NXP Semiconductors NE57811S,518

Overview

NE57811S,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,518 datasheet, NE57811S,518 pinout, NE57811S,518 application, or NE57811S,518 equivalent, this device is critical for stable DDR bus termination where fast transient response, tight output accuracy (±15 mV), low quiescent current in shutdown (1.2 mA), and thermal robustness in SPAK-5 package are essential selection criteria.

Technical Context

The NE57811S,518 operates as a precision linear "power op-amp" that sources and sinks current instantaneously to maintain VTT = VDD/2 under dynamic DDR bus loading-enabling operation without external inductors or switching FETs. Its internal resistor divider sets the reference, and the buffered RefOut provides a stable 1/2 VDD reference for other memory support circuitry.

It employs thermal shutdown at +150 °C with 20 °C hysteresis and current limiting at 3.6–5.6 A to protect against inrush and overload. Load regulation is ±6 mV at ±1.0 A and ±18 mV at ±3.5 A, supporting stable operation across DDR memory bus states with up to 192 terminated lines.

Key Specifications

Pinout & Package

The NE57811S,518 is housed in a thermally enhanced SPAK-5 (SOT756) plastic surface-mount package with an exposed thermal pad electrically connected to VSS. The package supports high-power dissipation (3.3 W max) and simplifies thermal design in space-constrained DIMM layouts.

Key Features

Applications

Equivalent & Alternatives

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

Compared with ISL6537CRZ and TPS51100PWR, the NE57811S,518 delivers simpler, lower-noise, inductor-free termination ideal for cost-sensitive commercial DDR-I/II platforms where thermal design can accommodate its linear dissipation profile.

Availability

NE57811S,518 is available at Aetrix Electronics and suitable for desktop microcomputer systems, workstations, and embedded systems requiring stable component supply for DDR memory termination.

Supply support for NE57811S,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 (originally Philips Semiconductors) is a global semiconductor leader focused on secure connectivity solutions for automotive, industrial, and consumer applications.

The NE57811S,518 belongs to NXP's legacy DDR power management portfolio, engineered specifically to simplify high-speed memory interface design by integrating precision termination regulation, protection, and reference functions into a single linear IC.

FAQ

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

The NE57811S,518 serves as a dedicated linear termination regulator that generates VTT at exactly half the DDR memory supply voltage (VDD/2) to terminate the memory bus. It sources and sinks up to ±3.5 A to maintain signal integrity across DDR-I and DDR-II interfaces, eliminating the need for discrete op-amps and resistor networks. Its design directly supports JEDEC-compliant DDR termination requirements.

Does the NE57811S,518 require external inductors or switching components?

No, the NE57811S,518 is a fully integrated linear regulator and does not require external inductors, switching FETs, or compensation networks. Its architecture relies on a high-gain power op-amp topology with internal feedback, enabling fast transient response and stable operation using only ceramic and bulk capacitors. This simplifies layout and reduces EMI compared to switching alternatives.

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

When the SHTDWN pin is pulled low, the NE57811S,518 disables its VTT output amplifier and places VTT in high-impedance (3-state) mode, reducing total quiescent current to ≤1.35 mA. RefOut remains active, providing VDD/2 reference. If left unconnected, an internal 10 kΩ pull-up to VDD keeps the device enabled. This feature enables dynamic power gating during memory idle states without disrupting system reference rails.

What is the maximum allowable VDD voltage for the NE57811S,518?

The absolute maximum VDD voltage for the NE57811S,518 is +3.6 V, as specified in its maximum ratings table. Operation is guaranteed across 1.6 V to 3.6 V, supporting both DDR-I (2.5 V) and DDR-II (1.8 V) memory supplies. Exceeding 3.6 V risks permanent damage; derating is recommended for long-term reliability at elevated temperatures.

Can the NE57811S,518 be used with DDR3 memory systems?

The NE57811S,518 is not designed for DDR3, which requires VTT = VDDQ/2 where VDDQ = 1.5 V and tighter output accuracy (±10 mV). While its VDD range covers 1.5 V, its specified accuracy is ±15 mV and its current limit and thermal design target DDR-I/II use cases. For DDR3, NXP recommends newer regulators like the TPS51100, which meets DDR3-specific tolerances and timing requirements.