My Inquiry
My Account
Texas Instruments SN74LS640-1NS
- Part No.:
- SN74LS640-1NS
- Manufacturer:
- Texas Instruments
- Package:
- 20-SOIC (0.209", 5.30mm Width)
- Datasheet:
-
SN74LS640-1NS.pdf
- Description:
- IC TXRX INVERT 5.25V 20SO
- Quantity:
- Payment:
- Shipping:
Inventory:3,240
Please send an inquiry. Send us your inquiry, and we will respond immediately.
Product details
Overview
SN74LS640-1NS from Renesas Electronics is an octal bus transceiver with inverted 3-state outputs, designed for asynchronous bidirectional data transfer between two 8-bit buses. It features direction control (DIR) and output enable (G), operates at 5 V ±5%, supports –20°C to +75°C industrial temperature range, and delivers tPLH/tPHL ≤15 ns propagation delay with 24 mA sink capability on B-side outputs.
For engineers reviewing the SN74LS640-1NS datasheet, SN74LS640-1NS pinout, SN74LS640-1NS application, or SN74LS640-1NS equivalent, this device is selected for legacy TTL-compatible bus isolation, microprocessor address/data bus expansion, and industrial control backplane interfacing where level-shifted bidirectional flow and bus contention prevention are required.
Technical Context
The SN74LS640-1NS implements eight independent inverting transceiver channels, each with complementary A/B port logic and shared DIR/G control. Its internal architecture uses standard LS-TTL circuitry with Schmitt-trigger input hysteresis (VT ≥0.2 V) and active-low 3-state output drivers enabling high-impedance isolation when G = H.
Directional data flow is strictly controlled by DIR: low enables B→A transmission, high enables A→B transmission. Output enable G overrides DIR - when G = H, all outputs enter high-impedance state regardless of DIR level, ensuring complete bus decoupling during system reset or arbitration.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Supply Voltage | 4.75 V to 5.25 V - ensures compatibility with standard 5 V TTL logic rails and stable operation under ±5% regulation tolerance. |
| Propagation Delay | tPLH/tPHL ≤15 ns - guarantees sub-16 ns timing margin for 50 MHz synchronous bus handshaking in legacy systems. |
| Output Drive | IOL = 24 mA (B-side), IOH = –15 mA - supports direct connection to multiple LS-TTL inputs without external buffering. |
| Input Thresholds | VIH ≥2.0 V, VIL ≤0.8 V - provides robust noise immunity against 0.4 V TTL-level noise margins. |
| Operating Temperature | –20°C to +75°C - validated for use in industrial control cabinets and non-automotive embedded equipment. |
| 3-State Enable Time | tZH/tZL ≤40 ns - ensures fast bus release during mode switching to prevent data collision in multiplexed architectures. |
Pinout & Package
SN74LS640-1NS is supplied in a 20-pin plastic DIP package (PRDP0020AC-B / DP-20NEV), 6.3 mm × 24.5 mm body with 2.54 mm pitch, RoHS-compliant Ni/Pd/Au plating.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 | GND | Ground reference for all internal logic and output drivers; must be connected to system common ground plane. |
| 2–9 | 1A–8A | Input/output terminals for A-side bus (inverted); drive B-side when DIR = H and G = L. |
| 10 | G | Active-low output enable; forces all A/B outputs into high-impedance state when logic high. |
| 11–18 | 1B–8B | Input/output terminals for B-side bus (inverted); drive A-side when DIR = L and G = L. |
| 19 | DIR | Direction control input; low enables B→A data flow, high enables A→B data flow. |
| 20 | VCC | +5 V power supply; requires local 0.1 µF ceramic decoupling capacitor placed within 10 mm of pin. |
Key Features
| Feature | Design Value |
|---|---|
| Inverted 3-state outputs | Ensures signal polarity consistency across bidirectional paths while allowing seamless integration into existing inverted-bus architectures (e.g., address latches). |
| Independent DIR and G controls | Enables hierarchical bus management: DIR selects data path direction, G globally disables outputs without affecting DIR state-critical for hot-swap or fault-isolation scenarios. |
| 24 mA B-side sink capability | Drives up to 10 standard LS-TTL loads directly, eliminating need for external bus buffers in mid-density backplane designs. |
| Input hysteresis ≥0.2 V | Rejects noise spikes up to 200 mV on DIR and G control lines, preventing spurious direction changes or unintended output enable. |
Applications
| Microprocessor Bus Expansion | Industrial PLC Backplane Interface |
|---|---|
|
Use Scenario: Expanding Z80 or 8085 CPU address/data bus to interface with additional memory or I/O peripherals. IC Role / Device Role / Timing Role: Bidirectional transceiver isolating main CPU bus from extended peripheral bus, with DIR synchronized to MREQ/IOREQ signals and G tied to bus grant. Use Value: Enables clean separation of timing domains while maintaining full LS-TTL voltage and drive compatibility-no level translation or timing recalibration needed. |
