Analog Devices Inc. AD7908BRUZ

Overview

AD7908BRUZ from Analog Devices is an 8-channel, 1 MSPS, 8-bit successive approximation ADC with integrated channel sequencer, operating from a single 2.7 V to 5.25 V supply and consuming ≤6 mW at 3 V. It features eight single-ended analog inputs, SPI-compatible serial interface, no pipeline delay, and supports 0 V to REFIN or 0 V to 2 × REFIN input ranges in straight binary coding - used in industrial sensor data acquisition systems requiring high channel density and low power.

For engineers reviewing the AD7908BRUZ datasheet, AD7908BRUZ pinout, AD7908BRUZ application, or AD7908BRUZ equivalent, key selection criteria include its 8-bit resolution, 1 MSPS throughput, TSSOP-20 package, sequencer-controlled multi-channel sampling, and VDRIVE-enabled 3 V/5 V logic compatibility - all critical for embedded control and real-time monitoring designs.

Technical Context

The AD7908BRUZ implements a standard SAR architecture with a track-and-hold amplifier supporting >8 MHz input bandwidth and 10 ns aperture delay. Conversion is initiated on the falling edge of CS and synchronized to SCLK, with fixed 16-cycle timing (800 ns max at 20 MHz) and no pipeline latency.

Its sequencer allows preprogrammed cycling across up to eight channels via control register configuration (ADD2–ADD0), while the VDRIVE pin decouples logic-level voltage (2.7 V–5.25 V) from AVDD, enabling direct interfacing with mixed-voltage microcontrollers without level shifters.

Key Specifications

Pinout & Package

AD7908BRUZ is housed in a 20-lead TSSOP package (4.4 mm × 6.5 mm, 0.65 mm pitch), qualified for automotive applications and optimized for thermal performance (θ_JA = 143°C/W).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar 8-channel SAR ADC applications.

Compared with AD7908BRUZ, AD7918BRUZ offers higher resolution at the cost of increased power and reduced throughput margin, while ADS8320IPW trades speed and integration for raw precision - making AD7908BRUZ optimal for cost-sensitive, high-channel-count, medium-accuracy real-time acquisition.

Availability

AD7908BRUZ is available at Aetrix Electronics and suitable for industrial automation, automotive BMS, and portable medical devices requiring stable component supply, long-term lifecycle support, and AEC-Q100-compliant sourcing.

Supply support for AD7908BRUZ 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 is a global leader in high-performance analog, mixed-signal, and digital signal processing semiconductors, serving industrial, automotive, communications, and healthcare markets since 1965.

The AD7908BRUZ belongs to the AD7908/AD7918/AD7928 family of high-speed, low-power, multi-channel SAR ADCs designed specifically for space- and power-constrained data acquisition systems demanding integrated sequencing and flexible voltage operation.

FAQ

What is the maximum sampling rate supported by the AD7908BRUZ?

The AD7908BRUZ supports a maximum throughput rate of 1 MSPS, achieved with a 20 MHz SCLK and 16-clock conversion cycle. At this rate, total conversion time is 800 ns max, and the device consumes 6 mW at 3 V supply. Lower SCLK frequencies proportionally reduce throughput, enabling adjustable speed/power trade-offs in battery-powered applications.

Does the AD7908BRUZ require an external reference voltage?

Yes, the AD7908BRUZ requires an external reference voltage applied to the REFIN pin. The datasheet specifies 2.5 V ±1% for guaranteed performance. REFIN sets the full-scale input range - either 0 V to REFIN (straight binary) or 0 V to 2 × REFIN (twos complement). The part does not include an internal reference, so a low-drift, low-noise external source or buffered reference IC is mandatory for precision applications.

How does the channel sequencer in the AD7908BRUZ operate?

The AD7908BRUZ sequencer uses three address bits (ADD2–ADD0) and the SEQ bit in its control register to define a programmable scan order across VIN0–VIN7. When enabled, it automatically cycles through selected channels without host intervention - reducing CPU load and ensuring deterministic timing. Sequencing is fully configurable per conversion cycle and supports both continuous and one-shot modes.

Can the AD7908BRUZ interface directly with a 3 V microcontroller while using a 5 V analog supply?

Yes, the AD7908BRUZ supports independent analog and digital supplies via separate AVDD and VDRIVE pins. With AVDD = 5 V and VDRIVE = 3 V, the serial interface (CS, SCLK, DIN, DOUT) operates at 3 V logic levels while the ADC core runs at 5 V - enabling direct connection to 3 V MCUs without level-shifting circuitry. This dual-supply flexibility simplifies mixed-voltage system design.

What is the purpose of the VDRIVE pin on the AD7908BRUZ?

The VDRIVE pin on the AD7908BRUZ sets the voltage threshold for all digital I/O pins (CS, SCLK, DIN, DOUT), decoupling logic interface levels from the analog supply AVDD. This allows the AD7908BRUZ to communicate with 3 V or 5 V processors regardless of AVDD value - eliminating external level shifters, reducing BOM cost, and improving signal integrity in heterogeneous voltage systems.