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Texas Instruments SN74BCT640NSR
- Part No.:
- SN74BCT640NSR
- Manufacturer:
- Texas Instruments
- Package:
- 20-SOIC (0.209", 5.30mm Width)
- Datasheet:
-
SN74BCT640NSR.pdf
- Description:
- IC TRANSCEIVER INVERT 5.5V 20SO
- Quantity:
- Payment:
- Shipping:
Inventory:1,428
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Product details
Overview
SN74BCT640NSR from Texas Instruments is an 8-bit non-inverting bus transceiver with direction control and 3-state outputs, designed for asynchronous bidirectional data transfer between A and B buses in TTL-level systems. It operates from 4.5 V to 5.5 V, supports 0°C to 70°C ambient temperature, delivers 64 mA low-level output current on B port, and features undershoot-protection circuitry and power-up high-impedance state.
For engineers reviewing the SN74BCT640NSR datasheet, SN74BCT640NSR pinout, SN74BCT640NSR application, or SN74BCT640NSR equivalent, key selection considerations include its BiCMOS architecture for reduced standby current, OE/DIR dual-control logic, 3.4 V minimum VOH at −3 mA (A port), and SOP-20 (NS) package compatibility with automated SMT assembly.
Technical Context
This device implements a dual-rail, non-inverting transceiver topology with separate direction (DIR) and output-enable (OE) inputs. Its BiCMOS design enables TTL-compatible input thresholds (VIH = 2 V min, VIL = 0.8 V max) while delivering CMOS-level drive strength and low ICCZ (4–11 mA) in 3-state mode.
The SN74BCT640NSR supports bidirectional flow: when OE = L and DIR = L, data passes from B to A; when OE = L and DIR = H, data passes from A to B. Propagation delays are asymmetric-tPHL ranges 0.5–3.7 ns, tPLH up to 6.5 ns-optimized for A→B and B→A paths under 50 pF load conditions.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Supply Voltage | 4.5 V to 5.5 V - Ensures stable operation across standard 5 V TTL rails with ±10% tolerance. |
| Operating Temperature | 0°C to 70°C - Qualified for commercial-grade industrial and computing applications. |
| Output Drive (B port) | 64 mA sink (IOL) - Supports driving multiple TTL loads or terminated transmission lines without external buffers. |
| Propagation Delay (A→B) | 0.5–6.5 ns - Enables high-speed bus handshaking in memory-mapped I/O and peripheral interfaces. |
| 3-State Leakage (ICCZ) | 4–11 mA - Low quiescent current during bus isolation minimizes system-level standby power. |
| Input Clamp Current | −18 mA - Protects control inputs against transient overvoltage events per MIL-STD-883C. |
| ESD Protection | >2000 V HBM - Meets military-grade ESD robustness for handling and board-level reliability. |
Pinout & Package
SOP-20 (NS) package: 12.8 mm × 7.5 mm body, 1.27 mm pitch, 2.65 mm max height, RoHS-compliant NiPdAu lead finish, MSL Level-1.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 | DIR | Direction control input: L enables B→A transfer; H enables A→B transfer. |
| 2–9 | A1–A8 | Input/output port A - Bidirectional TTL-compatible data lines tied to local bus segment. |
| 10 | GND | Ground reference - Shared return path for all internal logic and output drivers. |
| 11 | VCC | Power supply - Must be decoupled locally to suppress switching noise on 5 V rail. |
| 12–19 | B1–B8 | Input/output port B - Bidirectional TTL-compatible data lines tied to remote bus segment. |
| 20 | OE | Output-enable input - Active-low; drives all A/B pins to high-impedance when high. |
Key Features
| Feature | Design Value |
|---|---|
| BiCMOS process technology | Reduces ICCZ to 4–11 mA and cuts standby current vs. pure bipolar equivalents. |
| Undershoot-protection circuitry | Prevents negative voltage excursions below −0.5 V on I/O pins during fast edge transitions. |
| Power-up high-impedance state | Guarantees bus isolation at power-on reset without external pull-ups or sequencing. |
