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Texas Instruments SN74LS653NT
- Part No.:
- SN74LS653NT
- Manufacturer:
- Texas Instruments
- Package:
- -
- Datasheet:
-
SN74LS653NT.pdf
- Description:
- BUS TRANSCEIVER, LS SERIES TTL
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Inventory:2,377
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Product details
Overview
SN74LS653NT from Texas Instruments is an octal bus transceiver and register with 3-state outputs, designed for bidirectional data flow control in TTL-based systems. It features separate A- and B-bus ports, dual output-enable controls (OE1\, OE2\), and internal latching capability for data hold. Typical use includes address/data bus isolation in industrial control backplanes and legacy microprocessor system expansion.
For engineers reviewing the SN74LS653NT datasheet, SN74LS653NT pinout, SN74LS653NT application, or SN74LS653NT equivalent, key selection considerations include its 24-pin PDIP package, TTL-compatible input thresholds, 3-state output drive strength, and dual-latch functionality for synchronous bus arbitration.
Technical Context
The SN74LS653NT integrates two independent 8-bit bidirectional transceivers with transparent latch registers on each port. Each port supports asynchronous data transfer when enabled and holds registered data when clocked via G1 and G2 inputs.
It operates strictly within the standard TTL voltage range (VCC = 4.75 V to 5.25 V), exhibits typical propagation delay of 22 ns (A→B) and 24 ns (B→A), and drives ±24 mA at outputs - sufficient for direct interfacing with multiple LS-TTL loads without external buffers.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Logic Family | LS-TTL - ensures compatibility with legacy 74LS series logic and predictable noise margins. |
| Function | Octal bidirectional transceiver with dual 8-bit transparent latches - enables time-multiplexed bus sharing between two subsystems. |
| Supply Voltage | 4.75 V to 5.25 V - requires stable +5 V rail; not tolerant of undervoltage or overvoltage operation. |
| Propagation Delay | 22 ns (A→B), 24 ns (B→A) - defines maximum achievable bus cycle rate in synchronous systems. |
| Output Drive | ±24 mA (IOH/ IOL) - supports fan-out of up to 20 LS-TTL inputs per output. |
| Operating Temperature | 0 °C to +70 °C - rated for commercial-grade environments only; not suitable for extended industrial or automotive use. |
Pinout & Package
SN74LS653NT is supplied in a 24-pin plastic dual in-line package (PDIP-24) with 0.600-inch body width and through-hole mounting. Pin spacing conforms to JEDEC MS-001 standard.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1, 2, 3, 4, 5, 6, 7, 8 | A-bus data inputs/outputs | Bidirectional I/O port A; high-impedance when OE1\ and OE2\ are high. |
| 9, 10, 11, 13, 14, 15, 16, 17 | B-bus data inputs/outputs | Bidirectional I/O port B; direction controlled by relative enable states of OE1\ and OE2\. |
| 12 | GND | Signal reference ground connection. |
| 24 | VCC | +5 V power supply connection. |
| 18, 19 | OE1\, OE2\ | Active-low output enables; both must be low for bidirectional data flow between A and B ports. |
| 20, 21 | G1, G2 | Register clock inputs; latch data present on respective ports when pulsed low-to-high. |
| 22, 23 | DIR1, DIR2 | Direction control inputs; determine whether data flows A→B or B→A when OE1\ and OE2\ are active. |
Key Features
| Feature | Design Value |
|---|---|
| Dual 8-bit latched transceivers | Enables independent registration and transfer of two 8-bit data words - critical for handshake-based bus protocols. |
| Separate direction and enable controls | Allows fine-grained arbitration: one port can drive while the other is tri-stated, preventing bus contention. |
| TTL-compatible input thresholds | VIH = 2.0 V min, VIL = 0.8 V max - ensures reliable recognition of logic levels from standard 74LS/74S sources. |
| 3-state outputs with common enable | OE1\ and OE2\ jointly disable both A and B ports - simplifies system-level bus release sequencing. |
Applications
| Industrial Backplane Bus Isolation | Legacy Microprocessor System Expansion |
|---|---|
Use Scenario: Isolating CPU address/data buses from peripheral modules in programmable logic controllers (PLCs) with hot-swap capability. IC Role / Device Role / Timing Role: Bidirectional bus buffer with latching - holds address during peripheral access while allowing CPU to proceed. Use Value: Prevents signal contention during module insertion/removal and supports deterministic timing via registered outputs. | Use Scenario: Expanding Z80 or 8085-based single-board computers with additional memory or I/O cards. IC Role / Device Role / Timing Role: Octal transceiver with direction control - routes data between CPU and memory-mapped peripherals across shared bus segments. Use Value: Eliminates need for discrete bus switches and reduces PCB routing complexity with integrated 3-state control. |
| Test Equipment Data Path Switching | Automated Manufacturing Fixture Interface |
Use Scenario: Routing test vectors between pattern generator and device-under-test (DUT) in boundary-scan compatible ATE platforms. IC Role / Device Role / Timing Role: Registered bus interface - captures and forwards parallel stimulus data with precise edge-aligned timing. Use Value: Provides deterministic setup/hold timing margins for high-reliability test execution without external timing logic. | Use Scenario: Interfacing PLC I/O modules to custom sensor/actuator boards in factory automation jigs. IC Role / Device Role / Timing Role: Dual-port latch-transceiver - synchronizes control signals and status feedback between master controller and distributed nodes. Use Value: Enables robust handshaking and eliminates metastability risk in asynchronous inter-module communication. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar octal transceiver and register applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SN74LS652NT | Lacks internal latches; provides only transceiver function with direction control - no data hold capability. | Suitable where real-time bidirectional transfer is required but registration is handled externally. | Select SN74LS652NT when system design already includes external latching or when lower propagation delay (20 ns) is prioritized over register functionality. |
| SN74ALS653N | Advanced LS variant: higher speed (15 ns), lower power (19 mW), and improved noise immunity - but requires tighter VCC tolerance (4.5 V–5.5 V). | Preferred in new designs targeting improved timing margin or reduced power in commercial temperature range. | Choose SN74ALS653N if board layout allows updated decoupling and system timing budget permits faster edge rates. |
Compared with SN74LS652NT and SN74ALS653N, the SN74LS653NT uniquely combines latching and transceiving in one package at standard LS speed and power, making it optimal for maintaining compatibility in field-upgraded legacy systems where timing and pinout stability are mandatory.
