AD7687BCPZ-R2 - 16-Bit 250kSPS PulSAR Differential ADC | Analog Devices
MPN: AD7687BCPZ-R2 ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $11.5 | $11.50 |
| 10 | $10.35 | $103.50 |
| 100 | $9.2 | $920.00 |
| 500 | $8.3 | $4,150.00 |
| 1,000 | $7.5 | $7,500.00 |
| 2,500 | $6.85 | $17,125.00 |
AD7687BCPZ-R2 Overview
A successive-approximation register (SAR) ADC, also known as a PulSAR, performs conversion through charge redistribution on a capacitive DAC. This architecture delivers deterministic latency (no pipeline delay), inherent sample-and-hold behavior, and excellent DC accuracy, making SAR ADCs the preferred topology for precision multiplexed data acquisition, industrial instrumentation, and motor control feedback. Within the broader taxonomy, SAR ADCs sit under data converters -> ADCs -> precision ADCs.
Key features include a true differential analog input, ±VREF common-mode range, 1.5 LSB maximum INL, no missing codes at 16 bits, low power consumption proportional to throughput, an SPI-compatible serial interface with optional BUSY indicator via SDI, and daisy-chain capability for multi-ADC 3-wire buses. The integrated reference input and compact LFCSP-10 footprint simplify board layout while keeping noise immunity high through the exposed thermal pad tied to ground.
The internal conversion is governed by a precision DAC and comparator clocked by an internal oscillator; a single CNV rising edge initiates acquisition and conversion, and the BUSY line signals completion. Power dissipation scales linearly with throughput, so at 250 kSPS the part consumes its maximum rated current while at reduced sample rates power drops proportionally - a useful trait for battery-instrumented designs.
Typical applications include industrial process control and PLC analog input modules, medical instrumentation signal acquisition, battery-powered portable sensors, multi-channel data acquisition systems (DAQ), motor and motion control feedback loops, and precision weigh scales. The differential input and excellent DC accuracy make it especially suited to bridge and thermocouple front ends.
When designing with the AD7687BCPZ-R2, treat the exposed pad as the primary thermal and ground path - solder it to a sufficiently large ground plane. Use a low-noise reference (such as the ADR45xx family) and keep analog/digital ground returns separated until they join under the IC's exposed pad to preserve CMRR.
This page consolidates distributor pricing, drop-in alternatives, and applied design notes that go beyond the manufacturer datasheet's content to accelerate your precision-ADC design.
Drop-in alternatives for AD7687BCPZ-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 AD7687BCPZ-R2 (same form factor and footprint) — differing in Package, Architecture, Input Type, Resolution, Interface.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
AD7687BCPZ-RL
✅ Drop-In📋 Reference alternative (not in catalog)
AD7687ACPZ-R2
✅ Drop-In ⚠️ Specs Unverified📋 Reference alternative (not in catalog)
AD7689ACPZ
✅ Drop-In ⚠️ Specs Unverified📋 Reference alternative (not in catalog)
AD7685BCPZ-R2
✅ Drop-In ⚠️ Specs Unverified📋 Reference alternative (not in catalog)
AD7988-1BCPZ
✅ Drop-In ⚠️ Specs Unverified✓ In Stock
$8.1 / Unit
View Datasheet →AD7687BCPZ-R2 Maximum Ratings & Electrical Characteristics
| Resolution | 16 bits |
| Sample Rate | 250 kSPS |
| INL (Max) | 1.5 LSB |
| Number of Channels | 1 (differential) |
| Architecture | SAR (PulSAR, charge redistribution) |
| Analog Input Type | True differential, ±VREF common-mode range |
| Supply Voltage (VDD) | 2.3 V to 5.5 V |
| Digital I/O Supply (VIO) | 1.8 V / 2.5 V / 3.3 V / 5 V compatible |
| Reference | External (VREF input) |
| Interface | SPI-compatible serial (daisy-chain capable, optional BUSY on SDI) |
| Package | 10-pin LFCSP-WD (3x3 mm) with exposed pad |
| Operating Temperature | -40C to +85C |
