Renesas X9221AUP

Overview

X9221AUP from Intersil is a dual digitally controlled potentiometer (XDCP™) with 64-tap resolution per channel, 2-wire serial interface, and 50 kΩ end-to-end resistance in a 20-lead PDIP package. It functions as two independent programmable resistive dividers for analog signal conditioning and bias adjustment in precision instrumentation and embedded control systems.

For engineers reviewing the X9221AUP datasheet, X9221AUP pinout, X9221AUP application, or X9221AUP equivalent, this device supports volatile wiper position control, nonvolatile storage of up to four settings per pot, and direct register read/write via I²C-compatible protocol - critical for recalibration-critical and field-upgradable analog front-ends.

Technical Context

The X9221AUP implements two independent 63-segment resistor arrays with decoded 6-bit wiper counter registers (WCR), each paired with four nonvolatile data registers (DR0–DR3). Wiper position is set via Write WCR (3-byte) or transferred from DRx via XFR instructions, with power-up defaulting to DR0 contents.

Its 2-wire interface uses open-drain SDA with pull-up requirement, supports slave address configuration via A0–A3 pins (0101xxxx binary prefix), and enforces ACK polling during 10 ms nonvolatile writes. Increment/Decrement mode enables real-time fine-tuning with SCL-synchronized wiper stepping.

Key Specifications

Pinout & Package

Package: 20-lead plastic DIP (PDIP), 1.020" × 0.310", MDP0031 footprint, RoHS-compliant Pb-free option available (X9221AUPZ).

Key Features

Applications

Equivalent & Alternatives

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

Compared with AD5242BRUZ10 and MCP42050-I/P, the X9221AUP uniquely delivers dual 64-tap pots with integrated nonvolatile register storage in a legacy-compatible 20-pin PDIP, enabling compact analog calibration without external memory or protocol translation.

Availability

X9221AUP is available at Aetrix Electronics and suitable for instrumentation gain calibration, audio channel balance control, programmable sensor bias networks, and embedded power supply trim requiring stable component supply across long-lifecycle industrial programs.

Supply support for X9221AUP 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 precision power management, signal conditioning, and interface applications.

The X9221AUP belongs to the XDCP™ family of digitally controlled potentiometers engineered for replacing mechanical trimmers in recalibration-sensitive analog circuits where reliability, repeatability, and nonvolatile setting retention are essential.

FAQ

What is the maximum clock frequency supported by the X9221AUP's 2-wire interface?

The X9221AUP supports a maximum SCL clock frequency of 100 kHz, as specified in its AC characteristics table. This limit ensures reliable ACK generation, proper noise filtering (100 ns glitch rejection), and stable wiper response timing (tSTPWV ≤ 1000 µs after STOP). Exceeding 100 kHz may cause communication failures or incomplete nonvolatile writes. The X9221AUP's timing margins are validated under recommended operating conditions (0°C to +70°C, VCC = 5 V ±10%).

Does the X9221AUP retain wiper position after power cycling?

Yes, the X9221AUP automatically loads the contents of Data Register 0 (DR0) into the Wiper Counter Register (WCR) at power-up, ensuring a known, repeatable starting position. However, the WCR itself is volatile - any runtime changes not explicitly written to DR0 will be lost. To preserve a custom wiper position across power cycles, the host must execute a Write Data Register command to store it in DR0 before shutdown. The X9221AUP guarantees 100-year data retention in DR0 once written.

Can the X9221AUP be used as a two-terminal variable resistor?

Yes, the X9221AUP can operate as a two-terminal variable resistor by connecting either VH/RH or VL/RL to the wiper VW/RW, leaving the unused terminal open. In this configuration, resistance varies from near-zero (WCR = 0x00 or 0x3F) to the full end-to-end value (50 kΩ). Designers must observe the ±3 mA wiper current limit and 50 mW per-pot power rating to avoid thermal drift or damage. The X9221AUP's 40–130 Ω wiper resistance minimizes insertion loss in such configurations.

How many unique slave addresses can be configured on the X9221AUP?

The X9221AUP supports 16 unique slave addresses via the A0–A3 pins, which define the least significant 4 bits of the 8-bit address. The most significant 4 bits are fixed as 0101 (binary), resulting in base address 0x50. With A0–A3 tied to VSS or VCC, addresses range from 0x50 to 0x5F. This allows up to 16 X9221AUP devices on a single 2-wire bus, provided each has a distinct A0–A3 combination and sufficient bus capacitance margin (<400 pF).

What is the purpose of the RES (reserved) pins on the X9221AUP?

The X9221AUP has five RES (reserved) pins (pins 11–13 and 15–19) that are internally unconnected and must remain floating - they are not to be tied to VCC, VSS, or any signal. Connecting them may cause unpredictable behavior, increased leakage, or latch-up due to undefined internal node coupling. This requirement is explicitly stated in the datasheet's Pin Descriptions section and applies to all variants including X9221AUP. The X9221AUP's functional integrity depends on strict adherence to this no-connect rule.