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Analog Devices Inc. AD7685CRMZ
- Part No.:
- AD7685CRMZ
- Manufacturer:
- Analog Devices Inc.
- Category:
- Analog to Digital Converters (ADC)
- Package:
- 10-TFSOP, 10-MSOP (0.118", 3.00mm Width)
- Datasheet:
-
AD7685CRMZ.pdf
- Description:
- IC ADC 16BIT SAR 10MSOP
- Quantity:
- Payment:
- Shipping:
Inventory:1,341
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Product details
Overview
AD7685CRMZ from Analog Devices is a 16-bit, pseudo-differential, successive-approximation ADC with 250 kSPS throughput, ±2 LSB max INL, 93.5 dB SINAD at 20 kHz, and no pipeline delay-designed for high-precision data acquisition in battery-powered medical instruments and portable instrumentation.
For engineers reviewing the AD7685CRMZ datasheet, AD7685CRMZ pinout, AD7685CRMZ application, or AD7685CRMZ equivalent, this page delivers verified specs, validated MSOP-10 pin functions, real-world use cases in mobile communications and process control, and two confirmed alternative parts with documented technical and application differences.
Technical Context
The AD7685CRMZ employs a charge redistribution SAR architecture with integrated track-and-hold, enabling true 16-bit resolution without missing codes and zero latency conversion. Its analog input accepts 0 V to VREF differential range referenced to IN−, with VREF externally supplied up to VDD (5.5 V).
Digital interface supports SPI-/QSPI™-/MICROWIRE™-/DSP-compatible 3- or 4-wire modes plus daisy-chain capability via SDI/SDO, with BUSY indicator option and independent VIO supply (1.8 V to 5 V) decoupled from VDD (2.3 V to 5.5 V).
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Resolution | 16-bit with no missing codes-guarantees monotonicity and full-scale code coverage for precision measurement systems. |
| Throughput | 250 kSPS at VDD = 4.5–5.5 V-supports real-time sampling of audio-band and control-loop signals without undersampling. |
| INL | ±2 LSB maximum (±0.003% FSR)-enables accurate DC calibration and low-gain sensor interfacing without software correction. |
| SINAD | 93.5 dB at 20 kHz, VREF = 5 V-delivers >15.5 ENOB for high-fidelity signal capture in instrumentation-grade applications. |
| Power @ 100 kSPS | 1.35 mW at 2.5 V, 4 mW at 5 V-scales linearly with throughput, enabling ultra-low-power operation in sleep-wake cycles. |
| Standby Current | 1 nA-facilitates multi-year battery life in intermittent-sampling portable devices like PDAs and handheld meters. |
| Analog Input Range | 0 V to VREF (VREF ≤ VDD), pseudo-differential-simplifies front-end design by eliminating need for level-shifting or differential driver amplifiers in single-ended sensor interfaces. |
Pinout & Package
AD7685CRMZ is housed in a 10-lead MSOP package (3 mm × 3 mm, 0.5 mm pitch), RoHS-compliant, with exposed pad connected to GND (optional for thermal performance).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 REF | Analog reference input | Accepts external 0.5 V to VDD reference; requires local 10 µF decoupling for noise immunity and stability. |
| 2 VDD | Analog power supply | 2.3 V to 5.5 V single supply; powers internal SAR core, track-and-hold, and reference buffer. |
| 3 IN+ | Pseudo-differential analog input | Input voltage measured relative to IN−; range = 0 V to VREF-ideal for single-ended sensors with ground-referenced outputs. |
| 4 IN− | Analog ground sense | Provides remote ground reference point; connects to system analog ground plane to reject common-mode noise. |
| 5 GND | Power ground | Common return for VDD and analog circuitry; must be star-connected to minimize ground bounce. |
| 6 CNV | Convert trigger / interface mode select | Rising edge initiates conversion; logic level at CNV rising edge selects CS or Chain mode-no external clock required. |
| 7 SDO | Serial data output | 16-bit straight-binary output synchronized to SCK; tri-state when CNV/SDI high in CS mode. |
| 8 SCK | Serial clock input | Drives data shift-out; timing varies with VIO (15–40 ns period), supporting 1.8 V to 5 V host logic. |
| 9 SDI | Serial data input / mode control | Low at CNV edge enables daisy-chain mode; high enables CS mode-configures interface without register writes. |
| 10 VIO | Digital I/O supply | Independent 1.8 V to VDD supply for digital interface-enables mixed-voltage system integration without level shifters. |
Key Features
| Feature | Design Value |
|---|---|
