Analog Devices Inc. AD7896BR-REEL

Overview

AD7896BR-REEL from Analog Devices is a single-supply, 12-bit successive approximation ADC with 8 µs conversion time, 100 kHz throughput rate, and integrated track-and-hold amplifier - designed for space-constrained data acquisition in portable instrumentation and sensor interface systems.

For engineers reviewing the AD7896BR-REEL datasheet, AD7896BR-REEL pinout, AD7896BR-REEL application, or AD7896BR-REEL equivalent, key selection considerations include its VDD-referenced 0 V to VDD analog input range, 2-wire serial interface timing (10 MHz max SCLK), automatic power-down mode, and SOIC-8 package compatibility with industrial temperature operation.

Technical Context

The AD7896BR-REEL implements an R-2R ladder-based SAR architecture with laser-trimmed internal clock, eliminating external timing components. It operates in two distinct modes: Mode 1 (high-speed, 8 µs conversion, BUSY-driven timing) and Mode 2 (auto-sleep, 14 µs total cycle including 6 µs wake-up).

Its analog front-end accepts 0 V to VDD input with ≤1 kΩ source impedance, achieves ±1 LSB relative accuracy and 70 dB SNR at 10 kHz input, and uses VDD as both supply and reference - enabling true single-rail operation without external voltage references or precision buffers.

Key Specifications

Pinout & Package

AD7896BR-REEL is housed in an 8-lead SOIC package (3.9 mm × 4.9 mm, 1.27 mm pitch), RoHS-compliant, tape-and-reel format (REEL suffix). Pin 1 is VIN; pin 8 is SCLK. Package thermal resistance: θ_JA = 160°C/W.

Key Features

Applications

Equivalent & Alternatives

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

Compared with ADS7822U and MAX11100ETA+, the AD7896BR-REEL uniquely balances 12-bit precision, ultra-low power in sleep mode, and minimal external component count - making it optimal for compact, battery-operated measurement nodes where board area and energy budget are constrained.

Availability

AD7896BR-REEL is available at Aetrix Electronics and suitable for portable instrumentation, industrial sensor transmitters, and medical vital sign monitors requiring stable component supply across extended product lifecycles.

Supply support for AD7896BR-REEL 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, headquartered in Norwood, MA.

The AD7896BR-REEL belongs to Analog Devices' legacy precision data acquisition family, engineered specifically for low-power, space-constrained embedded systems needing self-contained 12-bit digitization without external support components.

FAQ

What is the maximum serial clock frequency supported by the AD7896BR-REEL?

The AD7896BR-REEL supports a maximum SCLK frequency of 10 MHz under 5 V operation. At 3.3 V, timing margins tighten - data access time increases to 100 ns, limiting practical SCLK to ≤7 MHz for robust operation. The part's t4 (data access time) and t5 (data hold time) specifications define the absolute limit; exceeding them risks read errors. Always verify timing with oscilloscope capture of SCLK and SDATA edges in your target system.

Does the AD7896BR-REEL require an external voltage reference?

No, the AD7896BR-REEL does not require an external voltage reference. Its internal reference is derived directly from the VDD supply, establishing the full-scale range as 0 V to VDD. This architecture eliminates external reference ICs, decoupling capacitors, and associated layout complexity. However, VDD regulation quality directly impacts accuracy - a 1% VDD variation causes ~1% full-scale error, so use a low-noise, well-decoupled supply.

How does the auto-sleep mode function in the AD7896BR-REEL?

In auto-sleep mode (Mode 2), the AD7896BR-REEL enters low-power state automatically when CONVST remains low after BUSY goes low at conversion completion. It "wakes up" on the rising edge of the next CONVST, requiring 6 µs before initiating the 8 µs conversion. Total cycle time is 14 µs minimum. This reduces average IDD to 5 µA (typ) at 2.7 V, making it ideal for infrequent sampling. Wake-up timing must be accounted for in firmware scheduling.

What is the analog input impedance of the AD7896BR-REEL, and how does it affect sensor interfacing?

The AD7896BR-REEL specifies ±2 µA max analog input current, implying effective input impedance >1 GΩ at DC. However, dynamic charging during track-to-hold transition imposes a 1 kΩ maximum source impedance requirement to achieve 12-bit settling within 1.5 µs acquisition time. Exceeding this causes code-dependent errors. For high-impedance sensors (e.g., pH electrodes), a unity-gain buffer amplifier is mandatory before VIN.

Can the AD7896BR-REEL interface directly with a standard SPI master?

Yes, the AD7896BR-REEL can interface with standard SPI masters, but requires careful configuration: it uses a 2-wire serial protocol (SCLK + SDATA) with no chip select (CS) - so the master must assert SCLK only when reading. The 16-bit frame (4 leading zeros + 12-bit result) aligns with SPI shift registers, but firmware must ignore the first four bits. Also, SDATA is three-stated after the 16th SCLK falling edge, so the master must complete reads within that window without extra clocks.