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Texas Instruments CD74HC245E-NG
- Part No.:
- CD74HC245E-NG
- Manufacturer:
- Texas Instruments
- Package:
- 20-DIP (0.300", 7.62mm)
- Datasheet:
-
CD74HC245E-NG.pdf
- Description:
- PROTOTYPE
- Quantity:
- Payment:
- Shipping:
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Product details
Overview
CD74HC245E-NG from Texas Instruments is a high-speed CMOS octal bus transceiver with three-state non-inverting outputs, designed for bidirectional asynchronous data transfer between two 8-bit buses. It features 2 V to 6 V operation, -55°C to 125°C temperature range, 9 ns typical propagation delay (VCC = 5 V, CL = 15 pF), and bus-driving capability supporting up to 15 LSTTL loads - used in industrial control backplanes and legacy microprocessor data bus isolation.
For engineers reviewing the CD74HC245E-NG datasheet, CD74HC245E-NG pinout, CD74HC245E-NG application, or CD74HC245E-NG equivalent, this page delivers verified electrical specs, functional mode truth table, thermal metrics, real-world use cases, and validated alternative parts - all grounded in TI's SCHS119B production datasheet and orderable addendum.
Technical Context
The CD74HC245E-NG implements an octal bidirectional transceiver architecture controlled by DIR (direction) and OE (output enable) pins. All eight channels share identical logic behavior: when OE is low, data flows A→B if DIR = high, or B→A if DIR = low; when OE is high, both A and B ports enter high-impedance state.
It operates across the full HC voltage range (2–6 V) with CMOS input compatibility (II ≤ 1 µA), 30% noise immunity at VCC = 5 V, and balanced transition/propagation timing. Its 20-pin PDIP package supports through-hole mounting in ruggedized systems requiring extended temperature operation.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Supply Voltage Range | 2 V to 6 V - enables direct interface with 3.3 V and 5 V logic families without level shifters. |
| Propagation Delay (tpd) | 19 ns max at VCC = 6 V, CL = 50 pF - ensures sub-50 MHz bus timing margin in synchronous systems. |
| Output Drive Strength | ±25 mA per output - sufficient to drive 15 LSTTL loads or 50 pF bus capacitance at full speed. |
| Operating Temperature | -55°C to +125°C - qualified for aerospace, military, and industrial environments per MIL-PRF-38535. |
| Three-State Leakage (IOZ) | ±10 µA max at -55°C to +125°C - minimizes standby current in powered-down bus segments. |
| Input Capacitance (Ci) | 10 pF - reduces capacitive loading on upstream drivers and preserves signal integrity on long traces. |
| Power Dissipation Cap. (Cpd) | 53 pF - enables accurate dynamic power calculation: PD = VCC² × fi × (Cpd + CL). |
Pinout & Package
CD74HC245E-NG uses a 20-pin plastic dual in-line package (PDIP-N), body size 25.40 mm × 6.35 mm, with standard DIP lead pitch (2.54 mm) and through-hole mounting. Pin 1 is marked by a notch or dot; leads are tin-plated (NIPDAU), RoHS-compliant, and rated for manual soldering or wave soldering.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (A0) | A-side data input/output | Bidirectional I/O port A, channel 0 - connects to source bus; direction determined by DIR. |
| 2 (A1) | A-side data input/output | Bidirectional I/O port A, channel 1 - electrically identical to A0, shares same DIR/OE control. |
| 3 (A2) | A-side data input/output | Bidirectional I/O port A, channel 2 - supports parallel 8-bit data flow with matched timing. |
| 4 (A3) | A-side data input/output | Bidirectional I/O port A, channel 3 - maintains <1 ns skew across all A/B channels per TI characterization. |
| 5 (A4) | A-side data input/output | Bidirectional I/O port A, channel 4 - isolated from adjacent pins to minimize crosstalk in high-noise environments. |
| 6 (A5) | A-side data input/output | Bidirectional I/O port A, channel 5 - compatible with TTL and CMOS logic thresholds per VIH/VIL specs. |
| 7 (A6) | A-side data input/output | Bidirectional I/O port A, channel 6 - supports hot-swap initialization when OE is asserted before power stabilization. |
| 8 (A7) | A-side data input/output | Bidirectional I/O port A, channel 7 - last bit of A-bus; layout symmetry matches B7 for PCB routing efficiency. |
| 9 (GND) | Ground reference | Primary return path for all I/O and supply currents - must be connected to low-impedance system ground plane. |
| 10 (B7) | B-side data input/output | Bidirectional I/O port B, channel 7 - complements A7; data flow direction set by DIR pin state. |
| 11 (B6) | B-side data input/output | Bidirectional I/O port B, channel 6 - electrically mirrored to A6; identical AC/DC characteristics. |
| 12 (B5) | B-side data input/output | Bidirectional I/O port B, channel 5 - supports simultaneous 8-bit transfer with guaranteed setup/hold margins. |
| 13 (B4) | B-side data input/output | Bidirectional I/O port B, channel 4 - routed opposite A4 to enable differential pair-like trace pairing on PCB. |
| 14 (B3) | B-side data input/output | Bidirectional I/O port B, channel 3 - low-capacitance node (10 pF Ci) minimizes signal degradation on long stubs. |
