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Texas Instruments CD74HC4538MG4
- Part No.:
- CD74HC4538MG4
- Manufacturer:
- Texas Instruments
- Category:
- Multivibrators
- Package:
- 16-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
CD74HC4538MG4.pdf
- Description:
- IC MULTIVIBRATOR 21NS 16SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:4,709
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Product details
Overview
CD74HC4538MG4 from Texas Instruments is a dual retriggerable/resettable monostable multivibrator in SOIC-16 package, operating from 2V to 6V with Schmitt-trigger inputs on A/B pins, independent trigger/reset propagation delays (e.g., 50 ns at 4.5V), and wide pulse-width tuning via external RX/CX components - used for precision timing in industrial control sequencers and digital signal edge detection.
For engineers reviewing the CD74HC4538MG4 datasheet, CD74HC4538MG4 pinout, CD74HC4538MG4 application, or CD74HC4538MG4 equivalent, key selection criteria include retriggerable mode operation, ±1% pulse width matching between channels, -55°C to +125°C temperature range, and compatibility with both HC-logic level thresholds and LSTTL input loads.
Technical Context
The CD74HC4538MG4 implements two independent monostable circuits, each with separate A (leading-edge) and B (trailing-edge) trigger inputs, dedicated R reset terminals, and buffered Q/Q̅ outputs. Timing is externally set by resistor RX and capacitor CX, with pulse width τ = 0.7 × RX × CX and minimum RX = 5 kΩ.
Propagation delays from A/B or R to Q/Q̅ are independent of RX and CX values, enabling stable timing across wide pulse-width ranges. Retrigger time is also independent of CX, supporting reliable multi-pulse synchronization in real-time event capture systems.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Supply Voltage Range | 2V to 6V - supports mixed-voltage system integration and battery-powered designs down to 2V logic levels. |
| Operating Temperature | -55°C to +125°C - qualified for extended industrial, aerospace, and automotive under-hood applications. |
| Propagation Delay (A/B → Q) | 50 ns max at VCC = 4.5V - enables sub-20 MHz timing resolution in high-speed digital state machines. |
| Pulse Width Accuracy | ±1% match between channels - ensures synchronized dual-output timing critical for differential clock generation or balanced PWM control. |
| Input Hysteresis | Schmitt-trigger on A/B inputs - rejects noise on slow-rising or noisy trigger signals without external conditioning. |
| Output Drive | 10 LSTTL loads - sufficient fanout to drive multiple downstream logic gates or small-signal buffers directly. |
| Quiescent Current | 8 µA typical at 25°C - ultra-low standby power ideal for always-on timing functions in energy-constrained systems. |
Pinout & Package
CD74HC4538MG4 is housed in a 16-pin SOIC (D) package, 7.5 mm × 10.3 mm body size, 1.27 mm pitch, RoHS-compliant NIPDAU lead finish, MSL Level-1 rating.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1, 2, 14, 15 | RXCX (Timing Network) | External RC timing node - connects to shared RX/CX network per monostable section; sets output pulse width τ = 0.7·RX·CX. |
| 3, 13 | R (Reset) | Asynchronous active-low reset - forces Q low and Q̅ high regardless of trigger state; unused resets must be tied to VCC. |
| 4, 12 | A (Leading-Edge Trigger) | Positive-edge sensitive input - triggers monostable on rising transition; unused A inputs must be tied to GND. |
| 5, 11 | B (Trailing-Edge Trigger) | Negative-edge sensitive input - triggers on falling transition; unused B inputs must be tied to VCC. |
| 6, 10 | Q (True Output) | Buffered active-high output - provides standard CMOS logic level with 10 LSTTL load capability. |
| 7, 9 | Q̅ (Complement Output) | Buffered active-low output - fully complementary to Q, enabling differential signaling or reset feedback paths. |
| 8 | GND | Ground reference - common return for all internal circuitry and external timing components. |
| 16 | VCC | Power supply - supplies entire IC; decoupling capacitor (0.1 µF) required near pin for noise immunity. |
Key Features
| Feature | Design Value |
|---|---|
| Retriggerable/Resettable Operation | Each monostable extends its output pulse on every new trigger - essential for continuous event monitoring without manual rearming. |
