The reference for the DAC is derived from the power supply inputs and thus gives the widest dynamic output range. These parts incorporate a power-on-reset circuit, which ensures that the DAC output powers-up to zero volts and remains there until a valid write takes place. The parts contain a power-down feature which reduces the current consumption of the device to 50 nA at 3 V and provides software-selectable output loads while in power-down mode.