Texas Instruments SN74LV245ATNSR

Overview

SN74LV245ATNSR from Texas Instruments is an octal bus transceiver with 3-state outputs, designed for asynchronous two-way data communication between A and B buses in 5-V digital systems. It operates from 4.5 V to 5.5 V, delivers typical propagation delay of 3.5 ns at 5 V, supports mixed-mode voltage operation on all ports, and features Ioff partial-power-down protection. It is used in bidirectional data buffering for microcontroller peripheral expansion and FPGA I/O bridging.

For engineers reviewing the SN74LV245ATNSR datasheet, SN74LV245ATNSR pinout, SN74LV245ATNSR application, or SN74LV245ATNSR equivalent, key selection criteria include direction-control logic behavior, 3-state enable timing (tPZH/tPLZ), output ground bounce (VOLP < 0.8 V), and compatibility with TTL-level inputs in 5-V systems.

Technical Context

The SN74LV245ATNSR implements dual-directional 8-bit data flow controlled by DIR (direction) and OE (output enable) inputs. DIR determines data path direction-low enables B→A transmission, high enables A→B transmission-while OE independently places all outputs in high-impedance state regardless of DIR state. The device uses advanced CMOS process to achieve low dynamic noise and robust latch-up immunity (>250 mA per JESD 17).

It supports partial-power-down via Ioff circuitry that disables outputs when VCC = 0, preventing backflow current during hot-insertion or power sequencing. Input thresholds are TTL-compatible (VIH = 2 V, VIL = 0.8 V), and all ports tolerate mixed-voltage signaling up to 5.5 V, enabling interoperability between 3.3-V and 5-V domains without level shifters.

Key Specifications

Pinout & Package

SOP (NS) package, 20-pin, 0.300-inch body width, 1.27 mm pitch, 2.65 mm max height, RoHS-compliant NiPdAu lead finish, MSL Level-1.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar octal transceiver applications.

Compared with SN74LV245ATNSR, SN74LVC245A offers better low-voltage compatibility but sacrifices 5-V interface capability and Ioff protection, while 74ACT245 provides stronger drive but lacks modern power management and thermal robustness for automotive or industrial deployment.

Availability

SN74LV245ATNSR is available at Aetrix Electronics and suitable for industrial automation, automotive body electronics, and FPGA-based embedded systems requiring stable component supply, long-term lifecycle assurance, and RoHS-compliant packaging.

Supply support for SN74LV245ATNSR 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 specializing in analog, embedded processing, and connectivity technologies, with decades of experience in high-reliability logic and interface solutions.

The SN74LV245ATNSR belongs to TI's LV-A family of low-voltage, high-speed logic devices engineered for robust 5-V system interfacing, mixed-signal coexistence, and extended-temperature industrial and automotive applications.

FAQ

What is the recommended power-up sequence for SN74LV245ATNSR?

TI recommends tying OE to VCC through a pullup resistor (minimum value determined by driver sink capability) during power-up to ensure all outputs remain in high-impedance state until system initialization completes. This prevents bus contention or unintended data latching. The SN74LV245ATNSR does not require specific VCC ramp rate or sequencing with other rails, but stable 4.5–5.5 V supply must be established before applying input signals. Always verify OE logic state before releasing reset in firmware.

Does SN74LV245ATNSR support hot-swap operation?

Yes, SN74LV245ATNSR supports hot-swap operation via its Ioff circuitry, which disables outputs and blocks current flow when VCC = 0 V. This prevents back-current from live buses into the unpowered device. For reliable hot-swap, ensure OE is held high (via external pullup) during insertion, and confirm that all input/output voltages remain within absolute maximum ratings (–0.5 V to 7 V) even when VCC is absent. The SN74LV245ATNSR is rated for this behavior per JESD 78.

Can SN74LV245ATNSR interface between 3.3-V and 5-V logic domains?

Yes, SN74LV245ATNSR supports mixed-mode voltage operation on all ports: inputs accept TTL-compatible thresholds (VIH = 2 V, VIL = 0.8 V) and tolerate up to 5.5 V, while outputs swing rail-to-rail (0 V to VCC) and drive 5-V buses directly. When VCC = 5 V, it safely accepts 3.3-V inputs and drives 5-V loads - no external level shifters needed. This capability is explicitly validated in the SN74LV245ATNSR datasheet Section 7.3.

What is the maximum capacitive load SN74LV245ATNSR can drive reliably?

SN74LV245ATNSR is characterized for CL = 15 pF and CL = 50 pF loads in its switching characteristics table. At 5 V VCC, it maintains tPHL/tPLH ≤ 10.7 ns and tPZH ≤ 17.3 ns up to 50 pF. For reliable signal integrity beyond 50 pF, add series termination or reduce trace length - the device's ±16 mA output drive supports typical PCB trace + connector + receiver capacitance up to ~45 pF at 20 MHz. Exceeding 50 pF may increase skew and degrade edge rates, affecting setup/hold margins.

How does DIR and OE interact in SN74LV245ATNSR functionality?

In SN74LV245ATNSR, OE is prioritized over DIR: when OE = high, all outputs go high-impedance regardless of DIR state; only when OE = low does DIR determine direction (DIR = low → B→A, DIR = high → A→B). This allows independent bus isolation and directional control. The function table in the SN74LV245ATNSR datasheet (Section 7.6) confirms that OE = high forces isolation even if DIR is actively toggled. No internal arbitration or race conditions exist between these controls.