SN74LVC245DWR Tech Specifications
Texas Instruments - SN74LVC245DWR technical specifications, attributes, parameters and parts with similar specifications to Texas Instruments - SN74LVC245DWR

Product Attribute	Attribute Value
Part Number	SN74LVC245DWR
Package	DAC91001
Description	DAC91001
Stock Condition	Get 12720 pcs available quantity at Allelco
Payment	PayPal / TT / Credit Card / Western Union
Allelco Certifications	ESD / ISO 9001 / ISO 13485 / ISO 28000

Product Attribute	Attribute Value
Manufacturer	Texas Instruments
RoHs Status	-
Warranty	100% Perfect Functions
Transport port	Hong Kong
Shipping by	DHL / FedEx / UPS / TNT / SF Express
RFQ Email	info@allelco.com

Frequently Asked Questions(FAQ)

How does the SN74LVC245DWR handle bidirectional voltage translation when interfacing a 3.3V microcontroller with a 5V peripheral, and what are the critical design considerations for ensuring reliable signal integrity across this interface?: The SN74LVC245DWR supports bidirectional voltage level shifting without direction control signals, making it ideal for asymmetric voltage domains such as 3.3V to 5V systems. Its I/O ports are 5V-tolerant, allowing safe connection to higher-voltage lines even if the IC is powered at 3.3V. When translating from 3.3V to 5V, the output high voltage (VOH) remains above 3.0V under typical load conditions, ensuring recognition by the 5V receiver. However, designers must ensure that the 3.3V side does not exceed its maximum input voltage rating during power-up sequencing or brownout events. Additionally, propagation delay increases slightly at lower supply voltages, which may affect timing margins in high-speed designs—typically around 3–5 ns depending on load capacitance.

What is the maximum data transfer rate achievable using the SN74LVC245DWR in a point-to-point bus configuration, and how does package parasitics impact performance compared to surface-mount alternatives like QFN?: The SN74LVC245DWR operates up to 100 Mbps (10 ns propagation delay) under standard 5V operation, but this degrades significantly at 3.3V due to reduced drive strength and increased RC time constants. In practice, reliable operation beyond 50 Mbps requires careful PCB layout with short traces and controlled impedance. The SOP7.2 package introduces higher inductance and capacitance than QFN variants, limiting slew rates and increasing electromagnetic emissions. For applications exceeding 75 Mbps, alternative packages or buffer architectures should be considered, though the SN74LVC245DWR remains effective for most embedded system communication protocols like UART, SPI, or I²C.

Can the SN74LVC245DWR be used to drive multiple 5V logic inputs simultaneously from a single 3.3V output pin, and what limitations arise from output current sourcing capability?: Yes, the SN74LVC245DWR can source sufficient current to drive multiple 5V CMOS inputs, as each output has a typical IOL of 32 mA at VCC = 3.3V. Assuming a 5V CMOS input draws only ~1 µA during logic-high reception, dozens of inputs can be driven safely. However, simultaneous switching of multiple outputs increases dynamic power consumption and thermal stress. Designers should verify total package power dissipation against thermal resistance (θJA ≈ 120°C/W for SOP7.2) and avoid continuous full-swing transitions at high frequencies. Decoupling capacitors near VCC and GND are essential to maintain stable rail voltage under transient loads.

What precautions should be taken when using the SN74LVC245DWR in hot-swappable USB host applications where VBUS may rise before local VCC?: In hot-plug scenarios, VBUS (typically 5V) may appear at the A-port before the device’s VCCB (B-side supply) is stabilized. Since the SN74LVC245DWR allows 5V input tolerance on all pins regardless of VCC level, reverse current flow into the B-side supply is possible if VCCB < VBUS. To prevent latch-up or excessive leakage, ensure that either side is powered first or use external clamping diodes (e.g., Schottky) between VCC and the non-powered side’s I/Os. Alternatively, enable OE (output enable) only after both supplies stabilize to minimize contention currents.

How does the SN74LVC245DWR compare to the SN74LVTH245DGGR in terms of power consumption and noise immunity when operating at 3.3V with mixed-voltage signaling?: The SN74LVC245DWR consumes less static power than the LVTH variant due to lower input leakage and optimized transistor sizing, making it preferable for battery-powered or low-noise environments. However, the LVTH245DGGR offers stronger 5V-compatible outputs and better ESD protection, which may justify its use in industrial settings with longer trace lengths or higher EMI susceptibility. At 3.3V operation, both devices exhibit similar propagation delays (~4 ns), but the LVC version has tighter voltage thresholds (±0.8V typical), improving noise margin in noisy 3.3V systems. The choice hinges on whether robustness or efficiency is prioritized.

Is it acceptable to leave the DIR and OE pins unconnected on the SN74LVC245DWR in a fixed-direction application, and what are the risks?: Leaving DIR unconnected results in undefined directionality, potentially causing bus contention if both sides attempt to drive simultaneously. OE should never be left floating unless actively pulled high to disable outputs. Best practice is to tie OE to VCC via a pull-up resistor and fix DIR based on system requirements (e.g., connect to GND for A→B direction). Unconnected control pins increase susceptibility to noise-induced state changes, especially in long cables or high-temperature environments. Always adhere to TI’s recommended pin handling guidelines to ensure deterministic behavior.