Availability
SN74LS653NT is available at Aetrix Electronics and suitable for industrial backplane isolation, legacy microprocessor expansion, and automated test equipment requiring stable component supply and long-term obsolescence management.
Supply support for SN74LS653NT 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 U.S.-based semiconductor company founded in 1930, specializing in analog, embedded processing, and logic solutions for industrial, automotive, and communications markets.
The SN74LS653NT belongs to TI's legacy 74LS logic family, engineered specifically for robust, pin-compatible replacement in discontinued or aging TTL-based control systems requiring proven reliability and long-term documentation support.
FAQ
What is the primary function of the SN74LS653NT?
The SN74LS653NT is an octal bus transceiver with dual 8-bit transparent latches, enabling bidirectional data transfer and registered hold capability between two 8-bit buses. Its core function is to isolate, route, and temporally synchronize data in TTL-based systems - especially where bus contention avoidance and deterministic timing are required. The SN74LS653NT integrates direction control, output enable, and clocked latching into a single 24-pin PDIP package.
Does the SN74LS653NT support 3.3 V operation?
No, the SN74LS653NT is strictly a 5 V TTL device with a specified supply range of 4.75 V to 5.25 V. It does not support 3.3 V operation, and applying 3.3 V to VCC will result in undefined logic behavior and failure to meet AC/DC specifications. For mixed-voltage systems, level-shifting circuitry or a 3.3 V–compatible alternative such as the SN74LVC8T245 must be used instead of the SN74LS653NT.
How many enable inputs does the SN74LS653NT have, and what do they control?
The SN74LS653NT has two active-low output-enable inputs: OE1\ and OE2\. Both must be low to activate bidirectional data flow between the A and B ports. When either is high, the corresponding port enters high-impedance state. This dual-enable architecture allows selective tri-stating of each bus segment - a key feature for avoiding contention in multi-master configurations using the SN74LS653NT.
Can the SN74LS653NT replace the SN74LS651NT or SN74LS652NT in an existing design?
The SN74LS653NT is not a drop-in replacement for SN74LS651NT (octal transceiver only) or SN74LS652NT (octal transceiver with direction control only), due to differences in internal register structure and pin assignment. While all three share the same 24-pin PDIP package, the SN74LS653NT adds latch clocks (G1/G2) and direction controls (DIR1/DIR2) not present in the others. Direct substitution requires schematic and layout revision to accommodate these extra signals - the SN74LS653NT cannot be used without design validation.
What is the maximum operating temperature range for the SN74LS653NT?
The SN74LS653NT is rated for commercial temperature operation from 0 °C to +70 °C. It is not specified or tested for extended temperature ranges such as –40 °C to +85 °C (industrial) or –55 °C to +125 °C (military). Using the SN74LS653NT outside its 0 °C to +70 °C range may result in parametric failure, increased propagation delay, or loss of 3-state control integrity - especially under sustained thermal stress.
SN74LS653NT Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- *
- Package/Case:
- -
- Packaging:
- Bulk
- Product Status:
- Active
- Logic Type:
- -
- Number of Elements:
- -
- Number of Bits per Element:
- -
- Input Type:
- -
- Output Type:
- -
- Current - Output High, Low:
- -
- Voltage - Supply:
- -
- Operating Temperature:
- -
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- -
- Supplier Device Package:
- -
SN74LS653NT FAQ
1.How can I place an order for SN74LS653NT through Aetrix?
Please submit a Request for Quotation (RFQ) for SN74LS653NT 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 SN74LS653NT reliable?
The price and inventory of SN74LS653NT are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74LS653NT is usually 5 days.
3.What payment methods are accepted for SN74LS653NT?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SN74LS653NT transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SN74LS653NT?
SN74LS653NT orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SN74LS653NT 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 SN74LS653NT?
For technical support, including SN74LS653NT datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74LS653NT requirements.
6.How does Aetrix verify that SN74LS653NT is sourced from the original manufacturer or authorized distributors?
All SN74LS653NT 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 SN74LS653NT meets industry standards.
7.What is the process for return or replacement of SN74LS653NT?
All SN74LS653NT units undergo pre-shipment inspection (PSI). If there is an issue with SN74LS653NT, 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 SN74LS653NT part is unused and in its original packaging.
Return procedure for SN74LS653NT:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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