Texas Instruments SN74ALVCH245PW

Overview

SN74ALVCH245PW from Texas Instruments is an octal bus transceiver with 3-state outputs, designed for asynchronous bidirectional data transfer between 1.65-V to 3.6-V buses. It features bus-hold circuitry on all A/B inputs, ±24-mA output drive at 3.3 V, and 3.4-ns max propagation delay. It is used in low-voltage system interconnects such as FPGA-to-ASIC communication and memory interface buffering.

For engineers reviewing the SN74ALVCH245PW datasheet, SN74ALVCH245PW pinout, SN74ALVCH245PW application, or SN74ALVCH245PW equivalent, key selection considerations include voltage compatibility (1.65–3.6 V), direction-control logic behavior, 3-state isolation timing (ten/tdis), bus-hold functionality, and TSSOP-20 thermal performance (θJA = 83°C/W).

Technical Context

The SN74ALVCH245PW implements dual-directional 8-bit data routing controlled by DIR (direction) and OE (output enable) inputs. Its bus-hold circuitry actively maintains valid logic states on undriven A/B inputs without external resistors, reducing BOM count and layout complexity. The device operates across the full 1.65–3.6-V supply range while maintaining specified timing and drive strength.

Propagation delay (tpd ≤ 3.4 ns at 3.3 V), enable/disable times (ten ≤ 5.5 ns, tdis ≤ 5.5 ns), and rail-to-rail input thresholds (VIH/VIL scaling with VCC) ensure reliable operation in mixed-voltage systems. Latch-up immunity exceeds 100 mA per JESD 78 Class II, supporting robust industrial deployment.

Key Specifications

Pinout & Package

TSSOP-20 package (PW), 6.5 mm × 4.4 mm footprint, 1.2 mm max height, 0.65 mm lead pitch, JEDEC MO-153 compliant. RoHS-compliant NIPDAU lead finish, MSL Level-1 (260°C peak reflow).

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74ALVCH245PW, SN74LVC245APW lacks bus-hold and has reduced low-voltage drive, increasing BOM and layout risk; 74AVC245TTR offers faster timing and identical voltage range but requires verification of footprint compatibility due to tighter pad pitch.

Availability

SN74ALVCH245PW is available at Aetrix Electronics and suitable for industrial PLC backplanes, FPGA I/O expansion bridges, and automotive body control modules requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for SN74ALVCH245PW 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 industrial, automotive, and communications markets.

The SN74ALVCH245PW belongs to TI's ALVC/ALVCH logic family, engineered for low-voltage, high-speed bidirectional bus interfacing in space-constrained and thermally demanding applications.

FAQ

What is the recommended power-up sequence for SN74ALVCH245PW?

TI recommends tying OE to VCC through a pullup resistor (minimum value determined by driver sink capability) to ensure outputs remain in high-impedance state during power-up. DIR may be left floating only if bus-hold is active, but best practice is to drive it to a known state. VCC must ramp monotonically; no sequencing required between A/B-side signals since the device is purely combinatorial.

Does SN74ALVCH245PW support mixed-voltage operation between A and B ports?

No - SN74ALVCH245PW has a single VCC pin powering both A and B I/O structures. All A/B inputs and outputs operate referenced to the same VCC rail (1.65–3.6 V). For true mixed-voltage translation (e.g., 1.8-V A side ↔ 3.3-V B side), a dedicated level-shifting transceiver like SN74AVCH4T245 is required.

Can bus-hold on SN74ALVCH245PW be disabled?

No - bus-hold is permanently enabled on all A and B inputs and cannot be disabled via configuration or external control. TI explicitly warns against using pullup/pulldown resistors concurrently with bus-hold, as they conflict and may cause excessive current draw or logic instability.

What is the maximum capacitive load SN74ALVCH245PW can drive reliably?

Based on switching characteristics and output drive specs, SN74ALVCH245PW maintains 3.4-ns tpd driving up to 50 pF total load (including trace and input capacitance) at 3.3 V. Driving >50 pF increases propagation delay nonlinearly and may violate setup/hold timing in high-speed systems; for heavier loads, consider adding local buffers or reducing trace length.

Is SN74ALVCH245PW pin-compatible with other TSSOP-20 transceivers like SN74LVC245A?

Yes - SN74ALVCH245PW shares identical TSSOP-20 pinout (PW package), including DIR, OE, GND, VCC, and A/B port assignments per TI's standard logic pin mapping. However, electrical differences (e.g., bus-hold presence, drive strength vs. VCC) require validation in the target application before substitution.