Use Scenario: Interfacing modular I/O cards to central controller in DIN-rail mounted programmable logic controllers. IC Role / Device Role / Timing Role: Isolating field-side digital input/output modules from controller-side logic using DIR to separate read/write cycles and G for module hot-swap disable. Use Value: Prevents bus contention during card insertion/removal and supports deterministic scan-cycle timing via guaranteed ≤40 ns output disable/enable. |
| Legacy Test Equipment Data Path | Avionics Ground Support Interface |
|
Use Scenario: Routing stimulus/response data between pattern generator and UUT in automated test systems based on TTL-era architecture. IC Role / Device Role / Timing Role: Direction-controlled data conduit between ATE controller and device-under-test, with G used for test sequence synchronization. Use Value: Provides precise 15 ns max propagation delay matching legacy instrument timing budgets and eliminates need for custom gate arrays. |
Use Scenario: Adapting MIL-STD-1553B subsystem diagnostics to ground maintenance benches using TTL-level monitoring interfaces. IC Role / Device Role / Timing Role: Level-shifting and bus isolation layer between avionics LRUs and ground support equipment, operating under controlled environmental conditions. Use Value: Meets Renesas "Standard" quality grade requirements for non-life-critical ground support tools, with verified –20°C to +75°C performance and RoHS compliance. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar octal bus transceiver applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SN74LS245N | Non-inverting outputs; identical pinout except DIR function mapped to OE and DIR pins swapped. | Requires logic inversion in external circuitry if replacing SN74LS640-1NS in inverted-bus systems. | Select when system design uses non-inverted bus signaling and board layout allows minor trace rework. |
| HD74LS640P | Same electrical specs and pinout; differs only in Renesas part numbering convention and packaging code (P vs -1NS). | No functional or application difference; both meet identical JEDEC MS-001 standards and Renesas Standard quality grade. | Preferred for new designs requiring direct Renesas-sourced HD74LS640 family continuity with identical form-fit-function. |
Compared with SN74LS245N and HD74LS640P, the SN74LS640-1NS offers native inverted-output behavior critical for legacy bus architectures without added inverters, while HD74LS640P provides identical functionality under Renesas' current naming scheme-making it the most seamless drop-in alternative.
Availability
SN74LS640-1NS is available at Aetrix Electronics and suitable for microprocessor bus expansion, industrial PLC backplane interface, and legacy test equipment data path applications requiring stable component supply and long-term obsolescence mitigation.
Supply support for SN74LS640-1NS 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
Renesas Electronics Corporation is a global semiconductor leader formed in 2010 through the merger of NEC Electronics and Renesas Technology, specializing in microcontrollers, analog, and legacy logic solutions.
The SN74LS640-1NS belongs to Renesas' HD74LS logic family, engineered for backward compatibility with industry-standard 74LS TTL devices in industrial control, instrumentation, and maintenance infrastructure systems.
FAQ
What is the function of the DIR pin on the SN74LS640-1NS?
The DIR (Direction Control) pin on the SN74LS640-1NS determines data flow direction: when DIR = L, data transfers from B bus to A bus; when DIR = H, data flows from A bus to B bus. This pin operates independently of the G (Enable) pin, allowing directional control even when outputs are enabled. The SN74LS640-1NS relies on DIR to maintain strict unidirectional signal integrity within each active cycle.
Does the SN74LS640-1NS support 3.3 V operation?
No, the SN74LS640-1NS is specified only for 4.75 V to 5.25 V supply operation and is not rated for 3.3 V logic levels. Its input thresholds (VIH ≥2.0 V, VIL ≤0.8 V) and output drive characteristics are optimized for 5 V TTL compatibility. Using the SN74LS640-1NS with 3.3 V systems risks undervoltage lockout, marginal noise margins, and potential damage due to VIH/VIL mismatch.
Is the SN74LS640-1NS pin-compatible with the SN74LS245?
No, the SN74LS640-1NS is not pin-compatible with the SN74LS245. Although both are 20-pin octal transceivers, their pin assignments differ: SN74LS640-1NS places DIR on pin 19 and G on pin 10, whereas SN74LS245 uses pin 1 for OE and pin 19 for DIR. Direct substitution would require PCB redesign. The SN74LS640-1NS requires its specific pin mapping for correct DIR/G interaction.
What is the maximum capacitive load the SN74LS640-1NS can drive?
