AD7801BRU-REEL7

Overview

The AD7801BRU-REEL7 is a single-channel, 8-bit voltage-output digital-to-analog converter (DAC) manufactured by Analog Devices Inc. It operates from a single +2.7 V to +5.5 V supply and features an on-chip precision output buffer that enables rail-to-rail output swing. The device utilizes a parallel microprocessor and DSP-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 1 µA in power-down mode. It is housed in a 20-lead TSSOP package.

Feature Summary

• Single 8-bit resolution with rail-to-rail voltage output capability
• Parallel interface compatible with standard microprocessors and DSPs
• Internal reference derived from VDD or external reference input at REFIN pin
• Low power operation: <1 µA current draw in power-down mode

Applications

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

Procurement Notes

Verify the specific ordering suffix RU-20 corresponds to the 20-lead Thin Shrink Small Outline package. Confirm the B version temperature range covers the required -40 °C to +105 °C operating environment. Ensure the reel packaging format matches the REEL7 designation for automated assembly processes.

Selection Notes

Select this component when a low-cost, single-supply DAC with rail-to-rail output is required. The internal reference simplifies design if VDD/2 is sufficient; otherwise, utilize the REFIN pin for external references between 1 V and VDD/2. Consider the 2 µs settling time and 1 LSB linearity for applications requiring moderate speed and accuracy.

Part Context

The AD7801 belongs to the AD7801 family of 8-bit DACs. The BRU variant specifically denotes the TSSOP-20 package option, distinct from the SOIC-20 package found in the BR variant. Both variants share identical electrical characteristics and functionality within the commercial temperature range.

Replacement Considerations

Direct substitutes include the AD7801BRZ for the SOIC-20 package variant. Verify pin compatibility and thermal impedance differences when replacing the TSSOP package with alternative form factors.

FAQ

How is the internal reference selected?

The internal reference is selected by tying the REFIN pin directly to VDD. A comparator detects this connection and switches the reference source to the internally generated VDD/2.

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. The device exits power-down in approximately 13 µs, restoring normal operation.