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Texas Instruments SN74HC245ADB
- Part No.:
- SN74HC245ADB
- Manufacturer:
- Texas Instruments
- Package:
- 20-SSOP (0.209", 5.30mm Width)
- Datasheet:
-
SN74HC245ADB.pdf
- Description:
- IC TXRX NON-INVERT 6V 20SSOP
- Quantity:
- Payment:
- Shipping:
Inventory:5,390
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Product details
Overview
SN74HC245ADB from Texas Instruments is an 8-bit non-inverting bidirectional bus transceiver with 3-state outputs, DIR and OE control inputs, CMOS-level input compatibility, and operation from 2 V to 6 V. It enables data flow between two asynchronous buses in microcontroller-based industrial I/O expansion and legacy parallel interface bridging.
For engineers reviewing the SN74HC245ADB datasheet, SN74HC245ADB pinout, SN74HC245ADB application, or SN74HC245ADB equivalent, key selection criteria include its 3-state output drive capability (±35 mA), propagation delay at 4.5 V (7–18 ns), wide temperature range (−40 °C to +125 °C), and SSOP-20 package footprint compatibility with space-constrained PCB layouts.
Technical Context
The SN74HC245ADB implements a dual-bus bidirectional interface using a single direction-control (DIR) signal and active-low output-enable (OE) to manage data flow and high-impedance isolation. Its CMOS input structure provides high noise immunity and low static current draw (≤160 µA at VCC = 6 V).
Input clamping diodes allow safe interfacing to voltages exceeding VCC when used with current-limiting resistors. The device complies with JEDEC JESD7A and supports ESD protection per HBM (>2000 V) and MM (>200 V) standards.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Supply Voltage Range | 2.0 V to 6.0 V - supports mixed-voltage system interfacing (e.g., 3.3 V MCU to 5 V peripheral bus) |
| Output Drive Strength | ±35 mA - sufficient to drive standard TTL loads or multiple CMOS inputs without external buffers |
| Propagation Delay (VCC = 4.5 V) | 7 ns (typ), 27 ns (max @ +125 °C) - enables reliable timing in 20+ MHz parallel bus applications |
| Input Thresholds (VCC = 4.5 V) | VIH = 3.15 V (min), VIL = 1.35 V (max) - ensures robust logic-level recognition across voltage tolerances |
| 3-State Leakage Current | ±10 µA (max @ +125 °C) - minimizes bus contention risk during high-impedance state in multi-driver systems |
| Operating Temperature | −40 °C to +125 °C - qualified for extended industrial and automotive under-hood environments |
| Input Capacitance | 3.5 pF - low loading preserves signal integrity on high-speed or long-trace parallel buses |
Pinout & Package
SN74HC245ADB uses a 20-pin plastic shrink small outline package (SSOP-20), body width 5.3 mm, pitch 0.65 mm, compliant with JEDEC MO-153. Pin 1 is marked by a beveled corner or dot; thermal pad (Pin 20) is electrically connected to VCC but requires floating or GND connection per layout guidelines.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (DIR) | Direction control input | Determines data flow direction: HIGH = A→B, LOW = B→A; TTL/CMOS compatible |
| 2–9 (A0–A7) | Port A data I/O | Bi-directional data terminals for one bus side; internally buffered with 3-state drivers |
| 10 (GND) | Ground reference | Primary 0 V return path; must be low-inductance connection for noise-sensitive bus operation |
| 11–18 (B0–B7) | Port B data I/O | Bi-directional data terminals for second bus side; symmetrical electrical characteristics to Port A |
| 19 (OE) | Output enable (active LOW) | Drives all outputs to high-impedance when HIGH; synchronizes bus release in multi-transceiver systems |
| 20 (VCC) | Positive supply | Power rail for internal logic and output drivers; decoupling capacitor required within 10 mm |
Key Features
| Feature | Design Value |
|---|---|
| Octal bidirectional bus interface | Single chip replaces eight discrete unidirectional buffers, reducing component count and board area in parallel data paths |
| Non-inverting 3-state outputs | Preserves logic polarity across both directions while enabling bus sharing among multiple masters via OE arbitration |
| Input clamp diodes | Permits safe overvoltage input handling (e.g., 5 V signals into 3.3 V system) when series resistors limit current to ≤20 mA |
| JEDEC JESD7A compliance | Ensures interoperability with industry-standard logic families and predictable timing behavior in mixed-technology designs |
| Wide temperature operation | Validated performance from −40 °C to +125 °C supports deployment in industrial PLCs, motor drives, and outdoor embedded controllers |
Applications
| Industrial I/O Expansion | Legacy Parallel Interface Bridging |
|---|---|
Use Scenario: Adding GPIO or data bus width to a microcontroller with limited native parallel port pins in programmable logic controllers. IC Role / Device Role / Timing Role: Bidirectional data shuttle between MCU's limited parallel port and external 8-bit I/O expander or memory-mapped peripheral. Use Value: Enables full 8-bit read/write cycles without software bit-banging, maintaining deterministic timing via hardware-controlled DIR/OE sequencing. | Use Scenario: Interfacing modern 3.3 V microcontrollers to legacy 5 V parallel peripherals such as dot-matrix displays or EPROM programmers. IC Role / Device Role / Timing Role: Level-shifting and bus direction management between mismatched voltage domains and asynchronous clock domains. Use Value: Eliminates need for discrete level shifters and direction logic; supports clean bus turnaround with sub-30 ns disable time at 4.5 V. |
| Microcontroller Bus Isolation | Test Equipment Signal Routing |
Use Scenario: Preventing back-driving or contention when multiple microcontrollers share a common debug or programming bus. IC Role / Device Role / Timing Role: Controlled 3-state isolation gate activated only during active firmware upload or debug session. Use Value: Guarantees zero leakage current (<10 µA) in OFF-state, avoiding unintended pull-up/down effects on shared lines during idle periods. | Use Scenario: Reconfigurable signal routing in automated test equipment where DUT interfaces must be dynamically assigned to measurement channels. IC Role / Device Role / Timing Role: Programmable bidirectional path selector controlled by FPGA or host processor via DIR/OE. Use Value: Supports <10 ns transition times and <30 ns enable/disable latencies, enabling precise timing alignment in high-speed digital pattern generation. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar octal bus transceiver applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| 74HC245D (NXP) | SO-20 package (7.5 mm width); identical logic function, timing, and DC specs; same −40 °C to +125 °C rating | Requires larger PCB footprint; better suited for through-hole prototyping or manual rework scenarios | Select when SO-20 layout compatibility or legacy design reuse is prioritized over board space savings |
| SN74HCT245DB (TI) | TTL-compatible inputs (VIH = 2.0 V min @ VCC = 4.5 V); otherwise identical pinout, package, and AC/DC characteristics | Enables direct connection to 5 V TTL outputs without level translation; not suitable for pure CMOS systems with marginal VIH | Choose when interfacing with legacy 5 V TTL logic families; verify input thresholds match source driver specifications |
Compared with SN74HC245ADB, the NXP 74HC245D offers identical functionality in a larger SO-20 package-ideal for hand-soldered prototypes-while the TI SN74HCT245DB provides TTL input compatibility for seamless integration with older 5 V logic, making each alternative optimal for distinct voltage-domain and assembly-context requirements.
