Analog Devices AD5220 Product Info

The AD5220 provides a single channel, 128-position digitally controlled variable resistor (VR) device. This device performs the same electronic adjustment function as a potentiometer or variable resistor. These products were optimized for instrument and test equipment push-button applications. A choice between bandwidth or power dissipation are available as a result of the wide selection of end-to-end terminal resistance values.

The AD5220 contains a fixed resistor with a wiper contact that taps the fixed resistor value at a point determined by a digitally controlled UP/DOWN counter. The resistance between the wiper and either end point of the fixed resistor provides a con stant resistance step size that is equal to the end-to-end resistance divided by the number of positions (e.g., R_STEP = 10 kΩ / 128 = 78Ω). The variable resistor offers a true adjustable value of resistance, between the A terminal and the wiper, or the B terminal and the wiper. The fixed A-to-B terminal resistance of 10 kΩ, 50 kΩ, or 100 kΩ has a nominal temperature coefficient of 800 ppm/°C.

The chip select CS, count CLK and U/D direction control inputs set the variable resistor position. These inp