AD8403ARZ100

• Product Introduction

AD8403ARZ100 4-channel digital potentiometer

The AD8400/AD8402/AD8403 are single/dual/quad-channel, 256-bit, digitally controlled variable resistor (VR) devices that provide the same electronic adjustment functions as potentiometers or variable resistors. The AD8400 has a built-in variable resistor in a compact SO-8 package. The AD8402 has two independent variable resistors in a space-saving SO-14 surface-mount package. The AD8403 has four independent variable resistors and is available in 24-pin PDIP, SOIC, and TSSOP packages. Each device has a fixed resistor with a vernier 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 any end of the fixed resistor varies linearly with the digital code transmitted to the VR latch. Between the A-end and the cursor or the B-end and the cursor, each variable resistor provides a fully programmable resistance 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 circuitry minimizes the high burrs inherent in traditional switching resistor designs, eliminating any close-and-open or open-and-close operation.          

Each VR has its own VR latch that stores its programmed resistance value. These VR latches are updated by an SPI-compliant serial to parallel shift register that loads data from a standard three-wire serial input digital interface. The data word composed of 10 data bits is read into the serial input register, and the data word is decoded, and the first 2 bits can determine the VR latch address that needs to load the last 8 bits of data. By using the serial data output pins on the opposite end of the serial register, multiple VRs can be easily daisy-chained without the need for additional external decoding logic.