Renesas ISL95811UFRTZ

Overview

ISL95811UFRTZ from Renesas Electronics (formerly Intersil) is a single-channel, 256-tap digitally controlled potentiometer (XDCP™) with integrated 5-byte non-volatile general-purpose memory and I²C interface. It features 50 kΩ end-to-end resistance, ±0.5 LSB differential non-linearity in rheostat mode, 70 Ω typical wiper resistance at 3.3 V, and operates from 2.7 V to 5.5 V across –40°C to +125°C. It is used for precision analog trimming in power supply feedback loops, sensor calibration circuits, and programmable gain amplifiers.

For engineers reviewing the ISL95811UFRTZ datasheet, ISL95811UFRTZ pinout, ISL95811UFRTZ application, or ISL95811UFRTZ equivalent, key selection considerations include its TDFN-8 (3×3 mm) package, hardware write-protection (WP) pin, non-volatile wiper recall at power-up, low 10 µA standby current, and compatibility with standard I²C bus timing at up to 400 kHz.

Technical Context

The ISL95811UFRTZ implements a monolithic CMOS resistor ladder with CMOS switch matrix, enabling precise wiper positioning via an 8-bit volatile Wiper Register (WR) and non-volatile Initial Value Register (IVR). Its I²C slave interface supports standard-mode (400 kHz) operation with open-drain SDA/SCL and hardware write protection via the active-low WP pin.

It operates in two primary analog configurations: voltage divider mode (RH–RL–RW) and rheostat mode (RW–RL or RW–RH), with monotonic tap response, <1 µs wiper settling time, and ratiometric temperature coefficient of ±4 ppm/°C in divider mode. The device recalls IVR contents to WR on power-up after V_POR ≥ 2.6 V, with 3 ms delay to full readiness.

Key Specifications

Pinout & Package

ISL95811UFRTZ is housed in an 8-lead 3×3 mm TDFN package (Pb-free, RoHS compliant) with exposed die pad internally connected to GND. Pin assignments are validated per FN6759 Rev 1.00, Page 2 (TDFN top view).

Key Features

Applications

Equivalent & Alternatives

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

Compared with ISL95811UFRTZ, ISL95810UFRTZ reduces feature count (no GP memory) while maintaining pinout and core DCP functionality, whereas AD5175BRMZ-50 trades hardware write protection and endurance for broader vendor support-but requires additional external protection logic for mission-critical calibration retention.

Availability

ISL95811UFRTZ is available at Aetrix Electronics and suitable for power supply trimming, sensor calibration, programmable gain amplification, and LED bias control requiring stable component supply across extended temperature ranges and long product lifecycles.

Supply support for ISL95811UFRTZ 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

Renesas Electronics Corporation is a global semiconductor leader delivering microcontrollers, analog power, and SoC solutions for industrial, automotive, and infrastructure markets.

The ISL95811UFRTZ belongs to Renesas' XDCP™ digitally controlled potentiometer family, designed specifically for replacing mechanical trimmers in high-reliability, programmable analog signal conditioning applications where non-volatile calibration storage and I²C configurability are essential.

FAQ

What is the default wiper position of the ISL95811UFRTZ at power-up?

At power-up, the ISL95811UFRTZ first resets the Wiper Register (WR) to 0x80 (128 decimal), placing the wiper near the center of the resistor ladder. Once V_CC exceeds the power-on recall threshold (min 2.6 V), it loads the stored value from the non-volatile Initial Value Register (IVR) into WR-so the final position depends on the last programmed IVR value. The device ships with IVR pre-programmed to 0x80.

Does the ISL95811UFRTZ require external pull-up resistors on SDA and SCL lines?

Yes, the ISL95811UFRTZ requires external pull-up resistors on both SDA and SCL pins because they are open-drain outputs. Recommended values range from ~2 kΩ (for 400 pF bus capacitance) to ~20 kΩ (for 40 pF), per I²C timing constraints in FN6759 Rev 1.00, Page 5. Failure to install pull-ups will prevent reliable I²C communication with the ISL95811UFRTZ.

Can the ISL95811UFRTZ be used in rheostat mode, and what are the key specifications in that configuration?

Yes, the ISL95811UFRTZ supports rheostat mode (RW–RL or RW–RH). In this configuration, it delivers ±0.5 MI differential non-linearity, ±1 MI integral non-linearity, and ±45 ppm/°C resistance temperature coefficient over –40°C to +125°C. The 50 kΩ total resistance remains fixed, and wiper resistance stays ≤200 Ω max-making it suitable for precision current-setting applications.

How does the write protection (WP) pin function on the ISL95811UFRTZ?

The WP pin on the ISL95811UFRTZ is an active-low hardware lock: when held LOW, all I²C write operations-including volatile WR updates and non-volatile IVR/GP register writes-are ignored, and the device responds with no ACK. This provides deterministic, EMC-robust protection against spurious writes, independent of firmware state. Pulling WP HIGH enables normal I²C write functionality.

What is the maximum allowable capacitive load on the SDA and SCL lines for reliable operation of the ISL95811UFRTZ?

The ISL95811UFRTZ supports a total bus capacitance (Cb) of up to 400 pF on SDA or SCL, as specified in FN6759 Rev 1.00, Page 5. Exceeding this limit risks violating rise/fall time (t_R/t_F ≤ 250 ns) and setup/hold timing requirements, potentially causing I²C communication failures. For Cb = 400 pF, pull-up resistors should be ≤2.5 kΩ; for lower capacitance, higher values (up to 20 kΩ) are permissible.