The AD5628/AD5648/AD5668 devices are low power， octal， 12-/14-/16-bit， buffered voltage-output DACs. All devices operate from a single 2.7 V to 5.5 V supply and are guaranteed monotonic by design. The AD5668 and AD5628 are available in both a 4 mm × 4 mm LFCSP and a 16-lead TSSOP， while the AD5648 is available in both a 14-lead and 16-lead TSSOP. The AD5628/AD5648/AD5668 have an on-chip reference with an internal gain of 2. The AD5628-1/AD5648-1/AD5668-1 have a 1.25 V 5 ppm/°C reference， giving a full-scale output range of 2.5 V; the AD5628-2/AD5648-2/AD5668-2 and AD5668-3 have a 2.5 V 5 ppm/°C reference， giving a full-scale output range of 5 V. The on-board reference is off at power-up， allowing the use of an external reference. The internal reference is enabled via a software write. The part incorporates a power-on reset circuit that ensures that the DAC output powers up to 0 V （AD5628-1/AD5648-1/AD5668-1， AD5628-2/AD5648-2/AD5668-2） or midscale （AD5668-3） and remains powered up at this level until a valid write takes place. The part contains a power-down feature that reduces the current consumption of the device to 400 nA at 5 V and provides softwareselectable output loads while in power-down mode for any or all DAC channels. The outputs of all DACs can be updated simultaneously using the LDAC function， with the added functionality of user-selectable DAC channels to simultaneously update. There is also an asynchronous CLR that updates all DACs to a userprogrammable code—zero scale， midscale， or full scale. The AD5628/AD5648/AD5668 utilize a versatile 3-wire serial interface that operates at clock rates of up to 50 MHz and is compatible with standard SPI?， QSPI?， MICROWIRE?， and DSP interface standards. The on-chip precision output amplifier enables rail-to-rail output swing.