AD9834

The AD9834 is a numerically controlled oscillator employing a phase accumulator, a SIN ROM and a 10-bit D/A converter integrated on a single CMOS chip.  Clock rates up to 50 MHz are supported with a power supply from 2.3 V to 5.5 V.Capability for phase modulation and frequency modula-tion is provided.  Frequency accuracy can be controlled to one part in 0.25 billion. Modulation is effected by loading registers through the serial interface.

The AD9834 offers the user a variety of output waveforms. The SIN ROM can be bypassed so that a linear up/down ramp is output from the DAC. If the SINn ROM is not by-passed, a sinusoidal output is available. Also, if a clock output is required, the MSB of the DAC data can be output, or the on-chip comparator can be used.

The digital section is driven by an on-board regulator which steps down the applied DVDD to +2.5 V when DVDD exceeds +2.5 V.  The analog and digital sections are independent and can be run from different power supplies e.g. AVDD can equals 5 V with DVDD equal to 3 V, etc.

The AD9834 has a power-down pin (SLEEP) which allows external control of a power-down mode. Sections of the device which are not being used can be powered down to minimise the current consumption e.g. the DAC can be powered down when a clock output is being generated. The part is available in a 20-pin  TSSOP package.