AD5203

The AD5203 provides a quad channel, 64-position digitallycontrolled variable resistor (VR) device. These parts perform the same electronic adjustment function as a potentiometer or variable resistor. The AD5203 contains four independent variable resistors in a 24-lead SOIC and the compact TSSOP-24 packages.Each part contains a fixed resistor with a wiper contact that taps the fixed resistor value at a point determined by a digital code loaded into the controlling serial input register. The resistance between the wiper and either endpoint of the fixed resistor varies linearly with respect to the digital code transferred into the VR latch. Each variable resistor offers a completely programmable 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 kW, or 100 kW has a ±1% channel-tochannel matching tolerance with a nominal temperature coefficient of 700 ppm/°C.

Each VR has its own VR latch which holds its programmed resistance value. These VR latches are updated from an internal serial-to-parallel shift register that is loaded from a standard 3-wire serial-input digital interface. Eight data bits make up the data word clocked into the serial input register. The data word is decoded where the first two bits determine the address of the VR latch to be loaded, the last 6-bits are data. A serial data output pin at the opposite end of the serial register allows simple daisychaining in multiple VR applications without additional external decoding logic.