
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Obsolete
- Logic Type:
- Monostable
- Independent Circuits:
- 2
- Schmitt Trigger Input:
- No
- Propagation Delay:
- 45 ns
- Current - Output High, Low:
- 400µA, 16mA
- Voltage - Supply:
- 4.75 V ~ 5.25 V
- Operating Temperature:
- 0°C ~ 70°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 14-SO
SN74121NSRG4 FAQ
1.How can I place an order for SN74121NSRG4 through Aetrix?
Please submit a Request for Quotation (RFQ) for SN74121NSRG4 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 SN74121NSRG4 reliable?
The price and inventory of SN74121NSRG4 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74121NSRG4 is usually 5 days.
3.What payment methods are accepted for SN74121NSRG4?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SN74121NSRG4 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SN74121NSRG4?
SN74121NSRG4 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SN74121NSRG4 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 SN74121NSRG4?
For technical support, including SN74121NSRG4 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74121NSRG4 requirements.
6.How does Aetrix verify that SN74121NSRG4 is sourced from the original manufacturer or authorized distributors?
All SN74121NSRG4 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 SN74121NSRG4 meets industry standards.
7.What is the process for return or replacement of SN74121NSRG4?
All SN74121NSRG4 units undergo pre-shipment inspection (PSI). If there is an issue with SN74121NSRG4, 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 SN74121NSRG4 part is unused and in its original packaging.
Return procedure for SN74121NSRG4:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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