SLIS135E December 2010 – February 2017
Protection diodes limit the voltage compliance at terminal H, terminal L, and terminal W, making it important to power up VDD first before applying any voltage to terminal H, terminal L, and terminal W. The diodes are forward-biasing, meaning VDD can be powered unintentionally if VDD is not powered first. The ideal power-up sequence is VDD, digital inputs, and VH, VL, and VW. The order of powering digital inputs, VH, VL, and VW does not matter as long as they are powered after VDD.
It is prudent to know that when the DPOT is powered off, the impedance of the device is not known. Upon power-up, the device will go to 0x80h code for a brief period of time while it loads the stored wiper position from the EEPROM, then goes to the stored position. This process happens in less than 100 µs.