| Independent Edge-Trigger Inputs | Dual A/B inputs per channel allow flexible triggering from rising or falling edges - eliminates need for external inverters in bidirectional signal detection. |
| RC Timing Independence | Propagation delay and retrigger time are unaffected by RX/CX values - guarantees consistent timing behavior across decades of pulse width adjustment. |
| Wide-Voltage CMOS Compatibility | 2V–6V operation with 30% noise margin (NIL/NIH) at 5V - interoperates with legacy 5V TTL, modern 3.3V microcontrollers, and low-power 2V sensors. |
| High Noise Immunity | Schmitt-trigger inputs reject >100 ns glitches - prevents false triggering in electrically noisy environments like motor drives or PLC backplanes. |
Applications
| Industrial Sequencing | Digital Pulse Width Modulation |
|---|---|
Use Scenario: Generating precise, adjustable delay intervals between actuator commands in programmable logic controllers. IC Role / Device Role / Timing Role: Dual monostable provides independent, retriggerable timing windows for valve sequencing and conveyor belt coordination. Use Value: ±1% inter-channel pulse width match ensures synchronized motion control without mechanical skew or software compensation. | Use Scenario: Converting analog sensor outputs into variable-duty-cycle digital pulses for isolated feedback in SMPS controllers. IC Role / Device Role / Timing Role: Monostable converts comparator output edges into fixed-width pulses; duty cycle modulated by input frequency. Use Value: Independent A/B edge triggering allows direct use of zero-crossing detector outputs without polarity inversion circuitry. |
| Test Equipment Signal Conditioning | Automotive Diagnostic Timing |
Use Scenario: Debouncing mechanical switch inputs and generating clean, jitter-free strobes for logic analyzers or boundary-scan test fixtures. IC Role / Device Role / Timing Role: Each monostable filters contact bounce and produces deterministic pulse widths for synchronous sampling clocks. Use Value: Schmitt-trigger inputs tolerate slow-rising switch waveforms; 50 ns propagation delay enables sub-20 MHz test clock generation. | Use Scenario: Timing CAN bus arbitration windows and fault response intervals in engine control units operating across extreme ambient temperatures. IC Role / Device Role / Timing Role: Provides robust, temperature-stable timing reference for ISO 11898-compliant bus recovery and error frame generation. Use Value: -55°C to +125°C qualification ensures reliable operation in under-hood ECU environments without derating. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar dual monostable multivibrator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| CD74HC4538M96 | Same die, identical electrical specs, SOIC-16 tape-and-reel packaging (2500 pcs/reel) vs. CD74HC4538MG4's tube packaging. | No functional difference; optimized for automated SMT assembly rather than manual prototyping or low-volume evaluation. | Select CD74HC4538M96 for high-volume production runs requiring reel-fed placement; CD74HC4538MG4 suits engineering validation and small-batch builds. |
| SN74LV4538ADR | Lower voltage range (2V–5.5V), higher drive strength (16 mA), but no Schmitt-trigger inputs and only -40°C to +125°C rating. | Lacks noise immunity on trigger inputs; unsuitable for noisy industrial environments where CD74HC4538MG4's hysteresis is critical. | Choose SN74LV4538ADR only when higher output current is mandatory and signal integrity is guaranteed; otherwise retain CD74HC4538MG4 for robust edge detection. |
Compared with CD74HC4538M96 and SN74LV4538ADR, the CD74HC4538MG4 uniquely combines Schmitt-trigger inputs, full military-grade temperature range, and proven retriggerable stability - making it the preferred choice for mission-critical timing where environmental resilience and noise rejection are non-negotiable.
Availability
CD74HC4538MG4 is available at Aetrix Electronics and suitable for industrial control systems, automotive diagnostic modules, and test equipment requiring stable component supply across extended temperature ranges and long product lifecycles.
Supply support for CD74HC4538MG4 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 leader delivering analog, embedded processing, and logic solutions with emphasis on reliability, longevity, and industrial-grade performance.
