Analog Devices Inc. AD7895ARZ-3REEL

Overview

AD7895ARZ-3REEL from Analog Devices is a 12-bit successive-approximation analog-to-digital converter (ADC) with integrated track/hold amplifier, on-chip clock, and high-speed serial interface. It operates from a single +5 V supply, delivers 3.8 µs conversion time in high-sampling mode, supports ±2.5 V bipolar input range, and consumes ≤20 mW. It is used in precision data acquisition systems requiring compact size and low power, such as portable instrumentation and industrial sensor interfaces.

For engineers reviewing the AD7895ARZ-3REEL datasheet, AD7895ARZ-3REEL pinout, AD7895ARZ-3REEL application, or AD7895ARZ-3REEL equivalent, key selection criteria include its 8-pin SOIC package, 2s complement output coding, 15 MHz max SCLK compatibility, ±1 LSB relative accuracy, and automatic power-down mode for battery-constrained designs.

Technical Context

The AD7895ARZ-3REEL implements a laser-trimmed internal clock driving a 12-bit R-2R ladder SAR core, with on-chip track/hold enabling full-scale sine wave digitization up to >100 kHz input bandwidth. Its analog front-end scales ±2.5 V inputs using internal resistor network (R1 = R2 = 6.5 kΩ), delivering 1.22 mV/LSB resolution with buffered 2.5 V reference input.

It features two operating modes: Mode 1 (high sampling) initiates conversion on CONVST falling edge with 3.8 µs conversion time; Mode 2 (auto sleep) enters power-down after conversion and wakes on CONVST rising edge, yielding 9.8 µs effective cycle time. Serial interface uses SCLK/SDATA two-wire protocol with 16-bit frame (4 leading zeros + 12 data bits), valid on SCLK falling edge with 10 ns hold time.

Key Specifications

Pinout & Package

AD7895ARZ-3REEL is housed in an 8-pin SOIC (SO-8) package, 3.9 mm × 4.9 mm body, 1.27 mm pitch, RoHS-compliant, tape-and-reel format (REEL).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar 12-bit serial ADC applications.

Compared with AD7895ARZ-3REEL, AD7894ARZ provides higher resolution in identical footprint for future-proofing, while ADS7822U offers wider supply range and smaller package but shifts track/hold design responsibility to the system engineer.

Availability

AD7895ARZ-3REEL is available at Aetrix Electronics and suitable for portable instrumentation, industrial process monitoring, and medical data acquisition requiring stable component supply, long-term manufacturability, and RoHS-compliant packaging.

Supply support for AD7895ARZ-3REEL 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, headquartered in Norwood, MA.

The AD7895 series was designed as a space-optimized, low-power 12-bit serial ADC family targeting embedded data acquisition where board area and power budget are critical constraints.

FAQ

What is the input voltage range supported by the AD7895ARZ-3REEL?

The AD7895ARZ-3REEL supports a bipolar analog input range of ±2.5 V, optimized for industrial sensors and transducers with symmetric output swing. This range is fixed per variant and cannot be reconfigured; the AD7895ARZ-3REEL does not support ±10 V or 0–2.5 V ranges. Input impedance is 9 kΩ minimum, and the internal scaling network ensures accurate full-scale digitization without external resistive dividers.

Does the AD7895ARZ-3REEL require an external reference voltage?

Yes, the AD7895ARZ-3REEL requires an external +2.5 V reference applied to the REF IN pin. The device includes on-chip buffering with ≤1 µA input current and 10 pF input capacitance. Reference accuracy directly impacts gain error; Analog Devices recommends the AD780 or AD680 for optimal performance. The AD7895ARZ-3REEL does not generate or regulate its own reference.

How does the power-down mode operate in the AD7895ARZ-3REEL?

In Mode 2 (auto sleep), the AD7895ARZ-3REEL automatically enters power-down after conversion completes (BUSY goes low) and remains in that state until the next CONVST rising edge triggers wake-up. During power-down, IDD drops to 5 µA max at +25°C. Wake-up latency is 6 µs, after which conversion begins; total effective cycle time is 9.8 µs. This mode cuts average power significantly in low-duty-cycle sampling applications.

What is the serial interface protocol used by the AD7895ARZ-3REEL?

The AD7895ARZ-3REEL uses a proprietary two-wire serial interface with SCLK and SDATA lines only-no chip select or frame sync required. Data is clocked out on the falling edge of SCLK; each frame contains 16 bits (4 leading zeros followed by 12-bit 2s complement result). The interface is electrically compatible with standard SPI masters but requires custom timing due to BUSY-driven handshaking and lack of CS assertion.

Is the AD7895ARZ-3REEL pin-compatible with other variants in the AD7895 family?

Yes, all AD7895 variants-including AD7895ARZ-3REEL, AD7895ARZ-2, and AD7895ARZ-10-share identical 8-pin SOIC pinout and electrical interface. Differences are limited to internal scaling resistors and output coding (2s complement for -3/-10, straight binary for -2), so PCB layout is fully reusable across variants. Firmware must be updated to match input range assumptions and data format interpretation.