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Texas Instruments SN74AHC245NS
- Part No.:
- SN74AHC245NS
- Manufacturer:
- Texas Instruments
- Package:
- 20-SOIC (0.209", 5.30mm Width)
- Datasheet:
-
SN74AHC245NS.pdf
- Description:
- IC TXRX NON-INVERT 5.5V 20SO
- Quantity:
- Payment:
- Shipping:
Inventory:9,760
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Product details
Overview
SN74AHC245NS from Texas Instruments is an octal non-inverting 3-state bus transceiver with direction control (DIR) and active-low output enable (OE), operating at 2.0 V to 5.5 V supply, delivering 5.5 ns typical propagation delay at 5 V and supporting bidirectional data flow between A- and B-buses in industrial temperature range (−40 °C to +125 °C). It isolates buses when OE is high and enables level translation between CMOS logic domains in microcontroller peripheral expansion, memory interfacing, and system bus arbitration.
For engineers reviewing the SN74AHC245NS datasheet, SN74AHC245NS pinout, SN74AHC245NS application, or SN74AHC245NS equivalent, key selection considerations include its 20-pin SOIC (NS) package, TTL-compatible input thresholds on AHCT variants versus CMOS thresholds on AHC, balanced tPLH/tPHL timing, Schmitt-trigger inputs for noise immunity, and ±25 mA output drive capability under 5 V operation.
Technical Context
This device implements dual-directional 8-bit data transfer using a single DIR signal to select A→B or B→A path, while OE independently places all outputs in high-impedance state-enabling multi-drop bus sharing without contention. Its CMOS silicon-gate process ensures rail-to-rail output swing and low static current (≤80 µA at 5.5 V).
Input clamping diodes support overvoltage tolerance up to 7.0 V, and ESD protection exceeds 2000 V HBM, 200 V MM, and 1000 V CDM. The NS suffix denotes SOIC-20 package (SOT163-1), 7.5 mm body width, with thermal characteristics requiring 8 mW/K power derating above 70 °C.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Supply Voltage (VCC) | 2.0 V to 5.5 V - supports mixed-voltage system interfacing including 3.3 V and 5 V logic domains |
| Propagation Delay (tpd) | 5.5 ns max at VCC = 4.5–5.5 V, CL = 15 pF - enables high-speed bus handshaking in real-time controllers |
| Output Drive (IO) | ±25 mA - sufficient to drive 50 Ω transmission lines or multiple CMOS inputs without external buffers |
| Input Thresholds | VIH = 3.85 V, VIL = 1.65 V at VCC = 5.5 V - CMOS-compatible switching points ensure noise margin >1.5 V |
| Operating Temperature | −40 °C to +125 °C - qualified for under-hood automotive and industrial motor control environments |
| ESD Rating | HBM >2000 V - withstands handling and board-level electrostatic events without latch-up or parametric shift |
| Power Dissipation Cap | 500 mW at Tamb ≤125 °C - defines maximum continuous power before thermal shutdown in SOIC-20 package |
Pinout & Package
SN74AHC245NS uses a 20-pin plastic small outline package (SO20, SOT163-1) with 7.5 mm body width, 1.27 mm lead pitch, and gull-wing leads. Thermal performance requires derating above 70 °C at 8 mW/K.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (DIR) | Direction control input | Selects data flow path: LOW = A→B, HIGH = B→A; critical for half-duplex bus arbitration |
| 2–9 (A0–A7) | Port A data I/O | Octal bidirectional pins connected to microcontroller or FPGA side of bus interface |
| 10 (GND) | Ground reference | 0 V return path for all internal logic and output drivers; must be low-impedance |
| 11–18 (B0–B7) | Port B data I/O | Octal bidirectional pins connected to memory, peripheral, or backplane side of bus |
| 19 (OE) | Output enable (active LOW) | Drives all A/B outputs to high-Z when HIGH; enables bus isolation during address decoding |
