Texas Instruments SN74ALVCH244PW

Overview

SN74ALVCH244PW from Texas Instruments is an octal buffer/driver with 3-state outputs, designed for 1.65-V to 3.6-V V_CC operation. It features two independent 4-bit channels, bus-hold circuitry on all data inputs, ±24-mA output drive at 3.3 V, and a maximum propagation delay of 2.8 ns. It is used in bidirectional data bus interfacing between low-voltage logic domains in industrial control and embedded computing systems.

For engineers reviewing the SN74ALVCH244PW datasheet, SN74ALVCH244PW pinout, SN74ALVCH244PW application, or SN74ALVCH244PW equivalent, key selection criteria include voltage compatibility (1.65–3.6 V), bus-hold functionality eliminating external resistors, 20-pin TSSOP package constraints, and 3-state output timing behavior under varying load and supply conditions.

Technical Context

The SN74ALVCH244PW implements dual 4-bit noninverting buffers with separate active-low output-enable (OE) controls per group - 1OE for Y1–Y4 and 2OE for Y1′–Y4′. Each channel passes A→Y when its OE is low; outputs enter high-impedance state when OE is high. Bus-hold circuitry actively maintains valid logic levels on undriven inputs without external pullups.

It operates across -40°C to +85°C with latch-up immunity >250 mA (JESD 17) and ESD protection exceeding 2000-V HBM and 200-V MM. The device supports mixed-voltage system interfacing due to input thresholds scaling with V_CC (e.g., V_IL = 0.35×V_CC at 1.65 V).

Key Specifications

Pinout & Package

TSSOP-20 (PW) package: 4.4 mm × 6.5 mm body, 0.65 mm lead pitch, 1.2 mm max height, gull-wing leads, RoHS-compliant NiPdAu finish, MSL Level-1.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74ALVCH244PW, SN74LVC244APW lacks bus-hold and offers reduced drive below 3.3 V, while 74AVC244PW delivers faster propagation with identical pinout but higher quiescent current - making SN74ALVCH244PW optimal for mixed-voltage industrial systems requiring robust floating-input handling.

Availability

SN74ALVCH244PW is available at Aetrix Electronics and suitable for industrial PLC backplanes, low-power MCU I/O expansion, embedded memory subsystems, test equipment signal conditioning, and mixed-voltage bus interfacing requiring stable component supply and long-term manufacturability.

Supply support for SN74ALVCH244PW 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 SN74ALVCH244PW belongs to TI's ALVC/ALVCH logic family, engineered for low-voltage, high-speed bus interface applications where voltage translation, noise immunity, and input stability are critical in harsh or mixed-supply environments.

FAQ

What is the recommended power-up sequence for SN74ALVCH244PW?

TI recommends tying both 1OE and 2OE to V_CC through a pullup resistor (minimum value determined by driver sink capability) to ensure outputs remain in high-impedance state during power ramp. This prevents bus contention before system initialization completes. The SN74ALVCH244PW datasheet specifies this practice to avoid unintended signal assertion on shared lines during V_CC rise.

Does SN74ALVCH244PW support hot-swap operation?

Yes - the SN74ALVCH244PW supports hot-swap operation due to its bus-hold circuitry, which maintains valid logic states on undriven inputs, and its 3-state outputs controlled independently by OE pins. When inserted into a live backplane, the device avoids bus contention if OE is held high until firmware configures the channel, and bus-hold prevents metastability on floating data lines.

Can SN74ALVCH244PW be used with 1.8-V-only systems?

Yes - the SN74ALVCH244PW operates down to 1.65 V, making it fully compatible with 1.8-V systems. At V_CC = 1.8 V, it delivers ±4 mA output drive and maintains VIH/VIL thresholds scaled to V_CC (e.g., V_IL = 0.63 V), ensuring reliable interfacing with 1.8-V microcontrollers and FPGAs without level translation.

What is the thermal resistance (θ_JA) of SN74ALVCH244PW in its TSSOP package?

The SN74ALVCH244PW in TSSOP-20 (PW) package has a junction-to-ambient thermal resistance (θ_JA) of 83 °C/W, as specified in the TI datasheet SCES112F. This value assumes standard JEDEC 2-layer board conditions; actual performance improves with added copper pour or thermal vias under the exposed pad region.

How does bus-hold functionality affect PCB layout for SN74ALVCH244PW?

Bus-hold eliminates the need for external pullup or pulldown resistors on SN74ALVCH244PW data inputs, simplifying layout and reducing component count. However, TI explicitly warns against using external resistors *with* bus-hold enabled, as they may conflict with internal hold current and cause excessive power draw or logic instability - so layout must omit such resistors entirely.