Renesas X9318WP8I

Overview

X9318WP8I from Intersil is a digitally controlled potentiometer (XDCP™) implementing a 10 kΩ end-to-end resistance with 100 wiper tap points, nonvolatile wiper position storage, and 3-wire serial interface (CS/U/D/INC). It operates from 4.5–5.5 V, supports terminal voltages up to +8 V, and delivers ±20% RTOTAL tolerance with temperature-compensated resistor array. Used for precision DC bias adjustment in industrial sensor signal conditioning circuits.

For engineers reviewing the X9318WP8I datasheet, X9318WP8I pinout, X9318WP8I application, or X9318WP8I equivalent, this page provides verified specifications, validated pin functions, confirmed operating temperature range (–40°C to +85°C), package mapping to 8-lead PDIP, and two field-validated alternative parts for trim-critical analog systems.

Technical Context

The X9318WP8I integrates a 99-element resistor ladder with make-before-break wiper switching, a 7-bit up/down counter, and nonvolatile memory for power-up recall. Its control logic responds to negative-edge-triggered INC pulses while U/D sets direction and CS enables selection or initiates store-on-high transitions.

It implements true three-terminal potentiometer operation (RH/RW/RL) or two-terminal variable resistor mode, with wiper resistance of 40 Ω typical and ratiometric temperature coefficient of ±20 ppm/°C - enabling stable voltage division across its full –40°C to +85°C industrial temperature range.

Key Specifications

Pinout & Package

Package: 8-lead plastic dual in-line package (PDIP), 0.300" wide, RoHS-compliant (Pb-free plus anneal).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar digitally controlled potentiometer applications.

Compared with AD5241BRMZ10 and MCP41010-I/P, the X9318WP8I offers guaranteed power-up wiper recall without host intervention, simpler 3-wire control (no protocol overhead), and proven reliability in long-life industrial deployments - making it optimal for unattended or safety-critical trim applications where initialization failure is unacceptable.

Availability

X9318WP8I is available at Aetrix Electronics and suitable for LCD bias control, DC bias adjustment, and voltage regulator output control requiring stable component supply across extended temperature ranges and multi-year production cycles.

Supply support for X9318WP8I 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

Intersil Corporation (now part of Renesas Electronics) is a U.S.-based analog and mixed-signal semiconductor company specializing in power management, precision analog, and interface ICs.

The X9318 family was designed for solid-state replacement of mechanical potentiometers in industrial, medical, and test equipment - emphasizing nonvolatile trim retention, temperature stability, and robust serial control under harsh operating conditions.

FAQ

What is the maximum allowable voltage on the RH, RL, and RW terminals of the X9318WP8I?

The X9318WP8I supports terminal voltages from VSS (ground) up to +8 V on RH, RL, and RW pins. This rating is absolute and independent of VCC, allowing use in circuits where the potentiometer operates across higher analog rails - such as +8 V LCD bias supplies - while VCC remains at +5 V. Exceeding +8 V risks permanent damage per Absolute Maximum Ratings.

Does the X9318WP8I retain its wiper position after power cycling?

Yes, the X9318WP8I automatically recalls the last stored wiper position from nonvolatile memory upon power-up. This occurs without host intervention because the device loads the stored value into its internal counter during the power-up stabilization period (≤500 µs after VCC reaches regulation). The X9318WP8I does not require external initialization commands to restore trim settings.

What is the recommended power-up sequence for reliable operation of the X9318WP8I?

The X9318WP8I requires VCC and VSS to be applied before any signals are driven on CS, U/D, or INC. Specifically, bring CS and INC high *before or concurrently* with VCC ramp-up to prevent spurious wiper movement or unintended store operations. The device becomes fully functional 1 ms after VCC reaches final value, and wiper position stabilizes within 500 µs of power-up completion.

Can the X9318WP8I be used as a two-terminal variable resistor?

Yes, the X9318WP8I supports two-terminal operation by connecting either RH or RL to RW (wiper), effectively using only one fixed terminal and the wiper. In this mode, resistance varies from near-zero (wiper at connected terminal) to RTOTAL (wiper at opposite terminal). The 40 Ω typical wiper resistance and make-before-break switching ensure smooth, glitch-free transitions - ideal for current-setting applications like laser diode bias.

How is wiper position stored in nonvolatile memory on the X9318WP8I?

Wiper position is stored when CS transitions from LOW to HIGH *while INC is held HIGH*. This store command writes the current 7-bit counter value to nonvolatile memory. No additional clock edges or timing windows are required - the store completes within 20 ms (tCPHS). Once stored, the value persists for 100 years and is automatically loaded at next power-up, making the X9318WP8I self-restoring without firmware dependency.