X9221AYSIT1

X9221AYSIT1 FEATURES

• Two XDCPs in one package • 2-wire serial interface • Register oriented format, 8 registers total—Directly write wiper position—Read wiper position—Store as many as four positions per pot • Instruction format—Quick transfer of register contents to resistorarray • Direct write cell—Endurance–100,000 writes per bit per register • Resistor array values—2k, 10k, 50k • Resolution: 64 taps each pot • 20 Ld plastic DIP and 20 Ld SOIC packages • Pb-free plus anneal available (RoHS compliant)

X9221AYSIT1 DESCRIPTION

The X9221A integrates two digitally controlled potenti-ometers (XDCP) on a monolithic CMOS integratedmicrocircuit.The digitally controlled potentiometer is implementedusing 63 resistive elements in a series array. Betweeneach element are tap points connected to the wiperterminal through switches. The position of the wiper onthe array is controlled by the user through the 2-wirebus interface. Each potentiometer has associated withit a volatile Wiper Counter Register (WCR) and 2 non-volatile Data Registers (DR0:DR1) that can be directlywritten to and read by the user. The contents of theWCR controls the position of the wiper on the resistorarray through the switches. Power up recalls the con-tents of DR0 to the WCR.The XDCP can be used as a three-terminal potentiom-eter or as a two-terminal variable resistor in a widevariety of applications including control, parameteradjustments, and signal processing.

X9221AYSIT1 PIN DESCRIPTIONS

X9221AYSIT1 Array Description

The X9221A is comprised of two resistor arrays. Eacharray contains 63 discrete resistive segments that areconnected in series. The physical ends of each array areequivalent to the fixed terminals of a mechanical potenti-ometer (VH/RH and VL/RL inputs).At both ends of each array and between each resistorsegment is a FET switch connected to the wiper(VW/RW) output. Within each individual array only oneswitch may be turned on at a time. These switches arecontrolled by the Wiper Counter Register (WCR). Thesix least significant bits of the WCR are decoded toselect, and enable, one of sixty-four switches.The WCR may be written directly, or it can be changedby transferring the contents of one of four associateddata registers into the WCR. These data registers andthe WCR can be read and written by the host system.