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STMicroelectronics 74VHCT238AMTR
- Part No.:
- 74VHCT238AMTR
- Manufacturer:
- STMicroelectronics
- Category:
- Signal Switches, Multiplexers, Decoders
- Package:
- 16-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
74VHCT238AMTR.pdf
- Description:
- IC DECODER/DEMUX 1 X 3:8 16SO
- Quantity:
- Payment:
- Shipping:
Inventory:2,525
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Product details
Overview
74VHCT238AMTR from STMicroelectronics is a high-speed CMOS 3-to-8 line decoder with TTL-compatible inputs, 5.5 ns typical propagation delay at 5 V, ±8 mA symmetrical output drive, and 4 µA max quiescent current at 25°C. It features three enable inputs (G1, G2A, G2B) for cascading in memory address decoding systems and operates across 4.5–5.5 V.
For engineers reviewing the 74VHCT238AMTR datasheet, 74VHCT238AMTR pinout, 74VHCT238AMTR application, or 74VHCT238AMTR equivalent, key selection criteria include enable-input logic architecture, 8 mA output drive capability under 5 V supply, latch-up immunity, and 0–7 V input tolerance independent of VCC.
Technical Context
The 74VHCT238AMTR implements active-high decode logic where outputs Y0–Y7 go high only when G1 = LOW and both G2A = LOW and G2B = HIGH - enabling hierarchical address decoding in multi-chip memory systems. Its input structure accepts 0–7 V regardless of VCC, supporting 5 V ↔ 3 V interfacing without level shifters.
All inputs and outputs integrate ESD protection rated to 2 kV per HBM, and the device uses sub-micron C2MOS technology to achieve balanced tPLH ≈ tPHL delays and power-down protection that prevents back-driving during supply-off conditions.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Propagation Delay | 5.5 ns typ. (A/B/C → Y, CL = 15 pF, VCC = 5 V) - enables sub-10 ns timing-critical address decode paths |
| Supply Voltage Range | 4.5–5.5 V - compatible with regulated 5 V rails and tolerant of ±10% variation |
| Output Drive | ±8 mA min. (IOH/IOL) - sufficient to directly drive multiple TTL inputs or small capacitive loads |
| Input Thresholds | VIH ≥ 2.0 V, VIL ≤ 0.8 V - ensures reliable recognition of TTL-level signals at 5 V supply |
| Quiescent Current | 4 µA max. at TA = 25°C - supports low-static-power system states in battery-backed or standby modes |
| Input Voltage Range | −0.5 to +7.0 V - allows safe operation with floating or overvoltage inputs, even when VCC = 0 V |
| ESD Immunity | 2 kV HBM - protects against handling-induced discharge without external clamping |
Pinout & Package
74VHCT238AMTR is packaged in a 16-pin SOIC (Small Outline Integrated Circuit) tape-and-reel format, compliant with JEDEC MS-012 and RoHS requirements. The body dimensions are 9.8–10.0 mm × 5.8–6.2 mm × 1.75 mm height, with 1.27 mm lead pitch.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1, 2, 3 | A, B, C | Binary address select inputs - determine active output Y0–Y7 when device is enabled |
| 4, 5 | G2A, G2B | Complementary enable inputs - G2A must be LOW and G2B HIGH for decode activation |
| 6 | G1 | Primary enable input - must be LOW to activate decoding function |
| 7, 9–15 | Y0–Y7 | Active-high decoded outputs - only one asserted per valid input combination |
| 8 | GND | Ground reference - common return path for all internal logic and I/O |
| 16 | VCC | Positive supply - powers internal logic and provides output voltage reference |
Key Features
| Feature | Design Value |
|---|---|
| Power-down input/output protection | Accepts 0–7 V on all pins with VCC = 0 V - eliminates need for external isolation during power sequencing |
| Symmetrical output impedance | |IOH| = |IOL| ≥ 8 mA - ensures matched rise/fall times and predictable bus loading |
| TTL-compatible input thresholds | VIH ≥ 2.0 V, VIL ≤ 0.8 V - interoperates directly with legacy 5 V TTL logic without level translation |
| Enhanced latch-up immunity | Qualified per JEDEC JESD78 - withstands >100 mA injected current without destructive latch-up |
| Cascade-ready enable architecture | Three independent enables (G1, G2A, G2B) - simplifies multi-stage address decoding in 64 KB+ memory maps |
Applications
| Memory Address Decoding | Industrial PLC I/O Expansion |
|---|---|
|
Use Scenario: Selecting one of eight peripheral devices (e.g., ADCs, DACs, UARTs) in a microcontroller-based data acquisition system. IC Role / Device Role / Timing Role: Address decoder mapping 3-bit address bus to individual chip-select lines with <5.5 ns latency. Use Value: Eliminates discrete gate logic; enables deterministic 5 V bus timing with guaranteed setup/hold margins. |
Use Scenario: Expanding digital input/output capacity in modular programmable logic controllers using parallel control buses. IC Role / Device Role / Timing Role: Translating 3-bit module ID into dedicated enable signals for up to eight I/O carrier boards. Use Value: Supports hot-swap-safe enable sequencing via G1/G2A/G2B logic, reducing firmware overhead. |
| Legacy System Bus Interface | Test Equipment Signal Routing |
|
Use Scenario: Interfacing modern microcontrollers to legacy ISA-bus peripherals requiring TTL-level chip selects. IC Role / Device Role / Timing Role: Level-shifting and decoding 5 V address/data bus signals while maintaining TTL input compatibility. Use Value: Removes need for external voltage translators; tolerates 0–7 V input transients during bus contention. |
Use Scenario: Configuring signal paths in automated test equipment where multiple DUT interfaces share a common stimulus source. IC Role / Device Role / Timing Role: Routing clock or trigger signals to one of eight test fixtures based on controller command. Use Value: Provides glitch-free, low-jitter output switching with matched tPLH/tPHL for synchronized test execution. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar 3-to-8 decoder applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SN74HCT238N | PDIP-16 package only; no tape-and-reel; identical AC/DC specs and pinout | Limited to through-hole prototyping or low-volume manual assembly | Select when board layout requires DIP footprint or hand-soldered evaluation |
| 74VHC238M | VHC family - wider 2–5.5 V supply range but lacks TTL input thresholds (VIH = 70% VCC) | Requires external level shifting when interfacing with TTL sources at 5 V | Select only if system uses mixed 3.3 V/5 V supplies and all drivers are CMOS-compatible |
Compared with SN74HCT238N and 74VHC238M, the 74VHCT238AMTR uniquely combines SOIC tape-and-reel packaging, guaranteed TTL input compatibility at 5 V, and industrial temperature support (−55°C to +125°C), making it optimal for volume-manufactured embedded controllers.
