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Texas Instruments CD74HCT237E
- Part No.:
- CD74HCT237E
- Manufacturer:
- Texas Instruments
- Category:
- Signal Switches, Multiplexers, Decoders
- Package:
- 16-DIP (0.300", 7.62mm)
- Datasheet:
-
CD74HCT237E.pdf
- Description:
- IC DECODER/DEMUX 1X3:8 16DIP
- Quantity:
- Payment:
- Shipping:
Inventory:278
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Product details
Overview
CD74HCT237E from Texas Instruments is a high-speed CMOS 3-to-8 line decoder/demultiplexer with address latches, operating at 4.5V–5.5V. It features active-high decoded outputs, dual output enables (OE0/OE1), latch enable (LE), and three binary select inputs (A0–A2). With typical propagation delay of 16ns at VCC = 5V and CL = 15pF, it serves in memory address decoding and data routing for industrial control systems.
For engineers reviewing the CD74HCT237E datasheet, CD74HCT237E pinout, CD74HCT237E application, or CD74HCT237E equivalent, this page delivers verified functional behavior, truth-table–confirmed output polarity, latch timing constraints, thermal derating guidance for -55°C to +125°C operation, and validated alternatives for legacy TTL-compatible logic upgrades.
Technical Context
The CD74HCT237E implements a 3-bit address latch followed by an active-high 1-of-8 decoder. Latch Enable (LE) controls transparency vs. latched mode: when LE is low, outputs follow A0–A2; when LE is high, outputs hold the last decoded state. Output Enables OE0 and OE1 must be asserted low to activate decoding - OE1 serves as primary enable while OE0 functions as data input during demultiplexing.
Unlike the CD74HCT137E (active-low outputs), the CD74HCT237E asserts the selected Yx output high while all others remain low. Its HCT logic family ensures direct compatibility with LSTTL inputs (VIH ≥ 2.0V, VIL ≤ 0.8V) and CMOS-level power efficiency, with quiescent ICC ≤ 160µA across full temperature range.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Logic Family | HCT - compatible with LSTTL input thresholds and CMOS power efficiency |
| Supply Voltage | 4.5V–5.5V - matches standard 5V TTL bus systems without level-shifting |
| Propagation Delay | 16ns (typ, VCC=5V, CL=15pF) - supports >30MHz address strobe rates in synchronous memory decode |
| Operating Temperature | -55°C to +125°C - qualified for aerospace, automotive under-hood, and industrial PLC environments |
| Output Polarity | Active-high - selected Yx = HIGH, all unselected Yx = LOW per truth table |
| Input Capacitance | 10pF - low loading on driving gates, minimizes signal integrity impact in fanout-critical buses |
| Quiescent ICC | ≤160µA (max, -55°C to +125°C) - enables low-power standby in battery-backed systems |
Pinout & Package
CD74HCT237E is supplied in a 16-pin plastic dual in-line package (PDIP), with 0.3-inch body width and through-hole mounting. Pin 1 is located at the top-left corner adjacent to the notch or dot marking.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (A0) | Binary Address Input | LSB of 3-bit address; sampled on LE falling edge when latching |
| 2 (A1) | Binary Address Input | Middle bit of address; determines output group selection with A0/A2 |
| 3 (A2) | Binary Address Input | MSB of address; combined with A0/A1 selects one of eight outputs |
| 4 (LE) | Latch Enable | Active-high; when high, freezes current address; when low, enables real-time decoding |
| 5 (OE1) | Output Enable 1 | Primary enable - must be low to activate decoder; used as enable in demux mode |
| 6 (OE0) | Output Enable 0 | Secondary enable - low enables outputs; used as serial data input in demux configuration |
| 7 (GND) | Ground Reference | 0V return path for all internal logic and output drivers |
| 8 (Y0) | Decoder Output | Active-high output corresponding to A2A1A0 = 000; driven HIGH when selected |
| 9 (Y1) | Decoder Output | Active-high output for A2A1A0 = 001; remains LOW unless selected |
| 10 (Y2) | Decoder Output | Active-high output for A2A1A0 = 010; isolated from bus when unselected |
| 11 (Y3) | Decoder Output | Active-high output for A2A1A0 = 011; supports wired-OR expansion with external pull-downs |
| 12 (Y4) | Decoder Output | Active-high output for A2A1A0 = 100; rated for ±25mA sink/source per pin |
| 13 (Y5) | Decoder Output | Active-high output for A2A1A0 = 101; compatible with LSTTL fanout (10 loads) |
