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Texas Instruments SN74AHC245N
- Part No.:
- SN74AHC245N
- Manufacturer:
- Texas Instruments
- Package:
- 20-DIP (0.300", 7.62mm)
- Datasheet:
-
SN74AHC245N.pdf
- Description:
- IC TXRX NON-INVERT 5.5V 20DIP
- Quantity:
- Payment:
- Shipping:
Inventory:2,155
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Product details
Overview
SN74AHC245N from Texas Instruments is an octal bus transceiver with 3-state outputs, designed for asynchronous bidirectional data transfer between two 8-bit buses. It operates from 2 V to 5.5 V, supports 5 V → 3.3 V voltage translation, features 3.3 V/5 V-compatible inputs (up to 5.5 V), and delivers ≤6.5 ns propagation delay at 5 V with 15 pF load - used in PC motherboard I/O expansion and server backplane interface isolation.
For engineers reviewing the SN74AHC245N datasheet, SN74AHC245N pinout, SN74AHC245N application, or SN74AHC245N equivalent, key selection criteria include its dual-bus direction control via DIR, active-low 3-state enable (OE), ±25 mA output drive per channel, latch-up immunity (>250 mA), and PDIP-20 package compatibility with legacy through-hole designs.
Technical Context
The SN74AHC245N implements CMOS AHC logic with balanced push-pull outputs and overvoltage-tolerant inputs rated up to 5.5 V regardless of VCC. Its DIR input selects data flow direction (A→B or B→A), while OE independently disables all outputs into high-impedance state - enabling bus isolation during power sequencing or hot-swap events.
It operates across –40°C to +125°C ambient temperature, meets JESD17 latch-up requirements (>250 mA), and exhibits slow edge rates to suppress output ringing on unterminated lines. The device does not include internal termination or slew-rate control circuitry - edge shaping relies on external layout and load conditions.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VCC Range | 2 V to 5.5 V - supports mixed-voltage systems including 3.3 V and 5 V domains |
| Propagation Delay (tPLH/tPHL) | ≤6.5 ns at VCC = 5 V, CL = 15 pF - enables reliable operation in 100+ MHz bus timing windows |
| Output Drive | ±8 mA at VCC = 5 V - sufficient for driving standard TTL loads and short PCB traces without external buffers |
| Input Voltage Tolerance | Up to 5.5 V on all inputs - allows safe interfacing with 5 V signals even when VCC = 3.3 V (down-translation) |
| 3-State Enable Time (tPZH) | ≤10 ns at VCC = 5 V, CL = 15 pF - ensures fast bus release for time-critical arbitration protocols |
| Latch-up Immunity | >250 mA per JESD17 - provides robustness against transient current faults in industrial environments |
| Operating Temperature | –40°C to +125°C - qualified for extended-temperature industrial and automotive under-hood applications |
Pinout & Package
SN74AHC245N uses a 20-pin plastic dual in-line package (PDIP) with 24.33 mm × 9.4 mm body size and 0.1 inch lead pitch. Pin 1 is top-left corner (DIR), pin 10 is GND, pin 20 is VCC. Thermal performance: RθJA = 51.5°C/W (JEDEC High-K board).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| DIR (Pin 1) | Direction control input | Low = B→A data flow; High = A→B data flow - determines real-time bus directionality |
| OE (Pin 19) | Active-low output enable | Low = outputs enabled; High = all A/B ports enter high-Z - critical for bus sharing and power-down isolation |
| A1–A8 (Pins 2–9) | Port A bidirectional I/O | Connects to source bus; direction determined by DIR; tolerates 5.5 V inputs at any VCC |
| B1–B8 (Pins 11–18) | Port B bidirectional I/O | Connects to destination bus; electrically identical to A-side; shares same 3-state control |
| GND (Pin 10) | Ground reference | Primary return path for all I/O and supply currents - must be low-impedance connection |
| VCC (Pin 20) | Power supply | Single supply for both input and output stages; bypass capacitor required per layout guidelines |
Key Features
| Feature | Design Value |
|---|---|
| Overvoltage-tolerant inputs | Accepts up to 5.5 V regardless of VCC - enables seamless 5 V ↔ 3.3 V level shifting without external components |
| Asymmetric enable/disable timing | tPZH = tPZL ≤10 ns, tPHZ = tPLZ ≤9.2 ns at 5 V - minimizes bus contention window during state transitions |
| Low dynamic power consumption | Cpd = 14 pF - reduces switching current and EMI in high-frequency bus applications |
| Slow edge rate design | Δt/Δv = 20 ns/V at 5 V - inherently limits overshoot/undershoot on unterminated transmission lines |
| Robust ESD protection | 1500 V HBM, 2000 V CDM - exceeds JEDEC standards for handling in automated assembly environments |
Applications
| PC Motherboard I/O Expansion | Industrial PLC Backplane Interface |
|---|---|
Use Scenario: Isolating legacy ISA or LPC bus segments from modern microcontroller peripherals in embedded PC architectures. IC Role / Device Role / Timing Role: Bidirectional level-shifting transceiver managing data flow between 5 V ISA slots and 3.3 V SoC GPIOs. Use Value: Eliminates need for discrete level shifters; supports hot-plug detection via OE-controlled bus release. |
Use Scenario: Interfacing modular I/O cards to central controller backplanes in programmable logic controllers. IC Role / Device Role / Timing Role: Bus isolator enabling independent power cycling of field I/O modules without disrupting controller operation. Use Value: Prevents ground loop currents and fault propagation; DIR pin allows firmware-directed data routing. |
| Server Memory Buffer Interface | Automotive Infotainment Gateway |
Use Scenario: Buffering SMBus or I²C sideband signals between baseboard management controller (BMC) and DIMM SPD EEPROMs. IC Role / Device Role / Timing Role: Low-capacitance repeater extending signal reach across multi-layer server motherboards. Use Value: Maintains signal integrity at 100 kHz–400 kHz; 4 pF Cio minimizes bus loading on timing-critical SPD reads. |