The CD74HC4538MG4 belongs to TI's High-Speed CMOS Logic family, designed specifically for precision timing applications demanding retriggerable behavior, wide voltage operation, and robust noise immunity in harsh environments.
FAQ
What is the minimum external timing resistor value supported by CD74HC4538MG4?
The CD74HC4538MG4 specifies a minimum external timing resistor RX of 5 kΩ, as confirmed in the Absolute Maximum Ratings and Operating Conditions sections of the official datasheet. Using lower values may exceed the 30 mA maximum current limit into pins 2 or 14, risking device damage or timing inaccuracy. Always verify RX ≥ 5 kΩ in all CD74HC4538MG4 designs.
Does CD74HC4538MG4 support non-retriggerable one-shot operation?
Yes, CD74HC4538MG4 supports non-retriggerable mode by connecting Q to B (for leading-edge A-triggered operation) or Q to A (for trailing-edge B-triggered operation). This configuration disables retriggering during the output pulse, fixing the timing interval to the first trigger only - a documented configuration shown in Figure 3 of the datasheet.
Can CD74HC4538MG4 operate reliably at 2.0V supply voltage?
Yes, CD74HC4538MG4 is fully specified for operation at 2.0V, with verified parameters including VIH = 1.5V, VIL = 0.5V, and propagation delay ≤375 ns. Its HC-series architecture ensures stable functionality across the full 2V–6V range, making it suitable for low-power battery-operated systems where CD74HC4538MG4 maintains timing accuracy without voltage scaling compromises.
What is the purpose of the Schmitt-trigger inputs on CD74HC4538MG4?
The Schmitt-trigger inputs on CD74HC4538MG4 provide hysteresis on A and B trigger pins, enabling reliable edge detection on slow-rising or noisy signals - such as mechanical switch closures or unconditioned sensor outputs. This eliminates false triggering and removes the need for external RC debounce networks, directly improving system robustness in industrial CD74HC4538MG4 implementations.
How does CD74HC4538MG4 handle power-down conditions with large timing capacitors?
When CX ≥ 0.5 µF, CD74HC4538MG4 requires external protection against rapid power-down discharge currents. The datasheet recommends either a 1N5395 diode (or equivalent) from pin 2/14 to ground, or a 51 Ω series resistor with corresponding RX adjustment - both methods prevent potential latch-up or junction damage during supply collapse, ensuring safe CD74HC4538MG4 operation in fault-prone power systems.
CD74HC4538MG4 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 74HC
- Package/Case:
- 16-SOIC (0.154", 3.90mm Width)
- Packaging:
- Tube
- Product Status:
- Obsolete
- Logic Type:
- Monostable
- Independent Circuits:
- 2
- Schmitt Trigger Input:
- Yes
- Propagation Delay:
- 21 ns
- Current - Output High, Low:
- 5.2mA, 5.2mA
- Voltage - Supply:
- 2 V ~ 6 V
- Operating Temperature:
- -55°C ~ 125°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 16-SOIC
CD74HC4538MG4 FAQ
1.How can I place an order for CD74HC4538MG4 through Aetrix?
Please submit a Request for Quotation (RFQ) for CD74HC4538MG4 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 CD74HC4538MG4 reliable?
The price and inventory of CD74HC4538MG4 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for CD74HC4538MG4 is usually 5 days.
3.What payment methods are accepted for CD74HC4538MG4?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for CD74HC4538MG4 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for CD74HC4538MG4?
CD74HC4538MG4 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your CD74HC4538MG4 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 CD74HC4538MG4?
For technical support, including CD74HC4538MG4 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your CD74HC4538MG4 requirements.
6.How does Aetrix verify that CD74HC4538MG4 is sourced from the original manufacturer or authorized distributors?
All CD74HC4538MG4 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 CD74HC4538MG4 meets industry standards.
7.What is the process for return or replacement of CD74HC4538MG4?
All CD74HC4538MG4 units undergo pre-shipment inspection (PSI). If there is an issue with CD74HC4538MG4, 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 CD74HC4538MG4 part is unused and in its original packaging.
Return procedure for CD74HC4538MG4:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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