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onsemi 74FST3244DT
- Part No.:
- 74FST3244DT
- Manufacturer:
- onsemi
- Package:
- -
- Datasheet:
-
74FST3244DT.pdf
- Description:
- BUS DRIVER
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Product details
Overview
74FST3244DT from ON Semiconductor is an 8-bit CMOS bus switch with two independent 4-bit sections, TTL/CMOS-compatible control inputs, typical on-resistance of 4 Ω at 4.5 V, sub-0.25 ns max propagation delay, and high-Z output disable. It enables bidirectional signal routing in high-speed digital backplanes and memory address/data buses.
For engineers reviewing the 74FST3244DT datasheet, pinout, applications, or equivalent options, this page delivers verified electrical specs, TSSOP-20 package details, truth table behavior, real-world timing performance, and validated alternative options for bus switching design.
Technical Context
The 74FST3244DT implements dual 4-bit analog-style transmission gates controlled by separate OE1 and OE2 pins - each enabling its respective A↔B path when low. Its CMOS structure ensures rail-to-rail signal pass-through with no level shifting or logic inversion.
It operates within 4.0–5.5 V supply range, supports 0–5.5 V input voltage, exhibits <1 µA standby current, and maintains <5 pF I/O capacitance - critical for minimizing signal integrity degradation in high-frequency data paths up to 200 MHz.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Supply Voltage | 4.0–5.5 V - compatible with standard 5 V TTL/CMOS systems without level translation |
| On-Resistance (RON) | 4 Ω typical at 4.5 V - ensures minimal voltage drop and power loss across switched signals |
| Propagation Delay | <0.25 ns max - adds negligible timing skew in synchronous bus architectures |
| I/O Capacitance | 5 pF max - preserves signal edge rate and reduces crosstalk in dense PCB layouts |
| Standby Current | <1 µA - enables ultra-low-power state retention in battery-backed or sleep-mode systems |
| ESD Rating | 2000 V HBM - meets industrial handling requirements without external protection |
| Operating Temp | −40°C to +85°C - qualified for commercial and extended industrial ambient environments |
Pinout & Package
TSSOP-20 package (Case 948E), Pb-free, 0.65 mm pitch, 6.4 mm × 4.4 mm footprint, 1.2 mm max height - optimized for high-density surface-mount assembly and thermal dissipation in compact systems.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| OE1, OE2 | Output Enable (active-low) | Independent control of two 4-bit switch sections; high = high-Z isolation |
| 1A0–1A3, 2A0–2A3 | Bus A inputs/outputs | First and second 4-bit source/sink ports; bidirectional signal path |
| 1B0–1B3, 2B0–2B3 | Bus B inputs/outputs | Corresponding destination/sink ports; electrically identical to A-side |
| VCC, GND | Power supply pins | Dual supply and ground connections - required for stable switching operation |
Key Features
| Feature | Design Value |
|---|---|
| No ground bounce or noise injection | Eliminates system-level signal integrity issues during high-speed switching transitions |
| Pin-for-pin compatibility | Direct replacement for QS3244, FST3244, and CBT3244 in existing TSSOP-20 layouts |
| Nearly zero propagation delay | Maintains precise timing alignment between parallel data lines in synchronous interfaces |
| TTL/CMOS-compatible inputs | Accepts standard 5 V logic thresholds without external biasing or level shifters |
| Inherently Pb-free construction | Meets RoHS compliance without post-process rework or material substitution |
Applications
| Memory Address Bus Switching | PCI/ISA Local Bus Isolation |
|---|---|
Use Scenario: Selectively route CPU address lines to multiple memory banks while preventing contention. IC Role / Device Role / Timing Role: Bidirectional analog switch enabling dynamic bus partitioning with sub-0.25 ns delay. Use Value: Eliminates need for discrete logic gating or multiplexers, reducing component count and board area. | Use Scenario: Isolate legacy ISA peripherals from PCI bus during hot-swap or configuration changes. IC Role / Device Role / Timing Role: High-Z bus barrier controlled by system management logic. Use Value: Prevents signal reflection and timing violations during bus arbitration transitions. |
| High-Speed Data Path Multiplexing | Test Access Port (TAP) Signal Routing |
Use Scenario: Route JTAG or boundary-scan test signals between multiple ASICs on a shared debug bus. IC Role / Device Role / Timing Role: Low-capacitance, low-RON switch preserving signal rise/fall times above 200 MHz. Use Value: Enables deterministic test coverage without degrading TCK timing margins. | Use Scenario: Dynamically reconfigure debug interface connections in FPGA-based prototyping platforms. IC Role / Device Role / Timing Role: Dual-section enable-controlled path selector for TMS/TDI/TDO/TCK lines. Use Value: Supports multi-device JTAG daisy chains without manual jumpering or solder bridges. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar bus switching applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| 74CBT3244DT | Higher RON (7 Ω typ), same pinout and voltage range | Slightly reduced drive capability for marginal load conditions | Prefer when cost sensitivity outweighs minimal RON increase |
| SN74FST3244DT | Identical electrical specs and pinout; Texas Instruments rebrand | No functional or layout impact; different manufacturer traceability | Select based on supply chain availability and qualification requirements |
Compared with 74FST3244DT, 74CBT3244DT trades 3 Ω higher on-resistance for broader process tolerance, while SN74FST3244DT offers identical performance with alternate sourcing - both require no PCB changes but differ in lifecycle support and qualification documentation.
