Analog Devices Inc. AD7686CRM

Overview

AD7686CRM from Analog Devices is a 16-bit, 500 kSPS pseudo-differential successive approximation ADC operating from a single 5 V supply. It delivers ±0.6 LSB typical INL, 92.5 dB SINAD at 20 kHz, and no pipeline delay, with 1.8 V to 5 V logic compatibility via separate VIO pin - used in portable instrumentation and battery-powered data acquisition systems.

For engineers reviewing the AD7686CRM datasheet, AD7686CRM pinout, AD7686CRM application, or AD7686CRM equivalent, this page provides verified specifications, MSOP-10 pin mapping, real-world performance metrics (INL, THD, power scaling), and validated alternatives for precision analog-to-digital conversion in space-constrained, low-power embedded designs.

Technical Context

The AD7686CRM implements a charge redistribution SAR architecture with on-chip track-and-hold, enabling true 16-bit resolution without missing codes and zero latency. Its pseudo-differential input accepts 0 V to VREF (up to VDD) with IN− as ground sense, supporting remote sensing and common-mode rejection.

It features a proprietary SPI-/QSPI-/MICROWIRE-/DSP-compatible serial interface with daisy-chain capability and busy indicator, plus independent VIO (1.8 V–5 V) for mixed-voltage system interfacing - all while maintaining full specification over −40°C to +85°C.

Key Specifications

Pinout & Package

AD7686CRM is housed in a 10-lead MSOP package (3 mm × 3 mm, 0.85 mm height), pin-compatible with AD7685/AD7687/AD7688. The exposed pad must be connected to GND for thermal and EMI performance.

Key Features

Applications

Equivalent & Alternatives

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

Compared with AD7685CRM and AD7687BRMZ, the AD7686CRM offers the tightest INL (±2 LSB max) within the MSOP-10 PulSAR family at full 500 kSPS, making it optimal for metrology-grade applications where linearity and speed are jointly critical.

Availability

AD7686CRM is available at Aetrix Electronics and suitable for portable medical sensors, battery-powered data loggers, and industrial process monitoring requiring stable component supply, guaranteed long-term sourcing, and full RoHS-compliant packaging.

Supply support for AD7686CRM 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 AD7686CRM belongs to the PulSAR® family of precision SAR ADCs designed specifically for high-resolution, low-power, and low-latency data acquisition in space-constrained industrial, medical, and instrumentation systems.

FAQ

What is the maximum recommended reference voltage for AD7686CRM?

The AD7686CRM supports an external reference voltage (REF) from 0.5 V up to VDD. Since VDD is specified from 4.5 V to 5.5 V, the maximum REF is 5.5 V. Operation at VREF = VDD = 5 V is typical and yields optimal SINAD (92.5 dB) and THD (−110 dB); exceeding VDD risks violating absolute maximum ratings and is not supported. Always decouple REF with a 10 µF ceramic capacitor placed close to the pin.

Does AD7686CRM require an external driver amplifier for its analog inputs?

The AD7686CRM includes an on-chip track-and-hold with 9 MHz −3 dB input bandwidth and 2.5 ns aperture delay, allowing direct connection to low-impedance sources (<100 Ω). For high-impedance or reactive sources (e.g., RC filters, thermistor networks), an external driver like ADA4941 is recommended to maintain THD and settling performance - especially above 100 kHz input frequencies or when source impedance exceeds 500 Ω.

How does the AD7686CRM handle power supply variations, and what is its PSRR?

The AD7686CRM exhibits ±0.05 LSB power supply sensitivity over VDD = 5 V ± 5%, meaning supply ripple or droop contributes less than 0.05 LSB of gain error. Its PSRR is not explicitly specified as a frequency-dependent curve, but the 100 µA REF load current and dedicated analog/digital supplies (VDD/VIO) provide inherent isolation. For best results, use separate LDOs for VDD and VIO, and ensure VDD has ≤10 mV p-p ripple at frequencies below 100 kHz.

Can AD7686CRM operate with a 1.8 V digital interface while using a 5 V analog supply?

Yes. The AD7686CRM's VIO pin accepts 1.8 V to VDD + 0.3 V, enabling full 1.8 V logic compatibility while VDD remains at 5 V. Digital pins (SDI, SCK, SDO, CNV) meet 1.8 V VIH/VIL thresholds when VIO = 1.8 V, and the part maintains full 500 kSPS throughput and AC specs. This dual-supply flexibility eliminates level shifters in mixed-voltage systems - confirmed in Table 3 and Figure 4 of the datasheet.

Is AD7686CRM pin-compatible with other PulSAR ADCs, and which ones?

Yes. The AD7686CRM is pin-for-pin compatible with AD7685CRM, AD7687BRMZ, and AD7688BRMZ in the 10-lead MSOP package. All share identical pinout (REF, VDD, IN+, IN−, GND, CNV, SDO, SCK, SDI, VIO), same footprint, and compatible interface protocols - enabling drop-in upgrades or design reuse across speed/grade variants without PCB changes.