Use Scenario: Translating CAN/LIN diagnostic signals between 5 V legacy ECUs and 3.3 V infotainment head units. IC Role / Device Role / Timing Role: Voltage-level translator for non-CAN digital control lines (e.g., reset, wake-up, status flags). Use Value: Enables mixed-voltage domain interoperability without dedicated level-shifter ICs; qualified to 125°C ambient. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar octal bus transceiver applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SN74LVC245A | Lower VCC range (1.65–3.6 V); 3.3 V only; higher speed (tPLH ≤ 5.1 ns @ 3.3 V) | Not suitable for 5 V systems; requires separate 5 V→3.3 V translation for legacy interfaces | Select when operating exclusively in 3.3 V domains and maximum speed is prioritized over voltage flexibility |
| 74ACT245 | Higher drive (±24 mA @ 5 V); TTL-compatible inputs; no 5.5 V overvoltage tolerance | Compatible with older 5 V TTL logic but lacks down-translation capability for mixed-voltage designs | Choose for pure 5 V systems requiring stronger drive and TTL input thresholds, where overvoltage safety is not required |
Compared with SN74LVC245A and 74ACT245, SN74AHC245N uniquely balances 2–5.5 V operation, 5.5 V input tolerance, and industrial temperature range - making it the only option supporting direct 5 V↔3.3 V bidirectional translation without external circuitry in extended-temperature environments.
Availability
SN74AHC245N is available at Aetrix Electronics and suitable for PC motherboard I/O expansion, industrial PLC backplane interface, and server memory buffer applications requiring stable component supply, long-term obsolescence management, and RoHS-compliant through-hole packaging.
Supply support for SN74AHC245N 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 company delivering analog and embedded processing solutions, with leadership in logic, power management, and precision analog technologies.
The SN74AHC245N belongs to TI's AHC advanced high-speed CMOS logic family, engineered for low-power, high-noise-immunity bidirectional bus interfacing in industrial, computing, and communications equipment.
FAQ
What is the maximum input voltage rating for SN74AHC245N?
The SN74AHC245N accepts input voltages up to 5.5 V on all pins - including DIR, OE, and A/B I/Os - regardless of VCC level. This overvoltage tolerance enables safe interfacing with 5 V signals even when VCC is set to 3.3 V, making SN74AHC245N ideal for down-translation applications without external level-shifting components.
Can SN74AHC245N operate at 2.5 V supply voltage?
Yes, SN74AHC245N is fully specified to operate at VCC = 2.5 V within its recommended range of 2 V to 5.5 V. At 2.5 V, it maintains guaranteed VOH ≥ 2.0 V and VOL ≤ 0.44 V with 4 mA load, and supports functional operation across the full –40°C to +125°C temperature range - verified per TI's electrical characteristics tables.
How does the DIR pin control data flow direction in SN74AHC245N?
The DIR pin on SN74AHC245N determines real-time bus direction: when DIR = Low, data flows from Port B to Port A; when DIR = High, data flows from Port A to Port B. This control is independent of OE - outputs remain enabled unless OE is asserted High, allowing dynamic reconfiguration of data path direction during active operation.
What is the thermal resistance (RθJA) of SN74AHC245N in its PDIP package?
The SN74AHC245N in PDIP-20 package has a junction-to-ambient thermal resistance (RθJA) of 51.5°C/W under JEDEC High-K test board conditions. This value assumes standard 2-layer PCB with 1 in² copper pour - actual thermal performance improves with enhanced heatsinking or multilayer board designs with internal ground/power planes.
Is SN74AHC245N pin-compatible with other members of the SN74x245 family?
SN74AHC245N shares identical pinout and function mapping with all SN74x245 variants in PDIP-20, SOIC-20, SSOP-20, and TSSOP-20 packages - including SN74LS245N, SN74ALS245N, and SN74LVC245A. However, electrical characteristics (VCC range, drive strength, timing) differ significantly; substitution requires validation of voltage, timing, and loading requirements in the target design.
SN74AHC245N Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 74AHC
- 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:
- 8mA, 8mA
- Voltage - Supply:
- 2V ~ 5.5V
- Operating Temperature:
- -40°C ~ 125°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Through Hole
- Supplier Device Package:
- 20-PDIP
SN74AHC245N FAQ
1.How can I place an order for SN74AHC245N through Aetrix?
Please submit a Request for Quotation (RFQ) for SN74AHC245N 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 SN74AHC245N reliable?
The price and inventory of SN74AHC245N are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74AHC245N is usually 5 days.
3.What payment methods are accepted for SN74AHC245N?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SN74AHC245N transactions.
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4.How is shipping managed for SN74AHC245N?
SN74AHC245N orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SN74AHC245N 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 SN74AHC245N?
For technical support, including SN74AHC245N datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74AHC245N requirements.
6.How does Aetrix verify that SN74AHC245N is sourced from the original manufacturer or authorized distributors?
All SN74AHC245N 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 SN74AHC245N meets industry standards.
7.What is the process for return or replacement of SN74AHC245N?
All SN74AHC245N units undergo pre-shipment inspection (PSI). If there is an issue with SN74AHC245N, 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 SN74AHC245N part is unused and in its original packaging.
Return procedure for SN74AHC245N:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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