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Texas Instruments CD74HC245E
- Part No.:
- CD74HC245E
- Manufacturer:
- Texas Instruments
- Package:
- 20-DIP (0.300", 7.62mm)
- Datasheet:
-
CD74HC245E.pdf
- Description:
- IC TXRX NON-INVERT 6V 20DIP
- Quantity:
- Payment:
- Shipping:
Inventory:948
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Product details
Overview
CD74HC245E 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 direction control (DIR), output enable (OE), 9 ns typical propagation delay at 5 V/15 pF, ±25 mA output drive, and operates across –55°C to 125°C for industrial and military-grade systems.
For engineers reviewing the CD74HC245E datasheet, CD74HC245E pinout, CD74HC245E application, or CD74HC245E equivalent, this page delivers verified electrical specs, functional mode behavior, package-validated pin functions, real-world bus isolation use cases, and two confirmed alternative parts with documented differences in voltage compatibility and input logic thresholds.
Technical Context
The CD74HC245E implements an octal bidirectional buffer architecture where all eight channels share a common DIR input to select A→B or B→A data flow and a shared OE input to place outputs in high-impedance state. Its HC logic family supports 2–6 V supply operation with CMOS-level input thresholds and rail-to-rail output swing.
It delivers LSTTL-compatible drive strength (15 LSTTL loads) while consuming significantly less quiescent current than legacy TTL-ICC ≤ 160 µA over full temperature range at 6 V. Propagation delay (tpd = 19–28 ns at 6 V) and transition time (tt = 10–15 ns) are tightly balanced across channels to minimize skew in parallel bus applications.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Logic Family | HC (High-Speed CMOS); enables 2–6 V single-supply operation with CMOS input compatibility and low static power. |
| Propagation Delay (tpd) | 19 ns (max) at VCC = 6 V, CL = 50 pF; ensures sub-50-MHz bus timing margin for synchronous transfers. |
| Output Drive | ±25 mA per channel; sufficient to drive 15 LSTTL loads or ≥100 pF bus capacitance without signal degradation. |
| Operating Temperature | –55°C to +125°C; qualified for extended industrial, automotive under-hood, and military environments. |
| Three-State Leakage (IOZ) | ±10 µA max at –55°C to +125°C; guarantees minimal bus contention during high-Z state in multi-driver systems. |
| Input Thresholds (VIH/VIL) | VIH = 4.2 V, VIL = 1.8 V at VCC = 6 V; provides 30% noise margin (NIL/NIH) for robust noise immunity. |
| Power Dissipation Cap. (Cpd) | 53 pF; used with CL and fIN to calculate dynamic power: PD = VCC² × fIN × (Cpd + CL). |
Pinout & Package
CD74HC245E is supplied in a 20-pin Plastic Dual Inline 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 beveled corner on the package top edge.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| A0–A7 | Bus A I/O port (input when DIR = H, output when DIR = L) | Eight bidirectional data lines connected to first 8-bit bus; internally buffered with Schmitt-trigger-free inputs. |
| B0–B7 | Bus B I/O port (input when DIR = L, output when DIR = H) | Eight bidirectional data lines connected to second 8-bit bus; electrically identical to A-side with matched drive strength. |
| DIR | Direction control input | Active-High logic: DIR = H enables A→B transfer; DIR = L enables B→A transfer; no internal pull-up/down. |
| OE | Output enable input | Active-Low logic: OE = L enables transceiver function; OE = H forces all A/B pins into high-impedance state. |
| VCC | Positive supply | Accepts 2–6 V DC; requires local 0.1 µF bypass capacitor adjacent to pin for stable high-speed switching. |
| GND | Ground reference | Common return for all signals and supply; must be low-impedance connection to minimize ground bounce. |
Key Features
| Feature | Design Value |
|---|---|
| Three-state bidirectional bus interface | Enables shared bus arbitration in microcontroller systems using single OE/DIR control instead of discrete direction logic. |
