40 Channels of Programmable Voltage with Excellent Temperature Drift Performance Using the AD5380 DAC

CIRCUIT FUNCTION AND BENEFITS
 This circuit is a multichannel DAC configuration with excellent temperature drift performance. It provides 40 individual output voltage channels with 14 bits of resolution and a temperature stability of typically less than 3 ppm/°C.

CIRCUIT DESCRIPTION
Figure 1 shows a typical configuration for the AD5380-5 when configured for use with an external reference. In the circuit shown, all AGND, SIGNAL_GND, and DAC_GND pins are tied together to a common AGND. AGND and DGND are connected together at the AD5380 device. On power-up, the AD5380 defaults to external reference operation. This design uses two separate 5.0 V power supplies—one to power the voltage reference and the analog portion of the AD5380 (AVDD) and the other to power the digital portion of the AD5380 (DVDD). For best performance, a linear regulator should always be used to power the analog portion of the circuit. If a switching regulator is used to power the digital portion, care should be taken to minimize switching noise at the DVDD supply pins. Additional decoupling using a series connected ferrite bead may be required. The AD5380 digital (DVDD) power supply can operate from a 3 V or 5 V supply, which provides for maximum flexibility when interfacing to digital components. Both supplies can be tied together to a common 5 V supply; it is derived from a linear regulator. Refer to the ADIsimPower™ design tool for guidance on the power supply designs.