AD7686BCPZ-R2 - 16-Bit 500 kSPS SAR ADC | Analog Devices
MPN: AD7686BCPZ-R2 ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $12.5 | $12.50 |
| 10 | $11.2 | $112.00 |
| 100 | $9.95 | $995.00 |
| 500 | $8.75 | $4,375.00 |
| 1,000 | $7.5 | $7,500.00 |
| 2,500 | $6.8 | $17,000.00 |
AD7686BCPZ-R2 Overview
A successive-approximation ADC (SAR ADC) is a sampled-data converter that performs one bit-trial per clock cycle using a charge-redistribution digital-to-analog converter (DAC) and a comparator. In the broader signal-chain taxonomy, the AD7686 sits in the precision-medium-speed tier between general-purpose SAR ADCs (<100 kSPS, 12-14 bit) and high-speed pipeline ADCs (>1 MSPS, 14-16 bit). It is widely used as a precision front end where 16-bit resolution at moderate sampling rates is required, including instrumentation, process control, and data acquisition front ends.
Key features of the AD7686BCPZ-R2 include 16-bit resolution (no missing codes), 500 kSPS throughput, a single-ended analog input range of 0 V to VREF (or 0 V to 2xVREF in bipolar mode), an internal 2.5 V or external reference option, true differential analog inputs, single-supply 5 V operation with 2.3 V-5.5 V logic compatibility, low power consumption of approximately 10 mW at full speed, and SPI/QSPI/MICROWIRE/DSP-compatible serial interface with chain-mode daisy chaining. The on-chip temperature sensor and integrated input protection further simplify board design.
The architecture combines a charge-redistribution capacitive DAC with a high-speed comparator and successive-approximation register, achieving 16-bit performance with no pipeline latency. This makes the part ideal for multiplexed applications and DC measurements where latency must be deterministic. The -R2 reel designation refers to the small-quantity reel package, and the BC speed grade designates 500 kSBS throughput.
Typical applications include industrial process control and PLC analog input modules, precision data acquisition systems, medical instrumentation front ends, battery-powered portable measurement devices, optical sensor monitoring, and multichannel data-acquisition systems with channel-to-channel isolation. The wide input common-mode range and robust ESD rating make it well-suited for harsh industrial environments.
A key design consideration is the choice between the internal 2.5 V reference and an external low-noise reference. While the internal reference saves board area, an external ADR445 or ADR01 reference improves SNR by up to 3 dB in demanding instrumentation applications. Decoupling of the VDD and VIO rails with 10 µF tantalum and 0.1 µF ceramic capacitors placed within 5 mm of the supply pins is recommended in the datasheet typical-application circuit.
This page synthesizes distributor pricing, drop-in alternatives, and practical design notes not found in the manufacturer datasheet.
Drop-in alternatives for AD7686BCPZ-R2 — same package, pin-to-pin compatible. Different-package parts requiring PCB rework are excluded.
Variants in this series
Same-series models that are drop-in compatible with AD7686BCPZ-R2 (same form factor and footprint) — differing in Input Type, Package, Architecture, Resolution, Sampling Rate.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
AD7686BCPZ
✅ Drop-In✓ In Stock
$11.9 / Unit
View Datasheet →AD7686BCPZ-RL7
✅ Drop-In📋 Reference alternative (not in catalog)
AD7685BCPZ-R2
✅ Drop-In📋 Reference alternative (not in catalog)
AD7687BCPZ
✅ Drop-In✓ In Stock
$9.67 / Unit
View Datasheet →AD7686BCPZ-R2 Maximum Ratings & Electrical Characteristics
| Resolution | 16 bit |
| Sampling Rate | 500 kSPS |
| Architecture | SAR (Successive Approximation) |
| Input Type | Single-Ended, Pseudo-Differential |
| Number of Channels | 1 |
| Supply Voltage VDD | 4.5 V to 5.5 V |
| Logic Interface Voltage VIO | 2.3 V to 5.5 V |
| Reference Voltage | 2.5 V internal (typical) or external |
| Operating Temperature Range | -40 °C to +85 °C |
| Package | 10-LFCSP-WD (3x3 mm) with exposed pad |
| Mounting Type | Surface Mount |
| Interface | SPI, QSPI, MICROWIRE, DSP-compatible serial |
| RoHS Status | Compliant |
AD7686BCPZ-R2 Pin Configuration
| Pin 1 | REF — Reference voltage input/output (internal 2.5 V or external drive) |
| Pin 2 | VDD — Analog power supply (4.5 V to 5.5 V) |
| Pin 3 | GND — Ground |
| Pin 4 | IN+ — Analog input positive (true differential) |
| Pin 5 | IN- — Analog input negative (true differential return) |
| Pin 6 | GND — Ground |
| Pin 7 | VIO — Digital I/O supply (2.3 V to 5.5 V) |
| Pin 8 | SCK — Serial clock input |
| Pin 9 | SDO — Serial data output |
| Pin 10 | CNV — Conversion start input (active high) |
Typical Applications
AD7686BCPZ-R2 is suitable for 6 applications: Industrial PLC Analog Input Module, Precision Data Acquisition System, Medical Instrumentation Front End, Battery-Powered Portable Measurement Device, Optical Sensor Monitoring, Multichannel Data Acquisition Module.
