Renesas ISL23445TFRZ

Overview

ISL23445TFRZ from Renesas Electronics (formerly Intersil) is a volatile quad digitally controlled potentiometer (DCP) with 256-tap resolution, SPI interface, and 100kΩ end-to-end resistance per channel. It operates from 1.7V to 5.5V analog supply (VCC) and 1.2V to 5.5V logic supply (VLOGIC), features 70Ω typical wiper resistance at 3.3V, and supports -40°C to +125°C industrial temperature range in a 20-lead 3×4 mm QFN package. It is used for precision gain adjustment in battery-powered instrumentation.

For engineers reviewing the ISL23445TFRZ datasheet, ISL23445TFRZ pinout, ISL23445TFRZ application, or ISL23445TFRZ equivalent, key selection considerations include its independent VLOGIC rail enabling direct low-voltage bus interfacing, shutdown mode forcing open-circuit DCP terminals, daisy-chainable SPI interface, and guaranteed monotonicity in both voltage divider and rheostat modes.

Technical Context

The ISL23445TFRZ integrates four independent DCP cores on a monolithic CMOS IC, each with an 8-bit volatile Wiper Register (WRi) directly accessible via SPI Mode 0. Wiper positioning uses make-before-break CMOS switches across resistor arrays, ensuring glitch-free transitions. Power-on default sets all WRi to 128 (mid-scale), and shutdown mode disconnects RH–RL paths while shorting RWi to RLi through internal 2kΩ resistors.

Its dual-supply architecture separates analog (VCC) and digital (VLOGIC) domains, allowing interoperability with 1.2V microcontrollers without level shifters. The SDO output is configurable as push-pull or open-drain via ACR[1], and all DCP channels share one SPI interface with chip-select (CS) control and daisy-chain capability.

Key Specifications

Pinout & Package

ISL23445TFRZ is housed in a 20-lead 3×4 mm QFN package (L20.3x4) with exposed thermal pad. Pin functions are defined per the official Renesas pinout diagram for the QFN variant.

Key Features

Applications

Equivalent & Alternatives

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

Compared with ISL23425TFRZ and AD5242BRUZ100, the ISL23445TFRZ delivers unique value through its quad-channel density, true 1.2V–5.5V VLOGIC independence, and industrial-grade thermal performance-enabling compact, low-power, mixed-voltage calibration in space-constrained embedded systems.

Availability

ISL23445TFRZ is available at Aetrix Electronics and suitable for power supply margining, sensor trimming, battery-powered instrument gain adjustment, and RF amplifier bias compensation requiring stable component supply across automotive, industrial, and medical device production cycles.

Supply support for ISL23445TFRZ 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 trusted embedded design innovation, with origins in Intersil's precision analog portfolio acquired in 2017.

The ISL23445TFRZ belongs to Renesas' XDCP™ (eXternally Digitally Controlled Potentiometer) family, engineered for high-reliability, software-configurable analog trimming in harsh-environment applications where mechanical potentiometers fail.

FAQ

What is the default wiper position of the ISL23445TFRZ at power-up?

At power-up, all four wiper registers (WR0–WR3) of the ISL23445TFRZ reset to 128 (0x80), positioning each wiper at mid-scale (50% of total resistance). This behavior is guaranteed across the full -40°C to +125°C operating range and applies regardless of VCC or VLOGIC ramp sequence, ensuring predictable startup in safety-critical systems.

Does the ISL23445TFRZ support daisy-chaining multiple devices on one SPI bus?

Yes, the ISL23445TFRZ supports daisy-chaining via its standard 4-wire SPI interface (CS, SCK, SDI, SDO). Multiple ISL23445TFRZ devices can share SCK, SDI, and CS lines, with SDO of one device connected to SDI of the next. This configuration reduces MCU pin count and simplifies layout in multi-channel calibration systems without requiring additional address decoding logic.

What is the maximum clock frequency supported by the ISL23445TFRZ SPI interface?

The ISL23445TFRZ supports up to 5 MHz SCK frequency when VLOGIC ≥ 1.7V. At lower logic supplies (1.2V ≤ VLOGIC < 1.7V), the maximum SCK frequency is reduced to 1 MHz to ensure reliable timing margins. All timing parameters-including tSU, tH, tWH, and tWL-are specified down to 1.2V VLOGIC, enabling robust operation with ultra-low-voltage microcontrollers.

How does the shutdown mode function in the ISL23445TFRZ?

In shutdown mode (enabled via SHDN bit in ACR), the ISL23445TFRZ forces each DCP into an end-to-end open circuit (RH–RL disconnected) and internally connects each RWi to its corresponding RLi through a 2kΩ series resistor. This isolates the DCP from the signal path, reducing system standby current to 1.5µA at 1.7V, while preserving WRi register values for instant recall upon exit.

Can the ISL23445TFRZ be used in rheostat mode, and what are its key specifications in that configuration?

Yes, the ISL23445TFRZ supports rheostat mode (RW–RL or RW–RH), with guaranteed monotonicity and ±0.15 LSB DNL for 100kΩ option. In this mode, it achieves 2.3 ppm/°C ratiometric temperature coefficient (TCV) and 50 ppm/°C end-to-end TCR, making it suitable for precision current-source biasing and programmable load applications where resistance linearity and thermal stability are critical.