NXP Semiconductors NE57811S/N1,518

Overview

NE57811S/N1,518 from NXP Semiconductors (formerly Philips) is a linear DDR memory termination regulator designed to supply VTT at precisely half the DDR memory supply voltage (VDD/2) for DDR-I (2.5 V) and DDR-II (1.8 V) systems. It delivers ±3.5 A output current, features integrated overtemperature and overcurrent protection, and includes a shutdown pin and buffered reference output (RefOut). It serves as the core termination power source on DIMM modules in high-speed memory subsystems.

For engineers reviewing the NE57811S/N1,518 datasheet, NE57811S/N1,518 pinout, NE57811S/N1,518 application, or NE57811S/N1,518 equivalent, key selection criteria include its 1/2-VDD tracking accuracy (±15 mV), fast transient response for 266+ MHz bus operation, thermal robustness in SPAK-5 package, and compatibility with both DDR-I and DDR-II termination topologies requiring bidirectional current sourcing/sinking.

Technical Context

The NE57811S/N1,518 implements a precision linear "power op-amp" architecture with an internal resistor divider that fixes VTT = VDD/2, referenced to VSS. Its output stage is fully bidirectional-capable of sourcing and sinking up to ±3.5 A-enabling instantaneous current delivery to match DDR bus state transitions without external switching components.

Protection is implemented via a 4.5 A typical current limit (3.6–5.6 A range) and thermal shutdown at +150 °C with 20 °C hysteresis. The RefOut pin provides a buffered copy of the internal VDD/2 reference, usable by memory controllers or other support ICs, while SHTDWN enables low-power mode with <800 µA quiescent current.

Key Specifications

Pinout & Package

The NE57811S/N1,518 is housed in a thermally enhanced SPAK-5 (SOT756) plastic surface-mount package with a thermal backside pad electrically connected to VSS. This 5-lead single-ended package supports high-power density mounting and requires no external inductors or FETs.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TPS51100DGQ and ISL6537CRZ, the NE57811S/N1,518 uniquely combines ±3.5 A bidirectional capability, integrated RefOut, and SOT756 thermal packaging-making it optimal for space-constrained, low-EMI DDR-I/II implementations where component count and layout simplicity are prioritized over peak efficiency.

Availability

NE57811S/N1,518 is available at Aetrix Electronics and suitable for desktop microcomputer systems, workstations, and servers requiring stable component supply, consistent DDR termination performance, and long-term lifecycle support for legacy DDR-I/DDR-II platforms.

Supply support for NE57811S/N1,518 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

NXP Semiconductors, formerly Philips Semiconductors, is a global leader in high-performance analog and mixed-signal ICs for automotive, industrial, and computing applications.

The NE57811S/N1,518 belongs to NXP's DDR memory interface power portfolio, engineered specifically to simplify termination power design in DDR-I and DDR-II systems while meeting JEDEC voltage accuracy and transient response requirements.

FAQ

What is the primary function of the NE57811S/N1,518 in a DDR memory system?

The NE57811S/N1,518 functions as a linear DDR termination regulator that generates VTT at exactly half the DDR memory supply voltage (VDD/2). It sources and sinks up to ±3.5 A to maintain stable termination voltage across DDR data, address, and control buses. Its bidirectional output stage, integrated reference, and shutdown capability make the NE57811S/N1,518 essential for signal integrity in DDR-I (2.5 V) and DDR-II (1.8 V) systems.

Does the NE57811S/N1,518 require external components to regulate VTT to VDD/2?

No, the NE57811S/N1,518 contains an internal precision resistor divider between VDD and VSS that inherently sets VTT = VDD/2. No external resistors are needed for basic operation. The device also provides a buffered RefOut pin replicating this same VDD/2 reference, eliminating the need for external op-amps or dividers in most DDR designs.

How does the SHTDWN pin affect the operation of the NE57811S/N1,518?

When the SHTDWN pin is driven LOW, the NE57811S/N1,518 disables its VTT output amplifier and places VTT in a high-impedance (3-state) condition. Quiescent current drops to ≤1.35 mA, and the RefOut remains active. If left unconnected, an internal 10 kΩ pull-up to VDD keeps the NE57811S/N1,518 enabled. This pin enables power sequencing and low-power states in DDR memory subsystems.

What is the maximum continuous output current supported by the NE57811S/N1,518?

The NE57811S/N1,518 supports ±3.5 A continuous output current when VDD is between 2.5 V and 3.6 V. At lower VDD (1.6 V), the rated output is ±2.5 A. These values reflect sustained bidirectional current capability-not peak pulses-and are validated across the 0 °C to +70 °C operating range with appropriate PCB thermal design per JEDEC JESD51-7.

Can the NE57811S/N1,518 be used with both DDR-I and DDR-II memory standards?

Yes, the NE57811S/N1,518 is explicitly designed for compatibility with both DDR-I (VDD = 2.5 V) and DDR-II (VDD = 1.8 V) systems. Its VDD range of 1.6 V to 3.6 V, VTT accuracy of ±15 mV, and ±3.5 A output capability meet JEDEC requirements for termination voltage stability and transient response in either standard. The NE57811S/N1,518 maintains VTT = VDD/2 across both configurations without reconfiguration.