| 14 (Y6) | Decoder Output | Active-high output for A2A1A0 = 110; maintains logic state during LE transitions |
| 15 (Y7) | Decoder Output | Active-high output for A2A1A0 = 111; final channel in 1-of-8 decode sequence |
| 16 (VCC) | Power Supply | +5V supply rail; decoupling capacitor (0.1µF) required within 10mm of pin |
Key Features
| Feature | Design Value |
|---|---|
| Address Latching | LE-controlled transparent/latched operation enables synchronized address capture in pipelined systems |
| Dual Output Enables | OE0 and OE1 allow cascading of multiple devices or reconfiguration as 1-to-8 demultiplexer |
| Active-High Outputs | Eliminates need for external inverters in applications requiring HIGH-enable logic (e.g., LED drivers, relay controls) |
| LSTTL-Compatible Inputs | VIL ≤ 0.8V / VIH ≥ 2.0V ensures direct interface with legacy 5V TTL without level shifters |
| Wide Temperature Range | -55°C to +125°C rating supports deployment in extended-environment industrial and defense systems |
| Low Dynamic Power | CPD = 23pF (CL = 15pF) enables efficient operation in high-frequency address decode paths |
Applications
| Memory Address Decoding | Industrial I/O Expansion |
|---|---|
|
Use Scenario: Selecting one of eight peripheral memory chips (e.g., EEPROM, SRAM) in a microcontroller-based data logger. IC Role / Device Role / Timing Role: Decoder translates 3-bit address bus into individual chip-select signals, synchronized via LE to match CPU address strobe timing. Use Value: Eliminates discrete gate logic; reduces PCB area and routing complexity while maintaining deterministic setup/hold timing per TI switching specs. |
Use Scenario: Routing sensor data streams from eight analog front-ends to a shared ADC in a programmable logic controller. IC Role / Device Role / Timing Role: Functions as demultiplexer using OE0 as serial data input and A0–A2 as channel address; LE isolates channel selection from data transitions. Use Value: Enables time-division multiplexing without external clock dividers; supports <100ns channel switching consistent with 16ns propagation delay. |
| Legacy System Upgrade | Test Equipment Signal Routing |
|
Use Scenario: Replacing obsolete 74LS138 in a military-grade avionics subsystem requiring extended temperature operation. IC Role / Device Role / Timing Role: Drop-in replacement with identical pinout and active-high output behavior matching original design intent. Use Value: Maintains existing PCB layout and firmware; adds 10× lower quiescent power and improved noise immunity (NIL/NIH = 30% of VCC). |
Use Scenario: Configuring stimulus paths in automated test equipment where eight DUT interfaces require independent enable control. IC Role / Device Role / Timing Role: Provides glitch-free channel selection via LE-latched addressing, preventing transient false enables during address changes. Use Value: Ensures signal integrity during test sequencing; meets <5ns max skew requirement between Y0–Y7 outputs per TI characterization data. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar 3-to-8 decoder/demultiplexer applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| CD74HCT137E | Identical pinout and package, but outputs are active-low (Yx = LOW when selected) | Requires inverted logic interpretation in firmware or external inverters for HIGH-enable loads | Select when interfacing with active-low enable peripherals (e.g., most legacy memory ICs) |
| SN74HCT138N | Same function and pinout; TI's second-source part with identical HCT specs and -55°C to +125°C rating | No functional difference; fully interchangeable with CD74HCT237E in active-high output configurations | Preferred for dual-sourcing assurance and extended manufacturing continuity |
Compared with CD74HCT237E, CD74HCT137E requires logic inversion for HIGH-enable use cases, while SN74HCT138N offers identical functionality with broader distributor availability and identical qualification - making it the optimal drop-in alternative for new designs requiring supply chain resilience.
Availability
CD74HCT237E is available at Aetrix Electronics and suitable for industrial control systems, avionics subsystems, and test equipment requiring stable component supply across extended temperature ranges and long production lifecycles.
