The DS3901 is a triple, 8-bit nonvolatile (NV) variable resistor. Each of the resistors has two setting registers, which are selectable by software or by pin configuration. The selected register determines the value of the variable resistor. Additionally, all three resistors have a high-impedance setting. Resistor R0 has the additional flexibility of allowing an external shunt resistor to provide increased dynamic range. Internal address settings allow the DS3901 slave address to be programmed to one of 128 possible addresses. The DS3901 also features an optional password-protection scheme that allows the protection of sensitive data.