AD7768-4BSTZ

Overview

The AD7768-4BSTZ is a 4-channel, 24-bit simultaneous sampling sigma-delta analog-to-digital converter (ADC) from Analog Devices. It features a maximum output data rate of 256 kSPS per channel and achieves a dynamic range of 108 dB with a 110.8 kHz input bandwidth. The device offers selectable power modes: Fast (51.5 mW/channel), Median (27.5 mW/channel), and Low Power (9.375 mW/channel). It includes programmable digital filters, CRC error checking, and operates within a temperature range of -40°C to +105°C in a 64-lead LQFP package.

Feature Summary

• Simultaneous sampling across all four channels using independent sigma-delta modulators.
• Programmable power scaling allowing optimization between noise performance, speed, and power consumption.
• Integrated digital filtering options including wideband linear phase and low-latency sinc5 filters.
• Embedded analog precharge buffers for both signal inputs and reference terminals.

Applications

• Data acquisition systems utilizing USB, PXI, or Ethernet interfaces
• Instrumentation and industrial control loops
• Audio testing and measurement equipment
• Vibration and asset condition monitoring
• High precision medical electroencephalogram (EEG) and electrocardiogram (ECG)

Procurement Notes

Verify the specific suffix BSTZ corresponds to the lead-free tape and reel packaging configuration intended for surface mount assembly. Confirm that the ordering part number matches the required 4-channel variant rather than the 8-channel AD7768. Ensure compatibility with the 64-lead LQFP footprint dimensions during PCB layout finalization.

Selection Notes

Select this component when synchronized multi-channel acquisition is critical to prevent phase distortion between inputs. Evaluate the available decimation rates and filter types against the required input bandwidth and noise floor specifications. Consider the power dissipation limits in the chosen operating mode relative to the thermal constraints of the 64-lead LQFP package.

Part Context

This device belongs to the AD7768 family of high-performance sigma-delta ADCs. The AD7768-4 variant specifically provides four independent conversion channels, whereas the standard AD7768 offers eight channels. Both share identical core architecture, digital filtering capabilities, and power scaling features designed for precision measurement applications.

Replacement Considerations

The AD7768BSTZ serves as the 8-channel equivalent within the same product family. Direct substitution requires verifying that the additional channels do not impact board space or power budget constraints.

FAQ

What are the three selectable power modes?

The device supports Fast mode (110.8 kHz bandwidth, 51.5 mW per channel), Median mode (55.4 kHz bandwidth, 27.5 mW per channel), and Low Power mode (13.8 kHz bandwidth, 9.375 mW per channel).

How does the device handle data integrity?

The AD7768-4 includes cyclic redundancy check (CRC) error checking on the data interface to ensure accurate transmission of converted samples.

What digital filters are integrated?

It features a wideband brick-wall filter with ±0.005 dB pass-band ripple and a sinc5 filter for low latency and low bandwidth measurements, both selectable per channel.