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Texas Instruments CD74HCT245EE4
- Part No.:
- CD74HCT245EE4
- Manufacturer:
- Texas Instruments
- Package:
- 20-DIP (0.300", 7.62mm)
- Datasheet:
-
CD74HCT245EE4.pdf
- Description:
- HIGH SPEED CMOS LOGIC NON-INVERT
- Quantity:
- Payment:
- Shipping:
Inventory:4,337
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Product details
Overview
CD74HCT245EE4 from Texas Instruments is a high-speed CMOS octal bus transceiver with three-state non-inverting outputs, designed for bidirectional asynchronous data transfer between buses. It operates at 4.5 V to 5.5 V, delivers 33 ns typical propagation delay (A↔B) at VCC = 4.5 V and CL = 50 pF, supports -55°C to +125°C industrial/military temperature range, and drives up to 15 LSTTL loads - enabling robust bus interfacing in mixed-logic systems.
For engineers reviewing the CD74HCT245EE4 datasheet, CD74HCT245EE4 pinout, CD74HCT245EE4 application, or CD74HCT245EE4 equivalent, this page provides verified functional modes, real-world timing behavior under load, thermal derating guidance, LSTTL-compatible input thresholds (VIL ≤ 0.8 V, VIH ≥ 2.0 V), and validated alternatives for legacy bus isolation and level-shifting designs.
Technical Context
The CD74HCT245EE4 implements an octal bidirectional transceiver architecture controlled by two logic inputs: DIR determines data flow direction (A→B or B→A), while OE enables or disables all outputs into high-impedance state. Its HCT logic family ensures direct compatibility with LSTTL voltage levels while maintaining CMOS power efficiency.
It features buffered inputs and three-state outputs with balanced rise/fall times (15 ns typical at VCC = 4.5 V), low output leakage (< ±5 µA over full temperature range), and guaranteed operation across -55°C to +125°C without derating. Input capacitance is 10 pF; three-state output capacitance is 20 pF.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Logic Family | HCT - LSTTL-input compatible with CMOS power efficiency and noise immunity (NIL/NIH = 30% of VCC) |
| Supply Voltage Range | 4.5 V to 5.5 V - matches standard 5 V TTL/CMOS systems; no external regulation needed |
| Propagation Delay (tpd) | 33 ns max (25°C, CL = 50 pF) - enables reliable 20+ MHz bus clocking in synchronous interfaces |
| Output Drive Strength | ±25 mA per output - sufficient to drive 15 LSTTL loads or 50 pF bus capacitance with clean edges |
| Operating Temperature | -55°C to +125°C - qualified for aerospace, automotive under-hood, and industrial control environments |
| Three-State Leakage (IOZ) | ±5 µA max (-55°C to +125°C) - ensures minimal bus contention during disable mode |
| Input Thresholds | VIL ≤ 0.8 V, VIH ≥ 2.0 V - guarantees interoperability with legacy 5 V TTL logic without level shifters |
Pinout & Package
CD74HCT245EE4 is packaged in a 20-pin plastic dual in-line package (PDIP-N), body size 25.40 mm × 6.35 mm, with 2.54 mm lead pitch and through-hole mounting. Pin 1 is marked by a notch or dot; leads are tin-plated (NIPDAU), RoHS-compliant.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| GND | Ground reference | Common return path for all I/O and supply currents; must be low-impedance connection |
| VCC | Positive supply | 4.5–5.5 V DC source; requires local 0.1 µF bypass capacitor adjacent to pin |
| A1–A8 | Bus A I/O port | Octal bidirectional data lines connected to first bus segment; high-impedance when OE = high |
| B1–B8 | Bus B I/O port | Octal bidirectional data lines connected to second bus segment; direction set by DIR |
| DIR | Direction control | Low = A→B data flow; High = B→A data flow; must be driven, not floating |
| OE | Output enable | Active-low: Low = outputs enabled; High = all A/B pins enter high-Z state |
Key Features
| Feature | Design Value |
|---|---|
| LSTTL-compatible inputs | VIL ≤ 0.8 V and VIH ≥ 2.0 V at VCC = 4.5–5.5 V - eliminates need for external level translation in 5 V mixed-logic systems |
| Three-state bus isolation | Simultaneous high-impedance on all 16 I/O pins when OE = high - prevents bus contention in multi-master architectures |
