AD7801BRU

Overview

The AD7801BRU is an 8-bit voltage-output digital-to-analog converter (DAC) from Analog Devices Inc., housed in a 20-lead TSSOP package. It operates on a single supply ranging from +2.7 V to +5.5 V and features an internal precision output buffer capable of rail-to-rail swing. The device utilizes a parallel microprocessor-compatible interface with double-buffered logic for synchronous or automatic updates. Key electrical specifications include a maximum settling time of 2 µs, ±1 LSB relative accuracy, and ±1 LSB differential nonlinearity. Power consumption is typically 5 mW at 3.3 V, reducing to less than 3 µW in power-down mode.

Feature Summary

• Single-supply operation (+2.7 V to +5.5 V) with low power consumption (1.75 mA max @ 3.3 V).
• On-chip buffered output amplifier providing rail-to-rail voltage swing.
• Internal reference derived from VDD or external reference input capability (1 V to VDD/2).
• Parallel data interface with asynchronous clear and power-down functions.

Applications

• Portable battery-powered instruments
• Digital gain and offset adjustment circuits
• Programmable voltage and current sources
• Programmable attenuators

Procurement Notes

Verify the specific suffix 'RU' corresponds to the 20-lead Thin Shrink Small Outline package as defined in the ordering guide. Confirm the temperature range matches the B version specification (-40 °C to +105 °C). Ensure compatibility with the required supply voltage range of 2.7 V to 5.5 V for the target application environment.

Selection Notes

Select this component when an 8-bit resolution with rail-to-rail output is required in a compact surface-mount package. The internal reference simplifies design by eliminating external reference components if tied to VDD. Consider the 2 µs settling time and parallel interface speed for system timing constraints. Verify that the load requirements (10 kΩ to VDD/GND and 100 pF) are within the output buffer's drive capabilities.

Part Context

The AD7801BRU is part of the AD7801 family, which includes variants in SOIC and TSSOP packages. The 'B' designation indicates the industrial temperature range (-40 °C to +105 °C), while 'RU' specifies the 20-lead TSSOP package option. This model is designed for applications requiring low power and simple parallel interfacing.

Replacement Considerations

Publicly confirmed substitute part numbers are not available in the provided documentation. Users should consult official Analog Devices resources for cross-reference information.

FAQ

How is the internal reference selected?

The internal reference is selected by tying the REFIN pin directly to VDD. The internal circuitry detects this connection and uses VDD/2 as the reference voltage.

What is the function of the CLR pin?

The CLR pin is an asynchronous clear input. When taken low, it loads all zeros into the DAC register, forcing the DAC output to zero volts immediately.

How does the power-down feature work?

Driving the PD pin low activates power-down mode, reducing current consumption to less than 1 µA at 25°C. The device typically exits power-down in 13 µs.