AD7804BRZ-REEL

Overview

The AD7804BRZ is a quad 10-bit digital-to-analog converter (DAC) featuring serial load capabilities. It operates from a +3.3 V to +5 V power supply and incorporates an on-chip bandgap reference outputting typically 1.23 V. The device provides four independent analog outputs with double-buffered data registers, allowing simultaneous updates via the LDAC input. Key electrical parameters include a maximum settling time of 4 ms, a gain error of ±3% FSR, and a differential nonlinearity of ±0.125 LSB typical. It supports both two's complement and offset binary input coding schemes.

Feature Summary

• Quad 10-bit resolution with serial SPI-compatible interface (FSIN, CLKIN, SDIN).
• Integrated system and channel control registers for individual DAC management.
• On-chip Sub-DAC allows shifting the transfer function around the VBIAS point.
• Supports Power-Down, System Standby, and Hardware Clear modes.

Applications

• Optical disk drives.
• Instrumentation and communication systems.
• Process control and voltage setpoint control.
• Trim potentiometer replacement.
• Automatic calibration circuits.

Procurement Notes

Verify the specific grade (B or C) and package variant when sourcing, as accuracy specifications vary between grades. Confirm that the REEL suffix indicates tape-and-reel packaging rather than tube packaging. Ensure compatibility with the host controller's serial clock speeds and voltage levels before integration.

Selection Notes

Select this component for applications requiring four independent low-cost 10-bit voltage outputs controlled via a serial bus. Choose the B grade for ±3 LSB relative accuracy or the C grade for ±4 LSB accuracy. Ensure the design accommodates the 16-bit serial word structure and utilizes the double-buffered registers for glitch-free multi-channel updates.

Part Context

The AD7804 belongs to the Analog Devices AD780x family of 10-bit DACs. It is the serial-loading counterpart to the AD7805, which offers parallel loading. The family also includes octal versions (AD7808/AD7809) for higher channel counts. All variants share similar internal architectures and control logic but differ in interface type and pin count.

Replacement Considerations

The AD7805BRZ serves as a direct functional substitute if parallel loading is acceptable instead of serial. For octal configurations, the AD7808 series is the equivalent option. Verify pinout compatibility and register mapping when substituting within the AD780x family.

FAQ

How are the DAC outputs updated simultaneously?

The AD7804 features double-buffered DAC registers. By asserting the LDAC input low, all analog outputs can be updated simultaneously with the contents of the data registers, regardless of the serial loading sequence.

What is the function of the COMP pin?

The COMP pin provides an output from the internal AVDD/2 divider. It is intended for AC bypass purposes using 1 nF capacitors to AVDD and AGND, but can also be overdriven by an external reference to enable dual external reference capability.

Can the output voltage range be shifted?

Yes, the complete transfer function of each DAC can be shifted around the VBIAS point using the on-chip 8-bit Sub-DAC, which is accessible via the serial interface.