Renesas ISL23315UFUZ-T7A

Overview

ISL23315UFUZ-T7A from Renesas (formerly Intersil) is a volatile, low-voltage, I²C-controlled digital potentiometer with 256 taps, 50 kΩ end-to-end resistance, 10-lead µTQFN package, and -40°C to +125°C operation. It functions as a programmable three-terminal potentiometer or two-terminal rheostat in precision biasing and margining circuits for RF power amplifiers and laser diodes.

For engineers reviewing the ISL23315UFUZ-T7A datasheet, ISL23315UFUZ-T7A pinout, ISL23315UFUZ-T7A application, or ISL23315UFUZ-T7A equivalent, key selection criteria include its dual-supply architecture (VCC = 1.7–5.5 V, VLOGIC = 1.2–5.5 V), 70 Ω typical wiper resistance at 3.3 V, shutdown mode with internal RW–RL short, ±0.15 LSB DNL in voltage divider mode, and 10 Ld µTQFN thermal performance (θJA = 145°C/W).

Technical Context

The ISL23315UFUZ-T7A implements a resistor ladder with CMOS switches operating in "make-before-break" mode, controlled by an 8-bit volatile Wiper Register (WR) accessible via I²C. Its dual-supply design isolates logic-level compatibility (down to 1.2 V on VLOGIC) from analog supply (VCC), enabling direct interfacing with low-voltage microcontrollers without level shifters.

It supports up to four devices per I²C bus using A0/A1 address pins, enters mid-scale (128) on power-up, and features a dedicated Shutdown bit (ACR[6]) that forces RH–RL open while shorting RW to RL through ~2 kΩ. Shutdown current is <2.8 µA max, and wiper settling time is 1.5 µs after recall from shutdown.

Key Specifications

Pinout & Package

ISL23315UFUZ-T7A uses a 10-lead 2.1 mm × 1.6 mm µTQFN package (Pb-free, RoHS compliant) with exposed thermal pad. Pin numbering follows top-view orientation per datasheet Figure 1 (µTQFN layout).

Key Features

Applications

Equivalent & Alternatives

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

Compared with ISL23315UFUZ-T7A, ISL23315TFUZ-TK offers higher resistance for reduced current consumption but larger footprint, while AD5175BRMZ-50 adds nonvolatility and SPI at the cost of higher tempco and no shutdown-mode RW–RL short.

Availability

ISL23315UFUZ-T7A is available at Aetrix Electronics and suitable for RF power amplifier biasing, laser diode control, LCD panel calibration, and power supply margining requiring stable component supply across extended temperature and long product lifecycles.

Supply support for ISL23315UFUZ-T7A 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 acquired Intersil in 2017 and maintains its precision analog portfolio, including digitally controlled potentiometers optimized for industrial and communications infrastructure.

The ISL23315 series was designed for high-reliability analog trimming in thermally demanding environments-targeting RF, optical, and power management subsystems where low noise, wide supply range, and robust I²C interoperability are essential.

FAQ

What is the default wiper position of the ISL23315UFUZ-T7A at power-on?

The ISL23315UFUZ-T7A powers up with its volatile Wiper Register (WR) preset to 128 (0x80 hex), placing the wiper at mid-scale-i.e., approximately 25 kΩ between RL and RW, and 25 kΩ between RW and RH. This behavior is guaranteed across all operating conditions and eliminates startup transients in sensitive bias networks.

Does the ISL23315UFUZ-T7A support true 1.2 V I²C bus operation?

Yes-the ISL23315UFUZ-T7A accepts VLOGIC down to 1.2 V, with validated input thresholds (VIL ≤ 0.3×VLOGIC, VIH ≥ 0.7×VLOGIC) and VOL ≤ 0.2×VLOGIC at 1.5 mA. This allows direct connection to 1.2 V microcontrollers without level-shifting circuitry, maintaining full I²C timing compliance at 400 kHz.

How does the shutdown mode function in the ISL23315UFUZ-T7A?

In shutdown mode (activated by setting SHDN bit in Access Control Register), the ISL23315UFUZ-T7A opens the RH–RL path and internally shorts RW to RL via a ~2 kΩ resistor. Wiper register contents are retained, and recovery takes 1.5 µs. Shutdown current remains below 2.8 µA, making it ideal for standby-state power gating.

Can the ISL23315UFUZ-T7A be used in rheostat mode?

Yes-the ISL23315UFUZ-T7A operates as a two-terminal variable resistor by connecting either RH or RL to the same node as RW (leaving the other terminal unconnected). In this configuration, it delivers 50 kΩ total resistance with ±0.3 MI differential non-linearity and 100 ppm/°C resistance tempco-validated per datasheet Table "Rheostat Mode" specifications.

What is the maximum capacitive load the ISL23315UFUZ-T7A SDA/SCL lines can drive?

The ISL23315UFUZ-T7A specifies a maximum bus capacitance (Cb) of 400 pF for reliable 400 kHz I²C operation. Its SDA/SCL pin capacitance is 10 pF, and rise/fall times are characterized up to 250 ns. External pull-up strength must be selected accordingly-e.g., 2.2 kΩ for 3.3 V buses with ≤200 pF total load-to meet tR/tF and timing budget requirements.