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onsemi 74ABT646CSCX
- Part No.:
- 74ABT646CSCX
- Manufacturer:
- onsemi
- Package:
- 24-SOIC (0.295", 7.50mm Width)
- Datasheet:
-
74ABT646CSCX.pdf
- Description:
- IC TXRX NON-INVERT 5.5V 24SOP
- Quantity:
- Payment:
- Shipping:
Inventory:1,069
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Product details
Overview
74ABT646CSCX from Fairchild Semiconductor is an octal transceiver and register IC with 3-STATE outputs, dual independent A/B data buses, clocked D-type flip-flops, and multiplexed real-time/stored data routing. It operates at 4.5–5.5 V, supports up to 200 MHz clock frequency, delivers ±64 mA sink/source drive, and is used in high-speed bus interface applications such as backplane data transfer and memory-mapped I/O expansion.
For engineers reviewing the 74ABT646CSCX datasheet, pinout, applications, or equivalent options, key selection criteria include guaranteed output skew (≤2.5 ns), simultaneous switching noise control, nondestructive hot insertion capability, and support for both 50 pF and 250 pF load conditions in industrial temperature range (−40°C to +85°C).
Technical Context
The 74ABT646CSCX implements a dual-bus architecture with independent CPAB/CPBA clocks and SAB/SBA select controls, enabling flexible data flow between A and B ports in transparent (real-time) or stored (register) modes. Direction (DIR) and output enable (OE) pins jointly determine active bus direction and 3-STATE state.
Its logic combines bus transceivers, edge-triggered D registers, and multiplexing circuitry - allowing concurrent storage of A→B or B→A data during isolation (OE HIGH), while supporting glitch-free bus loading across power-up/down cycles per guaranteed latchup protection and dynamic threshold specs.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Supply Voltage | +4.5 V to +5.5 V - ensures compatibility with standard 5 V TTL/CMOS systems and robust noise margin |
| Max Clock Frequency | 200 MHz - enables high-throughput data transfer in fast synchronous bus interfaces |
| Output Drive | 64 mA sink / 32 mA source - supports heavy capacitive loads and fanout to multiple inputs without external buffers |
| Propagation Delay | 1.5–5.6 ns (CL = 50 pF) - guarantees tight timing control in high-speed digital systems |
| Pin-to-Pin Skew | ≤2.5 ns (HL transitions) - critical for maintaining signal integrity across all 8-bit lanes |
| Operating Temperature | −40°C to +85°C - qualified for industrial-grade embedded and communications equipment |
| Input Voltage Thresholds | VIH = 2.0 V, VIL = 0.8 V - compatible with TTL and CMOS logic families |
Pinout & Package
74ABT646CSCX is housed in a 24-lead Small Outline Integrated Circuit (SOIC) package, JEDEC MS-153 compliant, 4.4 mm wide, with gull-wing leads and standard 1.27 mm pitch.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| A0–A7 | Data Register A Inputs / 3-STATE Outputs | Bidirectional A-bus interface with register storage and high-impedance control via OE/DIR |
| B0–B7 | Data Register B Inputs / 3-STATE Outputs | Bidirectional B-bus interface with independent register storage and multiplexed output routing |
| CPAB | Clock Pulse A→B | Edge-triggered clock that latches A-bus data into B-register on rising edge |
| CPBA | Clock Pulse B→A | Edge-triggered clock that latches B-bus data into A-register on rising edge |
| SAB | Select A→B | Controls multiplexing of A-register or real-time A-bus data onto B outputs |
| SBA | Select B→A | Controls multiplexing of B-register or real-time B-bus data onto A outputs |
| OE | Output Enable (Active LOW) | Global 3-STATE control: HIGH disables all outputs; LOW enables transceiver/register output paths |
| DIR | Direction Control | Determines primary data flow direction when OE is LOW: HIGH = A→B, LOW = B→A |
Key Features
| Feature | Design Value |
|---|---|
| Independent A/B Registers | Enables concurrent capture and retention of data from both buses without interference or arbitration delay |
