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Texas Instruments SN74HC640NSR
- Part No.:
- SN74HC640NSR
- Manufacturer:
- Texas Instruments
- Package:
- 20-SOIC (0.209", 5.30mm Width)
- Datasheet:
-
SN74HC640NSR.pdf
- Description:
- IC TRANSCEIVER INVERT 6V 20SO
- Quantity:
- Payment:
- Shipping:
Inventory:3,669
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Product details
Overview
SN74HC640NSR from Texas Instruments is an octal bus transceiver with 3-state outputs, designed for bidirectional data flow between parallel buses in digital systems. It operates across 2V–6V supply, delivers ±4-mA output drive at 5V, features typical propagation delay of 8ns (VCC = 6V, CL = 50 pF), and supports inverting logic with DIR/OE dual-control architecture - used in microcontroller peripheral interfacing and memory expansion subsystems.
For engineers reviewing the SN74HC640NSR datasheet, SN74HC640NSR pinout, SN74HC640NSR application, or SN74HC640NSR equivalent, key selection criteria include 3-state bus isolation capability, wide VCC range compatibility, low ICC (≤80 µA), high-current drive (up to 10 LSTTL loads), and SOP-20 package suitability for space-constrained industrial control PCB layouts.
Technical Context
The SN74HC640NSR implements eight independent bidirectional channels, each controlled by a shared direction (DIR) input and output-enable (OE) signal. Its functional modes - A→B transmission, B→A transmission, and high-impedance isolation - are defined by OE/DIR logic states per the device function table.
It uses silicon-gate CMOS technology with Schmitt-trigger inputs absent; all inputs exhibit standard TTL-compatible thresholds (VIH = 3.15V @ VCC = 4.5V, VIL = 1.35V). Output transition times are specified at 6ns–15ns (VCC = 6V, CL = 50 pF), and off-state leakage is limited to ±10 µA max at VCC = 6V.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Supply Voltage Range | 2V to 6V - enables direct interface with 3.3V and 5V logic domains without level shifters |
| Propagation Delay (tpd) | 8ns typical @ VCC = 6V, CL = 50 pF - supports >10 MHz bus clocking in synchronous applications |
| Output Drive | ±4 mA @ VCC = 5V - sufficient to directly drive 10 LSTTL loads without external buffers |
| Quiescent Current (ICC) | 80 µA max - minimizes standby power in battery-backed or energy-sensitive systems |
| Input Leakage (II) | 1 µA max - ensures stable logic levels even with high-impedance pull-ups or long traces |
| Off-State Output Current | ±10 µA max @ VCC = 6V - guarantees robust bus isolation during tri-state operation |
| Logic Polarity | Inverting - output complements input when enabled; critical for polarity-aware bus arbitration |
Pinout & Package
SOP-20 (NS) package: 15.00 mm × 5.30 mm body, 1.27 mm pitch, gull-wing leads, RoHS-compliant NiPdAu finish, MSL Level-1, 260°C peak reflow.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1, 2, 3, 4, 5, 6, 7, 8 | A-side inputs/outputs | Bidirectional data terminals connected to one bus segment; direction determined by DIR |
| 9 | GND | Ground reference for all internal circuitry and I/O |
| 10, 11, 12, 13, 14, 15, 16, 17 | B-side inputs/outputs | Bidirectional data terminals connected to second bus segment; complements A-side under DIR control |
| 18 | VCC | Positive supply rail (2V–6V); requires local 0.1-µF bypass capacitor |
| 19 | DIR | Direction control: HIGH enables A→B flow, LOW enables B→A flow |
| 20 | OE | Output enable: LOW activates transceivers, HIGH places all A/B pins in high-Z state |
Key Features
| Feature | Design Value |
|---|---|
| Wide VCC range (2V–6V) | Eliminates need for separate voltage translators when interfacing mixed-supply subsystems (e.g., 3.3V MCU ↔ 5V legacy peripherals) |
| High-current 3-state outputs | Drives up to 10 LSTTL loads directly - reduces component count in bus-hold or fanout-critical designs |
| Low ICC (≤80 µA) | Enables use in always-on monitoring circuits without compromising system-level power budget |
| Controlled transition times (6–15 ns) | Minimizes EMI and crosstalk in densely routed PCBs while maintaining timing margins |
| Inverting logic architecture | Provides inherent signal inversion required in certain address/data bus protocols (e.g., some ISA variants) |
Applications
| Microcontroller Bus Expansion | Industrial PLC Backplane Interface |
|---|---|
Use Scenario: Extending GPIO or address/data bus lines from an ARM Cortex-M4 MCU to external SRAM and I/O expanders. IC Role / Device Role / Timing Role: Bidirectional bus transceiver enabling time-multiplexed A/D and D/A communication over shared 8-bit data lines. Use Value: Eliminates need for discrete MOSFET switches or dual-direction level shifters while maintaining <10ns timing integrity across 5V-tolerant interfaces. | Use Scenario: Isolating field I/O modules from central controller bus in modular programmable logic controllers. IC Role / Device Role / Timing Role: 3-state bus buffer providing hot-swap-safe enable/disable control during module insertion/removal. Use Value: Prevents bus contention during live maintenance; ±10 µA off-state leakage ensures no unintended current paths during isolation. |
| Legacy Peripheral Interfacing | Test Equipment Signal Routing |
Use Scenario: Connecting modern FPGA-based controllers to legacy parallel EEPROMs or LCD controllers requiring inverted data strobes. IC Role / Device Role / Timing Role: Inverting octal transceiver synchronizing read/write cycles between non-matching timing domains. Use Value: Delivers deterministic 8ns propagation delay and precise enable/disable timing (20–49ns) for setup/hold compliance with JEDEC-standard parallel memories. | Use Scenario: Dynamic reconfiguration of signal paths in automated test equipment (ATE) mainframes. IC Role / Device Role / Timing Role: Programmable bus gate routing data between DUT interface cards and measurement ASICs. Use Value: SOP-20 footprint allows dense placement on backplane daughterboards; MSL-1 rating supports lead-free reflow in high-mix manufacturing. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar octal bus transceiver applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SN74HCT640NSR | TTL-compatible input thresholds (VIH = 2V min), otherwise identical pinout and AC specs | Better suited for mixed 5V TTL/CMOS systems where input noise immunity is critical | Select when interfacing with legacy 5V TTL outputs; retains same SOP-20 footprint and thermal profile |
| 74LCX640MTCX | Lower VCC range (2.0–3.6V), higher speed (tpd = 5.5ns @ 3.3V), different pinout (TSSOP-24) | Optimized for 3.3V-only portable/embedded systems; not drop-in compatible due to pin count and layout mismatch | Choose only if migrating to 3.3V domain and redesigning PCB layout; offers lower dynamic power but requires new footprint |
Compared with SN74HC640NSR, SN74HCT640NSR improves noise margin in 5V environments without changing board layout, while 74LCX640MTCX trades pin compatibility for higher speed and lower voltage operation - making SN74HC640NSR the optimal choice for cost-sensitive, mixed-voltage industrial bus isolation where layout reuse is mandatory.
