The AD5665R have an on-chip reference. The LFCSP versions of the AD56x5R have a 1.25 V or 2.5 V, 10 ppm/°C reference, giving a full-scale output range of 2.5 V or 5 V; the TSSOP versions of the AD56x5R have a 2.5 V, 5 ppm/°C reference, giving a full-scale output range of 5 V. The on-chip reference is off at power-up, allowing the use of an external reference. The internal reference is enabled via a software write. The AD5625/AD5665 require an external reference voltage to set the output range of the DAC.
The part incorporates a power-on reset circuit that ensures that the DAC output powers up to 0 V (POR = GND) or midscale (POR = VDD) and remains there until a valid write occurs. The on-chip precision output amplifier enables rail-to-rail output swing.
The AD56x5R/AD56x5 use a 2-wire I2C-compatible serial interface that operates in standard (100 kHz), fast (400 kHz), and high speed (3.4 MHz) modes.