FN7873 Rev 1.00 Page 1 of 20
September 11, 2015
FN7873
Rev 1.00
September 11, 2015
ISL23425
Dual, 256-Tap, Low Voltage Digitally Controlled Potentiometer (XDCP™)
DATASHEET
The ISL23425 is a volatile, low voltage, low noise, low power,
256-tap, dual digitally controlled potentiometer (DCP) with an
SPI Bus™ interface. It integrates two DCP cores, wiper switches
and control logic on a monolithic CMOS integrated circuit.
Each digitally controlled potentiometer is implemented with a
combination of resistor elements and CMOS switches. The
position of the wipers are controlled by the user through the
SPI bus interface. Each potentiometer has an associated
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
position of the wiper. When powered on, the wiper of each DCP
will always commence at mid-scale (128 tap position).
The low voltage, low power consumption, and small package
of the ISL23425 make it an ideal choice for use in battery
operated equipment. In addition, the ISL23425 has a V
LOGIC
pin allowing down to 1.2V bus operation, independent from the
V
CC
value. This allows for low logic levels to be connected
directly to the ISL23425 without passing through a voltage
level shifter.
The DCP can be used as a three-terminal potentiometer or as a
two-terminal variable resistor in a wide variety of applications
including control, parameter adjustments, and signal processing.
Applications
• Power supply margining
• Trimming sensor circuits
• Gain adjustment in battery powered instruments
• RF power amplifier bias compensation
Features
• Two potentiometers per package
• 256 resistor taps
•10k 50kor 100k total resistance
• SPI serial interface
- No additional level translator for low bus supply
- Daisy Chaining of multiple DCPs
• Maximum supply current without serial bus activity
(standby)
- 4µA @ V
CC
and V
LOGIC
= 5V
- 1.7µA @ V
CC
and V
LOGIC
= 1.7V
•Shutdown Mode
- Forces the DCP into an end-to-end open circuit and RWi is
connected to RLi internally
- Reduces power consumption by disconnecting the DCP
resistor from the circuit
•Power supply
-V
CC
= 1.7V to 5.5V analog power supply
-V
LOGIC
= 1.2V to 5.5V SPI bus/logic power supply
• Wiper resistance: 70 typical @ V
CC
= 3.3V
• Power-on preset to mid-scale (128 tap position)
• Extended industrial temperature range: -40
°C to +125°C
• 14 Ld TSSOP or 16 Ld µTQFN packages
• Pb-free (RoHS compliant)
FIGURE 1. FORWARD AND BACKWARD RESISTANCE vs TAP
POSITION, 10kΩ DCP
FIGURE 2. V
REF
ADJUSTMENT
0
2000
4000
6000
8000
10000
TAP POSITION (DECIMAL)
RESISTANCE (Ω)
0 64 128 192 256
V
REF_M
ISL28114
1 DCP
OF
ISL23325
+
-
V
REF
RL1
RW1
RH1