| Buffered control inputs | Minimizes DC loading on DIR/OE lines, enabling direct connection to FPGA or microcontroller GPIO. |
| TTL-compatible input thresholds | VIH ≥ 2 V and VIL ≤ 0.8 V ensure reliable interfacing with legacy 5 V logic families. |
Applications
| Industrial PLC Backplane Interface | Legacy ISA Bus Extension |
|---|---|
|
Use Scenario: Isolating CPU address/data bus from modular I/O expansion slots in programmable logic controllers. IC Role / Device Role / Timing Role: Bidirectional bus transceiver managing synchronous read/write cycles between host and field modules. Use Value: 64 mA B-port drive supports stub-loaded backplane traces; 3.7 ns max tPHL ensures timing compliance with 10 MHz ISA timing budgets. |
Use Scenario: Extending original IBM PC/AT ISA bus to accommodate additional peripheral cards in retro-computing or test equipment. IC Role / Device Role / Timing Role: Level-shifting and direction-controlled data bridge between motherboard and add-in card. Use Value: Undershoot protection prevents signal integrity degradation on long ISA ribbon cables; SOP-20 footprint fits dense legacy PCB layouts. |
| Automated Test Equipment (ATE) Signal Routing | Embedded Controller Local Bus Arbitration |
|
Use Scenario: Dynamically reconfiguring signal paths between DUT interface boards and pattern generators in semiconductor ATE platforms. IC Role / Device Role / Timing Role: Controlled bus isolator enabling on-the-fly channel mapping via DIR/OE signals from FPGA sequencer. Use Value: Power-up high-Z state prevents bus contention during power sequencing; 2000 V HBM ESD rating withstands repeated probe contact. |
Use Scenario: Arbitrating shared memory access between dual-core microcontrollers or DMA engines in real-time embedded systems. IC Role / Device Role / Timing Role: Directional data coupler synchronizing burst transfers across isolated subsystem domains. Use Value: Asymmetric propagation delay (tPHL < tPLH) optimizes write-to-read turnaround; BiCMOS leakage reduction extends battery-backed operation. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar bus transceiver applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SN74ABT640NSR | Higher drive (100 mA IOL), lower tPLH (3.5 ns), ABT family with improved AC specs and same SOP-20 pinout. | Preferred for new designs requiring faster timing margins or higher fanout; not drop-in due to different VIH/VIL thresholds. | Select SN74ABT640NSR when upgrading performance-critical bus segments where layout changes are acceptable. |
| 74ACT640SC | CMOS-based, 5 V only, 24 mA IOL, no undershoot protection, SOIC-20 package but different pin mapping (DIR/OE swapped). | Limited to low-noise, low-power environments; unsuitable for noisy industrial backplanes due to missing undershoot clamps. | Choose 74ACT640SC only for cost-sensitive, low-current applications where BiCMOS robustness is unnecessary. |
Compared with SN74BCT640NSR, SN74ABT640NSR offers superior speed and drive but requires validation of input threshold compatibility, while 74ACT640SC sacrifices ruggedness and pin alignment for lower static power-neither is pin-compatible nor functionally identical without schematic revision.
Availability
SN74BCT640NSR is available at Aetrix Electronics and suitable for industrial PLC backplane interfaces, legacy ISA bus extensions, and automated test equipment signal routing requiring stable component supply across extended production lifecycles.
Supply support for SN74BCT640NSR 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 industrial and automotive-grade components.
The SN74BCT640NSR belongs to TI's BCT logic family, engineered for high-drive, noise-tolerant bidirectional bus interfacing in legacy and mixed-signal systems operating at 5 V.
FAQ
What is the maximum output current capability of the SN74BCT640NSR on the B port?
