Renesas X9221AUSI

Overview

X9221AUSI from Intersil is a dual digitally controlled potentiometer (XDCP™) with 64-tap resolution per channel, 2-wire serial interface, and nonvolatile storage of four wiper positions per pot. It operates at 5V ±10%, supports -40°C to +85°C industrial temperature range, and is packaged in 20-lead SOIC for precision analog trimming in embedded control systems.

For engineers reviewing the X9221AUSI datasheet, X9221AUSI pinout, X9221AUSI application, or X9221AUSI equivalent, this device delivers deterministic wiper positioning, EEPROM-backed configuration retention, and I²C-compatible communication-critical for recalibration-critical instrumentation, programmable gain stages, and factory-trimmed sensor signal chains.

Technical Context

The X9221AUSI integrates two independent 63-segment resistor arrays with dedicated volatile Wiper Counter Registers (WCR) and four nonvolatile Data Registers (DR0–DR3) per pot. Each WCR controls FET-switched tap selection via 6-bit decoded output, enabling precise 1.6% step resolution.

Its 2-wire interface implements full I²C slave protocol compliance-including START/STOP detection, ACK polling during 10ms nonvolatile writes, and Increment/Decrement mode for real-time fine-tuning. Addressing uses A0–A3 pins to set LSBs of fixed 0101xxxx binary slave address.

Key Specifications

Pinout & Package

Package: 20-lead SOIC (300-mil), RoHS-compliant, MDP0027 footprint. Pin 1 marked with index notch; pins 11–20 are mirrored across centerline relative to pins 1–10.

Key Features

Applications

Equivalent & Alternatives

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

Compared with AD5242BRUZ10 and MCP42010-I/P, the X9221AUSI uniquely combines dual 64-tap channels, integrated nonvolatile register storage, and real-time increment/decrement control-all in a compact 20-lead SOIC package-making it optimal for space-constrained, self-calibrating analog systems.

Availability

X9221AUSI is available at Aetrix Electronics and suitable for industrial sensor calibration, programmable power supplies, audio signal processing, and medical instrumentation requiring stable component supply across extended temperature ranges and long product lifecycles.

Supply support for X9221AUSI 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) designs high-performance analog and mixed-signal ICs for industrial, computing, and communications markets, with ISO9001-certified manufacturing.

The X9221AUSI belongs to Intersil's XDCP™ family of digitally controlled potentiometers, engineered specifically for replacing mechanical pots in recalibration-sensitive analog signal chains where nonvolatile configuration retention and deterministic wiper control are essential.

FAQ

What is the default wiper position after power-up for the X9221AUSI?

The X9221AUSI automatically loads the contents of Data Register 0 (DR0) into the Wiper Counter Register (WCR) for each potentiometer upon power-up. This ensures a known, factory-programmed or user-defined wiper position without requiring host initialization. The DR0 value persists across power cycles due to its nonvolatile EEPROM storage, making the X9221AUSI suitable for systems demanding repeatable startup behavior. This behavior is guaranteed across the full -40°C to +85°C operating range.

Does the X9221AUSI support true I²C bus compatibility, including ACK polling?

Yes, the X9221AUSI fully complies with standard-mode I²C protocol: it recognizes START/STOP conditions, responds to its 8-bit slave address (0101xxxx), and issues ACK after address and command byte receipt. During nonvolatile writes (e.g., Write Data Register), it disables SDA to enable ACK polling-allowing the master to issue repeated START+address sequences until ACK confirms write completion (~10ms). This eliminates timeout-based waiting and ensures robust multi-master bus coordination in the X9221AUSI implementation.

Can the X9221AUSI be used as a two-terminal variable resistor, and what are the current limits?

Yes, the X9221AUSI supports two-terminal (rheostat) operation by connecting either VH/RH or VL/RL to VW/RW, leaving the other terminal open. Its absolute maximum wiper current is ±3mA per channel, with 50mW total power rating per potentiometer at +25°C. Exceeding these limits risks thermal drift or permanent damage. The wiper resistance is 40–130Ω, and voltage on any terminal must stay within -3.0V to +5.0V referenced to VSS. These constraints define safe operating boundaries for current-sensing or LED bias applications using the X9221AUSI.

How many unique wiper positions can be stored nonvolatively in the X9221AUSI?

The X9221AUSI provides four nonvolatile Data Registers (DR0–DR3) per potentiometer, allowing up to four distinct wiper positions to be stored per channel. Each register retains its value for 100 years under normal conditions and withstands 100,000 write cycles. These registers can hold factory calibration points, user presets, or fail-safe defaults. Values are transferred to the volatile WCR via XFR instructions, and DR0 is automatically loaded at power-up-enabling flexible, persistent configuration management in the X9221AUSI.

What is the significance of the "RES" pins on the X9221AUSI, and how should they be handled?

The X9221AUSI has four reserved pins (pins 12, 13, 14, and 18) labeled RES in the datasheet. These pins are internally unconnected and must not be bonded or routed on PCBs. Per Intersil's specification, they should remain floating or be tied to VSS (ground) for mechanical stability-never connected to VCC, signals, or pull-ups. Incorrect handling may cause latch-up or undefined behavior. This pin assignment is fixed for the 20-lead SOIC package (MDP0027) and applies identically to all variants including the X9221AUSI.