DATASHEET ISL23428 FN7904 Rev 2.00 Dual, 128-Tap, Low Voltage Digitally Controlled Potentiometer (XDCP) September 23, 2015 The ISL23428 is a volatile, low voltage, low noise, low power, Features 128-tap, dual digitally controlled potentiometer (DCP) with an Two potentiometers per package SPI Bus interface. It integrates two DCP cores, wiper switches and control logic on a monolithic CMOS integrated circuit. 128 resistor taps Each digitally controlled potentiometer is implemented with a 10k 50k or 100k total resistance combination of resistor elements and CMOS switches. The SPI serial interface position of the wipers are controlled by the user through the - No additional level translator for low bus supply SPI bus interface. Each potentiometer has an associated - Daisy Chaining of multiple DCPs volatile Wiper Register (WRi, i = 0, 1) that can be directly written to and read by the user. The contents of the WRi controls the Power supply position of the wiper. When powered on, the wiper of each DCP -V = 1.7V to 5.5V analog power supply CC will always commence at mid-scale (64 tap position). -V = 1.2V to 5.5V SPI bus/logic power supply LOGIC The low voltage, low power consumption, and small package Maximum supply current without serial bus activity of the ISL23428 make it an ideal choice for use in battery (standby) operated equipment. In addition, the ISL23428 has a V LOGIC - 4A V and V = 5V pin allowing down to 1.2V bus operation, independent from the CC LOGIC V value. This allows for low logic levels to be connected - 1.7A V and V = 1.7V CC CC LOGIC directly to the ISL23428 without passing through a voltage Shutdown Mode level shifter. - Forces the DCP into an end-to-end open circuit and RWi is The DCP can be used as a three-terminal potentiometer or as a connected to RLi internally two-terminal variable resistor in a wide variety of applications - Reduces power consumption by disconnecting the DCP including control, parameter adjustments, and signal processing. resistor from the circuit Wiper resistance: 70 typical V = 3.3V Applications CC Power-on preset to mid-scale (64 tap position) Power supply margining Extended industrial temperature range: -40C to +125C Trimming sensor circuits 14 Ld TSSOP or 16 Ld UTQFN packages Gain adjustment in battery powered instruments Pb-free (RoHS compliant) RF power amplifier bias compensation 10000 V REF 8000 6000 RH - V REF M 4000 RW ISL23428 + 2000 ISL28114 RL 0 032 64 96 128 TAP POSITION (DECIMAL) FIGURE 1. FORWARD AND BACKWARD RESISTANCE vs TAP FIGURE 2. V ADJUSTMENT REF POSITION, 10k DCP FN7904 Rev 2.00 Page 1 of 21 September 23, 2015 RESISTANCE ()ISL23428 Block Diagram V V RH0 RH1 LOGIC CC SCK POWER UP SDI INTERFACE, SPI CONTROL WR0 SDO WR1 INTERFACE AND VOLATILE VOLATILE STATUS CS REGISTER REGISTER LOGIC AND AND WIPER WIPER CONTROL CONTROL CIRCUITRY CIRCUITRY RW0 RL0 RW1 RL1 GND Pin Configurations Pin Descriptions TSSOP UTQFN SYMBOL DESCRIPTION ISL23428 (14 LD TSSOP) 1, 7 5, 6, 15 GND Ground pin TOP VIEW 216 V SPI bus/logic supply LOGIC Range 1.2V to 5.5V GND 1 14 V CC 3 1 SDO Logic Pin - Serial bus data output V 2 13 RL0 LOGIC (configurable) SDO 3 12 RW0 4 2 SCK Logic Pin - Serial bus clock input SCK 4 11 RH0 5 3 SDI Logic Pin - Serial bus data input SDI 5 10 RH1 64 CS Logic Pin - Active low chip select CS 6 9 RW1 8 8 RL1 DCP1 low terminal GND 7 8 RL1 99RW1 DCP1 wiper terminal 10 10 RH1 DCP1 high terminal ISL23428 11 11 RH0 DCP0 high terminal (16 LD UTQFN) 12 12 RW0 DCP0 wiper terminal TOP VIEW 13 13 RL0 DCP0 low terminal 14 14 V Analog power supply. CC Range 1.7V to 5.5V 1 12 - 7 NC Not Connected SDO RW0 SCK 2 11 RH0 SDI 3 10 RH1 CS 4 9 RW1 FN7904 Rev 2.00 Page 2 of 21 September 23, 2015 GND 5 16 V LOGIC GND 6 15 GND NC 7 14 V CC RL1 8 13 RL0