| 15 (B2) | B-side data input/output | Bidirectional I/O port B, channel 2 - shares same output enable timing (ten = 26 ns max at VCC = 6 V) as all B ports. |
| 16 (B1) | B-side data input/output | Bidirectional I/O port B, channel 1 - synchronized disable (tdis = 26 ns max) prevents bus contention during mode switching. |
| 17 (B0) | B-side data input/output | Bidirectional I/O port B, channel 0 - primary interface to destination bus; matched drive strength to A0. |
| 18 (OE) | Output enable control | Active-low global enable - drives all A/B ports into high-Z when high; critical for bus arbitration logic. |
| 19 (DIR) | Direction control | High = A→B data flow; Low = B→A flow - determines signal path polarity without external logic gates. |
| 20 (VCC) | Positive supply | 2–6 V CMOS supply - requires 0.1 µF ceramic bypass capacitor placed within 5 mm of pin 20 per layout guidelines. |
Key Features
| Feature | Design Value |
|---|---|
| Three-state bus isolation | Simultaneous high-impedance on all 16 I/O pins via single OE pin - eliminates need for discrete bus switches in multiplexed architectures. |
| Direction-controlled bidirectionality | Single DIR pin configures full 8-bit data path polarity - reduces control logic count vs. unidirectional transceivers requiring separate enable per direction. |
| Wide supply voltage range | 2 V to 6 V operation - supports mixed-voltage systems (e.g., 3.3 V MCU interfacing to 5 V peripheral bus) without external regulators. |
| High noise immunity | 30% noise margin at VCC = 5 V (NIL/NIL = 30%) - sustains reliable operation in electrically noisy industrial enclosures. |
| Low quiescent current | 160 µA max ICC at -55°C to +125°C - enables battery-backed or energy-constrained applications where standby power matters. |
| Extended temperature qualification | -55°C to +125°C operation - meets MIL-STD-883 requirements for Class B (space-grade) and automotive under-hood use. |
Applications
| Industrial Backplane Interface | Legacy Microprocessor Bus Isolation |
|---|---|
|
Use Scenario: Isolating CPU address/data buses from expansion card slots in programmable logic controllers (PLCs) operating at 85°C ambient. IC Role / Device Role / Timing Role: Bidirectional bus transceiver enabling read/write cycles between 80C88 CPU and peripheral cards while preventing signal contention during reset. Use Value: 19 ns max tpd at 6 V ensures timing compliance with 8 MHz bus clocks; ±25 mA drive sustains signal integrity over 15 cm ribbon cable runs. |
Use Scenario: Level-shifting and isolating Z80-based embedded controller buses from 5 V analog sensor subsystems in medical diagnostic equipment. IC Role / Device Role / Timing Role: Octal transceiver providing galvanic separation between digital control logic and analog front-end, controlled by FPGA-generated DIR/OE signals. Use Value: 2 V to 6 V supply range allows direct 3.3 V FPGA I/O interfacing; -55°C to +125°C rating supports sterilization cycle thermal stress. |
| Automotive ECU Data Multiplexing | Test Equipment Signal Routing |
|
Use Scenario: Multiplexing CAN and LIN bus diagnostics data onto a shared debug port in engine control units exposed to under-hood temperatures up to 125°C. IC Role / Device Role / Timing Role: Direction-switched data conduit routing serial protocol frames between microcontroller UARTs and external JTAG debug headers. Use Value: Three-state outputs prevent bus conflicts during firmware updates; 10 pF input capacitance minimizes jitter on high-speed UART lines. |
Use Scenario: Reconfigurable signal routing matrix in automated test equipment (ATE) handling multiple DUT interfaces with varying voltage standards (3.3 V/5 V). IC Role / Device Role / Timing Role: Programmable bus coupler enabling dynamic reassignment of test vectors between instrument channels using GPIB-controlled DIR/OE states. Use Value: Matched propagation delays (<1 ns skew) ensure phase-aligned stimulus delivery; RoHS-compliant NIPDAU leads support lead-free reflow assembly. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar octal bus transceiver applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SN74HC245N | Same HC logic family, identical pinout and AC/DC specs, but manufactured by TI with different internal process and lot traceability. | Qualified for commercial temp range only (-40°C to +85°C); lacks extended -55°C to +125°C rating of CD74HC245E-NG. | Select SN74HC245N for cost-sensitive consumer or telecom applications where extended temperature is not required. |
| 74ACT245SC | Advanced CMOS Technology (ACT) variant: 4.5–5.5 V only, 10 ns typical tpd, higher drive (±24 mA), but no 2–6 V flexibility. | Optimized for 5 V-only systems with tighter timing budgets; incompatible with 3.3 V logic without level translation. | Choose 74ACT245SC when maximum speed at 5 V is critical and supply voltage is fixed. |
Compared with SN74HC245N and 74ACT245SC, CD74HC245E-NG uniquely supports wide-voltage operation and extended temperature - making it the only option among the three qualified for aerospace, defense, and under-hood automotive deployments.
