Texas Instruments SN74GTLPH16945GR

Overview

SN74GTLPH16945GR from Texas Instruments is a 16-bit LVTTL-to-GTLP bidirectional bus transceiver in TSSOP-48 package, partitioned into two independent 8-bit channels. It provides level translation between 3.3-V LVTTL logic (5-V tolerant) and 1.5-V GTLP backplane signals, with medium-drive B-port outputs (50 mA), bus-hold on A-port inputs, and live-insertion support via Ioff, power-up 3-state, and BIAS VCC. It targets high-speed backplane interconnects in telecom line cards.

For engineers reviewing the SN74GTLPH16945GR datasheet, SN74GTLPH16945GR pinout, SN74GTLPH16945GR application, or SN74GTLPH16945GR equivalent, key selection considerations include GTLP/LVTTL voltage domain isolation, distributed-load timing performance (tPLH/tPHL ≤ 6.3 ns), live-insertion precharge behavior, and dual-channel direction-control architecture with per-segment OE/DIR.

Technical Context

The SN74GTLPH16945GR implements asynchronous bidirectional data flow using two independent DIR/OE control pairs-one per 8-bit segment-enabling simultaneous A→B and B→A transfers across separate buses. Its TI-OPC™ circuitry actively suppresses overshoot during low-to-high transitions on unevenly terminated backplanes, while OEC™ design minimizes bus settling time.

It supports dual-voltage operation: A-port and controls run at 3.3 V (VCC) with 5-V tolerance, while B-port I/O operates at GTLP levels (VTT = 1.5 V, VREF = 1 V). BIAS VCC powers precharge circuitry that conditions B-port pins before VCC ramp-up, enabling true hot-swap capability without disturbing active backplane traffic.

Key Specifications

Pinout & Package

TSSOP-48 (DGG) package: 12.4 mm × 6.0 mm × 1.2 mm body, 0.5 mm pitch, gull-wing leads, RoHS-compliant NiPdAu finish, MSL Level-1.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74GTLPH16945GR, SN74GTL16622DGGR offers lower cost but sacrifices live-insertion robustness and backplane drive strength, while SN74AVC16T245DGGR provides broader voltage range at the expense of GTLP-specific signal integrity enhancements and distributed-load timing performance.

Availability

SN74GTLPH16945GR is available at Aetrix Electronics and suitable for telecom line cards, industrial backplane systems, test equipment chassis, and high-density data acquisition requiring stable component supply, long-term lifecycle support, and consistent GTLP timing performance.

Supply support for SN74GTLPH16945GR 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 innovation in high-speed interface technology.

The SN74GTLPH16945GR belongs to TI's Widebus™ family of high-speed bus transceivers, engineered specifically for GTLP-based backplane interconnects in carrier-class and industrial systems demanding live insertion, signal integrity, and distributed-load timing accuracy.

FAQ

What is the primary function of the SN74GTLPH16945GR in a backplane system?

The SN74GTLPH16945GR serves as a bidirectional LVTTL-to-GTLP bus transceiver, translating signals between 3.3-V LVTTL logic on plug-in cards and 1.5-V GTLP signaling on the backplane. Its dual 8-bit segments, TI-OPC™ overshoot control, and medium-drive B-port outputs (50 mA) ensure reliable high-speed data transfer across electrically uneven backplanes. The SN74GTLPH16945GR enables asynchronous communication while maintaining signal integrity and supporting live insertion.

How does the BIAS VCC pin enable live insertion for the SN74GTLPH16945GR?

The BIAS VCC pin powers internal precharge circuitry that conditions the B-port I/O pins before main VCC ramps up during card insertion. This prevents transient disturbances on the active backplane by ensuring B-port pins reach a known DC state prior to full power application. For proper operation, BIAS VCC must be applied before VCC - a sequence enforced in the SN74GTLPH16945GR's live-insertion specification - allowing safe hot-plug without resetting the system.

Can the SN74GTLPH16945GR operate with standard GTL (not GTLP) voltage levels?

Yes, the SN74GTLPH16945GR supports both GTL and GTLP modes. In GTL mode, it uses VTT = 1.2 V and VREF = 0.8 V; in GTLP mode, it uses VTT = 1.5 V and VREF = 1.0 V. The device's AC specifications are guaranteed only for GTLP, but DC operation is valid across both standards. When operating in GTL mode, users must verify that the reduced noise margin and absence of TI-OPC™ activation (which requires VTT > VREF + 0.7 V) meet system timing and signal integrity requirements for the SN74GTLPH16945GR.

What is the role of bus-hold circuitry on the A-port inputs of the SN74GTLPH16945GR?

The bus-hold circuitry on the SN74GTLPH16945GR's A-port inputs actively maintains undriven or floating LVTTL inputs at their last valid logic state, eliminating the need for external pullup or pulldown resistors. It sources or sinks up to ±75 µA to sustain logic levels, reducing component count and PCB area. This feature is especially valuable in modular systems where connectors may be partially mated or signals temporarily unconnected - ensuring deterministic behavior without external biasing for the SN74GTLPH16945GR.

Why does the SN74GTLPH16945GR specify different timing values for lumped vs. distributed loads?

The SN74GTLPH16945GR's timing parameters differ because real backplanes behave as distributed RLC networks-not simple capacitive loads. The datasheet provides two sets: one for CL = 30 pF (lumped), and another derived from TI-SPICE models simulating a 19 Ω distributed load (Figure 3). The distributed-load values (e.g., tPLH = 4.3 ns) reflect actual performance in typical backplane geometries, where transmission-line effects dominate. Designers must use the distributed-load specs for accurate timing closure in systems using the SN74GTLPH16945GR on physical backplanes.