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Texas Instruments SN74ABT657ADW
- Part No.:
- SN74ABT657ADW
- Manufacturer:
- Texas Instruments
- Package:
- 24-SOIC (0.295", 7.50mm Width)
- Datasheet:
-
SN74ABT657ADW.pdf
- Description:
- IC TXRX NON-INVERT 5.5V 24SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:4,699
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Product details
Overview
SN74ABT657ADW from Texas Instruments is an octal transceiver with integrated parity generator/checker and 3-state outputs in a 24-pin SOIC (DW) package. It supports bidirectional data flow between A and B ports under T/R control, generates or verifies odd/even parity on the PARITY pin, and delivers high-drive outputs (–32 mA IOH, 64 mA IOL) for robust bus interfacing in industrial backplane and memory subsystem applications.
For engineers reviewing the SN74ABT657ADW datasheet, SN74ABT657ADW pinout, SN74ABT657ADW application, or SN74ABT657ADW equivalent, key selection considerations include its 5-V operation, ±100 µA input leakage at 25°C, 1.8 ns typical tPLH from A to PARITY, ERR output for real-time parity error detection, and guaranteed high-impedance state during power-up/down below 2.1 V.
Technical Context
This device implements a noninverting flow-through architecture with separate transmit/receive direction control (T/R) and output-enable (OE), enabling clean PCB layout and deterministic signal routing. Its parity logic operates synchronously with data transfer: in transmit mode, PARITY is driven to enforce user-selected odd/even parity across eight A-bus bits; in receive mode, ERR asserts low when B-bus + PARITY violates the selected parity sense.
The SN74ABT657ADW uses EPIC-IIB BiCMOS process technology to achieve low power dissipation while maintaining TTL-compatible voltage thresholds (VIH = 2 V min, VIL = 0.8 V max) and ESD robustness (>2000 V HBM). It features output ground bounce (VOLP) <1 V at VCC = 5 V and latch-up immunity exceeding 500 mA per JESD-17.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VCC Range | 4.5 V to 5.5 V - Ensures stable operation across standard 5-V supply tolerances. |
| IOH / IOL | –32 mA / 64 mA - Drives heavy capacitive loads and multiple TTL inputs without external buffers. |
| tPLH / tPHL (A→B) | 1 ns / 1 ns min, 4.6 ns / 4.3 ns max - Supports high-speed bus cycles up to ~200 MHz in short-trace configurations. |
| VIK (Input Clamp) | –1.2 V - Protects inputs against negative transients without external diodes. |
| IOZPU / IOZPD | ±50 µA - Maintains high-impedance state during power ramping (0–2.1 V), preventing bus contention. |
| θJA (DW Package) | 81°C/W - Enables thermal design margin of ~40°C rise at 100 mW dissipation in still air. |
| Operating Temperature | –40°C to +85°C - Qualified for industrial-grade embedded systems and communications equipment. |
Pinout & Package
SN74ABT657ADW is housed in a 24-pin plastic small-outline integrated circuit (SOIC) package (DW), 7.5 mm wide, with 0.65 mm lead pitch and RoHS-compliant NiPdAu finish. The package meets JEDEC MS-013AC and is rated MSL Level-1 (260°C peak reflow).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 | T/R | Transmit/Receive direction control: high = A→B, low = B→A. |
| 2–9 | A1–A8 | Noninverting data inputs/outputs for A-side bus interface. |
| 10 | ODD/EVEN | Selects parity mode: high = odd, low = even. |
| 11 | ERR | Parity error indicator: low = error detected in receive mode. |
| 12 | OE | Output enable: high = all ports in high-Z; low = active drive. |
| 13–20 | B1–B8 | Noninverting data inputs/outputs for B-side bus interface. |
| 21 | PARITY | Parity bit: output in transmit mode, input in receive mode. |
| 22, 23 | GND | Dual ground pins reduce ground bounce and improve noise immunity. |
| 24 | VCC | Positive supply pin - decoupling capacitor required within 1 cm. |
Key Features
| Feature | Design Value |
|---|---|
| Flow-through pinout | Minimizes trace crossing and stub length on dense PCBs, reducing signal integrity degradation. |