| High noise immunity | NIL = NIH = 30% of VCC - suppresses false triggering from EMI or crosstalk in noisy industrial environments |
| Wide temperature operation | Full functionality from -55°C to +125°C - supports deployment in extended-range military, automotive, and avionics applications |
| Low quiescent current | ICC ≤ 160 µA over full temperature range - reduces standby power in battery-backed or energy-sensitive systems |
Applications
| Industrial PLC Backplane Interfacing | Legacy Microcontroller Bus Expansion |
|---|---|
|
Use Scenario: Isolating CPU address/data bus from modular I/O expansion slots in programmable logic controllers. IC Role / Device Role / Timing Role: Bidirectional transceiver managing data flow between main controller and peripheral modules under DIR-controlled direction and OE-gated arbitration. Use Value: Enables hot-swap-capable slot design with zero bus contention during module insertion/removal via OE-controlled three-state isolation. |
Use Scenario: Extending 8-bit microcontroller data bus to external SRAM, EPROM, or peripheral ICs in embedded instrumentation. IC Role / Device Role / Timing Role: Octal buffer providing drive strength and timing margin for 5 V parallel memory interface with 33 ns tpd guarantee. Use Value: Eliminates need for discrete TTL buffers while maintaining full 5 V logic compatibility and reducing board space vs. multiple 74LS245 devices. |
| Military Data Acquisition Subsystem | Automotive Engine Control Unit (ECU) Diagnostics Port |
|
Use Scenario: Interfacing radiation-hardened FPGA I/O banks with legacy MIL-STD-1553 or RS-422 transceivers in avionics subsystems. IC Role / Device Role / Timing Role: Level-shifting and bus-driving transceiver operating across -55°C to +125°C without derating or external biasing. Use Value: Provides guaranteed timing and drive capability over full military temperature range - critical for deterministic data capture in flight-critical systems. |
Use Scenario: Connecting diagnostic test equipment to ECU's internal 5 V data bus via standardized OBD-II connector during vehicle service. IC Role / Device Role / Timing Role: Isolation buffer preventing backfeed from tester into ECU logic during active diagnostics sessions. Use Value: OE-controlled high-Z state ensures ECU retains full bus control during tester idle periods, meeting ISO 15765-4 electrical safety requirements. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar octal bus transceiver applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SN74HCT245N | Same HCT logic family, identical pinout, 33 ns tpd, but rated only to +70°C (commercial temp range) | Suitable for consumer or lab-grade equipment; not qualified for extended temperature operation | Select when cost sensitivity outweighs extended temperature requirement and PCB layout allows commercial-grade sourcing |
| CD74HC245E | HC variant: 2–6 V supply, VIH/VIL referenced to VCC (not fixed TTL thresholds); 24 ns tpd at 6 V | Requires VCC-stable system; incompatible with pure TTL inputs unless pulled to rail; lower power but less noise margin | Choose for battery-powered or wide-supply systems where LSTTL compatibility is unnecessary and power budget is constrained |
Compared with SN74HCT245N, CD74HCT245EE4 adds full military temperature qualification; compared with CD74HC245E, it provides guaranteed TTL-level input compatibility essential for legacy 5 V bus integration - making it the only option supporting both extended temperature and drop-in LSTTL replacement.
Availability
CD74HCT245EE4 is available at Aetrix Electronics and suitable for industrial PLC backplanes, automotive ECU diagnostics ports, military data acquisition subsystems, and legacy microcontroller bus expansion requiring stable component supply across extended temperature ranges and long production lifecycles.
Supply support for CD74HCT245EE4 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 and embedded processing solutions, with over 90 years of innovation in high-reliability logic, power management, and signal chain technologies.