| Multiplexed Real-Time & Stored Data | Allows seamless switching between live bus signals and registered values using SAB/SBA controls - essential for protocol bridging |
| Guaranteed Output Skew ≤2.5 ns | Ensures deterministic timing alignment across all 8-bit outputs, eliminating setup/hold violations in parallel interfaces |
| Nondestructive Hot Insertion | Permits safe board replacement in powered-backplane systems without damaging the device or adjacent circuitry |
| High-Impedance Glitch-Free Power Sequencing | Prevents bus contention during power-up/down by holding outputs in high-Z until VCC stabilizes |
Applications
| Backplane Data Routing | Memory-Mapped I/O Expansion |
|---|---|
Use Scenario: High-speed bidirectional communication between CPU and peripheral modules across a shared PCB backplane. IC Role / Device Role / Timing Role: Bus transceiver and register acting as a programmable data path controller with clocked storage and direction-selectable real-time forwarding. Use Value: Enables deterministic latency (≤5.6 ns propagation) and eliminates bus contention via synchronized 3-STATE control and DIR/OE coordination. | Use Scenario: Extending microcontroller address/data bus to external peripherals like ADCs, DACs, or FPGA configuration interfaces. IC Role / Device Role / Timing Role: Octal register-transceiver providing buffered, direction-controlled, and clock-synchronized interface between MCU and slow peripherals. Use Value: Supports mixed-speed system design by decoupling MCU timing from peripheral access windows using A/B register staging. |
| Industrial Protocol Bridge | Hot-Swappable Module Interface |
Use Scenario: Interfacing legacy parallel control buses (e.g., GPIB, IEEE-488 derivatives) with modern serial or packet-based controllers. IC Role / Device Role / Timing Role: Dual-bus register facilitating protocol translation through selective storage and multiplexed output re-timing. Use Value: Allows asynchronous handshake conversion using CPAB/CPBA clocks and SAB/SBA-driven data staging without external FIFOs. | Use Scenario: Modular rack systems where line cards are inserted/removed while main chassis remains powered. IC Role / Device Role / Timing Role: Isolation and buffering element ensuring safe bus disconnection/reconnection via nondestructive hot insertion and glitch-free power sequencing. Use Value: Prevents system reset or corruption during module swaps by maintaining high-Z state during voltage ramp and suppressing ground bounce. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar octal transceiver/register applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SN74ABT646N | Same logic function and AC/DC specs; packaged in PDIP (dual in-line) instead of SOIC | Preferred for prototyping or through-hole assembly; lacks SOIC thermal/mechanical advantages | Choose SN74ABT646N only if manual soldering or breadboard evaluation is required |
| 74LVTH16646MTD | 16-bit, 3.3 V operation, different pinout and register control scheme (no separate CPAB/CPBA) | Designed for low-voltage, high-density bus interfaces; not pin-compatible or functionally drop-in | Select 74LVTH16646MTD only when migrating to 3.3 V systems and redesigning layout/control logic |
Compared with SN74ABT646N and 74LVTH16646MTD, the 74ABT646CSCX uniquely provides SOIC packaging with guaranteed 200 MHz operation, independent A/B clocking, and nondestructive hot insertion - making it optimal for industrial 5 V backplane designs requiring field-replaceable modules.
Availability
74ABT646CSCX is available at Aetrix Electronics and suitable for industrial backplane routing, memory-mapped I/O expansion, protocol bridging, and hot-swappable module interfaces requiring stable component supply and long-term lifecycle support.
Supply support for 74ABT646CSCX 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
Fairchild Semiconductor was a leading analog and discrete semiconductor manufacturer, acquired by ON Semiconductor in 2016; its ABT logic family remains widely deployed in industrial and communications infrastructure.