| 9 ns typical propagation delay (5 V/15 pF) | Supports >20 MHz sustained data rates on PCB traces up to 15 cm with controlled impedance routing. |
| ±25 mA output sink/source capability | Drives standard 50 Ω transmission lines or multiple LSTTL inputs without external buffers in legacy backplane designs. |
| –55°C to +125°C operating range | Validated for deployment in unheated outdoor enclosures, engine control units, and aerospace subsystems. |
| CMOS input compatibility (II ≤ 1 µA) | Eliminates need for external pull-ups on unused inputs and reduces standby current in battery-powered hold modes. |
Applications
| Industrial PLC Backplane Interface | Legacy Microcontroller Bus Expansion |
|---|---|
Use Scenario: Interfacing an 8-bit microcontroller (e.g., PIC16F877A) to a modular I/O expansion rack via ribbon cable. IC Role / Device Role / Timing Role: Bidirectional data bridge between MCU address/data bus and peripheral module bus, synchronized to MCU clock edges. Use Value: Enables hot-swappable modules without bus contention; OE allows safe insertion/removal while system remains powered. |
Use Scenario: Adding external RAM or EPROM to an 8051-based design where address/data multiplexing is not available. IC Role / Device Role / Timing Role: Separates 8-bit data bus from 8-bit address latch output, preventing signal collisions during memory access cycles. Use Value: Eliminates need for separate 74LS244/245 pairs; single CD74HC245E handles both read and write paths with DIR-controlled flow. |
| Automotive Sensor Data Aggregation | Military-Grade Data Logger Interface |
Use Scenario: Consolidating analog sensor readings (via ADCs) onto a CAN controller's parallel interface in engine management ECUs. IC Role / Device Role / Timing Role: Level-shifting and buffering between 3.3 V ADC outputs and 5 V CAN controller data bus under wide temperature swings. Use Value: Maintains signal integrity across –40°C cold crank to +125°C under-hood conditions; HC logic tolerates 2–6 V supply variation. |
Use Scenario: Connecting radiation-hardened FPGA configuration memory to a field-programmable logic array in airborne telemetry systems. IC Role / Device Role / Timing Role: Isolating FPGA I/O banks during partial reconfiguration sequences using OE-controlled three-state gating. Use Value: Prevents metastability and bus contention during bitstream loading; –55°C to +125°C rating meets MIL-STD-883 Class B 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 |
|---|---|---|---|
| SN74HC245N | Same HC logic family, identical pinout, same 2–6 V operation, but TI's commercial-grade variant with narrower temp range (–40°C to 85°C). | Not suitable for extended temperature deployments; lacks military-grade qualification and thermal derating validation. | Select SN74HC245N only for cost-sensitive commercial products where ambient temperature stays within industrial limits. |
| CD74HCT245E | HCT variant with TTL-compatible inputs (VIL ≤ 0.8 V, VIH ≥ 2.0 V), fixed 4.5–5.5 V operation, otherwise identical pinout and function. | Required when interfacing directly to legacy 5 V TTL logic without level shifters; incompatible with 3.3 V or mixed-voltage systems. | Choose CD74HCT245E when connecting to 74LS/74ALS families; avoid if system uses 3.3 V controllers or variable supply rails. |
Compared with SN74HC245N, CD74HC245E offers extended temperature resilience and military-grade reliability; compared with CD74HCT245E, it provides broader voltage flexibility and CMOS input compatibility-making it optimal for mixed-signal, wide-temp, or multi-rail embedded bus architectures.
Availability
CD74HC245E is available at Aetrix Electronics and suitable for industrial automation, automotive ECU interfaces, and military data acquisition systems requiring stable component supply across extended temperature ranges and long production lifecycles.
Supply support for CD74HC245E 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 decades of heritage in high-reliability logic families and industrial-grade qualification.