Availability
74VHCT238AMTR is available at Aetrix Electronics and suitable for memory address decoding, industrial PLC expansion, legacy bus interfacing, and automated test equipment requiring stable component supply and long-term obsolescence management.
Supply support for 74VHCT238AMTR 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
STMicroelectronics is a global semiconductor leader headquartered in Geneva, specializing in automotive, industrial, and power management ICs with vertical manufacturing and broad analog/mixed-signal portfolio.
The VHCT logic family targets 5 V systems requiring TTL compatibility, low power, and robust ESD/latch-up performance - designed specifically for industrial control, instrumentation, and legacy interface consolidation.
FAQ
Is 74VHCT238AMTR pin-compatible with standard 74LS238?
Yes - it is functionally and pin-compatible with the 74LS238 and 74HC238, sharing identical pin assignments (A/B/C, G1/G2A/G2B, Y0–Y7, VCC, GND) and truth table behavior. However, it substitutes bipolar TTL with CMOS technology, delivering lower power and higher noise immunity while retaining TTL input thresholds.
Can 74VHCT238AMTR operate with VCC = 3.3 V?
No - the device is specified only for 4.5–5.5 V operation. At 3.3 V, VIH/VIL thresholds become non-compliant with TTL levels, and output drive falls below 8 mA minimum. For 3.3 V systems, consider the 74VHC238 or level-shifter solutions.
What does "power-down protection" mean for this decoder?
It means all inputs and outputs remain high-impedance and tolerate voltages from −0.5 V to +7.0 V even when VCC = 0 V - preventing back-powering, signal contention, or damage during power sequencing, hot-plug events, or brownout conditions.
How does the enable-input logic differ from standard 74xx238 variants?
The 74VHCT238AMTR uses active-LOW G1 combined with active-LOW G2A and active-HIGH G2B - requiring G1 = L, G2A = L, G2B = H to enable decoding. This asymmetric enable scheme simplifies cascading in multi-layer address decoders by allowing G2B of one stage to drive G1 of the next.
74VHCT238AMTR Specifications
- Product attributes
- Attribute value
- Manufacturer:
- STMicroelectronics
- Series:
- 74VHCT
- Package/Case:
- 16-SOIC (0.154", 3.90mm Width)
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Obsolete
- Type:
- Decoder/Demultiplexer
- Circuit:
- 1 x 3:8
- Independent Circuits:
- 1
- Current - Output High, Low:
- 8mA, 8mA
- Voltage Supply Source:
- Single Supply
- Voltage - Supply:
- 4.5V ~ 5.5V
- Operating Temperature:
- -55°C ~ 125°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 16-SO
74VHCT238AMTR FAQ
1.How can I place an order for 74VHCT238AMTR through Aetrix?
Please submit a Request for Quotation (RFQ) for 74VHCT238AMTR 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 74VHCT238AMTR reliable?
The price and inventory of 74VHCT238AMTR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for 74VHCT238AMTR is usually 5 days.
3.What payment methods are accepted for 74VHCT238AMTR?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 74VHCT238AMTR transactions.
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4.How is shipping managed for 74VHCT238AMTR?
74VHCT238AMTR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your 74VHCT238AMTR 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 74VHCT238AMTR?
For technical support, including 74VHCT238AMTR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 74VHCT238AMTR requirements.
6.How does Aetrix verify that 74VHCT238AMTR is sourced from the original manufacturer or authorized distributors?
All 74VHCT238AMTR 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 74VHCT238AMTR meets industry standards.
7.What is the process for return or replacement of 74VHCT238AMTR?
All 74VHCT238AMTR units undergo pre-shipment inspection (PSI). If there is an issue with 74VHCT238AMTR, 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 74VHCT238AMTR part is unused and in its original packaging.
Return procedure for 74VHCT238AMTR:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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