Texas Instruments LP2997M/NOPB

Overview

LP2997M/NOPB from Texas Instruments is a linear DDR-II termination regulator designed specifically for SSTL-18 bus termination. It sources and sinks up to ±500 mA continuous current, regulates VTT to VDDQ/2 (e.g., 0.9 V at VDDQ = 1.8 V), and features integrated VREF output and active-low shutdown for Suspend-to-RAM functionality in memory subsystems.

For engineers reviewing the LP2997M/NOPB datasheet, LP2997M/NOPB pinout, LP2997M/NOPB application, or LP2997M/NOPB equivalent, this page delivers verified electrical parameters, SOIC-8 package details, DDR-II memory interface context, thermal performance data, and validated alternative options for termination voltage regulation.

Technical Context

The LP2997M/NOPB implements a dual-rail linear topology: AVIN powers analog control circuitry (2.2–5.5 V), while PVIN supplies the output stage (≤AVIN), enabling thermal separation and reduced junction heating. Its high-speed op-amp and shoot-through–protected output stage deliver fast transient response required by DDR-II SDRAM load steps.

VDDQ feeds an internal 50kΩ/50kΩ resistor divider to generate a precise buffered VREF = VDDQ/2, which remains active during shutdown. VSENSE enables remote sensing at the bus midpoint to compensate for IR drop across long VTT planes-critical for maintaining ±25 mV VTT regulation accuracy under ±500 mA load.

Key Specifications

Pinout & Package

LP2997M/NOPB is packaged in an 8-pin SOIC (D) package with exposed pad not connected internally (non-PowerPAD variant per /NOPB suffix and D package code). Pin 1 is located at the top-left corner adjacent to the index notch.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar DDR-II termination regulator applications.

Compared with TPS51100PWR and LM1085IT-ADJ, LP2997M/NOPB delivers a purpose-built, pin-compatible DDR-II termination regulator with integrated VREF, VSENSE, and STR functionality - eliminating external components, simplifying layout, and guaranteeing JEDEC SSTL-18 compliance without noise or configuration trade-offs.

Availability

LP2997M/NOPB is available at Aetrix Electronics and suitable for DDR-II memory termination, server DIMM designs, and industrial embedded controllers requiring stable component supply, JEDEC-compliant voltage accuracy, and Suspend-to-RAM support.

Supply support for LP2997M/NOPB 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 high-reliability silicon solutions for industrial, automotive, and communications markets.

The LP2997M/NOPB belongs to TI's DDR memory interface power management product line, engineered specifically to meet JEDEC SSTL-18 termination requirements with integrated reference, sensing, and power-state control.

FAQ

What is the primary function of the LP2997M/NOPB in a DDR-II system?

The LP2997M/NOPB serves as a dedicated linear termination regulator that sources and sinks current to maintain VTT at exactly VDDQ/2 (e.g., 0.9 V when VDDQ = 1.8 V) for JEDEC SSTL-18 compliance. It integrates VREF generation, VSENSE remote sensing, and active-low shutdown - making LP2997M/NOPB a complete, single-chip solution for DDR-II memory bus termination without external resistors or support circuitry.

How does the VSENSE pin improve regulation accuracy in LP2997M/NOPB applications?

The VSENSE pin on the LP2997M/NOPB enables remote feedback by connecting to the midpoint of the VTT termination plane, compensating for IR voltage drop across PCB traces. This ensures LP2997M/NOPB regulates VTT precisely at the load rather than at the IC output, maintaining ±25 mV accuracy even across long memory buses - a requirement unmet by local-sense regulators.

Can LP2997M/NOPB operate with different VDDQ voltages, and how does it affect VTT?

Yes - LP2997M/NOPB dynamically tracks VDDQ: VTT = VDDQ/2. At VDDQ = 1.7 V, VTT = 0.856 V (typ); at VDDQ = 1.9 V, VTT = 0.957 V (typ). This scaling ensures LP2997M/NOPB remains compliant across DDR-II voltage tolerances while maintaining fixed 0.5× ratio - confirmed in Electrical Characteristics tables for LP2997M/NOPB across 1.7–1.9 V VDDQ range.

What happens to VREF and VTT when the SD pin is asserted low on LP2997M/NOPB?

When SD is pulled low, LP2997M/NOPB places VTT in high-impedance (tri-state) mode to halt termination current flow, while VREF remains fully active and regulated at VDDQ/2. This Suspend-to-RAM behavior reduces quiescent current to ≤150 µA and preserves reference integrity for fast memory resume - a key feature documented in LP2997M/NOPB's shutdown specifications.

Is LP2997M/NOPB compatible with both SOIC-8 and SO PowerPAD-8 packages?

No - LP2997M/NOPB specifically uses the SOIC-8 (D) package without thermal pad connection (per /NOPB suffix and D package code). The SO PowerPAD-8 variant is designated LP2997MR/NOPB (DDA package). Mixing these violates thermal and electrical specs: LP2997M/NOPB has θ_JA = 151°C/W vs. 43°C/W for MR variants, requiring distinct PCB layout and thermal design.