Texas Instruments SN74LVCH8T245NSR

Overview

SN74LVCH8T245 from Texas Instruments is an 8-bit dual-supply noninverting bus transceiver enabling bidirectional voltage-level translation between 1.65V–5.5V domains (e.g., 1.8V ↔ 3.3V, 3.3V ↔ 5V). It features bus-hold on all data inputs, Ioff partial-power-down protection, VCC isolation, and DIR/OE control referenced to VCCA. Used in industrial communications interfaces where mixed-voltage subsystems require glitch-free data exchange.

For engineers reviewing the SN74LVCH8T245 datasheet, SN74LVCH8T245 pinout, SN74LVCH8T245 application, or SN74LVCH8T245 equivalent, key selection criteria include dual-rail operating range (VCCA/VCCB = 1.65–5.5V), bus-hold functionality eliminating external resistors, Ioff leakage < ±2 µA at power-off, 3-state output enable timing (tPHZ/tPLZ ≤ 29.6 ns), and compatibility with SSOP/TVSOP/TSSOP/VQFN-24 packages.

Technical Context

The SN74LVCH8T245 implements a fully configurable dual-rail architecture: A-port I/Os and control pins (DIR, OE) are referenced to VCCA; B-port I/Os to VCCB. Both rails support independent 1.65V–5.5V operation, enabling universal translation across 1.8V, 2.5V, 3.3V, and 5V logic nodes without direction-dependent voltage constraints.

Its functional modes are defined by DIR (data direction) and OE (output enable): DIR = H + OE = L enables A→B transmission; DIR = L + OE = L enables B→A; OE = H forces both ports into high-impedance. Bus-hold circuitry sustains valid logic states on undriven inputs (IBHL up to 100 µA at 4.5V), and VCC isolation disables outputs if either supply drops below 100 mV or floats.

Key Specifications

Pinout & Package

SN74LVCH8T245 is available in four 24-pin packages: DB (SSOP), DGV (TVSOP), PW (TSSOP), and RHL (VQFN). All share identical pin functions and logic mapping, differing only in footprint and thermal performance (RHL offers lowest RθJA = 37.4°C/W).

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74AVCH8T245 and TXB0108, the SN74LVCH8T245 uniquely combines bus-hold, VCC isolation, and Ioff in a single 24-pin solution - making it the only choice for industrial systems requiring robustness against undriven lines, uncontrolled power sequencing, and subsystem-level power gating.

Availability

SN74LVCH8T245 is available at Aetrix Electronics and suitable for video surveillance, smart metering, and industrial wired networking applications requiring stable component supply, long-term lifecycle support, and traceable sourcing.

Supply support for SN74LVCH8T245 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 company delivering analog and embedded processing solutions for industrial, automotive, and personal electronics markets.

The SN74LVCH8T245 belongs to TI's LVCH logic family, designed specifically for robust, low-power voltage translation in mixed-supply systems where reliability under partial power-down and uncontrolled sequencing is mandatory.

FAQ

What voltage ranges does the SN74LVCH8T245 support on VCCA and VCCB?

The SN74LVCH8T245 supports independent supply voltages from 1.65V to 5.5V on both VCCA and VCCB. This enables translation between common logic families - such as 1.8V ↔ 3.3V, 2.5V ↔ 5V, or 3.3V ↔ 5V - without external components. The device remains functional across the full range, and its electrical characteristics (e.g., VOH, VOL, tPLH) are specified at multiple VCC combinations in the datasheet.

Does the SN74LVCH8T245 require external pull-up or pull-down resistors on its data lines?

No. The SN74LVCH8T245 integrates active bus-hold circuitry on all 16 data I/Os (A1–A8, B1–B8), which maintains valid logic states on undriven or floating inputs. Using external resistors defeats the bus-hold function and is explicitly discouraged in the datasheet. This feature reduces BOM cost, PCB area, and design complexity in systems with configurable or sparsely populated buses.

How does the SN74LVCH8T245 behave during power-up or power-down sequencing?

The SN74LVCH8T245 provides glitch-free power sequencing: either VCCA or VCCB may be powered on/off in any order without causing unintended output transitions. Its VCC isolation feature forces all outputs into high-impedance if either supply drops below ~100 mV or floats. To ensure safe startup, tie OE to VCCA through a pullup resistor - this guarantees 3-state behavior until firmware asserts valid DIR/OE states.

What is the maximum data rate supported by the SN74LVCH8T245?

The SN74LVCH8T245 does not specify a maximum data rate in MHz, but its switching characteristics define timing limits: propagation delay (tPLH/tPHL) is as low as 0.3 ns (VCCA = 5V, VCCB = 5V), and 3-state enable/disable times (tPHZ/tPLZ) are ≤ 29.6 ns. In practice, it reliably supports >100 Mbps NRZ signals in point-to-point configurations with proper layout - verified in TI's typical application circuits for SPI, UART, and parallel bus interfaces.

Can the SN74LVCH8T245 be used in partial-power-down systems?

Yes. The SN74LVCH8T245 includes Ioff circuitry that limits input/output leakage to ±2 µA when either VCCA or VCCB is at 0V, preventing damaging back-current flow into powered subsystems. This makes it suitable for applications like smart meters or medical devices where individual functional blocks (e.g., RF, display, sensor) are powered down independently to meet energy standards or safety requirements.