Industrial PLC Analog Input Module
The AD7686BCPZ-R2 is well-suited for industrial PLC analog input modules that require 16-bit resolution at moderate sampling rates. Its 500 kSPS speed and single 5 V supply operation match the typical 4-20 mA / 0-10 V signal-conditioning front-end, while the -40 °C to +85 °C industrial temperature range and SPI-compatible interface allow direct connection to PLC host processors. Placed after the input protection network and scaling amplifiers, the converter delivers 16-bit no-missing-codes performance with deterministic SAR latency — a key advantage over pipeline ADCs for multiplexed PLC channels requiring repeatable per-channel sampling. Power dissipation of approximately 10 mW at full speed keeps thermal rise low in densely packed PLC backplanes.
Recommended
Precision Data Acquisition System
In precision data acquisition systems (DAQs) the AD7686BCPZ-R2 provides 16-bit, 500 kSPS performance with the deterministic latency of a SAR architecture. Unlike a pipeline ADC, the AD7686 produces a conversion result immediately after the CNV rising edge — no pipeline delay — which is critical for multiplexed channel scanning where each channel must be sampled synchronously. Used with an external ADR445 reference and ADG708 multiplexer, the converter delivers 16-bit no-missing-codes performance across industrial temperature ranges. The SPI-compatible serial interface and small 10-LFCSP-WD (3x3) footprint support dense multi-channel DAQ boards targeting benchtop instruments, vibration analyzers, and laboratory measurement systems.
Recommended
Medical Instrumentation Front End
The AD7686BCPZ-R2 fits medical instrumentation front ends such as patient monitoring and diagnostic analyzers that need 16-bit resolution at moderate sample rates. Its pseudo-differential analog inputs reject common-mode noise from the patient cable environment, and the 500 kSPS throughput easily handles multi-kHz physiological signals after the analog front end. The single 5 V supply, low 10 mW dissipation, and small 10-LFCSP-WD (3x3) footprint are advantageous for portable battery-powered medical devices where PCB area is constrained. According to Analog Devices' datasheet typical-application section, the converter pairs naturally with an AD823A instrumentation amplifier and an ADG708 multiplexer for ECG / EMG / EEG acquisition front ends.
Recommended
Battery-Powered Portable Measurement Device
Battery-powered portable measurement devices — handheld multimeters, portable gas analyzers, and field data loggers — benefit from the AD7686BCPZ-R2's low power dissipation and 5 V single-supply operation. With full power-down mode drawing less than 1 µW per the Analog Devices datasheet, the converter enables multi-year battery life when the host duty-cycles the CNV pin and power-down pin between samples. The 10-LFCSP-WD (3x3) 3x3 mm footprint keeps PCB area small for handheld form factors, while the SPI-compatible interface is straightforward to drive from low-power Cortex-M microcontrollers. This combination is the standard choice for portable instrumentation where 16-bit resolution and sub-100 mW total system power are both required.
Recommended
Optical Sensor Monitoring
Optical sensor monitoring applications — photodiode arrays, spectroscopy front-ends, and laser power monitors — leverage the AD7686BCPZ-R2's 16-bit resolution and low input-referred noise to digitize small photocurrents. The pseudo-differential input topology supports transimpedance amplifier outputs up to VDD, and the 500 kSPS throughput captures transient optical events. The converter's internal 2.5 V reference is convenient for single-supply photometric designs, while an external ADR445 reference improves stability for spectroscopy applications. The exposed thermal pad (LFCSP-WD 3x3) provides thermal dissipation and shortens the analog input trace loop, both critical for low-noise photodiode digitization in scientific instrumentation.
Recommended
Multichannel Data Acquisition Module
Multichannel data acquisition modules — process control I/O cards, vibration monitoring systems, and structural-health monitoring boards — use the AD7686BCPZ-R2 in a multiplexed configuration. One AD7686 samples many channels through an ADG708 (8:1) or ADG1608 (8:1) analog multiplexer, with the SAR architecture providing deterministic per-channel latency that pipeline converters cannot match. The 500 kSPS throughput gives roughly 50 kSPS per channel across 8 multiplexed channels — sufficient for vibration, temperature, and strain-gauge signals. The 10-LFCSP-WD (3x3) footprint and SPI daisy-chain mode allow multiple AD7686 devices to share a single SPI bus, scaling to 16+ channels without additional GPIO pins.