| Mounting Type | Surface Mount |
| RoHS Status | Compliant |
| Lead-Free | Yes |
| MSL Level | 3 (per JEDEC J-STD-020) |
AD7687BCPZ-R2 Pin Configuration
| Pin 1 | REF — External reference voltage input (decouple to GND) |
| Pin 2 | VDD — Analog supply voltage (2.3 V to 5.5 V) |
| Pin 3 | VIO — Digital I/O supply voltage (1.8 V / 2.5 V / 3.3 V / 5 V) |
| Pin 4 | GND — Ground (additional ground connection via exposed pad) |
| Pin 5 | IN+ — True differential analog input, non-inverting |
| Pin 6 | IN- — True differential analog input, inverting |
| Pin 7 | SDI/BUSY — Serial data input / BUSY indicator (configurable) |
| Pin 8 | SCK — Serial clock input |
| Pin 9 | SDO — Serial data output |
| Pin 10 | CNV — Convert input (rising edge initiates conversion) |
| Pin EP | EP — Exposed pad - solder to ground plane (thermal and electrical) |
Typical Applications
AD7687BCPZ-R2 is suitable for 6 applications: Industrial Process Control & PLC Analog Input Modules, Medical Instrumentation Signal Acquisition, Battery-Powered Portable Sensor Systems, Multi-Channel Data Acquisition (DAQ) Systems, Motor & Motion Control Feedback Loops, Precision Weigh Scales & Strain-Gauge Front Ends.
Industrial Process Control & PLC Analog Input Modules
The AD7687BCPZ-R2's 16-bit resolution, 1.5 LSB INL, and 250 kSPS throughput make it a strong fit for industrial PLC analog input modules scanning 4-20 mA or voltage channels. Its true differential input and ±VREF common-mode range reject common-mode noise on long factory-floor cable runs, while the SAR architecture delivers deterministic zero-latency conversion required for closed-loop process control. The 10-LFCSP-WD (3x3 mm) footprint saves board area versus larger MSOP ADCs, and the SPI interface with optional BUSY indicator simplifies synchronization with industrial MCUs. Pair with the ADR4525 reference for stable readings across temperature swings from -40C to +85C.
Recommended
Medical Instrumentation Signal Acquisition
For medical instrumentation such as patient monitors, infusion pumps, and portable diagnostic devices, the AD7687BCPZ-R2 provides 16-bit precision with no missing codes, ensuring faithful acquisition of bioelectric signals. The 250 kSPS sample rate captures audio-bandwidth physiological waveforms (ECG, pulse oximetry plethysmograph) without aliasing, while the SAR architecture's deterministic latency simplifies medical-safety firmware timing analysis. Low power consumption that scales with throughput supports battery-powered wearable designs. The compact 10-LFCSP-WD (3x3 mm) package fits inside small-form-factor handheld instruments.
Recommended
Battery-Powered Portable Sensor Systems
Battery-powered portable sensor systems benefit from the AD7687BCPZ-R2's throughput-proportional power consumption: at lower sample rates the part draws proportionally less current, extending battery life for remote IoT sensor nodes. The wide 2.3 V to 5.5 V VDD range accepts a single-cell Li-ion or 3.3 V system rail directly, eliminating extra regulators. The VIO logic supply can be tied to a 1.8 V host MCU I/O domain, simplifying power tree design. SPI interface with daisy-chain support lets multiple sensors share one bus, reducing wiring in distributed sensor pods.
Recommended
Multi-Channel Data Acquisition (DAQ) Systems
In multi-channel data acquisition systems, the AD7687BCPZ-R2's daisy-chain SPI capability allows several ADCs to share a single 3-wire bus, dramatically reducing MCU pin count when scanning many channels. The true differential input accepts bipolar signals centered around any voltage up to ±VREF, simplifying signal conditioning for strain gauges and load cells. The 1.5 LSB INL and no-missing-codes guarantee ensures channel-to-channel matching across the DAQ scan list, while the SAR architecture provides deterministic sample timing for triggered acquisitions.
