ISL23428TFRUZ-T7A Datasheet Summary

1. General Overview

The ISL23428TFRUZ-T7A is a dual, 128-tap digitally controlled potentiometer (DCP) belonging to the ISL23428 series, developed by Renesas (formerly Intersil). It features a volatile design with low voltage, low noise, and low power consumption, integrated with an SPI Bus™ interface. The device combines two DCP cores, wiper switches, and control logic on a monolithic CMOS integrated circuit, supporting both three-terminal potentiometer and two-terminal variable resistor configurations for versatile applications in control systems, parameter adjustments, and signal processing.

2. Key Specifications

2.1 Core Parameters

• Potentiometer Configuration: Dual DCPs, 128 resistor taps per DCP
• Total Resistance: 100 kΩ (part marking: GBR)
• Power Supply:
• Temperature Range: Extended industrial range, -40°C to +125°C
• Wiper Initial Position: Powers up to mid-scale (64 tap position, 40h in hex)

2.2 Electrical Characteristics (Typical @ VCC​=3.3V, TA​=+25°C)

• Wiper Resistance: 70Ω
• Resistor Noise Density: 61 nV/√Hz (wiper at middle point)
• Integral Non-Linearity (INL): ±0.15 LSB (guaranteed monotonic)
• Differential Non-Linearity (DNL): ±0.15 LSB (guaranteed monotonic)
• Resistance Temperature Coefficient (TCR): 50 ppm/°C (wiper register set between 19h and 7Fh)
• Power Supply Reject Ratio (PSRR): -75 dB
• Digital Feed-through: -65 dB

2.3 Current Consumption

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3. Package Information

• Package Type: 16 Lead Ultra Thin Quad Flat No-Lead (UTQFN)
• Package Dimensions: 2.6mm × 1.8mm (nominal)
• Package Drawing Number: L16.2.6x1.8A
• Thermal Resistance: Typical θJA​=110°C/W, θJC​=64°C/W
• Lead Finish: NiPdAu plate-e4 (RoHS compliant, compatible with SnPb and Pb-free soldering)
• Moisture Sensitivity Level (MSL): Refer to device information page (see Tech Brief TB363 for details)

3.1 Pin Configuration (16 LD UTQFN, Top View)

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4. Functional Features

4.1 SPI Serial Interface

• Protocol: SPI mode 0, slave-only operation
• Clock Frequency: Up to 5MHz (when VLOGIC​=1.7V to 5.5V); up to 1MHz (when VLOGIC​=1.2V to 1.6V)
• Data Transfer: MSB first; supports write (2+ bytes) and read (4 bytes) operations
• Daisy Chain Support: Enables multi-device configuration without additional CS lines

4.2 Register Set

• Volatile Registers: 3 × 8-bit registers (WR0, WR1, ACR)

4.3 Shutdown Mode

• Forces DCPs into end-to-end open circuit; RWi internally connected to RLi via 2kΩ resistor
• Reduces power consumption by disconnecting DCP resistors from the circuit
• Maintains wiper register settings during shutdown; restores previous positions upon exit (recall time typ 1.5µs)

4.4 Wiper Control

• Wiper position controlled by WRi register (00h=closest to RLi, 7Fh=closest to RHi)
• “Make-before-break” switching to minimize transients
• Large signal wiper settling time: typ 300ns (from code 0 to 7Fh)
• Wiper response time: typ 3.5µs (10% to 90% of final value)

5. Application Areas

• Power supply margining
• Trimming sensor circuits
• Gain adjustment in battery-powered instruments
• RF power amplifier bias compensation

6. Ordering & Compliance Details

• Part Number: ISL23428TFRUZ-T7A
• Part Marking: GBR
• RoHS Compliance: Yes (Pb-free)
• Related Notes:
• Discontinuation Status: Active (not listed as obsolete; recommended replacement for discontinued variants like ISL23428UFRUZ-T7A)

7. Recommended Operating Conditions

• Temperature: 0°C to +125°C (extended range: -40°C to +125°C for storage)
• DCP Terminal Voltage: 0V to VCC​
• Max Wiper Current: 3mA
• Supply Ramp Rate: 0.01V/ms to 50V/ms (monotonic ramping recommended; VLOGIC​ ramp first if sequential)
• Decoupling Capacitors: 1µF parallel with 0.1µF capacitor close to VCC​ and VLOGIC​ pins