AD8403ARZ100

• Product introduction

AD8403ARZ100 4-channel digital potentiometer

The AD8400/AD8402/AD8403 are single/dual/quad, 256-bit, digitally controlled variable resistor (VR) devices that provide the same electronic adjustment functions as potentiometers or variable resistors. The AD8400 contains a variable resistor in a compact SO-8 package. The AD8402 contains two independent variable resistors in a space-saving SO-14 surface mount package. The AD8403 contains four independent variable resistors and is available in 24-lead PDIP, SOIC, and TSSOP packages. Each device contains a fixed resistor with a wiper contact that taps the fixed resistor value at a point determined by the digital code loaded into the control serial input register. The value of the resistance between the cursor and either end of the fixed resistor changes linearly with the digital code transmitted to the VR latch. Between A and the cursor or B and the wiver, each variable resistor provides a fully programmable resistor value. The A to B fixed termination resistors (1 kΩ, 10 kΩ, 50 kΩ, or 100 kΩ) have a channel-to-channel matching tolerance of ±1% and a nominal temperature coefficient of 500 ppm/°C. The unique switching circuit minimizes the high glitches inherent in traditional switch resistance designs, avoiding any turn-ahead or turn-before-close operation.

Each VR has its own VR latch that holds its programmed resistor value. These VR latches are updated by an SPI-compatible serial-to-parallel shift register that loads data from a standard 3-wire serial input digital interface. A data word consisting of 10 data bits is read into a serial input register, which is decoded to determine the address of the VR latch that needs to be loaded with the last 8 bits of data. Using the serial data output pin on the opposite side of the serial register, multiple VRs can be simply daisy-chained without the need for additional external decoding logic.