Texas Instruments SN74LVCH245N

Overview

SN74LVCH245 from Texas Instruments is an octal bus transceiver with 3-state outputs, designed for 2.7-V to 3.6-V V_CC operation and mixed-mode interfacing (5-V I/O with 3.3-V V_CC). It supports bidirectional data flow between A and B buses under DIR control, features bus-hold on all data inputs, and operates across –40°C to 85°C. Used in level-shifting backplane interfaces and isolated bus domains.

For engineers reviewing the SN74LVCH245 datasheet, SN74LVCH245 pinout, SN74LVCH245 application, or SN74LVCH245 equivalent, key selection criteria include 3-state output timing (t_pd ≤ 7 ns at 3.3 V), bus-hold functionality eliminating external pullups, ±24-mA drive strength at 3 V, and absolute input voltage tolerance up to 5.5 V.

Technical Context

The SN74LVCH245 implements asynchronous bidirectional data transfer using a single DIR input to select direction (A→B or B→A) and an active-low OE input to enable/disable all outputs into high-impedance state. Its EPIC™ submicron CMOS process enables low ground bounce (V_OLP < 0.8 V) and undershoot immunity (V_OHV > 2 V) at 3.3 V.

Bus-hold circuitry actively maintains valid logic levels on floating A/B inputs without external resistors, and the device tolerates input voltages from –0.5 V to 6.5 V while operating from 2.7 V to 3.6 V V_CC, enabling robust 5-V/3.3-V system interfacing.

Key Specifications

Pinout & Package

SN74LVCH245 is available in DB (SSOP-20), DW (SOIC-20), and PW (TSSOP-20) packages - all 20-pin surface-mount variants with identical pin mapping and 0.65-mm lead pitch.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74LVC245A and 74ALVC245, the SN74LVCH245 uniquely combines bus-hold functionality with 5-V-tolerant inputs and industrial temperature range-making it optimal for uncontrolled or partially populated bus environments where reliability trumps raw speed or quiescent current.

Availability

SN74LVCH245 is available at Aetrix Electronics and suitable for industrial backplane interfaces, memory expansion subsystems, and hot-swappable I/O modules requiring stable component supply, long-term lifecycle support, and guaranteed mixed-voltage interoperability.

Supply support for SN74LVCH245 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 delivering analog, embedded processing, and logic solutions for industrial, automotive, and communications markets.

The SN74LVCH245 belongs to TI's LVCH logic family-designed specifically for robust, mixed-voltage bus interfacing in industrial control and programmable logic systems where bus stability and voltage translation are critical.

FAQ

What is the function of the DIR pin on the SN74LVCH245?

The DIR (direction-control) pin on the SN74LVCH245 determines real-time data flow direction: logic low enables transmission from B bus to A bus, and logic high enables A-to-B transfer. It operates asynchronously with no clock dependency, allowing dynamic reconfiguration of bus topology during system operation without timing constraints or setup/hold requirements.

Does the SN74LVCH245 require external pullup resistors on its data inputs?

No, the SN74LVCH245 does not require external pullup resistors on its A1–A8 or B1–B8 inputs because it integrates active bus-hold circuitry. This feature maintains each floating input at its last valid logic level with ±75 µA hold current, eliminating risk of metastability and reducing component count-confirmed in the device's functional description and electrical characteristics table.

Can the SN74LVCH245 safely interface a 5-V microcontroller with a 3.3-V FPGA?

Yes, the SN74LVCH245 safely interfaces a 5-V microcontroller with a 3.3-V FPGA: its inputs tolerate up to 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. The device's mixed-mode specification explicitly supports "5-V input/output voltages with 3.3-V V_CC", making SN74LVCH245 ideal for this cross-voltage coupling.

What is the recommended power-up sequence for the SN74LVCH245?

To ensure high-impedance outputs during power-up, tie OE to V_CC through a pullup resistor-minimum value determined by the driver's current-sinking capability. The datasheet specifies this practice to prevent bus contention before system initialization completes. No special sequencing is required for DIR or data inputs, as SN74LVCH245 has no internal state dependencies.

How does the SN74LVCH245 handle ground bounce and output undershoot?

The SN74LVCH245 mitigates ground bounce and output undershoot via its EPIC™ submicron CMOS process: typical V_OLP (output ground bounce) is < 0.8 V and V_OHV (output VOH undershoot) exceeds 2 V at V_CC = 3.3 V and T_A = 25°C. These values are measured and specified in the Absolute Maximum Ratings and Electrical Characteristics sections of the SN74LVCH245 datasheet.