Analog Devices Inc. AD7895ARZ-2

Overview

AD7895ARZ-2 from Analog Devices is a 12-bit successive-approximation analog-to-digital converter (ADC) with on-chip track/hold, serial interface, and single +5 V supply operation. It delivers 3.8 µs conversion time in high-sampling mode, supports 0 V to +2.5 V unipolar input range, consumes ≤20 mW, and uses straight binary output coding - deployed in precision data acquisition systems for industrial sensor interfaces.

For engineers reviewing the AD7895ARZ-2 datasheet, AD7895ARZ-2 pinout, AD7895ARZ-2 application, or AD7895ARZ-2 equivalent, key selection considerations include its 8-pin SOIC package, 12-bit resolution with ±1 LSB relative accuracy, 70 dB SNR at 50 kHz, 0.61 mV LSB step size, and compatibility with microcontroller serial interfaces requiring minimal external components.

Technical Context

The AD7895ARZ-2 implements a laser-trimmed internal clock driving a 12-bit R-2R ladder SAR core, paired with a high-input-impedance track/hold amplifier optimized for ≤0.3 µs acquisition time. Its analog front-end accepts 0 V to +2.5 V inputs with <500 nA input current and requires an externally buffered +2.5 V reference (REF IN).

It operates in two modes: Mode 1 (high-speed sampling, 3.8 µs conversion initiated on CONVST falling edge) and Mode 2 (auto power-down after conversion, 9.8 µs total cycle including 6 µs wake-up). Serial data output (SDATA) delivers 16-bit frames - four leading zeros followed by 12-bit straight binary conversion result - synchronized to SCLK falling edges.

Key Specifications

Pinout & Package

AD7895ARZ-2 is housed in an 8-pin SOIC (SO-8) package, 3.9 mm × 4.9 mm body, 1.27 mm pitch, RoHS-compliant, with exposed pad not electrically connected.

Key Features

Applications

Equivalent & Alternatives

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

Compared with AD7895ARZ-2, AD7495BRMZ-REEL offers higher speed but demands external track/hold and reference management, while ADS7822U reduces power consumption at the expense of missing on-chip signal conditioning - making AD7895ARZ-2 uniquely balanced for compact, self-contained 12-bit DAQ designs requiring minimal support circuitry.

Availability

AD7895ARZ-2 is available at Aetrix Electronics and suitable for industrial sensor interfaces, portable data loggers, test equipment front-ends, and medical instrumentation requiring stable component supply, long-term lifecycle assurance, and traceable sourcing.

Supply support for AD7895ARZ-2 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 Wilmington, MA.

The AD7895ARZ-2 belongs to Analog Devices' precision data acquisition ADC product line, engineered for applications demanding high resolution, low power, and integration of track/hold and serial interface in minimal footprint - targeting industrial automation, portable instrumentation, and medical diagnostics.

FAQ

What is the input voltage range supported by the AD7895ARZ-2?

The AD7895ARZ-2 supports a unipolar 0 V to +2.5 V analog input range. This matches common sensor output levels and eliminates the need for external level-shifting circuitry. The input presents high impedance (<500 nA bias current) and connects directly to the on-chip track/hold amplifier. Operation outside this range may cause damage or invalid conversion results, per absolute maximum ratings.

Does the AD7895ARZ-2 require an external reference voltage?

Yes, the AD7895ARZ-2 requires an external +2.5 V reference applied to the REF IN pin. The internal reference buffer accepts ±5% tolerance (2.375 V to 2.625 V), with ≤1 µA input current. Precision references such as the AD780 or AD680 are recommended to maintain specified gain accuracy and SNR performance. No internal reference is provided.

How does the AD7895ARZ-2 handle power management during low-duty-cycle operation?

The AD7895ARZ-2 features an automatic power-down mode (Mode 2) that reduces supply current to 5 µA max after conversion completion. It "wakes up" upon the rising edge of CONVST, with a 6 µs wake-up time before initiating conversion. This feature significantly lowers average power in intermittent-sampling applications like battery-powered data loggers, without requiring external control logic.

What serial interface protocol does the AD7895ARZ-2 use, and how is data formatted?

The AD7895ARZ-2 uses a proprietary 2-wire synchronous serial interface: SCLK (input) and SDATA (output), plus BUSY for status. Each conversion yields a 16-bit frame - four leading zeros followed by 12-bit straight binary result - clocked out MSB-first on the falling edge of SCLK. Data is valid 10 ns after each SCLK falling edge, supporting up to 15 MHz clock rates.

Can the AD7895ARZ-2 be used with microcontrollers lacking native SPI hardware?

Yes, the AD7895ARZ-2 is fully compatible with GPIO bit-banged serial interfaces due to its simple 2-wire timing and lack of complex protocol overhead. Its SCLK and SDATA signals require only basic edge detection and state sampling. The BUSY pin provides hardware-ready indication, enabling efficient polling or interrupt-driven reads without precise timing margins - ideal for resource-constrained MCUs.