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NXP Semiconductors 74LVT646PW,118
- Part No.:
- 74LVT646PW,118
- Manufacturer:
- NXP Semiconductors
- Package:
- 24-TSSOP (0.173", 4.40mm Width)
- Datasheet:
-
74LVT646PW,118.pdf
- Description:
- IC TXRX NON-INVERT 3.6V 24TSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:4,245
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Product details
Overview
74LVT646PW,118 from Philips Semiconductors is a 3.3V octal bus transceiver/register with 3-State outputs, combining bidirectional data transfer and dual independent D-type register functionality in a single 24-pin TSSOP package. It supports real-time and stored-data multiplexing between A and B buses, delivers ±32mA/±64mA output drive (IOL/IOH), and interfaces directly with 5V TTL systems while operating at VCC = 2.7–3.6V. It is used in high-speed backplane and motherboard bus management where latch-controlled data staging and direction-controlled transceivers are required.
For engineers reviewing the 74LVT646PW,118 datasheet, 74LVT646PW,118 pinout, 74LVT646PW,118 application, or 74LVT646PW,118 equivalent, key selection criteria include its dual-register architecture, bus-hold inputs eliminating external pull-ups, power-up 3-State behavior, live insertion capability, and compatibility with mixed-voltage (3.3V core / 5V I/O) system designs.
Technical Context
The 74LVT646PW,118 implements a BiCMOS-based octal transceiver with integrated edge-triggered D-flip-flops on both A and B sides, enabling simultaneous storage and real-time transfer. Its control logic uses separate clock (CPAB/CPBA), select (SAB/SBA), direction (DIR), and output enable (OE) inputs to configure four distinct operational modes: real-time A↔B transfer, isolated register storage, and selective transfer of stored data.
It features TTL-compatible input thresholds (VIL = 0.8V, VVIH = 2.0V), 5V-tolerant I/Os, bus-hold circuitry on all data pins (±75µA hold current), and robust ESD protection (>2000V HBM). Propagation delays are tightly specified: tPLH/tPHL = 2.8/2.7ns (A↔B), 1.8/2.1ns (clock-to-output), with maximum clock frequency up to 180MHz at VCC = 2.7V.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VCC Supply Range | 2.7V to 3.6V - Enables stable operation across industrial-grade voltage tolerances and low-noise 3.3V rail designs. |
| Output Drive (IOL/IOH) | 64mA sink / –32mA source - Supports heavy capacitive loads and fan-out to multiple TTL inputs without external buffers. |
| Propagation Delay (A↔B) | 2.8ns (tPLH), 2.7ns (tPHL) at CL = 50pF - Ensures sub-3ns latency for time-critical bus arbitration and synchronous data routing. |
| Input Thresholds | VIL ≤ 0.8V, VVIH ≥ 2.0V - Guarantees reliable interfacing with legacy 5V TTL logic without level shifters. |
| Bus-Hold Current | ±75µA - Actively holds unused A-side inputs at valid logic levels, eliminating need for external pull-up/pull-down resistors. |
| Power-Up State | 3-State outputs - Prevents bus contention during power ramp-up, critical for hot-pluggable and modular backplane systems. |
| ESD Rating | >2000V HBM - Meets MIL-STD-883 Class 3A requirements for handling and board assembly robustness. |
Pinout & Package
74LVT646PW,118 is housed in a 24-pin plastic thin shrink small outline package (TSSOP), body width 4.4 mm, per SOT360-1 standard. Pin pitch is 0.65 mm; package is RoHS-compliant and lead-free compatible.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VCC (Pin 24) | Positive supply | 3.3V core power rail; decoupling capacitor must be placed within 5 mm for noise suppression. |
| GND (Pin 12) | Ground reference | Common return path for all internal logic and I/O drivers; requires low-inductance connection to PCB ground plane. |
| OE (Pin 21) | Active-low output enable | Controls 3-State output drivers on both A and B buses; high = high-impedance, low = enabled. |
| DIR (Pin 3) | Direction control | Determines data flow direction when OE is active: low = B→A, high = A→B. |
| CPAB (Pin 1), CPBA (Pin 23) | Edge-triggered clocks | CPAB clocks A-bus data into B-register; CPBA clocks B-bus data into A-register (↑ transition only). |
| SAB (Pin 2), SBA (Pin 22) | Select inputs | Enable real-time (SAB/SBA = L) or stored-data (SAB/SBA = H) transfer mode for respective bus paths. |
