Texas Instruments SN74LVCH244ANSR

Overview

SN74LVCH244ANSR from Texas Instruments is an octal buffer/line driver with 3-state outputs, designed for 1.65 V to 3.6 V operation. It features two independent 4-bit channels, bus-hold circuitry eliminating external pull resistors, I_off support for partial-power-down mode, and mixed-mode signal translation (5-V inputs compatible with 3.3-V V_CC). It is used in address/data bus buffering and level translation in industrial control and embedded interface systems.

For engineers reviewing the SN74LVCH244ANSR datasheet, SN74LVCH244ANSR pinout, SN74LVCH244ANSR application, or SN74LVCH244ANSR equivalent, key selection criteria include its 20-pin SOP-NS package, 5.9 ns max propagation delay at 3.3 V, ±24 mA output drive, bus-hold input retention, and I_off protection for hot-swap and power sequencing scenarios.

Technical Context

The SN74LVCH244ANSR implements dual 4-bit noninverting buffers with independent 3-state output-enable (OE) controls per group. Its bus-hold circuitry actively maintains valid logic states on undriven inputs without external components, reducing BOM count and layout complexity. The device supports mixed-voltage interfacing: inputs tolerate up to 5.5 V while operating from as low as 1.65 V V_CC, enabling seamless bridging between legacy 5-V and modern 3.3-V or 1.8-V subsystems.

I_off functionality disables outputs during power-down, preventing back-current flow when V_CC = 0 V - critical for system-level power management in multi-rail designs. Propagation delay (t_pd) is specified down to 5.9 ns at V_CC = 3.3 V, with output enable/disable times (t_en/t_dis) of 7.6 ns/5.8 ns under same conditions, supporting high-speed bus arbitration and dynamic bus sharing.

Key Specifications

Pinout & Package

SOP-NS package: 20-pin plastic small-outline package, 0.635 mm pitch, 7.5 mm × 12.8 mm body, 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 buffer applications.

Compared with SN74LVC244APWR and 74ALVC244MTCX, the SN74LVCH244ANSR uniquely combines bus-hold, I_off, and 5-V-tolerant inputs in a single SOP-NS package - essential for robust, maintenance-free bus interfaces in industrial and automotive environments.

Availability

SN74LVCH244ANSR is available at Aetrix Electronics and suitable for industrial PLC backplanes, automotive body control modules, embedded microcontroller bus expansion, and test equipment digital pattern generation requiring stable component supply and long-term lifecycle support.

Supply support for SN74LVCH244ANSR 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 over 90 years of innovation in industrial, automotive, and communications markets.

The SN74LVCH244ANSR belongs to TI's LVCH logic family, engineered for low-voltage, high-speed, mixed-signal interface applications where bus integrity, power sequencing resilience, and voltage translation are critical design requirements.

FAQ

What is the maximum operating frequency supported by the SN74LVCH244ANSR?

The SN74LVCH244ANSR does not specify a maximum clock frequency, as it is a non-clocked buffer. Its usable data rate is determined by propagation delay (5.9 ns max at 3.3 V) and system rise/fall times. In practice, it reliably supports bus toggle rates exceeding 100 MHz in well-terminated, low-capacitance layouts. For precise timing margins, designers must calculate setup/hold windows using actual load capacitance and driver characteristics - the SN74LVCH244ANSR itself imposes no inherent frequency ceiling beyond its t_pd and t_en/t_dis limits.

Can the SN74LVCH244ANSR safely interface a 5-V microcontroller with a 3.3-V FPGA?

Yes, the SN74LVCH244ANSR can safely interface a 5-V microcontroller with a 3.3-V FPGA. Its inputs tolerate 0–5.5 V regardless of V_CC, and its outputs swing rail-to-rail within the 3.3-V domain when V_CC = 3.3 V. This makes the SN74LVCH244ANSR ideal for unidirectional signal translation from 5-V logic to 3.3-V logic. For bidirectional translation, external direction control or complementary devices are required - the SN74LVCH244ANSR itself is noninverting and unidirectional per channel.

Does the SN74LVCH244ANSR require external pullup resistors on its inputs?

No, the SN74LVCH244ANSR does not require external pullup or pulldown resistors on its inputs due to integrated bus-hold circuitry. This feature actively maintains the last-valid logic state on undriven or floating inputs, consuming only ±75 µA at V_CC = 3.0 V. Using external resistors with the SN74LVCH244ANSR is discouraged, as they conflict with bus-hold operation and may cause excessive current draw or metastability. The bus-hold function is always enabled and cannot be disabled.

What is the thermal resistance (θ_JA) of the SN74LVCH244ANSR in its SOP-NS package?

The SN74LVCH244ANSR in the SOP-NS (NS) package has a junction-to-ambient thermal resistance (θ_JA) of 60 °C/W, as specified in TI's official thermal data. This value assumes standard JEDEC 2-layer board conditions (1-inch² copper pad, 2 oz Cu). Actual θ_JA in end-user PCBs will vary based on copper area, layer stackup, and airflow. For thermal design, peak power dissipation per buffer is ~2.5 mW at 3.3 V and 10 MHz toggle rate; total worst-case power for all eight buffers remains below 25 mW, making thermal management straightforward in typical industrial layouts.

Is the SN74LVCH244ANSR pin-compatible with the SN74LVC244A series?

Yes, the SN74LVCH244ANSR is pin-compatible with the SN74LVC244A series in the same SOP-NS package, including identical pin numbering, function mapping, and footprint. Both share the same 20-pin layout: 1OE, 1A1–1A4, 2Y4–2Y1, GND, V_CC, 2OE, 1Y1–1Y4, 2A4–2A1. However, the SN74LVCH244ANSR adds bus-hold and enhanced I_off versus the base LVC version - meaning it can directly replace SN74LVC244ANSR without layout changes, while delivering improved robustness in floating-input and partial-power-down scenarios.