Analog Devices Inc. AD7768-4BSTZ

Overview

AD7768-4BSTZ from Analog Devices is a 4-channel, 24-bit simultaneous-sampling sigma-delta ADC optimized for high-precision ac/dc measurement systems. It delivers 108 dB dynamic range, ±2 ppm INL, −120 dB THD, and supports selectable power modes (fast/median/low) with corresponding input bandwidths up to 110.8 kHz - enabling use in 3-phase power quality analyzers and medical EEG/EMG front-ends.

For engineers reviewing the AD7768-4BSTZ datasheet, AD7768-4BSTZ pinout, AD7768-4BSTZ application, or AD7768-4BSTZ equivalent, key selection criteria include per-channel digital filtering (wideband/sinc5), CRC-protected SPI interface, daisy-chain capability, analog input precharge buffers, and operation across −40°C to +105°C in a 64-lead LQFP package.

Technical Context

The AD7768-4BSTZ integrates four independent Σ-Δ modulators and digital filters, enabling true simultaneous sampling across all channels without inter-channel skew. Its architecture supports per-channel filter selection (wideband linear-phase or low-latency sinc5), decimation rates from ×32 to ×1024, and programmable power-speed-bandwidth trade-offs via three discrete operating modes.

Each channel features embedded analog precharge buffers for analog inputs and reference terminals, reducing input current and reference glitches. The device accepts external references (1 V to AVDD1 − AVSS), operates from dual analog supplies (AVDD1 = 5 V, AVDD2 = 2.25–5 V), and supports IOVDD at 1.8 V, 2.5 V, or 3.3 V - ensuring compatibility with mixed-voltage system designs.

Key Specifications

Pinout & Package

AD7768-4BSTZ is housed in a 64-lead LQFP (10 mm × 10 mm, 0.5 mm pitch) with no exposed pad. Pin functions are defined per the official Analog Devices pin configuration diagram (Rev. D, p.24).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar multichannel precision ADC applications.

Compared with AD7768BSTZ, AD7768-4BSTZ reduces channel count and BOM cost without sacrificing per-channel accuracy, noise, or feature set; compared with LTC2378-20, it provides true simultaneity, superior dynamic range, and integrated digital filtering - making it the optimal choice for coherent multi-signal acquisition.

Availability

AD7768-4BSTZ is available at Aetrix Electronics and suitable for 3-phase power quality analyzers, vibration condition monitoring systems, and high-precision medical EEG/EMG devices requiring stable component supply across extended product lifecycles.

Supply support for AD7768-4BSTZ includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

Analog Devices, Inc. is a global leader in high-performance analog, mixed-signal, and digital signal processing semiconductors, serving industrial, automotive, communications, and healthcare markets.

The AD7768-4BSTZ belongs to Analog Devices' precision sigma-delta ADC product line, engineered specifically for simultaneous multi-channel data acquisition systems demanding ultra-low noise, high linearity, and flexible power-performance scaling.

FAQ

What is the maximum output data rate per channel for AD7768-4BSTZ?

The AD7768-4BSTZ supports a maximum output data rate of 256 kSPS per channel in fast mode. This corresponds to a 110.8 kHz input bandwidth and consumes 51.5 mW per channel. Lower data rates (128 kSPS and 32 kSPS) are available in median and low-power modes, respectively, with proportional reductions in bandwidth and power consumption - all configurable via SPI register writes to the Power Mode Select Register.

Does AD7768-4BSTZ support daisy-chained operation?

Yes, AD7768-4BSTZ supports hardware daisy-chaining via its DOUTx and DIN pins. When configured in daisy-chain mode, multiple AD7768-4BSTZ devices share a single SPI bus, with DRDY signals synchronized to enable simultaneous sampling across all devices. The digital filter RAM and status registers remain independently accessible per device using frame-based addressing, preserving per-unit configurability without requiring additional chip-select lines.

What reference voltage range is supported by AD7768-4BSTZ?

AD7768-4BSTZ accepts an external differential reference voltage (REFx+ − REFx−) ranging from 1 V to (AVDD1 − AVSS). Absolute reference terminal voltages must stay within AVSS to AVDD1 when reference precharge buffers are enabled, or AVSS − 0.05 V to AVDD1 + 0.05 V when disabled. The device does not include an internal reference; precision external references (e.g., ADR45xx series) are recommended to maintain ±2 ppm INL and ±50 µV offset performance.

Can AD7768-4BSTZ operate with a 1.8 V IOVDD supply?

Yes, AD7768-4BSTZ fully supports 1.8 V IOVDD operation as specified in Table 2 of the Rev. D datasheet. Logic inputs meet VIH ≥ 1.17 V and VIL ≤ 0.7 V; outputs drive VOH ≥ 1.44 V (at 200 µA) and VOL ≤ 0.4 V (at 400 µA). All SPI timing parameters, register access, and data output formats remain valid at 1.8 V, enabling direct interfacing with low-voltage FPGAs and microcontrollers without level-shifting.

How does the analog input precharge buffer improve system performance in AD7768-4BSTZ?

The analog input precharge buffer in AD7768-4BSTZ reduces differential input current to <−20 µA (vs. ±48 µA/V unbuffered), minimizing voltage drop across source impedances and eliminating settling errors in high-impedance sensor interfaces like piezoelectric accelerometers or strain gauge bridges. This feature directly improves effective resolution and long-term baseline stability - especially critical in dc-coupled medical EEG/EMG systems where electrode polarization effects would otherwise dominate offset drift.