| High-impedance during power sequencing | Guaranteed Hi-Z state when VCC is between 0 and 2.1 V, eliminating bus conflicts at power-up/down. |
| EPIC-IIB BiCMOS process | Reduces dynamic power vs. bipolar-only equivalents while retaining TTL drive strength and speed. |
| Output ground bounce (VOLP) | <1 V at VCC = 5 V - Limits simultaneous switching noise in multi-bit bus environments. |
| Latch-up immunity | >500 mA per JESD-17 - Ensures robustness against transient overcurrent events. |
Applications
| Industrial Backplane Interface | Memory Subsystem Data Path |
|---|---|
|
Use Scenario: Bidirectional data transfer between CPU and peripheral modules across a 24-bit parallel backplane with parity protection. IC Role / Device Role / Timing Role: Octal transceiver managing A↔B port directionality and generating/checking parity in real time during each bus cycle. Use Value: Eliminates need for discrete parity logic and separate bus drivers, reducing component count and board area by >30%. |
Use Scenario: Interfacing a microcontroller's address/data bus to SRAM or ROM with hardware parity validation. IC Role / Device Role / Timing Role: Parity generator/checker synchronized to memory read/write strobes, asserting ERR on mismatch before data latching. Use Value: Enables single-cycle parity verification without CPU intervention, improving system reliability in safety-critical firmware storage. |
| Legacy Bus Protocol Translation | Test Equipment Signal Conditioning |
|
Use Scenario: Adapting TTL-level parallel I/O between legacy instrumentation controllers and modern FPGA-based test sequencers. IC Role / Device Role / Timing Role: Level-shifting and direction-controlled buffer with parity support for protocol-compliant data exchange. Use Value: Maintains backward compatibility with IEEE-488-style handshaking while adding error detection not present in original designs. |
Use Scenario: Driving high-capacitance probe cables and fixture wiring in automated test equipment (ATE) digital pattern generators. IC Role / Device Role / Timing Role: High-drive 3-state buffer isolating DUT signals during test vector loading and enabling precise timing alignment. Use Value: Delivers 64-mA sink current to overcome cable capacitance-induced rise/fall time degradation, preserving signal fidelity at 50-MHz toggle rates. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar octal transceiver with parity applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SN74ABT657ADBR | SSOP-24 (DB) package, same electrical specs, 2000-piece tape-and-reel only. | Preferred for automated SMT assembly; requires different footprint and stencil design. | Select when volume production and pick-and-place compatibility outweigh manual prototyping convenience. |
| SN74F657N | Bipolar TTL process, higher ICC (40 mA typ), slower propagation (7 ns max), no guaranteed Hi-Z below 2.1 V. | Suitable only for legacy designs where speed and power are secondary to pinout compatibility. | Choose only if replacing existing F-series parts in fielded equipment with no redesign allowance. |
Compared with SN74ABT657ADW, SN74ABT657ADBR offers identical functionality in a surface-mount-optimized package but requires PCB layout revision, while SN74F657N provides pin-compatible legacy support at the cost of speed, power efficiency, and power-sequence robustness.
Availability
SN74ABT657ADW is available at Aetrix Electronics and suitable for industrial backplane interfaces, memory subsystem data paths, legacy bus protocol translation, and test equipment signal conditioning requiring stable component supply and long-term lifecycle support.
Supply support for SN74ABT657ADW 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 founded in 1930, delivering analog, embedded processing, and logic solutions for industrial, automotive, and communications markets.
The ABT logic family-including SN74ABT657ADW-was engineered for high-speed, low-power 5-V TTL-compatible bus interfacing with enhanced noise immunity and power sequencing safety.