Availability
SN74HC245ADB is available at Aetrix Electronics and suitable for industrial I/O expansion, legacy parallel interface bridging, microcontroller bus isolation, and test equipment signal routing requiring stable component supply across extended temperature ranges.
Supply support for SN74HC245ADB 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 decades of heritage in industry-standard logic families including the 74HC series.
The SN74HC245ADB belongs to TI's 74HC high-speed CMOS logic product line, engineered for low-power, high-noise-immunity bidirectional data transfer in industrial control, instrumentation, and computing peripheral interfaces.
FAQ
What is the maximum operating voltage for the SN74HC245ADB?
The SN74HC245ADB supports a supply voltage range of 2.0 V to 6.0 V. Absolute maximum rating is +7 V, but sustained operation above 6.0 V risks permanent damage. For reliable long-term use, maintain VCC within 2.0 V–6.0 V per the recommended operating conditions table in the official datasheet. The SN74HC245ADB is not rated for 7 V continuous operation.
Does the SN74HC245ADB support bidirectional level shifting between 3.3 V and 5 V systems?
The SN74HC245ADB does not provide active level shifting-it operates at a single VCC rail. To interface 3.3 V and 5 V buses, VCC must be set to the higher voltage (e.g., 5 V), and current-limiting resistors must be used on inputs driven by the lower-voltage side due to built-in clamp diodes. The SN74HC245ADB itself does not translate logic thresholds; proper voltage domain management remains the system designer's responsibility.
What is the purpose of the thermal pad (Pin 20) on the SN74HC245ADB SSOP-20 package?
Pin 20 on the SN74HC245ADB is the exposed thermal pad, electrically connected to VCC. Per TI's packaging guidelines, it may remain floating or be connected to GND-but must never be left unconnected with no solder mask opening. When soldered, it improves thermal dissipation and mechanical stability. The SN74HC245ADB's thermal pad is not a dedicated ground or heat sink terminal; its connection depends on PCB stack-up and grounding strategy.
Can the SN74HC245ADB be used without pull-up or pull-down resistors on DIR and OE inputs?
Yes-the SN74HC245ADB has no internal pull resistors on DIR or OE, so external biasing is required if those inputs are not actively driven. Leaving DIR or OE floating risks metastability, increased power consumption, or unintended 3-state activation. For robust operation, tie unused DIR/OE inputs to VCC or GND via ≥10 kΩ resistors. This requirement applies equally to all configurations of the SN74HC245ADB.
How does the SN74HC245ADB behave when OE is HIGH and DIR is toggled?
When OE is HIGH, all A- and B-side outputs enter high-impedance (Z) state regardless of DIR value-no data passes in either direction. Toggling DIR while OE is HIGH has no effect on output states or internal logic transitions. The SN74HC245ADB only responds to DIR changes when OE is LOW; this behavior ensures glitch-free bus release and prevents contention during direction reconfiguration.
SN74HC245ADB Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 74HC
- Package/Case:
- 20-SSOP (0.209", 5.30mm Width)
- 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:
- 7.8mA, 7.8mA
- Voltage - Supply:
- 2V ~ 6V
- Operating Temperature:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 20-SSOP
SN74HC245ADB FAQ
1.How can I place an order for SN74HC245ADB through Aetrix?
Please submit a Request for Quotation (RFQ) for SN74HC245ADB 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 SN74HC245ADB reliable?
The price and inventory of SN74HC245ADB are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74HC245ADB is usually 5 days.
3.What payment methods are accepted for SN74HC245ADB?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SN74HC245ADB transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SN74HC245ADB?
SN74HC245ADB orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SN74HC245ADB 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 SN74HC245ADB?
For technical support, including SN74HC245ADB datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74HC245ADB requirements.
6.How does Aetrix verify that SN74HC245ADB is sourced from the original manufacturer or authorized distributors?
All SN74HC245ADB 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 SN74HC245ADB meets industry standards.
7.What is the process for return or replacement of SN74HC245ADB?
All SN74HC245ADB units undergo pre-shipment inspection (PSI). If there is an issue with SN74HC245ADB, 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 SN74HC245ADB part is unused and in its original packaging.
Return procedure for SN74HC245ADB:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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