onsemi 74ALVCH16245DT

Overview

74ALVCH16245DT from onsemi is a low-voltage, non-inverting 16-bit bus transceiver with bus-hold circuitry, designed for bidirectional data flow control in 1.65–3.6 V systems. It features byte-wise direction control (T/R1/T/R2), dual independent 8-bit sections, 3-state outputs, and ±24 mA drive capability at 3.0 V - used in high-speed memory/data bus interfacing between ASICs and FPGAs.

For engineers reviewing the 74ALVCH16245DT datasheet, pinout, applications, or equivalent options, key selection criteria include voltage compatibility (1.65–3.6 V operation), bus-hold input retention, propagation delay (≤3.0 ns at 3.3 V), IOFF protection during power-off, and TSSOP-48 package constraints for high-density PCB layouts.

Technical Context

The 74ALVCH16245DT implements two independent 8-bit bidirectional transceiver blocks, each controlled by dedicated Transmit/Receive (T/Rn) and Output Enable (OEn) inputs. Direction is determined by active-HIGH T/Rn: HIGH enables A→B data flow; LOW enables B→A flow.

Its bus-hold circuitry actively maintains valid logic states on unused or floating inputs without external pull-ups, drawing only 500 µA at VCC = 3.6 V. The IOFF specification ensures high-impedance outputs when VCC = 0 V, supporting live insertion and hot-swap applications.

Key Specifications

Pinout & Package

TSSOP-48 package (Case 1201), 7.95 mm × 6.00 mm body, 0.5 mm pitch, 0.1 mm max lead thickness, moisture sensitivity level 1 - suitable for fine-pitch automated assembly and reflow.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar 16-bit transceiver applications.

Compared with SN74ALVCH16245DGGR, the 74ALVCH16245DT offers identical functionality and pinout from a second-source supplier, while 74LVC16245APAG trades bus-hold integration for lower unit cost - requiring additional passives and careful input management in uncontrolled signal environments.

Availability

74ALVCH16245DT is available at Aetrix Electronics and suitable for memory interface buffering, FPGA-to-ASIC bridging, and hot-swappable backplane modules requiring stable component supply, long-term lifecycle assurance, and traceable sourcing.

Supply support for 74ALVCH16245DT 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

onsemi (formerly ON Semiconductor) is a global semiconductor manufacturer specializing in energy-efficient power management, analog, logic, and sensor solutions for automotive, industrial, and cloud infrastructure markets.

The 74ALVCH16245DT belongs to the ALVCH advanced low-voltage CMOS logic family, engineered for high-speed, low-power bidirectional bus interfacing in mixed-voltage embedded systems with stringent reliability and hot-swap requirements.

FAQ

What voltage range does the 74ALVCH16245DT support, and how does it handle mixed-voltage interfaces?

The 74ALVCH16245DT operates from 1.65 V to 3.6 V and features 3.6 V tolerant inputs and outputs - meaning it accepts 0–3.6 V logic signals regardless of its own VCC setting. This allows direct interfacing between 1.8 V, 2.5 V, and 3.3 V subsystems without external level shifters. Its bus-hold circuitry further stabilizes inputs during voltage transitions, making the 74ALVCH16245DT ideal for mixed-domain data buses where voltage sequencing is non-synchronous.

How does the bus-hold feature of the 74ALVCH16245DT eliminate the need for external pull-up resistors?

The 74ALVCH16245DT integrates active bus-hold circuitry on all 32 I/O pins (A0–A15, B0–B15), which detects floating input states and applies a weak but sufficient current (≥75 µA at 3.0 V) to retain the last valid logic level. This prevents undefined states during tri-state transitions or unconnected stubs, removing the need for discrete 10–100 kΩ pull-up/down resistors - reducing BOM count, PCB area, and potential signal integrity issues caused by resistor parasitics in high-speed layouts.

What is the significance of the IOFF specification in the 74ALVCH16245DT, and when does it matter most?

The IOFF specification guarantees that the 74ALVCH16245DT outputs remain in high-impedance state even when VCC = 0 V - preventing back-current flow into unpowered sections of a system. This is critical during live insertion, partial power-down, or hot-swap operations (e.g., adding a module to an active backplane). Unlike standard 3-state devices, the 74ALVCH16245DT's IOFF behavior is tested and guaranteed, ensuring safe isolation without relying on external power sequencing controls.

Can the 74ALVCH16245DT be used as two independent 8-bit transceivers, and how is that configured?

Yes - the 74ALVCH16245DT is explicitly designed with byte control: OE1/T/R1 governs A0–A7 ↔ B0–B7, while OE2/T/R2 controls A8–A15 ↔ B8–B15. By driving OE1 and OE2 separately, designers can operate the two halves independently - for example, reading from one peripheral while writing to another, or isolating fault domains. Tying OE1/OE2 and T/R1/T/R2 together configures it as a unified 16-bit transceiver, offering flexibility without hardware modification.

What are the thermal and packaging considerations for the 74ALVCH16245DT in high-density PCB layouts?

The 74ALVCH16245DT uses a TSSOP-48 package (Case 1201) with 0.5 mm pitch, 7.95 mm × 6.00 mm footprint, and moisture sensitivity level 1 - compatible with standard SMT reflow and exempt from bake requirements. Its θJA of 90 °C/W (FR4, 2-oz copper) requires minimal thermal relief; three VCC and four GND pins distribute power/ground currents to suppress simultaneous switching noise. For high-density routing, the pinout supports orthogonal escape patterns - A/B ports are interleaved to simplify length-matching of differential-like bus pairs.