What happens to the output state of the SN74LVC245DWR when VCCA drops below VCCB during operation, and how can this condition be mitigated?: If VCCA falls below VCCB while data flows from A to B, unintended conduction paths may develop through parasitic diodes, leading to incorrect logic levels or excessive power dissipation. This violates the absolute maximum ratings and risks damaging the die. Mitigation strategies include ensuring supply sequencing (power A-side before B-side), using enable signals synchronized to supply rails, or inserting series resistors (>1 kΩ) to limit sneak currents. Monitoring VCCA-VCCB differential with supervisory circuits provides an additional layer of protection in safety-critical systems.

How many clock cycles would it take for the SN74LVC245DWR to reliably transfer a 16-bit word over a synchronous serial interface running at 20 MHz, assuming worst-case propagation delay and setup/hold constraints?: At 20 MHz, each clock cycle is 50 ns. With a typical propagation delay of 4.5 ns and required setup time of 1.2 ns (from datasheet), the total latency per bit is approximately 5.7 ns, well within one clock period. Therefore, a 16-bit word transfers fully in a single cycle with ample timing margin. However, cumulative skew across parallel lines must be minimized through matched routing. The SN74LVC245DWR’s consistent channel-to-channel delay (<0.5 ns skew) makes it suitable for wide-word transfers in FPGA-to-memory interfaces or sensor buses.

Can the SN74LVC245DWR replace discrete MOSFET-based level shifters in space-constrained PCBs, and what trade-offs emerge regarding cost and reliability?: Yes, the SN74LVC245DWR integrates 8 bidirectional channels in a compact SOP7.2 package, eliminating the need for multiple discrete components. Compared to MOSFET solutions like BSS138 arrays, it offers superior speed, lower capacitance, and built-in ESD protection (HBM ±2 kV). However, discrete approaches consume less power in sleep modes and allow independent voltage pairing per channel. The SN74LVC245DWR excels in cost-sensitive, high-volume designs where board real estate and routing complexity outweigh marginal power savings. Its integrated nature also reduces solder joints, enhancing long-term reliability in harsh environments.

What environmental factors influence the long-term stability of the SN74LVC245DWR’s threshold voltages, and how might this affect legacy system compatibility?: Elevated temperatures accelerate threshold voltage drift due to semiconductor dopant diffusion, potentially shifting VIL/VIH margins in older systems expecting tight 3.3V logic levels. Over a 10-year lifespan at 85°C, the SN74LVC245DWR’s input thresholds may shift by up to ±100 mV, risking misinterpretation of edge cases. To maintain compatibility, designers should derate operating temperatures, avoid marginal logic margins, or implement software-based calibration if adaptive thresholds are supported. This is particularly relevant in automotive or medical applications where component aging cannot be assumed negligible.

Does the SN74LVC245DWR support partial bus isolation during system reset sequences, and how does OE behavior interact with power-up states?: The SN74LVC245DWR features active-low OE pins that default to high-impedance when unpowered, preventing back-driving during resets. During power-up, OE should remain asserted (low) until both supply rails stabilize to avoid glitches. Once enabled, the device maintains directionality until explicitly changed. This enables clean bus segmentation—for example, isolating a microcontroller from flash memory during reset by holding OE high until firmware initializes. Proper OE management ensures no contention occurs between subsystems recovering at different rates.

How should termination resistors be applied when using the SN74LVC245DWR in a multi-drop RS-485 network spanning 10 meters?: While the SN74LVC245DWR itself is not a transceiver, it can buffer digital signals destined for an RS-485 driver. Termination resistors (120 Ω) should be placed at the far end of the twisted-pair cable, not at the buffer output. The SN74LVC245DWR’s low output impedance (≈15 Ω) minimizes reflections when driving into properly terminated lines. However, ensure the downstream transceiver meets RS-485 standards (e.g., ±12 V differential swing). The buffer enhances signal integrity by reducing rise/fall times and isolating capacitive loads, but adds propagation delay (~5 ns), which may require adjustment in baud rate selection for long distances.

What is the significance of the SN74LVC245DWR’s 5V-tolerant inputs when used in a 3.3V-only system with occasional debug headers carrying 5V signals?: The 5V-tolerant inputs allow temporary connection of diagnostic tools (e.g., JTAG adapters, logic analyzers) without risk of damage, even if those tools operate at 5V while the main system runs at 3.3V. This simplifies test infrastructure reuse and avoids costly custom adapter boards. However, prolonged exposure to 5V inputs without proper current limiting increases electromigration risk in metal interconnects. For permanent connections, use series resistors (100–470 Ω) to dampen transients and comply with absolute maximum ratings. The feature enhances flexibility but does not eliminate the need for robust ESD protection in production units.