Recommended
Motor & Motion Control Feedback Loops
Motor and motion control applications require ADCs with deterministic latency so the control loop stays in phase with PWM switching. The AD7687BCPZ-R2 SAR architecture provides zero pipeline delay - the conversion result is available a fixed number of clock cycles after the CNV edge, simplifying field-oriented control (FOC) firmware. The 250 kSPS rate is sufficient for current-sense feedback on most industrial motor drives, while the differential input rejects common-mode switching noise injected by the power stage. Compact 10-LFCSP-WD package fits inside space-constrained integrated motor controller boards.
Recommended
Precision Weigh Scales & Strain-Gauge Front Ends
Precision weigh scales and load-cell applications benefit from the AD7687BCPZ-R2's 16-bit resolution and 1.5 LSB INL, which together with a low-noise instrumentation front end provide stable readings across the load-cell dynamic range. The true differential input directly accepts the ratiometric output of a bridge sensor excited by the ADC reference voltage, cancelling reference drift in the measurement. The 250 kSPS sample rate supports fast settling between weighments in production-line scales, while the small 10-LFCSP-WD (3x3) package suits compact retail bench scales.
Recommended
Recommended Products Summary
Engineering reference data for AD7687BCPZ-R2 — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | AD7687BCPZ-RL | AD7687ACPZ-R2 | AD7689ACPZ | AD7685BCPZ-R2 | AD7988-1BCPZ |
|---|---|---|---|---|---|---|
| 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 | 10-LFCSP (3x3) - same family |
| Brand | Analog Devices | Analog Devices | Analog Devices | Analog Devices | Analog Devices | Analog Devices |
| Resolution | 16 bits | 16 bits | 16 bits | 16 bits | 16 bits | 16 bits |
| Sample Rate | 250 kSPS | 250 kSPS | 250 kSPS | 250 kSPS | 250 kSPS | 100 kSPS (varies by grade) |
| Input Type | True differential | True differential | True differential | True differential (pseudobipolar via INL pair) | Pseudo-differential | True differential |
| Channels | 1 | 1 | 1 | 1 | 1 | 1 |
| VDD Supply | 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 | 2.375 V to 5.5 V |
Key Differentiators
- True differential input vs pseudo-differential family member (vs AD7685BCPZ-R2)
- Same PulSAR family as higher-speed AD7988 part (vs AD7988-1BCPZ)
- Optional BUSY indicator via shared SDI pin (vs AD7689ACPZ)
Design Notes
Solder the exposed pad (EP) of the 10-LFCSP-WD (3x3) package to a continuous ground plane. The EP is the primary thermal path and the lowest-impedance ground return. A grid of thermal vias beneath the EP - typical 0.3 mm drill, 0.6 mm pitch, plugged and capped - conducts heat into inner ground layers and prevents ground-bounce coupling into the analog inputs. Without proper EP soldering, INL can degrade by 0.5-1 LSB and noise pickup increases noticeably.
Keep analog and digital ground returns separate until they join under the IC's exposed pad. Route the REF decoupling capacitor (typically 10 uF ceramic in parallel with 0.1 uF) within 2 mm of the REF pin to suppress reference-induced conversion noise. Route SCK away from analog input traces, or place a ground guard ring around IN+/IN- if the board is densely packed; SAR ADC input capacitance causes kick-back current at the start of each conversion, which couples through the analog front end if traces are not properly guarded.
Do not assume the AD7687 is pin-compatible with the AD7685 - the AD7685 is pseudo-differential (single-ended true input plus ground-referenced input), whereas the AD7687 is true differential. Swapping them produces incorrect readings. Also, the BUSY/SDI pin is dual-function; if you do not need BUSY output, leave SDI as logic input only, otherwise drive it correctly during the BUSY indicator window. Estimated: typical quiescent current at 250 kSPS is about 1.7 mA from VDD at 5 V, scaling linearly with throughput - confirm against datasheet before budgeting battery life.
Compliance Information
RoHS compliant per Analog Devices product page. Not AEC-Q100 qualified - this is a precision industrial/medical/consumer-grade ADC; AEC-Q100 variants are not offered in the AD7687 family.
