AD7687BRMZRL7: High-precision 16-bit single-channel SAR ADC, 250 kSPS
Product Overview and Core Features
The AD7687BRMZRL7 belongs to the Analog Devices PulSAR® series of high-performance ADCs. It adopts a load-distributed SAR architecture and features 16-bit full-resolution, no-code loss sampling capability. It supports differential input of positive and negative reference voltages. This device can operate under a single power supply (2.3-5.5 V), and the digital I/O is compatible with 1.8, 2.5, 3.3, 5 V levels, which is very flexible.
High resolution and high precision: 16-bit, INL maximum ±1.5 LSB, DNL ±1 LSB
Powerful sampling performance: up to 250 kSPS, signal-to-noise ratio up to 95 dB (20 kHz), total harmonic distortion ≈ -118 dB
Input structure differential: Differential or single-ended support, input range ±VREF
Diverse and flexible interfaces: SPI/QSPI / 3-wire / 4-wire/MICROWIRE, including BUSY indication
Low power consumption: typical 4 mW@5 V/100 kSPS, sleep current only ~1 nA
Fast response: No pipeline delay, sampling can be done instantly upon switching, with precise phase
Key specification parameters
Parameter numerical description
Resolution: 16 bits
Sampling rate: 250 kSPS per channel
Single-ended/differential input supports ±VREF range, with VREF being equal to VDD at most
The external reference voltage VREF can be equal to VDD at most
Single power supply range: 2.3-5.5 V
Digital I/O voltage compatible with independent VIO, 1.8/2.5/3.3/5 V
Linear error INL ±1.5 LSB, DNL ±1 LSB
Signal-to-noise ratio/sampling bandwidth 95 dB @ 20 kHz
Total harmonic distortion - 118 dB
The interface supports SPI/QSPI/MICROWIRE and BUSY signals
Operating temperature: -40 °C to +85 °C
Package MSP-10 or 3×3 mm QFN, height approximately 0.85 mm
VIO: Digital I/O level interface, supporting multiple voltage domains
Typical application circuit
Differential input connection example: +VREF───┬──REF | CREF | GND IN+ ── VIN+ IN- ── VIN- CNV ── MCU GPIO BUSY ← MCU GPIO MCU SPI SCLK, SDI, SDO, CS ↔ ADC External reference capacitor filtering and voltage stabilization The MCU controls the sampling timing of the CNV and reads the data after waiting for the BUSY response Differential input enhances anti-interference capability and is suitable for precision measurement systems
Application scenarios and advantage expansion
Battery and portable device power monitoring: Low power consumption, wide voltage compatible Ri cells for accurate measurement
Industrial/process control systems: High-precision multi-channel measurement adapted to ±VREF input
Instruments and meters (oscilloscopes, multimeters, etc.) : High-precision signal sampling
Medical equipment and vital sign measurement: Low noise and high resolution performance ensure signal quality
Differential sensor (such as bridge structure) signal acquisition: Enhance common-mode suppression capability
Design suggestions and wiring experience
Low-resistance ground design: Check if the REF and the adjacent GND at the input end are complete, and the ground wire must not be shared
High-speed SPI line layout: SCLK and SDI adopt impedance matching and line length control
VIO independent power supply: Matches the MCU level to avoid interference
Sampling synchronization: The combined use of CNV and BUSY enhances control reliability
Compatibility and alternative solution suggestions
AD7685 / AD7686 / AD7688: Protocol compatibility, different precision/rate and packaging methods, can be replaced as needed Microchip MCP3202:12-bit alternative, low cost, moderate precision, suitable for control applications TI ADS8686:16-bit differential input, built-in PGA/NVP, suitable for high-precision demand platforms Maxim MAX11210: Low-power 24-bit ADC, suitable for scenarios with low sampling rate requirements but extremely high precision
Summary
The AD7687BRMZRL7, with its high precision, low power consumption, high-speed differential sampling capability and flexible interface, is the preferred ADC device for modern measurement, control and monitoring systems. It is applicable to fields such as instrumentation, battery monitoring, industrial control, and medical testing, and can significantly enhance the accuracy and stability of the system.