Can two SN74LVC245DWRs be cascaded to create a 16-bit bidirectional bus translator, and what synchronization challenges arise?: Cascading two SN74LVC245DWRs is feasible for expanding bus width, but requires careful coordination of DIR and OE signals. Both devices must share identical direction and enable states. Propagation delays accumulate additively, potentially exceeding timing budgets in high-speed designs—each stage adds ~4.5 ns, totaling ~9 ns for 16 bits. Skew between channels must be minimized through matched trace lengths (<10 mm difference). Additionally, ensure power supplies are well-decoupled to prevent ground bounce affecting control signals. This approach suits moderate-speed applications like parallel EEPROM interfacing but becomes impractical above 50 MHz.

How does the SN74LVC245DWR perform in radiated emission tests, and what layout practices reduce EMI from its fast-switching outputs?: Due to its high slew rates (up to 5 V/ns) and compact SOP7.2 footprint, the SN74LVC245DWR can generate measurable RF emissions above 30 MHz, particularly in dense clocked systems. To mitigate EMI, route high-speed signals perpendicular to adjacent layers, use ground planes beneath the package, and keep unused outputs disabled. Series termination (33–100 Ω) near the source reduces overshoot and ringing. Avoid stubs and minimize loop areas in return paths. These measures align with CISPR Class B limits when combined with proper enclosure shielding, making the SN74LVC245DWR viable for commercial electronics despite its inherent aggressiveness.

What role does the SN74LVC245DWR play in protecting sensitive 3.3V ASICs from electrostatic discharge during manual probing or automated test fixtures?: Although the SN74LVC245DWR lacks dedicated ESD diodes beyond standard HBM protection, its 5V-tolerant inputs provide a degree of robustness against brief ESD events (e.g., human contact). However, for rigorous test environments, supplement it with external TVS diodes rated for ±8 kV air discharge. The buffer isolates the ASIC’s internal circuitry from voltage spikes on external connectors, preventing latch-up triggered by parasitic thyristor structures. Proper grounding of the test fixture and use of guarded probes further enhance protection, ensuring the SN74LVC245DWR functions as part of a layered defense strategy rather than a standalone safeguard.

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Customer Reviews

Evaluation: 10 Articles

Nath***rooks

Jun 11, 2026

Installed this power component in a converter board. Output remained stable under different load conditions and thermal performance was better than expected.
Dani***alkerTech

Jun 1, 2026

Product works, but setup took more effort than expected. Once configured the MCU ran reliably, although documentation support felt older compared with newer platforms. Fine for maintenance projects.
Yuki***aka88

May 26, 2026

信号通信プロジェクトでこのRS-485トランシーバーを使用しました。設置は簡単で、長距離ケーブルでも通信は安定していました。消費電力も、以前使用していたものより低くなっています。
Stev***aker

May 20, 2026

Solid diode for power rectification. Works well in switching circuits.
Bran***Lewis

May 11, 2026

Compact FPGA with good performance. Suitable for basic signal processing tasks.
Oliv***arris

May 7, 2026

Reliable I/O expander. Works well in embedded control applications.
Jess***Jones

Apr 17, 2026

It offers good value for the price, and the specifications match the description. I’ve been using it for two days with no issues, and I’ll definitely buy it again if I need it in the future.
Mich***Smith

Apr 17, 2026

Shipping was on time, the component pins are neatly aligned, and I tested 10 of them with a multimeter—all readings were within the specified range. Highly recommended.
Aman***arris

Apr 3, 2026

It was great—the entire process, from placing the order to receiving the package, went very smoothly. The components were consistent, the price was fair, and I had a very pleasant shopping experience.
Mike***nch

Apr 3, 2026

Better than expected! The resistance and capacitance readings were spot-on, and it passed the test on the first try. The service was reliable, and the packaging was thoughtful—I highly recommend it.

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SN74LVC245DWR

Texas Instruments
32D-SN74LVC245DWR

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SN74LVC245DWR - Texas Instruments

Specifications

Frequently Asked Questions(FAQ)

Customers Also Interested in

Recommended Products

Customer Reviews

Evaluation: 10 Articles

Installed this power component in a converter board. Output remained stable under different load conditions and thermal performance was better than expected.

Product works, but setup took more effort than expected. Once configured the MCU ran reliably, although documentation support felt older compared with newer platforms. Fine for maintenance projects.

信号通信プロジェクトでこのRS-485トランシーバーを使用しました。設置は簡単で、長距離ケーブルでも通信は安定していました。消費電力も、以前使用していたものより低くなっています。

Solid diode for power rectification. Works well in switching circuits.

Compact FPGA with good performance. Suitable for basic signal processing tasks.

Reliable I/O expander. Works well in embedded control applications.

It offers good value for the price, and the specifications match the description. I’ve been using it for two days with no issues, and I’ll definitely buy it again if I need it in the future.

Shipping was on time, the component pins are neatly aligned, and I tested 10 of them with a multimeter—all readings were within the specified range. Highly recommended.

It was great—the entire process, from placing the order to receiving the package, went very smoothly. The components were consistent, the price was fair, and I had a very pleasant shopping experience.

Better than expected! The resistance and capacitance readings were spot-on, and it passed the test on the first try. The service was reliable, and the packaging was thoughtful—I highly recommend it.