The AD57801 is a true 18-bit， unbuffered voltage output DAC that operates from a bipolar supply of up to 33 V. The AD5780 accepts a positive reference input range of 5 V to VDD ? 2.5 V and a negative reference input range of VSS + 2.5 V to 0 V. Both reference inputs are buffered on chip and external buffers are not required. The AD5780 offers a relative accuracy specification of ±1 LSB maximum range， and operation is guaranteed monotonic with a ±1 LSB DNL maximum range specification. The part uses a versatile 3-wire serial interface that operates at clock rates of up to 35 MHz and is compatible with standard SPI， QSPI?， MICROWIRE?， and DSP interface standards. The part incorporates a power-on reset circuit that ensures that the DAC output powers up to 0 V in a known output impedance state and remains in this state until a valid write to the device takes place. The part provides an output clamp feature that places the output in a defined load state.