Analog Devices Inc. AD7688BCPZ-R2

Overview

AD7688BCPZ-R2 from Analog Devices is a 16-bit, charge redistribution successive approximation ADC with true differential analog input (±VREF), 500 kSPS throughput, ±1.5 LSB max INL, 96.5 dB dynamic range, and no pipeline delay. It operates from a single 5 V supply with 1.8 V–5 V logic interface (VIO) and targets high-precision data acquisition in space-constrained industrial instrumentation.

For engineers reviewing the AD7688BCPZ-R2 datasheet, AD7688BCPZ-R2 pinout, AD7688BCPZ-R2 application, or AD7688BCPZ-R2 equivalent, key selection criteria include its differential input architecture, daisy-chain SPI-compatible serial interface, sub-1 µs conversion time, 1 nA standby current, and dual-package availability in 10-lead LFCSP and MSOP.

Technical Context

The AD7688BCPZ-R2 implements a charge redistribution DAC-based SAR architecture with on-chip track-and-hold, enabling zero-latency conversion and full-scale step response in 400 ns. Its differential input stage supports common-mode rejection up to 65 dB at 250 kHz and accepts true bipolar inputs from −VREF to +VREF.

Conversion is initiated by the CNV rising edge; the internal clock eliminates SCK dependency for core conversion timing. The serial interface supports CS mode (3-/4-wire) and chain mode with BUSY indicator, and is compatible with SPI/QSPI/MICROWIRE/DSP controllers across 1.8 V–5 V logic levels via dedicated VIO supply.

Key Specifications

Pinout & Package

The AD7688BCPZ-R2 is available in a 10-lead 3 mm × 3 mm LFCSP (lead-frame chip-scale package) with exposed paddle requiring GND connection, and also in 10-lead MSOP. Both packages share identical pinout and functionality.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar 16-bit SAR ADC applications.

Compared with AD7685BRMZ and AD7687BRMZ, the AD7688BCPZ-R2 delivers 2× and 2× higher throughput respectively while maintaining identical pinout, interface, and power architecture - making it the optimal upgrade path for designs needing full 500 kSPS capability without layout changes.

Availability

AD7688BCPZ-R2 is available at Aetrix Electronics and suitable for battery-powered equipment, medical instruments, industrial process controls, and portable test & measurement systems requiring stable component supply and long-term production continuity.

Supply support for AD7688BCPZ-R2 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 AD7688BCPZ-R2 belongs to the PulSAR™ family of precision SAR ADCs designed specifically for high-resolution, low-power, and space-constrained data acquisition in instrumentation and portable medical systems.

FAQ

What is the maximum sampling rate supported by the AD7688BCPZ-R2?

The AD7688BCPZ-R2 supports a maximum throughput of 500 kSPS under specified conditions (VDD = 4.5 V–5.5 V, TA = −40°C to +85°C). This corresponds to a minimum conversion cycle time of 2 µs and enables accurate digitization of signals with bandwidths up to ~200 kHz. At lower throughput rates, power consumption scales linearly - e.g., 3.75 µW at 100 SPS - making the AD7688BCPZ-R2 highly adaptable across duty-cycled and continuous-sampling use cases.

Does the AD7688BCPZ-R2 require an external reference voltage?

Yes, the AD7688BCPZ-R2 requires an external reference voltage applied to the REF pin. The REF input accepts voltages from 0.5 V to VDD, and sets the full-scale differential input range to ±VREF. A typical implementation uses a precision 5 V reference (e.g., ADR4550) with a local 10 µF ceramic decoupling capacitor. The device does not include an internal reference, and reference stability directly impacts gain error and SNR performance - especially critical in metrology and calibration applications.

Can the AD7688BCPZ-R2 interface directly with a 1.8 V microcontroller?

Yes, the AD7688BCPZ-R2 supports direct interfacing with 1.8 V microcontrollers via its dedicated VIO supply pin. When VIO = 1.8 V, the digital interface (CNV, SCK, SDI, SDO) operates with VIH ≥ 1.26 V and VIL ≤ 0.54 V, fully compliant with standard 1.8 V CMOS logic levels. This eliminates level-shifting circuitry and simplifies integration with ultra-low-power MCUs such as the Silicon Labs EFM32 or STMicroelectronics STM32L4 series while maintaining robust noise immunity.

What package options are available for the AD7688BCPZ-R2?

The AD7688BCPZ-R2 is offered exclusively in the 10-lead 3 mm × 3 mm LFCSP (lead-frame chip-scale package) with exposed thermal pad. Unlike the base AD7688, the "BCPZ-R2" variant denotes this specific LFCSP configuration - distinct from the MSOP version (e.g., AD7688BRMZ). The LFCSP provides superior thermal performance (θJA = 48.7°C/W) and board-area efficiency, making it ideal for compact, high-density PCB layouts in portable instrumentation and medical devices.

How does the daisy-chain mode work on the AD7688BCPZ-R2?

Daisy-chain mode on the AD7688BCPZ-R2 is enabled when SDI is held low during the CNV rising edge. In this mode, multiple AD7688BCPZ-R2 devices share a single SDO line: each device shifts its 16-bit result onto the bus sequentially, with the first device's MSB appearing 16 SCK cycles after the initiating CNV edge. The host reads all results in one continuous stream - e.g., two devices yield 32 bits - eliminating the need for individual chip-select lines and reducing interconnect complexity in multi-channel systems.