| No pipeline delay | Conversion result available immediately after tCONV (≤2.2 µs); eliminates FIFO buffering and simplifies real-time control loop timing. |
| Proprietary serial interface | Hardware-configurable CS or Chain mode via CNV/SDI logic levels-no firmware initialization or configuration registers needed. |
| Single-supply operation | VDD = 2.3–5.5 V + VIO = 1.8–5 V-reduces BOM count by eliminating dual-rail supplies and LDOs for digital interface. |
| Ultra-low standby current | 1 nA at 25°C-enables microamp-level system sleep states without sacrificing wake-up latency or accuracy. |
| Pin-for-pin compatibility | With AD7686/AD7687/AD7688-allows scalable resolution upgrades (14/16/18-bit) within same PCB layout and firmware framework. |
Applications
| Portable Medical Monitoring | Battery-Powered Data Loggers |
|---|---|
Use Scenario: Continuous ECG waveform digitization in handheld patient monitors with 24-hour battery life. IC Role / Device Role / Timing Role: Primary 16-bit ADC capturing analog front-end output at 250 kSPS with zero-latency conversion for real-time arrhythmia detection. Use Value: 93.5 dB SINAD ensures clean baseline resolution; 1 nA standby current extends battery runtime between charges. |
Use Scenario: Environmental sensor node logging temperature, humidity, and pressure over weeks on coin-cell power. IC Role / Device Role / Timing Role: Low-duty-cycle ADC activated only during scheduled sampling bursts, minimizing average power draw. Use Value: Linear power scaling (1.4 µW @ 100 SPS) and hardware-triggered conversion eliminate MCU polling overhead. |
| Industrial Process Control | Mobile Communications Test Equipment |
Use Scenario: High-accuracy analog input module in PLC I/O cards measuring 4–20 mA transducer outputs. IC Role / Device Role / Timing Role: Precision ADC with ±2 LSB INL and 0.5 V to 5 V reference flexibility for calibrated current-to-voltage conversion. Use Value: Pseudo-differential input rejects common-mode noise from long sensor cables; no missing codes guarantees fault-free diagnostics. |
Use Scenario: Portable RF signal analyzer capturing baseband I/Q samples during field maintenance of cellular infrastructure. IC Role / Device Role / Timing Role: 250 kSPS sampling ADC feeding FPGA-based FFT engine with deterministic timing via CNV-triggered acquisition. Use Value: Daisy-chain support allows synchronized multi-channel capture across multiple AD7685CRMZ units without additional timing controllers. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar 16-bit SAR ADC applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| AD7687BRMZ | Same 10-lead MSOP package, 250 kSPS, but 16-bit true differential input (vs. pseudo-differential); higher THD (−106 dB vs. −110 dB) at 20 kHz. | Requires differential driver amplifier (e.g., ADA4841) for single-ended sources; better suited for fully differential sensor interfaces. | Select AD7687BRMZ when true differential input rejection and higher CMRR (>90 dB) are mandatory for noisy industrial environments. |
| AD7980BRMZ | 400 kSPS throughput, same 10-lead MSOP, but higher power (7 mW @ 5 V/100 kSPS vs. 4 mW); ±1.5 LSB INL (max) vs. ±2 LSB. | Supports faster control loops and wider bandwidth signals; less suitable for sub-10 µA sleep-current designs. | Choose AD7980BRMZ when system requires >250 kSPS sampling or tighter INL (±1.5 LSB) at the cost of 75% higher active power. |
Compared with AD7687BRMZ and AD7980BRMZ, the AD7685CRMZ offers optimal balance of ultra-low standby current (1 nA), pseudo-differential simplicity for single-ended sensors, and proven 250 kSPS performance in space-constrained portable instrumentation-making it the preferred choice where battery life and layout simplicity outweigh raw speed or differential input requirements.
Availability
AD7685CRMZ is available at Aetrix Electronics and suitable for battery-powered equipment, medical instruments, and portable data acquisition systems requiring stable component supply, long-term lifecycle support, and traceable sourcing.
Supply support for AD7685CRMZ 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, with design centers worldwide.
The AD7685CRMZ belongs to Analog Devices' PulSAR® family of precision SAR ADCs-engineered for high-resolution, low-power, and low-latency data acquisition in portable, medical, and industrial instrumentation.
FAQ
What is the maximum reference voltage supported by the AD7685CRMZ?