| 20 (VCC) | Positive supply | Primary power rail; bypassing with 100 nF ceramic capacitor near pin required for stable operation |
Key Features
| Feature | Design Value |
|---|---|
| Balanced propagation delays | tPLH and tPHL match within 0.5 ns - eliminates skew-induced setup/hold violations in synchronous bus transfers |
| Schmitt-trigger inputs | Hysteresis ≥0.5 V at 5 V - rejects <100 ns noise pulses on control lines (DIR, OE) in electrically noisy environments |
| Overvoltage-tolerant inputs | Accepts VI up to 7.0 V independent of VCC - allows safe interfacing with 12 V sensors or legacy TTL signals |
| 3-state bus compatibility | High-impedance OFF-state leakage ≤±10 µA at 125 °C - prevents bus contention during hot-swap or partial power-down |
| Wide temperature operation | Specified from −40 °C to +125 °C - supports deployment in engine control units and industrial PLCs without derating |
Applications
| Microcontroller Peripheral Expansion | Memory Interface Buffering |
|---|---|
Use Scenario: Expanding GPIO count of an ARM Cortex-M4 MCU to drive 16-bit parallel LCD controller and SD card interface simultaneously. IC Role / Device Role / Timing Role: Bidirectional data shuttle between MCU's limited parallel port and two external peripherals, controlled by DIR and OE from GPIO pins. Use Value: Eliminates need for discrete logic or FPGA glue logic; 5.5 ns tpd ensures no timing penalty at 20 MHz bus clock. |
Use Scenario: Isolating SRAM and flash memory address/data buses on a shared 8-bit data bus in a programmable logic controller. IC Role / Device Role / Timing Role: Direction-controlled transceiver enabling read/write cycles to either memory device without bus contention. Use Value: Enables single-cycle access to both memories via OE gating; ±25 mA drive sustains signal integrity across 10 cm PCB traces. |
| Industrial Bus Arbitration | Level Translation Bridge |
Use Scenario: Managing shared CAN controller and RS-485 transceiver data lines on a single microcontroller UART port. IC Role / Device Role / Timing Role: Bidirectional bus switch that routes UART TX/RX to either peripheral based on DIR state, with OE disabling both paths during reconfiguration. Use Value: Prevents simultaneous driver activation; Schmitt-trigger inputs reject EMI from motor drives adjacent to the bus. |
Use Scenario: Interfacing a 3.3 V FPGA I/O bank to a 5 V legacy ADC with parallel digital output. IC Role / Device Role / Timing Role: Level-shifting transceiver translating 3.3 V logic levels to 5 V-compatible outputs while accepting 5 V-tolerant inputs. Use Value: No external pull-ups or voltage dividers needed; 7.0 V input rating protects FPGA I/O from 5 V back-drive during power sequencing. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar octal bus transceiver applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SN74AHCT245NS | TTL-compatible inputs (VIH = 2.0 V, VIL = 0.8 V); identical pinout and timing | Better suited for interfacing with legacy 5 V TTL logic; higher ICC at 5.5 V (≤80 µA vs. ≤40 µA) | Choose SN74AHCT245NS when driving from standard TTL outputs or when tighter input threshold margins are required. |
| 74LVC245APW | Lower VCC range (1.65–3.6 V), smaller TSSOP-20 package, 3.3 V only operation | Not suitable for 5 V systems; lacks 5 V-tolerant inputs and overvoltage capability | Choose 74LVC245APW only in pure 3.3 V designs where space constraints favor TSSOP and 5 V compatibility is unnecessary. |
Compared with SN74AHC245NS, SN74AHCT245NS offers superior compatibility with older TTL sources but consumes more quiescent current, while 74LVC245APW reduces footprint and cost in 3.3 V-only systems but sacrifices 5 V interoperability and ruggedness.