Availability
74FST3244DT is available at Aetrix Electronics and suitable for memory subsystems, industrial backplanes, test equipment interconnects, and embedded controller bus expansion requiring stable component supply and RoHS-compliant packaging.
Supply support for 74FST3244DT 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
ON Semiconductor is a global semiconductor supplier delivering energy-efficient, high-performance silicon solutions for automotive, industrial, cloud computing, medical, and consumer electronics.
The 74FST3244DT belongs to the FST (Fast Switching Transistor) family - designed specifically for low-noise, high-speed digital bus switching in mission-critical data-path applications.
FAQ
What is the maximum operating voltage for the 74FST3244DT?
The 74FST3244DT supports a DC supply voltage range of 4.0 V to 5.5 V per the Recommended Operating Conditions table. Its Absolute Maximum Rating extends to 7.0 V, but sustained operation above 5.5 V may compromise reliability or violate specification limits. Always operate the 74FST3244DT within 4.0–5.5 V for guaranteed performance and lifetime compliance.
Does the 74FST3244DT support bidirectional signal flow?
Yes, the 74FST3244DT supports fully bidirectional signal flow on all A/B port pairs. Each switch section behaves as a passive analog gate - signals pass identically in either direction when enabled, with no internal logic directionality. This makes the 74FST3244DT ideal for data/address bus sharing where direction changes dynamically.
What is the thermal resistance (θJA) of the 74FST3244DT in TSSOP-20 package?
The 74FST3244DT in TSSOP-20 package has a junction-to-ambient thermal resistance (θJA) of 128 °C/W under standard FR4 board conditions (10 mm × 1 inch, 2-ounce copper trace, no airflow). This value is specified in the Maximum Ratings table and applies directly to the 74FST3244DT DT suffix device.
Can unused OE pins on the 74FST3244DT be left floating?
No, unused OE pins on the 74FST3244DT must not be left floating. The datasheet explicitly states that "unused control inputs may not be left open" and requires all control inputs to be tied to a defined logic level - either VCC or GND - to prevent undefined switching states, increased current draw, or potential latch-up. This rule applies to both OE1 and OE2 on the 74FST3244DT.
Is the 74FST3244DT pin-compatible with SOIC-20 and QSOP-20 variants?
No, the 74FST3244DT is not physically pin-compatible with SOIC-20 or QSOP-20 variants due to differing package footprints and lead pitches. While all three packages share identical pin functions and numbering (per Figure 1), the 74FST3244DT uses TSSOP-20 (0.65 mm pitch), whereas SOIC-20 is 1.27 mm pitch and QSOP-20 is 0.635 mm pitch - requiring separate PCB layouts. The 74FST3244DT remains functionally and logically identical.
74FST3244DT Specifications
- Product attributes
- Attribute value
- Manufacturer:
- onsemi
- 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:
- -
74FST3244DT FAQ
1.How can I place an order for 74FST3244DT through Aetrix?
Please submit a Request for Quotation (RFQ) for 74FST3244DT 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 74FST3244DT reliable?
The price and inventory of 74FST3244DT are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for 74FST3244DT is usually 5 days.
3.What payment methods are accepted for 74FST3244DT?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for 74FST3244DT transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for 74FST3244DT?
74FST3244DT orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your 74FST3244DT 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 74FST3244DT?
For technical support, including 74FST3244DT datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your 74FST3244DT requirements.
6.How does Aetrix verify that 74FST3244DT is sourced from the original manufacturer or authorized distributors?
All 74FST3244DT 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 74FST3244DT meets industry standards.
7.What is the process for return or replacement of 74FST3244DT?
All 74FST3244DT units undergo pre-shipment inspection (PSI). If there is an issue with 74FST3244DT, 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 74FST3244DT part is unused and in its original packaging.
Return procedure for 74FST3244DT:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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