Analog Devices Inc. AD7856KR-REEL

Overview

AD7856KR-REEL from Analog Devices is a 14-bit, 285 kSPS sampling ADC with eight single-ended or four pseudo-differential analog inputs, operating from a single 5 V supply. It features on-chip reference (4.096 V), self- and system calibration, SPI/QSPI/μP-compatible serial interface, and automatic power-down after conversion - enabling high-accuracy data acquisition in battery-powered instrumentation.

For engineers reviewing the AD7856KR-REEL datasheet, AD7856KR-REEL pinout, AD7856KR-REEL application, or AD7856KR-REEL equivalent, key selection considerations include its K-grade temperature range (0°C to +105°C), 24-lead SOIC package, 14-bit resolution with ±2 LSB INL, 78 dB SNR at 10 kHz input, and flexible serial interface timing for embedded microcontroller integration.

Technical Context

The AD7856KR-REEL implements a successive approximation register (SAR) architecture with integrated track-and-hold, charge redistribution DAC, and calibration memory. Its pseudo-differential input multiplexer supports channel selection via control register bits SGL/DIFF and CH2–CH0, while internal reference buffering enables operation with external references from 1.2 V to VDD.

Calibration logic executes self-calibration on power-up (via CAL pin or internal capacitor), supports system offset/gain calibration, and stores coefficients in ten dedicated registers. Power management uses SLEEP pin and PMGT1/PMGT0 bits to enable full or partial power-down modes, reducing IDD to 10 µA (typ) with external clock active.

Key Specifications

Pinout & Package

AD7856KR-REEL is housed in a 24-lead small outline integrated circuit (SOIC) package, 0.3 inch wide, RoHS-compliant, with standard JEDEC MS-013AC footprint and 1.27 mm pitch.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar 14-bit SAR ADC applications.

Compared with AD7856AR-REEL, the AD7856KR-REEL trades 183 kSPS throughput and extended cold-temperature capability for lower cost and reduced clock frequency drive requirements; versus AD7682BCPZ-RL7, it offers faster conversion, on-chip reference, and simpler system-level calibration at the expense of 2-bit resolution.

Availability

AD7856KR-REEL is available at Aetrix Electronics and suitable for battery-powered instrumentation, industrial process monitoring, medical vital sign monitoring, and high-speed modem signal conditioning requiring stable component supply across multi-year production cycles.

Supply support for AD7856KR-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, Inc. is a global leader in high-performance analog, mixed-signal, and digital signal processing semiconductors, headquartered in Norwood, MA.

The AD7856KR-REEL belongs to Analog Devices' precision SAR ADC product line, designed specifically for medium-speed, high-accuracy data acquisition in space- and power-constrained systems where calibration integrity and supply simplicity are critical.

FAQ

What is the operating temperature range for the AD7856KR-REEL?

The AD7856KR-REEL is rated for operation from 0°C to +105°C, corresponding to the K-grade specification. This makes it suitable for industrial control systems and commercial equipment where ambient temperatures remain above freezing but may reach elevated levels during sustained operation. The part maintains ±2 LSB INL and 78 dB SNR across this full range when calibrated per datasheet procedures.

Does the AD7856KR-REEL require external reference components?

Yes, the AD7856KR-REEL requires two external capacitors: a 0.1 µF multilayer ceramic capacitor (CREF1) and a 0.01 µF multilayer ceramic capacitor (CREF2), both connected between their respective pins (CREF1, CREF2) and AGND. These stabilize the internal 4.096 V reference and DAC charge redistribution network. No external voltage reference IC is needed unless overriding the internal reference with an external source.

How does the AD7856KR-REEL handle channel selection for pseudo-differential inputs?

The AD7856KR-REEL selects input channels via the SGL/DIFF bit and CH2–CH0 bits in its 14-bit control register. When SGL/DIFF = 0, the device operates in pseudo-differential mode, pairing AIN1–AIN2, AIN3–AIN4, AIN5–AIN6, and AIN7–AIN8. Each pair's positive/negative configuration is fixed per datasheet Table III; no software reassignment of pin roles is supported - only channel activation via register write.

Can the AD7856KR-REEL perform system calibration, and what is required?

Yes, the AD7856KR-REEL supports system calibration for offset and gain errors introduced by external front-end circuitry. It requires applying known reference voltages to selected analog inputs while asserting CAL and setting CALMD = 1 and appropriate CALSLT bits. System calibration adjusts internal coefficients stored in calibration registers, and the resulting values remain valid until overwritten - no recalibration is needed unless hardware changes occur.

What serial interface modes does the AD7856KR-REEL support, and how are they configured?

The AD7856KR-REEL supports two serial interface modes: Mode 2 (standard 3-wire SPI) and Mode 1 (2-wire, where DIN serves as bidirectional data line). Mode selection is controlled by the 2/3 MODE bit in the control register: 0 = Mode 2 (default), 1 = Mode 1. Mode 1 requires toggling the 2/3 MODE bit in every write cycle, as it resets to 0 after each read operation per datasheet timing requirements.