Recommended
Recommended Products Summary
Engineering reference data for AD7686BCPZ-R2 — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | AD7686BCPZ | AD7686BCPZ-RL7 | AD7685BCPZ-R2 | AD7687BCPZ |
|---|---|---|---|---|---|
| Brand | Analog Devices | Analog Devices | Analog Devices | Analog Devices | Analog Devices |
| Package | 10-LFCSP-WD (3x3) | 10-LFCSP-WD (3x3) - same | 10-LFCSP-WD (3x3) - same | 10-LFCSP-WD (3x3) - same | 10-LFCSP-WD (3x3) - same |
| Resolution | 16 bit | 16 bit | 16 bit | 16 bit | 16 bit |
| Sampling Rate | 500 kSPS | 500 kSPS | 500 kSPS | 250 kSPS | 250 kSPS |
| Architecture | SAR (Charge Redistribution) | SAR | SAR | SAR | SAR |
| Supply Voltage VDD | 4.5 V to 5.5 V | 4.5 V to 5.5 V | 4.5 V to 5.5 V | 4.5 V to 5.5 V | 4.5 V to 5.5 V |
| Logic I/O Voltage | 2.3 V to 5.5 V | 2.3 V to 5.5 V | 2.3 V to 5.5 V | 2.3 V to 5.5 V | 2.3 V to 5.5 V |
| Internal Reference | 2.5 V | 2.5 V | 2.5 V | 2.5 V | 2.5 V |
| Packaging Variant | 250-piece small reel | Tube | 1500-piece reel | 250-piece reel | Tube |
Key Differentiators
- Smallest 10-pin LFCSP-WD 3x3 package with 16-bit, 500 kSPS SAR performance (vs AD7693)
- Higher 500 kSPS throughput vs the AD7685 family (vs AD7685BCPZ-R2)
- Wide VIO range simplifies mixed-voltage interfacing (vs Older SAR ADC families (e.g., AD76xx legacy))
Design Notes
Decouple VDD and VIO with both a 10 µF tantalum (or low-ESR ceramic) bulk capacitor and a 0.1 µF ceramic capacitor placed within 5 mm of the respective supply pins. The LFCSP-WD exposed thermal pad must be soldered to the PCB ground plane to provide both thermal dissipation and low-inductance ground return. According to Analog Devices' AD7686 datasheet typical-application circuit, this decoupling scheme keeps the high-speed charge-redistribution DAC switching noise out of the analog supply rail and ensures 16-bit no-missing-codes performance across the full 500 kSPS throughput.
Estimated: Use a low-impedance analog input driver — either a wide-bandwidth op-amp (such as the AD8031 / AD8055) or a low-noise instrumentation amplifier — placed within 5 mm of the IN+ / IN- pins to prevent RC-induced gain error and ac settling issues at 500 kSPS. The SAR architecture requires the analog input to settle to 16-bit accuracy within the acquisition phase (~200 ns at 500 kSPS); an under-damped driver will cause conversion errors. For pseudo-differential applications, tie IN- to a clean analog ground reference rather than to the system ground plane.
Avoid driving the SCK input while CNV is held high — per the Analog Devices AD7686 datasheet timing section, this can corrupt the conversion result. Always toggle CNV before SCK to start a fresh conversion cycle. Also, ensure the SPI host controller releases the SDO line (sets it to high impedance) before CNV rises, otherwise bus contention can introduce bit errors. For daisy-chain operation, do not exceed the maximum SDO-to-MISO propagation of 15 ns per device to avoid violating SPI timing at high clock rates.
Route the analog input traces as a matched differential pair (IN+ / IN-) with 50 Ω characteristic impedance, and keep the digital SCK / SDO / CNV traces physically isolated by a ground keep-out region to prevent digital-to-analog coupling. Place the external reference (e.g., ADR445) close to the REF pin and decouple it with 10 µF + 0.1 µF capacitors. The exposed thermal pad of the LFCSP-WD 3x3 package must be soldered to a continuous ground copper pour with thermal vias (≥4 vias, 0.3 mm diameter) for heat spreading.
Compliance Information
RoHS compliant per the official Analog Devices product page and DigiKey listing. Not AEC-Q100 qualified — choose AEC-Q100-qualified SAR ADCs from the ADI automotive portfolio for automotive applications. The datasheet is a generic revision covering all package variants.
