AD7782BRUZ-REEL

Overview

The AD7782BRUZ-REEL is a 2-channel, 24-bit sigma-delta analog-to-digital converter (ADC) designed for low-frequency measurement applications. It features pin-configurable input channels and ranges without programmable registers. The device operates from a single 3 V or 5 V supply with typical power dissipation of 3.9 mW at 3 V. It provides a fixed output update rate of 19.79 Hz, enabling simultaneous 50 Hz and 60 Hz rejection. The ADC offers 24-bit no missing codes performance, with peak-to-peak resolutions of 18.5 bits in the ±2.56 V range and 16.5 bits in the ±160 mV range. It utilizes a 32.768 kHz crystal oscillator and supports master or slave serial interface modes.

Feature Summary

• Pin-configurable architecture eliminates the need for internal register programming for channel selection and input range settings.
• Integrated digital filter provides simultaneous rejection of 50 Hz and 60 Hz line frequencies to enhance measurement accuracy.
• Dual fully differential analog input channels accommodate high source impedances suitable for direct sensor connection.
• Read-only digital interface supports both master and slave operation modes for flexible system integration.

Applications

• Sensor Measurement
• Industrial Process Control
• Temperature Measurement
• Pressure Measurements
• Weigh Scales

Procurement Notes

Verify the specific ordering suffix against the manufacturer's current documentation to confirm package type and reel specifications. Ensure the component meets RoHS compliance requirements if mandated by the design. Confirm availability status as distribution channels may vary. Cross-reference the part number with official Analog Devices databases to validate authenticity and revision level before procurement.

Selection Notes

Select this component for applications requiring high-resolution, low-frequency signal acquisition without complex configuration overhead. The fixed 19.79 Hz data rate is optimal for environments with significant 50/60 Hz interference. Consider the ±160 mV or ±2.56 V input ranges based on the sensor output amplitude. Ensure the system can provide a stable 32.768 kHz crystal and appropriate reference voltage for accurate conversion.

Part Context

The AD7782 belongs to the AD778x family of precision analog front ends. It is functionally similar to the AD7783, which includes integrated current sources and a single differential input channel. Both devices share the same core sigma-delta architecture and pinout compatibility for basic configurations, allowing for design flexibility within industrial sensing systems.

Replacement Considerations

The AD7783 is a related device in the same family but differs in having integrated current sources and only one differential input channel. Direct substitution requires verifying that the additional current sources do not interfere with the application circuit and that the single-channel limitation meets the system requirements.

FAQ

How are the input channels and voltage ranges configured?

The AD7782 uses external hardware pins for configuration. The CH1/CH2 pin selects between the two differential input channels, and the RANGE pin sets the full-scale input range to either ±160 mV or ±2.56 V. No internal software registers are used for these settings.

What is the purpose of the MODE pin?

The MODE pin determines the operational mode of the serial interface. When pulled low, the device operates in master mode, generating its own serial clock. When pulled high, it operates in slave mode, accepting an external serial clock from a microcontroller or processor.

Why is a 32.768 kHz crystal required?

The AD7782 uses a 32.768 kHz watch crystal connected to XTAL1 and XTAL2 pins. An internal Phase-Locked Loop (PLL) multiplies this frequency to generate the precise internal clocking necessary for the sigma-delta modulator and the fixed 19.79 Hz output data rate.