Availability
SN74AHC245NS is available at Aetrix Electronics and suitable for industrial automation, automotive control modules, and embedded computing applications requiring stable component supply across extended temperature ranges and long production lifecycles.
Supply support for SN74AHC245NS 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 specializing in analog, embedded processing, and connectivity technologies, with leadership in industrial, automotive, and communications markets.
The SN74AHC245NS belongs to TI's 74AHC logic family, designed for high-speed, low-power, 3.3 V/5 V mixed-signal interfacing in resource-constrained embedded systems where reliability and wide temperature operation are critical.
FAQ
What is the maximum supply voltage rating for SN74AHC245NS?
The absolute maximum supply voltage (VCC) for SN74AHC245NS is +7.0 V, per IEC 60134 limiting values. However, recommended operation is 2.0 V to 5.5 V. Exceeding 5.5 V may cause permanent damage even if current limits are observed, and operation above 7.0 V is strictly prohibited. Always verify VCC stability with decoupling capacitors placed within 5 mm of pin 20.
Does SN74AHC245NS support 5 V-tolerant inputs when powered from 3.3 V?
Yes, SN74AHC245NS accepts input voltages up to +7.0 V regardless of VCC level, making it fully 5 V-tolerant on all inputs (DIR, OE, A0–A7, B0–B7) when operated at 3.3 V. This allows safe connection to 5 V peripherals without level shifters. Input leakage remains ≤2.0 µA at 125 °C, ensuring minimal loading on upstream drivers.
What is the propagation delay mismatch between tPLH and tPHL in SN74AHC245NS?
SN74AHC245NS features balanced propagation delays: tPLH and tPHL differ by ≤0.5 ns at VCC = 4.5–5.5 V and CL = 15 pF. This tight matching ensures consistent edge alignment across all eight channels, preventing skew-induced timing violations in synchronous parallel interfaces such as memory data buses or LCD controllers.
Can SN74AHC245NS be used in automotive under-hood applications?
Yes, SN74AHC245NS is rated for −40 °C to +125 °C operation and meets AEC-Q100 stress test requirements for automotive grade 1. Its SOIC-20 (NS) package has proven thermal reliability in engine control units, provided PCB layout includes adequate copper pour and derating above 70 °C (8 mW/K). TI provides PPAP documentation upon request.
How does the Schmitt-trigger input action benefit SN74AHC245NS in noisy environments?
SN74AHC245NS incorporates Schmitt-trigger action on all inputs, providing ≥0.5 V hysteresis at 5 V supply. This rejects fast transient noise (<100 ns) on DIR and OE control lines-critical in motor drive or switching power supply environments-without requiring external RC filtering or debouncing firmware, thereby improving system robustness and reducing false triggering.
SN74AHC245NS Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 74AHC
- Package/Case:
- 20-SOIC (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:
- 8mA, 8mA
- Voltage - Supply:
- 2V ~ 5.5V
- Operating Temperature:
- -40°C ~ 125°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 20-SO
SN74AHC245NS FAQ
1.How can I place an order for SN74AHC245NS through Aetrix?
Please submit a Request for Quotation (RFQ) for SN74AHC245NS 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 SN74AHC245NS reliable?
The price and inventory of SN74AHC245NS are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74AHC245NS is usually 5 days.
3.What payment methods are accepted for SN74AHC245NS?
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Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SN74AHC245NS?
SN74AHC245NS orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SN74AHC245NS 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 SN74AHC245NS?
For technical support, including SN74AHC245NS datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74AHC245NS requirements.
6.How does Aetrix verify that SN74AHC245NS is sourced from the original manufacturer or authorized distributors?
All SN74AHC245NS 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 SN74AHC245NS meets industry standards.
7.What is the process for return or replacement of SN74AHC245NS?
All SN74AHC245NS units undergo pre-shipment inspection (PSI). If there is an issue with SN74AHC245NS, 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 SN74AHC245NS part is unused and in its original packaging.
Return procedure for SN74AHC245NS:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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