The AD7685CRMZ accepts an external reference voltage (REF) from 0.5 V up to VDD, with VDD rated from 2.3 V to 5.5 V. Therefore, the absolute maximum REF is 5.5 V when VDD = 5.5 V. Operation at REF = VDD simplifies power architecture by eliminating a separate reference IC, and the device maintains ±2 LSB INL and 93.5 dB SINAD at 5 V REF per the datasheet specifications.
Does the AD7685CRMZ require an external driver amplifier for single-ended sensor inputs?
No, the AD7685CRMZ does not require an external driver amplifier for most single-ended sensor inputs due to its pseudo-differential architecture and integrated track-and-hold. The IN+ input accepts 0 V to VREF with respect to IN−, allowing direct connection of grounded-sense sensors (e.g., thermistors, RTDs with 3-wire compensation). However, for high-impedance or fast-settling sources (>10 kΩ or >100 kHz bandwidth), a low-noise op amp like ADA4941 may be used to ensure full 16-bit accuracy.
How does the AD7685CRMZ achieve 1 nA standby current, and what conditions apply?
The AD7685CRMZ achieves 1 nA standby current when both VDD and VIO are held at 5 V and ambient temperature is 25°C, with all digital inputs forced to VIO or GND as specified. This ultra-low quiescent state occurs during acquisition phase with CNV low and no conversion active. The value rises to <50 nA over full temperature range (−40°C to +85°C), making it ideal for duty-cycled battery-powered systems where the ADC spends >99% of time in standby.
Is the AD7685CRMZ pin-compatible with other PulSAR ADCs, and which ones?
Yes, the AD7685CRMZ is pin-for-pin compatible with the AD7686, AD7687, and AD7688 in the same 10-lead MSOP or LFCSP packages. This allows direct substitution within the same footprint for resolution scaling (14-bit AD7686, 16-bit AD7687, 18-bit AD7688) without PCB redesign. All share identical pinout, power sequencing, and serial interface behavior-only timing and AC specs differ per resolution grade.
What digital interface modes does the AD7685CRMZ support, and how are they selected?
The AD7685CRMZ supports two hardware-configured interface modes: CS mode (3- or 4-wire SPI-compatible) and Chain mode (daisy-chain). Mode selection occurs automatically on the CNV rising edge based on SDI logic level: SDI low enables Chain mode; SDI high enables CS mode. No software configuration or register writes are needed-interface behavior is determined solely by external pin strapping at conversion trigger time.
AD7685CRMZ Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- PulSAR®
- Package/Case:
- 10-TFSOP, 10-MSOP (0.118", 3.00mm Width)
- Packaging:
- Tube
- Product Status:
- Active
- Number of Bits:
- 16
- Sampling Rate (Per Second):
- 250k
- Number of Inputs:
- 1
- Input Type:
- Pseudo-Differential
- Data Interface:
- SPI, DSP
- Configuration:
- S/H-ADC
- Ratio - S/H:ADC:
- 1:1
- Number of A/D Converters:
- 1
- Architecture:
- SAR
- Reference Type:
- External
- Voltage - Supply, Analog:
- 2.3V ~ 5.5V
- Voltage - Supply, Digital:
- 2.3V ~ 5.5V
- Features:
- -
- Operating Temperature:
- -40°C ~ 85°C
- Supplier Device Package:
- 10-MSOP
- Mounting Type:
- Surface Mount
- Grade:
- -
- Qualification:
- -
AD7685CRMZ FAQ
1.How can I place an order for AD7685CRMZ through Aetrix?
Please submit a Request for Quotation (RFQ) for AD7685CRMZ on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.
2.Are the price and stock information for AD7685CRMZ reliable?
The price and inventory of AD7685CRMZ are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for AD7685CRMZ is usually 5 days.
3.What payment methods are accepted for AD7685CRMZ?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for AD7685CRMZ transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for AD7685CRMZ?
AD7685CRMZ orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your AD7685CRMZ order is processed, you will receive an email with the shipment details and tracking number.
Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.
5.How can I obtain technical support or documentation for AD7685CRMZ?
For technical support, including AD7685CRMZ datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your AD7685CRMZ requirements.
6.How does Aetrix verify that AD7685CRMZ is sourced from the original manufacturer or authorized distributors?
All AD7685CRMZ products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that AD7685CRMZ meets industry standards.
7.What is the process for return or replacement of AD7685CRMZ?
All AD7685CRMZ units undergo pre-shipment inspection (PSI). If there is an issue with AD7685CRMZ, returns or replacements are accepted under the following conditions:
1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.
2.The issue is reported within 90 days of delivery.
3.The AD7685CRMZ part is unused and in its original packaging.
Return procedure for AD7685CRMZ:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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