AD9834BRUZ

Overview

The AD9834BRUZ is a complete Direct Digital Synthesis (DDS) device manufactured by Analog Devices Inc. It operates on a 2.3 V to 5.5 V power supply and supports a master clock frequency up to 75 MHz, enabling output frequencies up to 37.5 MHz. The component features a 10-bit DAC with a full-scale current of 3.0 mA and utilizes a 28-bit phase accumulator for high-resolution tuning. It includes an integrated comparator for square wave generation and communicates via a 3-wire SPI interface. The device is housed in a 20-lead TSSOP package and functions within an extended temperature range of -40°C to +105°C.

Feature Summary

• Generates sine, triangular, and square waveforms using a 28-bit phase accumulator and internal SIN ROM.
• Supports frequency and phase modulation through software control or dedicated hardware select pins.
• Integrates a high-speed comparator to produce digital square wave outputs directly from the analog signal path.
• Features independent analog and digital power supplies to optimize performance and reduce noise coupling.

Applications

• Frequency stimulus and waveform generation
• Low power RF and communications systems
• Liquid and gas flow measurement
• Proximity, motion, and defect detection sensors
• Test and medical equipment

Procurement Notes

Verify the specific grade (B or C) required for your application, as specifications such as maximum clock speed and dynamic performance vary between versions. Confirm that the serial interface timing parameters align with your microcontroller's capabilities. Ensure proper decoupling capacitors are placed near the AVDD and DVDD pins to maintain signal integrity and meet the absolute maximum ratings defined in the datasheet.

Selection Notes

Select the B Grade variant if the system requires a master clock frequency up to 50 MHz, or the C Grade for operation up to 75 MHz. Consider the power-down options available via the SLEEP pin to minimize current consumption when the DAC is not actively generating signals. Evaluate the need for external filtering based on the desired Spurious-Free Dynamic Range (SFDR) requirements for narrowband versus wideband applications.

Part Context

The AD9834BRUZ belongs to the AD9834 series of low-power DDS devices designed for precise frequency synthesis. It replaces traditional discrete oscillator circuits by integrating the numerically controlled oscillator, phase modulator, and DAC into a single chip. This integration allows for compact designs in battery-powered and space-constrained environments while maintaining high spectral purity and fast switching speeds.

Replacement Considerations

Direct substitutes include other parts within the AD9834 family, such as the AD9834BCPZ or AD9834BRMZ, which share identical functional block diagrams but differ in packaging or operating temperature grades. Verify pin compatibility and electrical specifications before swapping components.

FAQ

How is the full-scale output current of the AD9834 determined?

The full-scale current is set by connecting a resistor (RSET) between the FSADJUST pin and AGND. The relationship is defined as IOUT FULL SCALE = 18 × FSADJUST / RSET, where FSADJUST is nominally 1.15 V.

Can the AD9834 generate square waves without external circuitry?

Yes, the device includes an on-board comparator. By setting the appropriate control register bits, the comparator can convert the filtered sinusoidal DAC output into a square wave available on the SIGN BIT OUT pin.

What is the resolution of the frequency tuning?

The AD9834 uses a 28-bit frequency register. With a 75 MHz clock rate, it achieves a frequency resolution of 0.28 Hz. At a 1 MHz clock rate, the resolution improves to 0.004 Hz.