The AD5222 provides a dual 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. Choices between bandwidth or power dissipation are available as a result of the wide selection of end-to-end terminal resistance values. The AD5222 contains two fixed resistors with wiper contacts that tap 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 constant resistance step size that is equal to the end-to-end resistance divided by the number of positions (e.g., R STEP = 10 k/128 = 78 ). The variable resistor offers a true adjustable value of resistance, between Terminal A and the wiper, or Terminal B and the wiper. The fixed A-to-B terminal resistance of 10 k , 50 k, 100 k , or 1 M has a nominal temperature coefficient of 35 ppm/C.