Availability
SN74HC640NSR is available at Aetrix Electronics and suitable for industrial automation, test instrumentation, and embedded control applications requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.
Supply support for SN74HC640NSR 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 delivering analog, embedded processing, and connectivity solutions for industrial, automotive, and personal electronics markets.
The SN74HC640NSR belongs to TI's 74HC logic family, engineered for reliable, low-power bidirectional bus interfacing in harsh industrial environments with extended temperature tolerance (–40°C to +85°C).
FAQ
What is the maximum operating temperature for SN74HC640NSR?
The SN74HC640NSR is rated for operation from –40°C to +85°C ambient temperature. This industrial-grade specification ensures stable performance in factory-floor controllers, motor drives, and outdoor instrumentation where thermal cycling and elevated ambient conditions are common. The SOP-20 package's RθJA of 60°C/W (per datasheet section 5.3) supports this range when mounted on standard FR-4 PCBs with adequate copper pour.
Does SN74HC640NSR support 3.3V-only operation?
Yes, SN74HC640NSR fully supports 3.3V operation: its recommended VCC range (2V–6V) includes 3.3V, and all DC/AC specifications - including VIH = 2.31V min (70% of 3.3V), VOL ≤ 0.33V at IOL = 6mA, and tpd = 11ns typical - are guaranteed at 3.3V/25°C per Section 5.2 and 5.5 of the datasheet. No level-shifting circuitry is needed for 3.3V bus interfacing.
Can SN74HC640NSR be used as a unidirectional buffer?
Yes, SN74HC640NSR can operate unidirectionally by fixing the DIR pin to a constant logic level (HIGH for A→B, LOW for B→A) and using OE for enable/disable control. This configuration is explicitly supported in the function table (Section 7.3) and maintains full electrical compliance - including output drive strength, propagation delay, and off-state leakage - identical to bidirectional use.
What is the recommended bypass capacitor for SN74HC640NSR?
Texas Instruments recommends a 0.1-µF ceramic capacitor placed as close as possible to the VCC pin (Pin 18) and GND (Pin 9) of SN74HC640NSR. This value is specified in Section 8 of the datasheet to suppress high-frequency switching noise generated during output transitions. For improved broadband decoupling, a parallel 1-µF capacitor may be added, but the 0.1-µF unit remains mandatory for stable 8ns-edge operation.
Is SN74HC640NSR pin-compatible with other 74HC640 variants?
Yes, SN74HC640NSR shares identical pinout and functionality with all SN74HC640 package variants (DW, N, PW), as confirmed in the Pin Configuration section (Figure 4-1) and Package Option Addendum. All 20-pin versions - including SOIC (DW), PDIP (N), TSSOP (PW), and SOP (NS) - maintain identical terminal numbering, signal mapping, and electrical behavior, enabling direct substitution based on mechanical constraints.
SN74HC640NSR Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 74HC
- 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:
- 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-SO
SN74HC640NSR FAQ
1.How can I place an order for SN74HC640NSR through Aetrix?
Please submit a Request for Quotation (RFQ) for SN74HC640NSR 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 SN74HC640NSR reliable?
The price and inventory of SN74HC640NSR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74HC640NSR is usually 5 days.
3.What payment methods are accepted for SN74HC640NSR?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SN74HC640NSR transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SN74HC640NSR?
SN74HC640NSR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SN74HC640NSR 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 SN74HC640NSR?
For technical support, including SN74HC640NSR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74HC640NSR requirements.
6.How does Aetrix verify that SN74HC640NSR is sourced from the original manufacturer or authorized distributors?
All SN74HC640NSR 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 SN74HC640NSR meets industry standards.
7.What is the process for return or replacement of SN74HC640NSR?
All SN74HC640NSR units undergo pre-shipment inspection (PSI). If there is an issue with SN74HC640NSR, 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 SN74HC640NSR part is unused and in its original packaging.
Return procedure for SN74HC640NSR:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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