SN74LS640NS Texas Instruments In Stock
SN74LS640NS is an octal bus transceiver with inverting outputs by Texas Instruments in a 20-pin SOIC package. Key specs: 4.75V-5.25V supply, TTL-compatible LS series, bidirectional data flow with output enable control. From $1.10, in stock with worldwide shipping.
- Manufacturer
- Texas Instruments
- Package
- —
- Lifecycle
- ACTIVE
- Datasheet
- N/A
- Price
- From $0.9780(MOQ 1)
- RoHS
- Compliant
- Lead Time
- 3–7 business days
- Shipping
- DHL Express · Worldwide
Key Features
- Octal bidirectional bus transceiver enables high-drive bus interfacing between two 8-bit data buses in both directions
- Inverting output configuration supports active-low bus architectures common in legacy TTL microprocessor systems
- Three-state outputs with output-enable control allow safe bus sharing and eliminates contention in multi-master designs
- TTL-compatible LS-series technology provides reliable 5V operation with established low-power Schottky performance
Applications
The SN74LS640NS is used as a bidirectional data bus interface in microprocessor and microcontroller systems, enabling data transfer between a CPU bus and peripheral address/data buses with drive capability enhancement. Its inverting transceiver functionality is common in legacy TTL-based computing systems, industrial PLCs, and embedded controllers requiring active-low bus signal inversion. The device is frequently used in memory expansion boards, I/O port buffers, and bus isolation circuits in industrial and telecommunications equipment.
Compliance & Regulatory
| RoHS Status | Compliant |
| Lead-Free | Yes (Pb-Free) |
Alternate & Equivalent Parts
No known alternates. Submit an RFQ and our team can suggest alternatives.
Frequently Asked Questions
What is the function of the SN74LS640NS?
The SN74LS640NS is an octal bus transceiver that provides bidirectional signal transfer between two 8-bit buses with inverted outputs, allowing data to flow in either direction under the control of direction and output-enable pins at standard 5V TTL logic levels.
What makes the SN74LS640NS different from the SN74LS245?
The SN74LS640NS provides inverting outputs (logic inversion during transfer), while the SN74LS245 is a non-inverting bus transceiver. Both are 8-bit bidirectional transceivers with three-state outputs, but the SN74LS640NS is used in systems requiring active-low bus signal inversion for compatibility.
What package does the SN74LS640NS come in?
The SN74LS640NS is packaged in a 20-pin narrow SOIC (Small Outline Integrated Circuit) surface-mount package, which is suitable for automated PCB assembly and provides a smaller footprint than equivalent through-hole DIP packages for bus transceiver applications.
What are typical applications for the SN74LS640NS?
Typical applications include data bus buffering between CPUs and memory or I/O peripherals, bidirectional level driving in backplane systems, industrial PLC I/O expansion, microprocessor bus isolation, and legacy TTL system bus interfacing where inverting transceiver functionality is required.
Related Guides
1206 100 uF MLCC Design Guide for Compact Bulk Decoupling
Design guidance for applying CL31A107MQHNNNE and related 1206 MLCCs in compact bulk decoupling networks.
Jul 3, 2026
0402 10 nF MLCC Design Guide for High-Speed Decoupling
Practical design guidance for using CL05B103KB5NNNC and related 0402 MLCCs in high-speed decoupling networks.
Jul 3, 2026
CL31A107MQHNNNE 1206 100 uF MLCC Selection Guide
How to choose CL31A107MQHNNNE and related 1206 MLCCs for low-voltage bulk capacitance and regulator stability.
Jul 2, 2026
CL05B103KB5NNNC 0402 10 nF X7R MLCC Selection Guide
How to choose CL05B103KB5NNNC and related 0402 MLCCs for bypassing, filtering, voltage derating, and sourcing.
Jul 2, 2026
Why Buy from FindMyChip
About Texas Instruments
Texas Instruments (TI) is a global semiconductor company headquartered in Dallas, Texas. TI designs and manufactures analog and embedded processing chips used in industrial, automotive, consumer, communications, and enterprise systems.
| Qty. | Unit Price | Ext. Price |
|---|---|---|
| 1+ | $2.4450 | $2.44 |
| 42+ | $1.2225 | $51.34 |
| 165+ | $0.9780 | $161.37 |
In Stock · 24h Response · Worldwide Shipping
Response within 24 hours · Worldwide shipping
“Their engineering team helped us find a pin-compatible alternative when our original MCU went EOL.”