AD7808BR

Overview

The AD7808BR is an octal 10-bit digital-to-analog converter manufactured by Analog Devices Inc. It features serial loading capabilities and operates from a +3.3 V to +5 V power supply with an on-chip reference. The device incorporates double-buffered DAC registers, allowing simultaneous analog output updates via the asynchronous LDAC input. Key electrical parameters include a maximum relative accuracy of -4 LSB (B Grade), a typical settling time of 1.5 ms, and a normal mode current consumption of 18 mA. It supports dual external reference capability and includes control features such as power-down and standby modes.

Feature Summary

• Octal configuration with eight independent 10-bit voltage-output DACs in a single package.
• Serial interface utilizing FSIN, CLKIN, and SDIN lines for data input.
• On-chip 1.23 V bandgap reference with dual external reference capability via REFIN.
• Double-buffered data registers enable simultaneous update of all analog outputs.

Applications

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

Procurement Notes

Verify the B grade accuracy specification (-4 LSB max) against application requirements. Confirm that the serial interface timing constraints, specifically the CLKIN cycle time and data setup/hold times, are compatible with the host controller. Ensure the operating temperature range of -40°C to +85°C meets environmental specifications.

Selection Notes

Select the AD7808BR over parallel variants when board space for address/data buses is limited. Verify that the 16-bit serial word structure aligns with the system's microcontroller or DSP interface. Consider the 18 mA normal mode current draw for power budgeting, noting the lower consumption in standby or power-down modes.

Part Context

The AD7808BR belongs to the AD780x family of CMOS DACs, which also includes the quad-channel AD7804 (serial) and AD7805 (parallel), as well as the octal parallel AD7809. The 'BR' suffix indicates a 24-lead Small Outline IC (SOIC) package with commercial plastic construction. This family shares common internal architecture but differs in channel count and data loading methods.

Replacement Considerations

The AD7804BN serves as a functional substitute if only four channels are required, though it uses a 16-lead DIP package. For direct pin-compatible replacement in an octal serial application, verify availability of the AD7808BN in a PDIP package, noting the package dimension differences between SOIC and DIP formats.