The SN74LS640-1NS is characterized for CL = 45 pF in switching tests (tPLH/tPHL), and its output drivers are rated for 24 mA sink current. Driving loads beyond 45 pF may increase propagation delay and cause signal integrity issues such as ringing or undershoot. For reliable operation, keep total trace + load capacitance ≤45 pF per output, as validated in the SN74LS640-1NS datasheet test conditions.
Can the SN74LS640-1NS be used in automotive applications?
No, the SN74LS640-1NS is classified under Renesas' "Standard" quality grade and is not qualified for automotive use. Its recommended operating temperature range (–20°C to +75°C) and qualification scope exclude automotive environments, which require "High Quality" grade parts with extended temperature ranges (–40°C to +125°C), AEC-Q100 stress testing, and enhanced reliability validation. Use of SN74LS640-1NS in automotive systems is outside its intended application scope.
SN74LS640-1NS Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 74LS
- Package/Case:
- 20-SOIC (0.209", 5.30mm Width)
- Packaging:
- Bulk
- 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:
- 15mA, 48mA
- Voltage - Supply:
- 4.75V ~ 5.25V
- Operating Temperature:
- 0°C ~ 70°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 20-SO
SN74LS640-1NS FAQ
1.How can I place an order for SN74LS640-1NS through Aetrix?
Please submit a Request for Quotation (RFQ) for SN74LS640-1NS 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 SN74LS640-1NS reliable?
The price and inventory of SN74LS640-1NS are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74LS640-1NS is usually 5 days.
3.What payment methods are accepted for SN74LS640-1NS?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SN74LS640-1NS transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SN74LS640-1NS?
SN74LS640-1NS orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SN74LS640-1NS 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 SN74LS640-1NS?
For technical support, including SN74LS640-1NS datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74LS640-1NS requirements.
6.How does Aetrix verify that SN74LS640-1NS is sourced from the original manufacturer or authorized distributors?
All SN74LS640-1NS 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 SN74LS640-1NS meets industry standards.
7.What is the process for return or replacement of SN74LS640-1NS?
All SN74LS640-1NS units undergo pre-shipment inspection (PSI). If there is an issue with SN74LS640-1NS, 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 SN74LS640-1NS part is unused and in its original packaging.
Return procedure for SN74LS640-1NS:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
SN74LS640-1NS Tags
-
SN74LVC1G17DBVR
Texas Instruments
-
SN74LVC1G07DCKR
Texas Instruments
-
SN74LVC1G17DCKR
Texas Instruments
-
SN74LVC1G07DBVR
Texas Instruments
-
SN74LVC1G125DCKR
Texas Instruments
-
SN74AHCT1G126DBVR
Texas Instruments
-
SN74LVC1G125DBVR
Texas Instruments
-
SN74AHCT1G125DBVR
Texas Instruments
-
SN74LVC2G17DBVR
Texas Instruments
-
SN74LVC2G07DCKR
Texas Instruments
-
SN74LVC1G34DCKR
Texas Instruments
-
SN74LVC2G17DCKR
Texas Instruments
Tech Hub
A practical engineering guide to 3.3V and 5V logic compatibility, input thresholds, resistor dividers, translator ICs, MOSFET level shifting, I2C pull-ups, timing limits and power-sequencing risks.
The 74HC595 uses push-pull logic outputs, while the TPIC6B595 uses 50 V open-drain DMOS sinks for higher-power loads. This guide compares timing, current limits, 3.3 V interfacing, load wiring, thermal…
The 74HC595 converts serial data into eight stable parallel outputs. This guide covers pin functions, shift and storage timing, OE and MR behavior, drive-current limits, cascading, voltage compatibilit…
A technical comparison of level-sensitive latches and edge-triggered flip-flops, covering timing windows, setup and hold limits, master–slave operation, time borrowing, race-through, HDL inference and…
A D latch stores one bit while Enable controls when data can pass. This reference covers gate-level operation, truth tables, transparency, setup and hold timing, LE versus OE, common ICs and practical …
An SR latch stores one bit through cross-coupled feedback. This engineering reference covers NOR and NAND implementations, truth tables, forbidden-state recovery, gated operation, switch debouncing, fa…
Latch circuits retain one bit through feedback. This technical reference covers SR and D latches, truth tables, transparency, timing limits, latch-versus-flip-flop behavior, applications and common log…
An engineering guide to LED driver operation, constant-current and constant-voltage outputs, linear and switching topologies, dimming, IC selection, calculations, replacement compatibility, and fault c…
Operational amplifier guide covering op amp basics, feedback, ideal vs real op amps, common configurations, buffer circuits, offset, bias current, gain-bandwidth, slew rate, rail-to-rail limits and sel…
Jumper cables guide covering safe connection order, red and black clamp placement, final ground connection, cable gauge, length, clamp quality, copper vs CCA cables, jump starter comparison and battery…