The 74ABT646CSCX belongs to Fairchild's Advanced BiCMOS Transceiver (ABT) logic series, engineered for high-speed, low-noise 5 V bus interfacing with robust ESD and latchup immunity in harsh environments.
FAQ
What is the maximum clock frequency supported by the 74ABT646CSCX?
The 74ABT646CSCX supports a maximum clock frequency of 200 MHz under standard operating conditions (VCC = 5.0 V, TA = +25°C, CL = 50 pF). This specification is guaranteed across the full industrial temperature range (−40°C to +85°C) and applies to both CPAB and CPBA clock inputs. The 74ABT646CSCX achieves this performance using advanced BiCMOS process technology optimized for speed and noise immunity.
Does the 74ABT646CSCX support hot insertion in live backplane systems?
Yes, the 74ABT646CSCX features nondestructive hot insertion capability, verified per Fairchild's characterization. Its input clamping diodes, controlled power-up sequencing, and high-impedance glitch-free behavior during voltage ramp ensure safe insertion into powered systems without damaging the device or causing bus contention. This makes the 74ABT646CSCX suitable for modular industrial chassis where field-replaceable units operate under live power.
What are the key differences between the 74ABT646CSCX and the 74LVTH16646MTD?
The 74ABT646CSCX is an 8-bit, 5 V device with independent CPAB/CPBA clocks and SAB/SBA select controls, while the 74LVTH16646MTD is a 16-bit, 3.3 V device lacking separate clock inputs and using different register control logic. They differ in voltage rating, bit width, pinout, and functional architecture - the 74LVTH16646MTD is not a drop-in replacement for the 74ABT646CSCX and requires PCB and firmware redesign.
How does the 74ABT646CSCX handle simultaneous switching noise (SSN)?
The 74ABT646CSCX guarantees simultaneous switching noise level and dynamic threshold performance per its datasheet specifications. It incorporates internal design techniques including staggered output drivers and optimized power distribution to limit ground bounce and supply droop during multi-bit transitions. These features are validated for both 50 pF and 250 pF load conditions, ensuring reliable operation in dense PCB layouts with high fanout.
Can the 74ABT646CSCX operate with a 4.75 V supply voltage?
Yes, the 74ABT646CSCX is fully specified to operate across a supply voltage range of +4.5 V to +5.5 V, so 4.75 V falls well within its recommended operating conditions. All DC and AC electrical characteristics - including VIH/VIL thresholds, VOL/VOH levels, propagation delays, and output drive strength - are guaranteed at this voltage. The 74ABT646CSCX maintains full functionality and timing compliance at 4.75 V without derating.
74ABT646CSCX Specifications
- Product attributes
- Attribute value
- Manufacturer:
- onsemi
- Series:
- 74ABT
- Package/Case:
- 24-SOIC (0.295", 7.50mm Width)
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Obsolete
- 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-SOP
74ABT646CSCX FAQ
1.How can I place an order for 74ABT646CSCX through Aetrix?
Please submit a Request for Quotation (RFQ) for 74ABT646CSCX 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 74ABT646CSCX reliable?
The price and inventory of 74ABT646CSCX are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for 74ABT646CSCX is usually 5 days.
3.What payment methods are accepted for 74ABT646CSCX?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 74ABT646CSCX transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for 74ABT646CSCX?
74ABT646CSCX orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your 74ABT646CSCX 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 74ABT646CSCX?
For technical support, including 74ABT646CSCX datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 74ABT646CSCX requirements.
6.How does Aetrix verify that 74ABT646CSCX is sourced from the original manufacturer or authorized distributors?
All 74ABT646CSCX 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 74ABT646CSCX meets industry standards.
7.What is the process for return or replacement of 74ABT646CSCX?
All 74ABT646CSCX units undergo pre-shipment inspection (PSI). If there is an issue with 74ABT646CSCX, 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 74ABT646CSCX part is unused and in its original packaging.
Return procedure for 74ABT646CSCX:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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