| A0–A7 (Pins 4–11) | Bidirectional A-side I/O | Octal data interface with bus-hold; functions as input (storage) or output (transmission) depending on DIR/OE state. |
| B0–B7 (Pins 13–20) | Bidirectional B-side I/O | Octal data interface with bus-hold; mirrors A-side behavior with independent register control. |
Key Features
| Feature | Design Value |
|---|---|
| Dual independent registers | Enables concurrent capture of A-bus and B-bus data without cross-talk, supporting asynchronous staging in multi-master bus architectures. |
| Multiplexed real-time + stored data paths | Allows dynamic switching between live bus traffic and pre-latched values using SAB/SBA, ideal for protocol bridging and glitch-free arbitration. |
| 5V-tolerant I/O with TTL thresholds | Permits direct connection to legacy 5V peripherals or controllers without external level translation, reducing BOM count and layout complexity. |
| Live insertion/extraction support | Guarantees safe hot-swap operation in modular systems by preventing bus contention and latch-up during plug/unplug events. |
| Power-up 3-State and reset | Ensures outputs remain high-impedance until VCC stabilizes, eliminating spurious signals during power sequencing in complex embedded systems. |
Applications
| Backplane Bus Arbitration | Modular I/O Expansion |
|---|---|
Use Scenario: Managing shared data paths between CPU module and interchangeable peripheral cards in a 19-inch rack-mounted system. IC Role / Device Role / Timing Role: Bidirectional bus transceiver with register staging enables deterministic handshaking and eliminates timing skew between card-insertion events and data readiness. Use Value: Eliminates need for discrete latches and direction-control logic, reducing interconnect latency by 3.5ns versus cascaded 74LVT245+74LVT574 solutions. |
Use Scenario: Adding isolated digital I/O banks to an industrial PLC base unit via hot-swappable daughterboards. IC Role / Device Role / Timing Role: Acts as voltage-translating, register-buffered interface between 3.3V controller and 5V field I/O modules, with bus-hold maintaining signal integrity during card removal. Use Value: Enables zero-downtime maintenance and field upgrades while preserving signal integrity on shared backplane lines during live extraction. |
| Memory-Mapped Peripheral Interface | Legacy System Upgrade Bridge |
Use Scenario: Connecting a modern 3.3V microcontroller to legacy 5V SRAM or EPROM devices on a shared address/data bus. IC Role / Device Role / Timing Role: Provides direction-controlled transceivers with latch capability to isolate memory access cycles from peripheral control logic, preventing bus collisions. Use Value: Delivers 2.7ns A↔B propagation delay-1.2ns faster than standard 74LVT245-enabling tighter memory timing margins at 100MHz bus speeds. |
Use Scenario: Retrofitting a 5V ISA bus system with a 3.3V FPGA co-processor while retaining full software compatibility. IC Role / Device Role / Timing Role: Functions as bi-directional voltage-aware bridge with register buffering to absorb timing mismatches between ISA clock domain and FPGA logic. Use Value: Removes requirement for external pull-ups and level shifters, cutting interface component count by 12 parts per channel and simplifying PCB routing. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar octal transceiver/register applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SN74LVC646APW | Lower drive (±24mA), 1.65–3.6V VCC, no bus-hold, no 5V-tolerant I/O | Requires external level shifters for 5V interfacing; unsuitable for live insertion due to missing power-up 3-State | Choose only for pure 3.3V-only systems with tight power budgets and no legacy I/O. |
| 74ALVC646PW | Same pinout, 1.65–3.6V VCC, ±24mA drive, no bus-hold, no 5V tolerance | Lacks 5V I/O compatibility and bus-hold; higher propagation delay (4.2ns A↔B) | Select only if replacing 74LVT646PW,118 in non-5V environments where cost reduction outweighs performance loss. |
Compared with SN74LVC646APW and 74ALVC646PW, the 74LVT646PW,118 uniquely delivers 5V-tolerant I/O, ±64mA sink capability, bus-hold inputs, and guaranteed power-up 3-State-all in the same TSSOP24 footprint-making it irreplaceable in mixed-voltage, high-reliability backplane and upgrade-bridge applications.
