Texas Instruments SN74LVTH646IPWREP

Overview

SN74LVTH646IPWREP from Texas Instruments is a 3.3-V octal bus transceiver and register with dual-clock D-type flip-flops, DIR/OE/SAB/SBA control, bus-hold inputs, and hot-insertion support. It operates from 2.7 V to 3.6 V, supports mixed-mode 5-V input/3.3-V output interfacing, and delivers 150-MHz clock frequency with ≤5.6 ns propagation delay. It is used in backplane data routing and legacy-to-modern voltage interface bridging.

For engineers reviewing the SN74LVTH646IPWREP datasheet, SN74LVTH646IPWREP pinout, SN74LVTH646IPWREP application, or SN74LVTH646IPWREP equivalent, key selection criteria include bidirectional bus management with storage capability, Ioff-enabled hot-swap compatibility, bus-hold elimination of external resistors, and TSSOP-24 packaging for high-density board layouts.

Technical Context

The SN74LVTH646IPWREP integrates two independent 8-bit data paths (A↔B) with separate clock inputs (CLKAB, CLKBA), direction control (DIR), output enable (OE), and select controls (SAB, SBA) enabling real-time or registered data transfer. Its dual-register architecture allows simultaneous latching of A- and B-bus data on clock edges.

It features active bus-hold circuitry on all A/B data inputs (±500 µA hold current at 3.6 V), Ioff protection (±100 µA at VCC = 0), and power-up 3-state behavior ensuring high-impedance outputs during power ramping (0–1.5 V). The device meets JEDEC JESD78 latch-up (>500 mA) and JESD22 ESD standards (2000-V HBM, 200-V MM).

Key Specifications

Pinout & Package

TSSOP-24 package (PW), 0.65-mm pitch, 7.8-mm × 4.4-mm body, RoHS-compliant green finish, moisture sensitivity level 1 (260°C).

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74LVTH646IPWREP, SN74LVT646PWRE4 offers lower cost but no extended temperature or reliability assurance, while SN74LVTH16245ADGGR provides greater bandwidth and pin count at the expense of missing critical functions - storage, 5-V input tolerance, and bus-hold - essential for legacy interface and modular system design.

Availability

SN74LVTH646IPWREP is available at Aetrix Electronics and suitable for industrial backplane interfaces, legacy voltage translation, and hot-swappable module carriers requiring stable component supply across extended temperature and long production lifecycles.

Supply support for SN74LVTH646IPWREP 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 logic solutions, with decades of experience in high-reliability industrial and aerospace-grade components.

The SN74LVTH646IPWREP belongs to TI's LVTH logic family, engineered for robust mixed-voltage system interfacing in harsh industrial environments where signal integrity, hot-swap safety, and long-term supply continuity are mandatory.

FAQ

What is the primary function of the SN74LVTH646IPWREP?

The SN74LVTH646IPWREP is an octal bus transceiver with dual D-type registers, enabling bidirectional data transfer between two 8-bit buses (A and B) with selectable real-time or stored output. It supports mixed 5-V input/3.3-V output operation, bus-hold, and hot-insertion - making it ideal for voltage-bridging and modular system interconnects. Its core function is synchronized, direction-controlled bus management with storage capability.

Does the SN74LVTH646IPWREP support hot-swap operation?

Yes, the SN74LVTH646IPWREP supports hot-swap operation via integrated Ioff and power-up 3-state circuitry. When powered down (VCC = 0), Ioff limits current backflow to ±100 µA. During power-up/power-down (VCC between 0–1.5 V), outputs remain in high-impedance state regardless of OE state - preventing bus conflicts. This functionality is validated per JEDEC JESD78 and industry hot-insertion standards.

Can the SN74LVTH646IPWREP interface 5-V logic signals to a 3.3-V system?

Yes, the SN74LVTH646IPWREP accepts 5-V TTL-level inputs while operating at 3.3-V VCC. Its input voltage range extends to 5.5 V, and it maintains valid VIH/VIL thresholds (2.0 V/0.8 V) under 3.3-V supply - enabling direct connection to 5-V microcontrollers, FPGAs, or legacy peripherals without external level shifters. Output swing remains compatible with 3.3-V CMOS inputs.

What is the purpose of the SAB and SBA pins on the SN74LVTH646IPWREP?

The SAB (Select A→B) and SBA (Select B→A) pins control multiplexing between real-time (transparent) and registered data paths. When SAB = L, real-time A-bus data appears on B-bus outputs; when SAB = H, stored A-data from CLKAB-triggered registers is output. Similarly, SBA selects between real-time and registered B-data for A-bus outputs - enabling flexible time-multiplexed bus arbitration in the SN74LVTH646IPWREP.

Is bus-hold functionality enabled by default on the SN74LVTH646IPWREP?

Yes, bus-hold circuitry is permanently active on all A1–A8 and B1–B8 inputs of the SN74LVTH646IPWREP and requires no configuration. It sources or sinks up to ±500 µA to maintain floating inputs at valid logic levels, eliminating the need for external pullup/pulldown resistors. Use of external resistors with enabled bus-hold is explicitly discouraged in the datasheet due to potential contention and increased power draw.