Texas Instruments LP2998QMR/NOPB

Overview

LP2998QMR/NOPB from Texas Instruments is a linear DDR bus termination regulator designed for SSTL-2, SSTL-18, DDR3, and DDR3L memory systems. It delivers ±1.5 A continuous and ±3 A peak sink/source current to VTT while regulating VTT = VDDQ/2 with ≤30 mV output offset, 0.75 V VREF output, and thermal shutdown at 165°C - used in motherboard DIMM termination networks.

For engineers reviewing the LP2998QMR/NOPB datasheet, LP2998QMR/NOPB pinout, LP2998QMR/NOPB application, or LP2998QMR/NOPB equivalent, key selection considerations include VDDQ tracking accuracy, VSENSE remote sensing capability, active-low SD for Suspend-to-RAM mode, SO PowerPAD-8 thermal performance (RθJA = 43°C/W), and dual-rail AVIN/PVIN input architecture.

Technical Context

The LP2998QMR/NOPB integrates a high-speed op-amp feedback loop with internal 50 kΩ resistor divider to generate VREF = VDDQ/2 and regulate VTT precisely to that reference. Its output stage prevents shoot-through during bidirectional current transitions required by DDR bus signaling.

It uses separate AVIN (analog control supply) and PVIN (power output rail) inputs to minimize thermal dissipation and enable flexible system-level power partitioning - critical for maintaining stable VTT under fast load transients up to 3 A while supporting DDR1–DDR3L standards.

Key Specifications

Pinout & Package

LP2998QMR/NOPB uses an 8-pin SO PowerPAD™ package (4.89 mm × 3.90 mm) with exposed thermal pad (EP) connected to GND for enhanced heat dissipation (RθJA = 43°C/W).

Key Features

Applications

Equivalent & Alternatives

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

Compared with TPS51200DRCR, LP2998QMR/NOPB provides integrated VREF buffering and VSENSE remote sensing essential for DDR compliance, while LM1085IT-ADJ lacks all DDR-specific features and cannot replace LP2998QMR/NOPB in termination roles without major redesign.

Availability

LP2998QMR/NOPB is available at Aetrix Electronics and suitable for DDR memory termination, automotive infotainment systems, and FPGA-based embedded designs requiring stable component supply, long-lifecycle support, and AEC-Q100-aligned reliability.

Supply support for LP2998QMR/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 company specializing in analog and embedded processing technologies, with leadership in power management, signal chain, and interface solutions.

The LP2998QMR/NOPB belongs to TI's DDR termination regulator product line, engineered specifically for JEDEC-compliant memory bus termination in computing, automotive, and industrial platforms - emphasizing precision VDDQ/2 tracking, bidirectional current handling, and thermal robustness.

FAQ

What is the function of the VSENSE pin on the LP2998QMR/NOPB?

The VSENSE pin on the LP2998QMR/NOPB provides remote feedback for improved load regulation. It connects to the midpoint of the VTT bus to compensate for IR voltage drop along PCB traces, ensuring VTT remains within ±30 mV of target across the entire DDR bus - a requirement for JEDEC SSTL compliance. If unused, VSENSE must be tied directly to VTT.

Does the LP2998QMR/NOPB support DDR3L memory systems?

Yes, the LP2998QMR/NOPB supports DDR3L termination with VDDQ as low as 1.35 V, delivering VTT = 0.675 V (nominal) with ±30 mV offset. Its electrical characteristics table explicitly specifies VTT and VREF performance at 1.35 V, 1.5 V, and 1.6 V VDDQ levels - meeting JEDEC DDR3L SSTL-15 specifications.

How does the SD pin affect VREF and VTT operation in the LP2998QMR/NOPB?

When SD is pulled low on the LP2998QMR/NOPB, VTT enters high-impedance (tri-state) mode while VREF remains fully active and regulated - enabling Suspend-to-RAM functionality. Quiescent current drops to 115–150 µA, and VREF continues supplying the chipset and DIMMs, preserving memory data integrity without external reference circuitry.

What is the maximum continuous output current for the LP2998QMR/NOPB at 125°C junction temperature?

The LP2998QMR/NOPB delivers ±1.5 A continuous current at 125°C junction temperature when mounted on a SO PowerPAD-8 board with proper thermal vias and copper area. Its maximum continuous current is thermally limited - at 125°C ambient and RθJA = 43°C/W, power dissipation must stay below ~1.16 W to avoid triggering 165°C thermal shutdown.

Can the LP2998QMR/NOPB be used with separate AVIN and PVIN supplies?

Yes, the LP2998QMR/NOPB supports independent AVIN and PVIN supplies: AVIN powers internal analog circuitry (recommended 2.2–5.5 V), while PVIN supplies the output stage (0–AVIN). This separation reduces thermal load and improves noise immunity - for example, AVIN = 2.5 V and PVIN = 3.3 V increases max continuous current but requires thermal derating per RθJA = 43°C/W.