10 Power Supply Recommendations

The DACx750 family operates within the specified single-supply range of 10 V to 36 V applied to the AVDD pin. The digital supply, DVDD, operates within the specified supply range of 2.7 V to 5.5 V or powered by the internal 4.6-V LDO, as described in Section 8.3.4.

Switching power supplies and DC/DC converters often have high-frequency glitches or spikes riding on the output voltage. In addition, digital components can create similar high-frequency spikes. This noise can be easily coupled into the DAC output voltage or current through various paths between the power connections and analog output. To further reduce noise, include bulk and local decoupling capacitors.

CAUTION: Do not ramp the supplies for the DACx750 faster than 1 V/ns or damage may result to the device. A 10-Ω series resistor from the analog supply to the device AVDD connection helps reduce the supply ramp.

The DACx750 has internal power on reset (POR) circuitry for both the digital DVDD and analog AVDD supplies. This circuitry makes sure that the internal logic and power-on state of the DAC power up to the proper state independent of the supply sequence. The recommended power-supply sequence is to first have the analog AVDD supply come up, followed by the digital DVDD supply. DVDD can come up first as long as AVDD ramps to at least 5 V within 50 μs. If neither condition can be satisfied, issue a software reset command using the SPI bus after both AVDD and DVDD are stable.

The current consumption on the AVDD pin and current ranges for the current output are listed in Section 7.5. The power supply must meet the requirements listed in Section 7.5.