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Texas Instruments SN74AC245NSR
- Part No.:
- SN74AC245NSR
- Manufacturer:
- Texas Instruments
- Package:
- 20-SOIC (0.209", 5.30mm Width)
- Datasheet:
-
SN74AC245NSR.pdf
- Description:
- IC TXRX NON-INVERT 6V 20SO
- Quantity:
- Payment:
- Shipping:
Inventory:1,444
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Product details
Overview
SN74AC245NSR from Texas Instruments is an octal bus transceiver with 3-state outputs, designed for asynchronous bidirectional data transfer between A and B buses in mixed-voltage systems. It operates from 2 V to 6 V, accepts inputs up to 6 V, delivers ≤7 ns propagation delay at 5 V, and features direction (DIR) and output-enable (OE) control for isolated bus communication in industrial I/O and legacy interface bridging.
For engineers reviewing the SN74AC245NSR datasheet, SN74AC245NSR pinout, SN74AC245NSR application, or SN74AC245NSR equivalent, key selection criteria include its wide VCC range (2–6 V), 3.3 V/5 V interoperability, 20-pin SOP (NS) package with 12.6 mm × 7.8 mm footprint, and verified 24 mA output drive capability per channel at 5 V.
Technical Context
The SN74AC245NSR implements a dual-bus transceiver architecture with independent DIR and OE logic control, enabling configurable unidirectional or bidirectional data flow without external timing circuitry. Its CMOS design provides balanced output drive, slow edge rates to suppress ringing, and input tolerance beyond VCC-critical for level-shifting between 3.3 V microcontrollers and 5 V peripheral buses.
Functional modes are strictly defined by OE and DIR states: OE = L enables bidirectional transfer (DIR = L → B→A; DIR = H → A→B), while OE = H forces all outputs into high-impedance isolation. The device requires no pull-up on DIR but recommends OE tied to VCC via external resistor during power sequencing to ensure default high-Z state.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VCC Range | 2 V to 6 V - supports direct interfacing between 3.3 V and 5 V domains without level shifters |
| Max Propagation Delay | 7 ns at 5 V - enables reliable operation in sub-100 MHz digital bus applications |
| Output Drive | ±24 mA per channel at 4.5–5.5 V - sufficient to drive TTL loads and moderate-capacitance PCB traces |
| Input Voltage Tolerance | Up to 6 V regardless of VCC - allows safe connection to higher-voltage buses without clamping diodes |
| Operating Temperature | −40 °C to +85 °C - qualified for industrial-grade embedded control and factory automation environments |
| ESD Rating | ±3000 V HBM - meets standard handling requirements for automated assembly and field service |
| Power Dissipation Cap | 45 pF typical Cpd per transceiver - limits dynamic power consumption in high-frequency toggling scenarios |
Pinout & Package
The SN74AC245NSR is packaged in a 20-pin SOP (NS) with 12.6 mm × 7.8 mm body size and 12.6 mm × 5.3 mm footprint, compliant with JEDEC MS-012, and rated for surface-mount reflow per Level-1-260°C.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 DIR | Direction Control Input | Determines data flow direction: DIR = H enables A→B; DIR = L enables B→A |
| 2–9 A1–A8 | Port A I/O Terminals | Bidirectional data lines connected to source bus; high-impedance when OE = H |
| 10 GND | Ground Reference | Primary return path for all internal logic and output current; must be low-inductance |
| 11–18 B8–B1 | Port B I/O Terminals | Bidirectional data lines connected to destination bus; pin order reversed for compact layout routing |
| 19 OE | Output Enable Input | Active-low control: OE = L enables ports; OE = H forces all A/B pins to high-Z isolation |
| 20 VCC | Supply Voltage | Single power rail (2–6 V); requires local 0.1 µF bypass capacitor adjacent to pin |
Key Features
| Feature | Design Value |
|---|---|
| Wide Supply Range | 2 V to 6 V operation enables seamless integration across 3.3 V microcontrollers and 5 V legacy peripherals |
| Over-Voltage Tolerant Inputs | Accepts up to 6 V on any input regardless of VCC - eliminates need for external voltage translators |
| Controlled Edge Rates | Slower rise/fall times minimize signal overshoot and EMI in noisy industrial environments |
| Bus Isolation Capability | True 3-state outputs with guaranteed high-Z when OE = H - prevents bus contention during hot-swap or reset |
| Low Static Current | Max 40 µA ICC at 5.5 V - reduces quiescent power in always-on industrial monitoring nodes |
Applications
| Industrial I/O Expansion | Legacy System Interfacing |
|---|---|
Use Scenario: Adding GPIO expansion to a PLC controller using a 3.3 V ARM Cortex-M4 MCU while driving 5 V discrete I/O modules. IC Role / Device Role / Timing Role: Bidirectional level-translating bus transceiver managing data flow between MCU's A-port and 5 V relay/driver board's B-port. Use Value: Eliminates need for separate level shifters; 24 mA drive directly activates optocouplers and small relays without buffer stages. | Use Scenario: Connecting modern FPGA-based video processing board (3.3 V) to legacy VGA timing generator (5 V). IC Role / Device Role / Timing Role: Synchronous data bridge isolating timing-critical pixel clock domain from slower control bus signals. Use Value: 7 ns max tPD ensures setup/hold timing margins are preserved; overvoltage-tolerant inputs prevent damage from 5 V back-driving. |
| Factory Automation Bus | Pro Audio Signal Routing |