The SN74BCT640NSR supports up to 64 mA low-level output current (IOL) on the B port under recommended operating conditions (VCC = 4.5 V, TA = 0°C to 70°C). This rating allows direct driving of multiple TTL inputs or moderate-impedance transmission lines without external buffering. The A port supports 24 mA IOL. Exceeding these values risks parametric shift or thermal stress.
Does the SN74BCT640NSR support hot insertion or live bus swapping?
The SN74BCT640NSR incorporates undershoot-protection circuitry and a power-up high-impedance state, which mitigate bus contention during power sequencing-but it is not explicitly qualified for hot-swap operation. Its absolute maximum rating for I/O port voltage is −0.5 V to 5.5 V, and ESD protection exceeds 2000 V HBM, supporting robust handling. For true hot-swap compliance, external current-limiting and sequencing circuitry is required.
Can the SN74BCT640NSR operate reliably at 4.5 V supply voltage?
Yes, the SN74BCT640NSR is fully characterized from 4.5 V to 5.5 V. At VCC = 4.5 V, it guarantees VOH ≥ 2.4 V (A port, IOH = −3 mA) and VOL ≤ 0.55 V (B port, IOL = 64 mA), meeting TTL output standards. Propagation delays remain within spec (tPHL ≤ 3.7 ns, tPLH ≤ 6.5 ns), confirming stable operation across the full recommended range.
What is the pin configuration difference between SN74BCT640NSR and SN74BCT640N?
Both SN74BCT640NSR (SOP-20, NS package) and SN74BCT640N (PDIP-20, N package) share identical pin functions and ordering: DIR (pin 1), A1–A8 (pins 2–9), GND (10), VCC (11), B1–B8 (12–19), OE (20). Mechanical dimensions, thermal characteristics, and moisture sensitivity differ, but electrical behavior and pinout are functionally equivalent across packages.
Is the SN74BCT640NSR compatible with 3.3 V logic systems?
No, the SN74BCT640NSR is a 5 V-only device. Its input thresholds (VIH = 2 V min, VIL = 0.8 V max) and output levels (VOH ≥ 2.4 V at 4.5 V) are specified for TTL/5 V CMOS interfaces. Driving it from 3.3 V sources may result in marginal VIH margin, and connecting its 5 V outputs to 3.3 V inputs risks overvoltage damage unless level-shifting or clamping is implemented externally.
SN74BCT640NSR Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 74BCT
- Package/Case:
- 20-SOIC (0.209", 5.30mm Width)
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Logic Type:
- Transceiver, Inverting
- Number of Elements:
- 1
- Number of Bits per Element:
- 8
- Input Type:
- -
- Output Type:
- 3-State
- Current - Output High, Low:
- 3mA, 24mA; 15mA, 64mA
- Voltage - Supply:
- 4.5V ~ 5.5V
- Operating Temperature:
- 0°C ~ 70°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 20-SO
SN74BCT640NSR FAQ
1.How can I place an order for SN74BCT640NSR through Aetrix?
Please submit a Request for Quotation (RFQ) for SN74BCT640NSR 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 SN74BCT640NSR reliable?
The price and inventory of SN74BCT640NSR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74BCT640NSR is usually 5 days.
3.What payment methods are accepted for SN74BCT640NSR?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SN74BCT640NSR transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SN74BCT640NSR?
SN74BCT640NSR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SN74BCT640NSR 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 SN74BCT640NSR?
For technical support, including SN74BCT640NSR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74BCT640NSR requirements.
6.How does Aetrix verify that SN74BCT640NSR is sourced from the original manufacturer or authorized distributors?
All SN74BCT640NSR 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 SN74BCT640NSR meets industry standards.
7.What is the process for return or replacement of SN74BCT640NSR?
All SN74BCT640NSR units undergo pre-shipment inspection (PSI). If there is an issue with SN74BCT640NSR, 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 SN74BCT640NSR part is unused and in its original packaging.
Return procedure for SN74BCT640NSR:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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