In an open loop system, the DAC must offer precise INL and DNL. In this example, the LTC2641 DAC programs the voltage at the SET pin on the LT3080 linear regulator, through the LTC6078 buffer. The LT3080’s SET pin is the input to the error amplifier and the regulation set point for the LDO. A fixed current of 10mA flows out of the SET pin, which programs the output voltage of the linear regulator. The LT3080’s output voltage range is zero to the absolute maximum rated output voltage. The LTC2641’s 16-bit resolution allows fine 76µV steps in voltage at the SET pin, which then determines the voltage at the OUT pin. This allows the LT3080 to effectively margin its output in very small increments. Other important parameters in an open loop system are offset, gain error, and error of the reference voltage along with the stability of these parameters over time and temperature. INL is of particular importance, because in contrast to the closed loop system, the INL of the DAC has a direct bearing on the overall linearity of the system.