Use Scenario: Isolating sensor data acquisition bus from motor control bus in CNC machine controller to prevent noise coupling. IC Role / Device Role / Timing Role: Direction-controlled transceiver enabling diagnostic readback from analog front-end while blocking PWM noise ingress. Use Value: OE-driven high-Z state provides galvanic separation during fault conditions; −40 °C to +85 °C rating sustains operation near motors and drives. | Use Scenario: Routing digital audio control signals (I²C, SPI) between 3.3 V DSP and 5 V analog codec in stage mixer. IC Role / Device Role / Timing Role: Low-noise bidirectional interface preserving signal integrity for real-time mute/unmute and gain commands. Use Value: Slow edge rates suppress RF emissions in EMI-sensitive audio racks; 3000 V HBM withstands static discharge from stage handling. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar bus transceiver applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SN74LVC245A | Lower VCC range (1.65–3.6 V); 3.3 V only; 24 mA drive at 3.3 V; faster tPD (5.3 ns) | Not suitable for 5 V bus interfacing; requires external level translation for mixed-voltage systems | Select when system is fully 3.3 V and speed >7 ns is required |
| SN74AHCT245 | TTL-compatible inputs (VIH = 2 V min); 4.5–5.5 V only; 8 mA drive; 8 ns tPD | Compatible only with 5 V logic families; lacks overvoltage tolerance and wide-supply flexibility | Select for cost-sensitive 5 V-only designs where TTL input thresholds are mandatory |
Compared with SN74LVC245A and SN74AHCT245, the SN74AC245NSR uniquely supports 2–6 V operation with 6 V-tolerant inputs-making it the only option among the three capable of direct 3.3 V ↔ 5 V bidirectional bridging without ancillary components.
Availability
SN74AC245NSR is available at Aetrix Electronics and suitable for industrial I/O expansion, legacy system interfacing, and factory automation bus isolation requiring stable component supply across extended temperature ranges and mixed-voltage environments.
Supply support for SN74AC245NSR 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 industrial and automotive qualification expertise.
The SN74AC245NSR belongs to TI's AC-series advanced CMOS logic family, engineered for robust bidirectional bus interfacing in mixed-voltage industrial control, automation, and instrumentation systems.
FAQ
What is the maximum operating voltage for SN74AC245NSR?
The SN74AC245NSR supports a supply voltage range of 2 V to 6 V. Its inputs tolerate voltages up to 6 V regardless of VCC level, enabling safe interfacing with higher-voltage buses. This specification is confirmed in Section 5.3 (Recommended Operating Conditions) and Section 5.1 (Absolute Maximum Ratings) of the official TI datasheet SCAS461I.
Does SN74AC245NSR require external pull-up resistors on DIR or OE pins?
The SN74AC245NSR does not require a pull-up on DIR, but TI strongly recommends tying OE to VCC through an external pull-up resistor to ensure high-impedance outputs during power-up and power-down sequences. This prevents bus contention and is specified in Section 7.1 (Overview) of the datasheet.
Can SN74AC245NSR be used for level shifting between 3.3 V and 5 V systems?
Yes, SN74AC245NSR is explicitly designed for this use case. With 2–6 V VCC operation and inputs tolerant up to 6 V, it enables direct bidirectional level shifting between 3.3 V controllers and 5 V peripherals without additional translators - a capability validated in TI's Application Information (Section 8.1) and Typical Application schematic (Figure 8-1).
What is the thermal resistance (RθJA) of SN74AC245NSR in its NS package?
The SN74AC245NSR in the SOP (NS) package has a junction-to-ambient thermal resistance (RθJA) of 60 °C/W, as documented in Table 5-4 (Thermal Information) of the SCAS461I datasheet. This value assumes standard JEDEC 2-layer board conditions and confirms suitability for industrial ambient temperatures up to +85 °C.
Is SN74AC245NSR pin-compatible with other packages in the SN74AC245 family?
Yes, all SN74AC245 variants-including DB, DGS, DW, NS, PW, and RKS-share identical 20-pin functional pinouts and logic behavior. The SN74AC245NSR uses the same pin configuration shown in Figure 4-1 (DB/DGS/DW/N/NS/PW package top view), ensuring mechanical and electrical compatibility across package options.
SN74AC245NSR Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 74AC
- Package/Case:
- 20-SOIC (0.209", 5.30mm Width)
- Packaging:
- Tape & Reel (TR)
- 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:
- 24mA, 24mA
- Voltage - Supply:
- 2V ~ 6V
- Operating Temperature:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 20-SO
SN74AC245NSR FAQ
1.How can I place an order for SN74AC245NSR through Aetrix?
Please submit a Request for Quotation (RFQ) for SN74AC245NSR 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 SN74AC245NSR reliable?
The price and inventory of SN74AC245NSR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74AC245NSR is usually 5 days.
3.What payment methods are accepted for SN74AC245NSR?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SN74AC245NSR transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SN74AC245NSR?
SN74AC245NSR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SN74AC245NSR 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 SN74AC245NSR?
For technical support, including SN74AC245NSR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74AC245NSR requirements.
6.How does Aetrix verify that SN74AC245NSR is sourced from the original manufacturer or authorized distributors?
All SN74AC245NSR 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 SN74AC245NSR meets industry standards.
7.What is the process for return or replacement of SN74AC245NSR?
All SN74AC245NSR units undergo pre-shipment inspection (PSI). If there is an issue with SN74AC245NSR, 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 SN74AC245NSR part is unused and in its original packaging.
Return procedure for SN74AC245NSR:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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