The AD5678 has an on-chip reference with an internal gain of 2. The AD5678-1 has a 1.25 V 5 ppm/°C reference, giving a full-scale output of 2.5 V; the AD5678-2 has a 2.5 V 5 ppm/°C reference, giving a full-scale output 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 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 software-selectable 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 clears all DACs to a software-selectable code—0 V, midscale or full scale.
The AD5678 utilizes 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.
