TheAD5204/AD5206 provide 4-/6-channel, 256-position digitally controlled variable resistor (VR) devices. These devices perform the same electronic adjustment function as a potentiometer or variable resistor. Each channel of the AD5204/AD5206 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 SPI-compatible 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. The 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 kΩ, 50 kΩ, or 100 kΩ has a nominal temperature coefficient of 700 ppm/°C.Each VR has its own VR latch that 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. Eleven data bits make up the data-word clocked into the serial input register. The first three bits are decoded to determine which VR latch is loaded with the last eight bits of the data-word when theCSstrobe is returned to logic high. A serial data output pin at the opposite end of the serial register (AD5204 only) allows simple daisy chaining in multiple VR applications without requiring additional external decoding logic.An optional reset (PR) pin forces all the AD5204 wipers to the midscale position by loading 0x80 into the VR latch.The AD5204/AD5206 are available in the 24-lead surface-mount SOIC and TSSOP packages. The AD5204 is also available in a 32-lead, 5 mm × 5 mm LFCSP package. All parts are guaranteed to operate over the extended industrial temperature range of −40°C to +85°C. For additional single-, dual-, and quad-channel devices, see the AD8400/AD8402/AD8403 data sheets.APPLICATIONSMechanical potentiometer replacementInstrumentation: gain, offset adjustmentProgrammable voltage-to-current conversionProgrammable filters, delays, time constantsLine impedance matching