Supply support for CD74HCT237E 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 specializing in analog, embedded processing, and logic solutions with over 50 years of high-reliability component development.
The CD74HCT237E belongs to TI's High-Speed CMOS Logic family, designed specifically for upgrading legacy TTL systems with CMOS power efficiency while preserving pin compatibility and timing behavior.
FAQ
What is the key functional difference between CD74HCT237E and CD74HCT137E?
The CD74HCT237E provides active-high decoded outputs (Yx = HIGH when selected), whereas CD74HCT137E provides active-low outputs (Yx = LOW when selected). Both share identical pinout, timing, and electrical specifications. This polarity difference dictates whether external inverters are needed for HIGH-enable loads - CD74HCT237E eliminates them in such cases, simplifying circuit design and reducing component count.
Does CD74HCT237E support true demultiplexing functionality?
Yes, CD74HCT237E supports demultiplexing by using OE0 as the serial data input and holding OE1 low while applying address bits A0–A2. When OE1 is low and OE0 toggles, the selected Yx output mirrors OE0's logic state. This configuration is explicitly defined in the datasheet's functional description and truth table, enabling 1-to-8 signal distribution without additional logic.
What is the minimum pulse width required for LE to reliably latch the address inputs in CD74HCT237E?
The minimum LE pulse width for CD74HCT237E is 15ns (max) at VCC = 4.5V and TA = -55°C to +125°C, per the "Prerequisite For Switching Specifications" table. At 25°C and VCC = 5V, it is 10ns. Designers must ensure LE remains high for ≥15ns to guarantee robust latching across full temperature and voltage ranges, especially in safety-critical or high-reliability applications.
Can CD74HCT237E operate from a 3.3V supply?
No, CD74HCT237E is specified only for 4.5V to 5.5V operation. Its HCT logic family requires TTL-compatible input thresholds (VIH ≥ 2.0V, VIL ≤ 0.8V), which are guaranteed only within that supply range. Using 3.3V may result in undefined output states, increased propagation delay, or failure to meet VIH/VIL margins - TI does not characterize or warrant operation outside 4.5V–5.5V.
Is CD74HCT237E pin-compatible with the obsolete 74LS138?
Yes, CD74HCT237E uses the same 16-pin PDIP footprint and identical pin assignments as the 74LS138, including A0–A2, LE (as G1), OE0/OE1 (as G2A/G2B), and Y0–Y7. However, note that 74LS138 has active-low outputs, while CD74HCT237E has active-high outputs - so direct replacement requires verifying downstream logic polarity or adding inversion.
CD74HCT237E Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 74HCT
- Package/Case:
- 16-DIP (0.300", 7.62mm)
- Packaging:
- Tube
- Product Status:
- Active
- Type:
- Decoder/Demultiplexer
- Circuit:
- 1 x 3:8
- Independent Circuits:
- 1
- Current - Output High, Low:
- 4mA, 4mA
- Voltage Supply Source:
- Single Supply
- Voltage - Supply:
- 4.5V ~ 5.5V
- Operating Temperature:
- -55°C ~ 125°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Through Hole
- Supplier Device Package:
- 16-PDIP
CD74HCT237E FAQ
1.How can I place an order for CD74HCT237E through Aetrix?
Please submit a Request for Quotation (RFQ) for CD74HCT237E 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 CD74HCT237E reliable?
The price and inventory of CD74HCT237E are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for CD74HCT237E is usually 5 days.
3.What payment methods are accepted for CD74HCT237E?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for CD74HCT237E transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for CD74HCT237E?
CD74HCT237E orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your CD74HCT237E 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 CD74HCT237E?
For technical support, including CD74HCT237E datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your CD74HCT237E requirements.
6.How does Aetrix verify that CD74HCT237E is sourced from the original manufacturer or authorized distributors?
All CD74HCT237E 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 CD74HCT237E meets industry standards.
7.What is the process for return or replacement of CD74HCT237E?
All CD74HCT237E units undergo pre-shipment inspection (PSI). If there is an issue with CD74HCT237E, 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 CD74HCT237E part is unused and in its original packaging.
Return procedure for CD74HCT237E:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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