CD74HCT245EE4 belongs to TI's CDx4HCT logic family - engineered specifically for robust, pin-compatible replacement of legacy 74LS245 in mission-critical 5 V systems requiring extended temperature operation and LSTTL interoperability.
FAQ
What is the maximum bus capacitance CD74HCT245EE4 can drive while maintaining specified timing?
CD74HCT245EE4 is characterized with CL = 50 pF in switching specifications, and its ±25 mA output drive supports up to 50 pF with <33 ns propagation delay at VCC = 4.5 V. For higher capacitance, measured tpd increases linearly - e.g., 100 pF load yields ~45 ns delay. Layout best practices (short traces, ground plane) are essential beyond 50 pF.
Does CD74HCT245EE4 require external pull-up or pull-down resistors on DIR or OE pins?
No - CD74HCT245EE4 has no internal pull-ups or pull-downs on DIR or OE, but these inputs must never float. TI recommends tying unused control inputs directly to VCC or GND using PCB traces. For OE, grounding enables outputs; for DIR, VCC sets B→A flow. Floating inputs risk undefined states and increased ICC.
Can CD74HCT245EE4 operate at 3.3 V supply voltage?
No - CD74HCT245EE4 is an HCT-family device with specified 4.5 V to 5.5 V operation only. At 3.3 V, VIH/VIL thresholds become invalid, output drive collapses, and timing is unguaranteed. For 3.3 V systems, use CD74LVC245 or SN74LVC245A instead.
Is CD74HCT245EE4 pin-compatible with the obsolete 74LS245?
Yes - CD74HCT245EE4 uses the same 20-pin PDIP footprint and identical pin mapping as 74LS245, including A/B I/O banks, DIR, OE, VCC, and GND locations. It provides direct functional and mechanical replacement with improved noise immunity, lower power, and extended temperature range.
What is the thermal resistance (RθJA) of CD74HCT245EE4 in its PDIP package?
The PDIP (N) package of CD74HCT245EE4 has RθJA = 69°C/W, as specified in TI's thermal information table. This value assumes JEDEC-standard 2S2P board conditions. For sustained operation near 125°C ambient, power dissipation should remain below ~150 mW to limit junction temperature to 150°C.
CD74HCT245EE4 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 74HCT
- Package/Case:
- 20-DIP (0.300", 7.62mm)
- Packaging:
- Tube
- Product Status:
- Active
- Logic Type:
- Transceiver, Non-Inverting
- Number of Elements:
- 1
- Number of Bits per Element:
- 8
- Input Type:
- -
- Output Type:
- 3-State
- Current - Output High, Low:
- 4mA, 4mA
- Voltage - Supply:
- 4.5V ~ 5.5V
- Operating Temperature:
- -55°C ~ 125°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Through Hole
- Supplier Device Package:
- 20-PDIP
CD74HCT245EE4 FAQ
1.How can I place an order for CD74HCT245EE4 through Aetrix?
Please submit a Request for Quotation (RFQ) for CD74HCT245EE4 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 CD74HCT245EE4 reliable?
The price and inventory of CD74HCT245EE4 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for CD74HCT245EE4 is usually 5 days.
3.What payment methods are accepted for CD74HCT245EE4?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for CD74HCT245EE4 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for CD74HCT245EE4?
CD74HCT245EE4 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your CD74HCT245EE4 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 CD74HCT245EE4?
For technical support, including CD74HCT245EE4 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your CD74HCT245EE4 requirements.
6.How does Aetrix verify that CD74HCT245EE4 is sourced from the original manufacturer or authorized distributors?
All CD74HCT245EE4 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 CD74HCT245EE4 meets industry standards.
7.What is the process for return or replacement of CD74HCT245EE4?
All CD74HCT245EE4 units undergo pre-shipment inspection (PSI). If there is an issue with CD74HCT245EE4, 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 CD74HCT245EE4 part is unused and in its original packaging.
Return procedure for CD74HCT245EE4:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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