AD7608BSTZ

ADCs/DACs - Special Purpose Overview

The AD7608BSTZ is an 18-bit, 8-channel simultaneous sampling data acquisition system (DAS) manufactured by Analog Devices Inc. It integrates analog input clamp protection, a second-order antialiasing filter, track-and-hold amplifiers, and a charge redistribution SAR ADC. The device operates from a single 5 V analog supply and accepts true bipolar ±10 V or ±5 V inputs with a fixed 1 MΩ input impedance. Key electrical specifications include a throughput rate of 200 kSPS per channel, a signal-to-noise ratio (SNR) of 99.5 dB at 130 Hz with 16x oversampling, and total harmonic distortion (THD) of -107 dB. Power consumption is 100 mW in normal mode and 25 mW in standby.

ADCs/DACs - Special Purpose Feature Summary

• 18-Bit Resolution: Provides 18-bit resolution without missing codes for high-precision measurements.
• Simultaneous Sampling: Features 8 channels sampled simultaneously to ensure phase coherence across all inputs.
• Integrated Signal Chain: Includes analog input clamp protection (±16.5 V tolerance), a 1 MΩ input buffer, and a second-order antialiasing filter with a 22 kHz cutoff.
• Flexible Interface: Supports both parallel and serial (SPI/QSPI/MICROWIRE/DSP compatible) digital interfaces.

ADCs/DACs - Special Purpose Applications

• Power line monitoring and protection systems
• Multiphase motor controls
• Instrumentation and control systems
• Multiaxis positioning systems
• Data acquisition systems (DAS)

ADCs/DACs - Special Purpose Procurement Notes

Verify the specific ordering suffix against the manufacturer's current documentation to confirm package type and reel specifications. Ensure that the voltage levels on the VDRIVE pin are compatible with the host interface logic requirements before integration.

ADCs/DACs - Special Purpose Selection Notes

Select this component when 18-bit resolution and simultaneous multi-channel sampling are required. It eliminates the need for external driver amplifiers due to its high input impedance and integrated filtering. Consider the 200 kSPS throughput limit and the 22 kHz antialiasing filter bandwidth during system design.

ADCs/DACs - Special Purpose Part Context

The AD7608 belongs to the AD760x family of high-resolution, bipolar input, simultaneous sampling DAS solutions. It serves as the 18-bit, 8-channel variant within this series, offering higher resolution compared to the 16-bit AD7606 or the 14-bit AD7607 models.

ADCs/DACs - Special Purpose Replacement Considerations

Pin-compatible alternatives within the same family include the AD7606 (16-bit) and AD7607 (14-bit). These devices share the same package and interface but offer lower resolution.

ADCs/DACs - Special Purpose FAQ

What is the maximum voltage the analog inputs can tolerate?

The analog input clamp protection circuitry allows the AD7608 to tolerate transient voltages up to ±16.5 V relative to AGND.

Does the AD7608 require an external reference voltage?

No, it includes an internal 2.5 V reference. However, an external reference can be used if the REF SELECT pin is tied low.

How does the device handle oversampling?

Oversampling is controlled via three pins (OS2, OS1, OS0). It allows for ratios from 1x to 64x, which improves SNR and reduces the 3 dB bandwidth.