FAQ
What is the function of the ODD/EVEN pin on the SN74ABT657ADW?
The ODD/EVEN pin selects the parity mode for the SN74ABT657ADW: a logic high configures odd parity generation/checking, while a logic low configures even parity. During transmit mode, this setting determines whether the PARITY output is driven high or low to ensure the total number of high bits across A1–A8 plus PARITY matches the selected parity sense. In receive mode, it defines the expected relationship between B1–B8 and PARITY for ERR assertion.
Does the SN74ABT657ADW support hot insertion or live bus swapping?
Yes, the SN74ABT657ADW supports controlled hot insertion due to its guaranteed high-impedance state when VCC is between 0 and 2.1 V, and its input clamp current rating of –18 mA. However, OE must be held high (via pullup) during insertion to prevent partial enablement; TI recommends tying OE to VCC through a ≤10-kΩ resistor to ensure robust Hi-Z entry before full power stabilization.
Can the ERR output of the SN74ABT657ADW drive a standard TTL input directly?
Yes, the ERR output of the SN74ABT657ADW can directly drive a standard TTL input: it sources ≥2 mA at VOH = 2.5 V (VCC = 4.5 V, IOH = –3 mA) and sinks ≥48 mA at VOL = 0.55 V (VCC = 4.5 V, IOL = 48 mA), meeting TTL VIH/VIL thresholds and fanout requirements. No external pullup is needed for TTL load interfacing.
What is the maximum recommended capacitive load for SN74ABT657ADW outputs?
The SN74ABT657ADW is characterized with CL = 50 pF for timing specifications, and its high-drive capability (64 mA IOL) supports heavier loads. For reliable operation within datasheet timing margins, TI recommends limiting total output capacitance-including trace, via, and receiver input-to ≤75 pF. Beyond that, propagation delays increase nonlinearly, and ground bounce may exceed 1 V.
How does the SN74ABT657ADW handle power-down sequencing relative to system buses?
The SN74ABT657ADW enters a high-impedance state automatically when VCC drops below 2.1 V, preventing bus contention during uncontrolled power-down. To ensure full Hi-Z above 2.1 V, OE must be actively held high-TI specifies using a pullup resistor to VCC (minimum value determined by driver sink strength). This behavior makes SN74ABT657ADW suitable for systems with asynchronous rail shutdown sequences.
SN74ABT657ADW Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- 74ABT
- Package/Case:
- 24-SOIC (0.295", 7.50mm Width)
- Packaging:
- Bulk
- Product Status:
- Active
- Logic Type:
- Transceiver, Non-Inverting
- Number of Elements:
- 1
- Number of Bits per Element:
- 8
- Input Type:
- -
- Output Type:
- 3-State
- Current - Output High, Low:
- 32mA, 64mA
- Voltage - Supply:
- 4.5V ~ 5.5V
- Operating Temperature:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 24-SOIC
SN74ABT657ADW FAQ
1.How can I place an order for SN74ABT657ADW through Aetrix?
Please submit a Request for Quotation (RFQ) for SN74ABT657ADW 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 SN74ABT657ADW reliable?
The price and inventory of SN74ABT657ADW are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SN74ABT657ADW is usually 5 days.
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SN74ABT657ADW orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SN74ABT657ADW 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 SN74ABT657ADW?
For technical support, including SN74ABT657ADW datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SN74ABT657ADW requirements.
6.How does Aetrix verify that SN74ABT657ADW is sourced from the original manufacturer or authorized distributors?
All SN74ABT657ADW 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 SN74ABT657ADW meets industry standards.
7.What is the process for return or replacement of SN74ABT657ADW?
All SN74ABT657ADW units undergo pre-shipment inspection (PSI). If there is an issue with SN74ABT657ADW, 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 SN74ABT657ADW part is unused and in its original packaging.
Return procedure for SN74ABT657ADW:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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