ISL23428 Datasheet, PDF (1/21 Pages) Intersil Corporation – Dual, 128-Tap, Low Voltage Digitally Controlled Potentiometer (XDCP™)

Dual, 128-Tap, Low Voltage Digitally Controlled
Potentiometer (XDCP™)
ISL23428
The ISL23428 is a volatile, low voltage, low noise, low power,
128-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 (64 tap position).
The low voltage, low power consumption, and small package
of the ISL23428 make it an ideal choice for use in battery
operated equipment. In addition, the ISL23428 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 ISL23428 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
• 128 resistor taps
• 10k 50kor 100k total resistance
• SPI serial interface
- No additional level translator for low bus supply
- Daisy Chaining of multiple DCPs
• Power supply
- V_CC = 1.7V to 5.5V analog power supply
- V_LOGIC = 1.2V to 5.5V SPI bus/logic power supply
• 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
• Wiper resistance: 70 typical @ V_CC = 3.3V
• Power-on preset to mid-scale (64 tap position)
• Extended industrial temperature range: -40°C to +125°C
• 14 Ld TSSOP or 16 Ld UTQFN packages
• Pb-free (RoHS compliant)
10000
8000
6000
4000
2000
0
0
32
64
96
128
TAP POSITION (DECIMAL)
FIGURE 1. FORWARD AND BACKWARD RESISTANCE vs TAP
POSITION, 10kΩ DCP
VREF
RH
ISL23428
RW
RL
-
+
ISL28114
VREF_M
FIGURE 2. V_REF ADJUSTMENT
August 25, 2011
1
FN7904.0
CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures.
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