Availability
74LVT646PW,118 is available at Aetrix Electronics and suitable for backplane bus arbitration, modular I/O expansion, memory-mapped peripheral interfacing, and legacy system upgrade bridge applications requiring stable component supply, long-term lifecycle assurance, and traceable sourcing.
Supply support for 74LVT646PW,118 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
Philips Semiconductors (now NXP Semiconductors) is a global semiconductor innovator founded in the Netherlands, specializing in high-performance logic, analog, and interface ICs for industrial, automotive, and communications markets.
The 74LVT646PW,118 belongs to Philips' LVT (Low-Voltage TTL) family, designed specifically for 3.3V systems requiring seamless interoperability with 5V TTL infrastructure, high-speed bus control, and robust physical layer reliability in mission-critical embedded platforms.
FAQ
What is the maximum clock frequency supported by the 74LVT646PW,118?
The 74LVT646PW,118 supports a maximum clock frequency of 180MHz at VCC = 2.7V and 150MHz at VCC = 3.3V ± 0.3V, as verified in the AC Characteristics table under fMAX. This rating applies to CPAB and CPBA inputs driving register capture; real-time A↔B transfer operates independently of this clock and is limited only by propagation delay (2.8ns).
Does the 74LVT646PW,118 support live insertion and extraction?
Yes, the 74LVT646PW,118 explicitly supports live insertion/extraction, as confirmed in the FEATURES section and reinforced by its power-up 3-State behavior, latch-up protection (>500mA), and bus-hold inputs. These features prevent bus contention, ground bounce, and signal corruption during hot-swap events in modular backplane systems.
Can the 74LVT646PW,118 interface directly with 5V logic without level shifters?
Yes, the 74LVT646PW,118 has 5V-tolerant inputs and outputs, with VI and VOUT ratings up to +7.0V, and TTL-compatible input thresholds (VIL = 0.8V, VVIH = 2.0V). Its I/Os can safely connect to 5V systems while powered from a 3.3V supply, eliminating the need for external level-shifting components.
What is the function of the SAB and SBA pins on the 74LVT646PW,118?
The SAB (Pin 2) and SBA (Pin 22) pins control data path selection: when low, they enable real-time transceiver mode (A↔B); when high, they enable stored-data transfer mode (register-to-bus). This allows the 74LVT646PW,118 to operate either as a transparent bus switch or as a registered buffer, depending on system timing requirements.
Is bus-hold functionality available on both A and B ports of the 74LVT646PW,118?
Bus-hold is implemented only on the A-side inputs (A0–A7), as specified in the DC ELECTRICAL CHARACTERISTICS table under "IHOLD Bus Hold current A inputs". The B-side inputs (B0–B7) do not feature bus-hold and require external termination if left floating.
74LVT646PW,118 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- NXP Semiconductors
- Series:
- 74LVT
- Package/Case:
- 24-TSSOP (0.173", 4.40mm 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:
- 2.7V ~ 3.6V
- Operating Temperature:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 24-TSSOP
74LVT646PW,118 FAQ
1.How can I place an order for 74LVT646PW,118 through Aetrix?
Please submit a Request for Quotation (RFQ) for 74LVT646PW,118 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 74LVT646PW,118 reliable?
The price and inventory of 74LVT646PW,118 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for 74LVT646PW,118 is usually 5 days.
3.What payment methods are accepted for 74LVT646PW,118?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 74LVT646PW,118 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for 74LVT646PW,118?
74LVT646PW,118 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your 74LVT646PW,118 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 74LVT646PW,118?
For technical support, including 74LVT646PW,118 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 74LVT646PW,118 requirements.
6.How does Aetrix verify that 74LVT646PW,118 is sourced from the original manufacturer or authorized distributors?
All 74LVT646PW,118 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 74LVT646PW,118 meets industry standards.
7.What is the process for return or replacement of 74LVT646PW,118?
All 74LVT646PW,118 units undergo pre-shipment inspection (PSI). If there is an issue with 74LVT646PW,118, 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 74LVT646PW,118 part is unused and in its original packaging.
Return procedure for 74LVT646PW,118:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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