AD5262

The AD5260/AD5262 provide a single- or dual-channel, 256- position, digitally controlled variable resistor (VR) device.* These devices perform the same electronic adjustment function as a potentiometer or variable resistor. Each channel of the AD5260/ AD5262 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 end point 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 20 kW, 50 kW, or 200 kW has a nominal temperature coefficient of 35 ppm/C. Unlike the majority of the digital potentiometers in the market, these devices can operate up to 15 V or ±5 V provided proper supply voltages are furnished. 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, which is loaded from a standard 3-wire serial-input digital interface. The AD5260 contains an 8-bit serial register while the AD5262 contains a 9-bit serial register. Each bit is clocked into the register on the positive edge of the CLK. The AD5262 address bit determines the corresponding VR latch to be loaded with the last 8 bits of the data word during the positive edging of CS strobe. A serial data output pin at the opposite end of the serial register enables simple daisy chaining in multiple VR applications without additional external decoding logic. An optional reset pin (PR) forces the wiper to the mid-scale position by loading 80H into the VR latch.