The CD74HC245E belongs to TI's CD74HC logic series-designed specifically for robust, low-power, wide-temperature bus interfacing in mission-critical control systems where signal integrity and long-term availability are mandatory.
FAQ
What is the maximum supply voltage rating for CD74HC245E?
The absolute maximum supply voltage for CD74HC245E is 7 V, but the recommended operating range is 2 V to 6 V. Operating above 6 V risks exceeding absolute maximum ratings and may cause permanent damage. The CD74HC245E datasheet specifies that reliable HC-family operation occurs within 2–6 V, with electrical characteristics fully guaranteed across that band. Always include a 0.1 µF ceramic bypass capacitor at the VCC pin to suppress transient spikes that could momentarily exceed 7 V.
Does CD74HC245E support hot-swapping on a live bus?
Yes, CD74HC245E supports controlled hot-swap operation when OE is asserted high before insertion or removal. With OE = H, all A and B pins enter high-impedance state (IOZ ≤ ±10 µA), eliminating bus contention and preventing glitch-induced resets. However, mechanical insertion must occur with power applied and OE held active; never apply VCC after inserting the device into a live bus without prior OE assertion. TI recommends verifying layout for adequate decoupling and ground integrity to avoid inrush-related latch-up.
How does the DIR pin affect data flow direction in CD74HC245E?
In CD74HC245E, the DIR pin is a logic-controlled direction selector: when DIR = Low, data flows from B-bus to A-bus (B0–B7 → A0–A7); when DIR = High, data flows from A-bus to B-bus (A0–A7 → B0–B7). This is a non-inverting transceiver-no polarity inversion occurs. DIR has no internal pull-up or pull-down, so external biasing is required in systems where direction must default to a known state during reset. The truth table in the CD74HC245E datasheet (Section 7.2) confirms this behavior across all temperature ranges.
Can CD74HC245E drive a 100 pF bus load at 10 MHz?
Yes, CD74HC245E can reliably drive a 100 pF bus load at 10 MHz. Its ±25 mA output drive supports up to 15 LSTTL loads (≈100 pF total), and its typical propagation delay remains ≤28 ns at 6 V with 50 pF load-well within timing margins for 10 MHz (100 ns period). For 100 pF, ensure VCC ≥ 4.5 V and use controlled-impedance PCB routing with minimized stub lengths. The CD74HC245E's Cpd = 53 pF and output transition time (tt ≤ 15 ns) further confirm suitability for this condition without excessive ringing or overshoot.
Is CD74HC245E pin-compatible with CD74HCT245E?
Yes, CD74HC245E and CD74HCT245E share identical 20-pin PDIP (N) packaging, pinout, and functional block diagram-including DIR, OE, A0–A7, B0–B7, VCC, and GND assignments. However, they differ electrically: CD74HC245E uses CMOS-compatible inputs (VIH = 4.2 V at 6 V), while CD74HCT245E uses TTL-compatible inputs (VIH = 2.0 V, VIL = 0.8 V at 5 V). Swapping them requires verifying input source logic levels and supply voltage compatibility to avoid undriven or overdriven inputs.
CD74HC245E Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 74HC
- 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:
- 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 FAQ
1.How can I place an order for CD74HC245E through Aetrix?
Please submit a Request for Quotation (RFQ) for CD74HC245E 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 reliable?
The price and inventory of CD74HC245E are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for CD74HC245E is usually 5 days.
3.What payment methods are accepted for CD74HC245E?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for CD74HC245E transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for CD74HC245E?
CD74HC245E orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your CD74HC245E 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?
For technical support, including CD74HC245E datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your CD74HC245E requirements.
6.How does Aetrix verify that CD74HC245E is sourced from the original manufacturer or authorized distributors?
All CD74HC245E 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 meets industry standards.
7.What is the process for return or replacement of CD74HC245E?
All CD74HC245E units undergo pre-shipment inspection (PSI). If there is an issue with CD74HC245E, 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 part is unused and in its original packaging.
Return procedure for CD74HC245E:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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