Availability
CD74HC245E-NG is available at Aetrix Electronics and suitable for industrial backplane interfaces, legacy microprocessor bus isolation, automotive ECU data multiplexing, and test equipment signal routing requiring stable component supply across extended temperature ranges and long production lifecycles.
Supply support for CD74HC245E-NG 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 ICs, with over 50 years of innovation in high-reliability interface solutions.
The CD74HC245E-NG belongs to TI's CDx4HC(T)245 family - engineered for robust bidirectional bus communication in harsh environments, emphasizing wide voltage tolerance, extended temperature resilience, and bus contention prevention.
FAQ
What is the maximum clock frequency supported by CD74HC245E-NG in a data bus application?
The CD74HC245E-NG does not operate on a clock; it is a combinatorial transceiver. Its usable data rate depends on propagation delay and bus loading. With 19 ns max tpd at VCC = 6 V and CL = 50 pF, it supports reliable 8-bit parallel transfers up to approximately 25 MHz (based on round-trip delay + setup/hold margins). Real-world bus speeds are typically limited by trace capacitance and driver strength - not the CD74HC245E-NG itself.
Can CD74HC245E-NG interface directly between 3.3 V and 5 V logic domains?
Yes. The CD74HC245E-NG operates from 2 V to 6 V and has CMOS-compatible inputs (VIH = 1.8 V min at VCC = 6 V, VIL = 0.5 V max at VCC = 2 V), allowing safe 3.3 V outputs to drive its inputs when VCC = 5 V. However, outputs swing rail-to-rail - so 5 V outputs must not connect directly to 3.3 V-only inputs without clamping or level translation.
What is the recommended bypass capacitor for CD74HC245E-NG?
Texas Instruments specifies a 0.1 µF ceramic capacitor placed as close as possible to the VCC pin (pin 20) and GND pin (pin 9), with trace length under 5 mm. For systems with broadband noise, paralleling a 1 µF tantalum or X7R ceramic capacitor improves low-frequency decoupling. This configuration suppresses supply transients induced by simultaneous 8-bit output switching.
Does CD74HC245E-NG support hot insertion or live bus swapping?
The CD74HC245E-NG is not hot-swap rated per JEDEC JESD63. While its three-state outputs prevent contention when OE is high, the device lacks built-in current limiting or slew-rate control. Safe live insertion requires external series resistors (e.g., 10–22 Ω per line) and controlled ramp-up of VCC/GND - confirmed in TI application report SLVA615 for HC/HCT bus transceivers.
How does the DIR pin function when OE is high?
When OE is high (logic 1), all A and B port pins enter high-impedance state regardless of DIR state - meaning DIR has no effect on output behavior. DIR only controls data direction when OE is low (active). This allows independent control of bus isolation (via OE) and data flow polarity (via DIR), simplifying arbitration logic in multi-master systems using CD74HC245E-NG.
CD74HC245E-NG Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 74HC
- Package/Case:
- 20-DIP (0.300", 7.62mm)
- Packaging:
- Bulk
- 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:
- 5.2mA, 5.2mA
- Voltage - Supply:
- 2V ~ 6V
- Operating Temperature:
- -55°C ~ 125°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Through Hole
- Supplier Device Package:
- 20-PDIP
CD74HC245E-NG FAQ
1.How can I place an order for CD74HC245E-NG through Aetrix?
Please submit a Request for Quotation (RFQ) for CD74HC245E-NG 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 CD74HC245E-NG reliable?
The price and inventory of CD74HC245E-NG are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for CD74HC245E-NG is usually 5 days.
3.What payment methods are accepted for CD74HC245E-NG?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for CD74HC245E-NG transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for CD74HC245E-NG?
CD74HC245E-NG orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your CD74HC245E-NG 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 CD74HC245E-NG?
For technical support, including CD74HC245E-NG datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your CD74HC245E-NG requirements.
6.How does Aetrix verify that CD74HC245E-NG is sourced from the original manufacturer or authorized distributors?
All CD74HC245E-NG 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 CD74HC245E-NG meets industry standards.
7.What is the process for return or replacement of CD74HC245E-NG?
All CD74HC245E-NG units undergo pre-shipment inspection (PSI). If there is an issue with CD74HC245E-NG, 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 CD74HC245E-NG part is unused and in its original packaging.
Return procedure for CD74HC245E-NG:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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