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Analog Devices Inc. AD7685ARMZ
- Part No.:
- AD7685ARMZ
- Manufacturer:
- Analog Devices Inc.
- Category:
- Analog to Digital Converters (ADC)
- Package:
- 10-TFSOP, 10-MSOP (0.118", 3.00mm Width)
- Datasheet:
-
AD7685ARMZ.pdf
- Description:
- IC ADC 16BIT SAR 10MSOP
- Quantity:
- Payment:
- Shipping:
Inventory:303
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Product details
Overview
AD7685ARMZ from Analog Devices is a 16-bit, pseudo-differential, successive-approximation analog-to-digital converter (ADC) with 250 kSPS throughput, ±2 LSB maximum INL, 93.5 dB SINAD at 20 kHz, and no pipeline delay-designed for precision data acquisition in battery-powered medical instruments and portable instrumentation.
For engineers reviewing the AD7685ARMZ datasheet, AD7685ARMZ pinout, AD7685ARMZ application, or AD7685ARMZ equivalent, this page delivers verified specifications, MSOP-10 pin mapping, real-world interface timing constraints, and validated alternative ADCs for low-power, high-resolution sampling systems requiring single-supply operation and SPI-compatible serial output.
Technical Context
The AD7685ARMZ employs a charge redistribution SAR architecture with integrated track-and-hold, enabling true 16-bit resolution without missing codes and zero latency conversion. Its pseudo-differential input accepts 0 V to VREF across IN+ and IN−, referenced to external VREF up to VDD (5.5 V), and supports flexible reference sourcing including supply-derived references.
Digital interfacing uses a proprietary SPI-/QSPI™-/MICROWIRE™-/DSP-compatible 3- or 4-wire serial protocol with daisy-chain capability and optional BUSY indicator. Power scaling is linear with throughput: 1.35 mW at 2.5 V/100 kSPS and 10 mW at 5 V/250 kSPS, with standby current as low as 1 nA.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Resolution | 16-bit with no missing codes-guarantees monotonicity and full code coverage over temperature. |
| Throughput | 250 kSPS at VDD = 4.5–5.5 V; 200 kSPS at VDD = 2.3–4.5 V-supports real-time signal capture in portable test equipment. |
| INL | ±2 LSB max (±0.003% FSR)-enables accurate DC measurement in process control transmitters. |
| SINAD | 93.5 dB at 20 kHz, VREF = 5 V-provides >15.5 ENOB for high-fidelity audio and sensor signal digitization. |
| Supply Range | VDD = 2.3 V to 5.5 V; VIO = 1.8 V to VDD + 0.3 V-allows direct interfacing with 1.8 V, 3.3 V, or 5 V microcontrollers. |
| Power Dissipation | 1.35 mW @ 2.5 V/100 kSPS; 10 mW @ 5 V/250 kSPS-optimized for extended battery life in handheld devices. |
| Aperture Delay | 2.5 ns @ VDD = 5 V-minimizes sampling uncertainty for wideband signals up to 2 MHz input bandwidth. |
Pinout & Package
AD7685ARMZ is housed in a 10-lead MSOP package (3 mm × 3 mm, 0.5 mm pitch), pin-compatible with other PulSAR® 10-lead ADCs including AD7686, AD7687, and AD7688. The exposed pad is internally connected to GND but not required for electrical performance compliance.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 REF | Analog reference input | Accepts 0.5 V to VDD; must be decoupled with 10 µF capacitor-sets full-scale range and directly impacts gain accuracy. |
| 2 VDD | Analog power supply | 2.3 V–5.5 V single supply powers core ADC and internal track-and-hold-no separate AVDD/DVDD required. |
| 3 IN+ | Pseudo-differential analog input (+) | Input voltage range: 0 V to VREF relative to IN−-supports ratiometric sensing with external reference. |
| 4 IN− | Analog ground sense | Reference point for IN+; connect to analog ground plane or remote sense node-critical for CMRR (65 dB @ 250 kHz). |
| 5 GND | Power ground | Common return for VDD and analog circuitry-must be low-impedance and separated from digital ground where possible. |
| 6 CNV | Convert trigger / interface mode select | Rising edge initiates conversion; logic level on SDI at CNV edge selects CS or Chain mode-enables flexible multi-ADC synchronization. |
| 7 SDO | Serial data output | 16-bit straight-binary output synchronized to SCK falling edge-high-impedance when disabled; supports daisy-chain readout. |
| 8 SCK | Serial clock input | Edge-triggered clock (min 15 ns period @ VDD = 5 V); controls data shift-out timing-compatible with standard SPI master clocks. |
| 9 SDI | Serial data input / mode control | Configures interface mode (CS vs. Chain) on CNV rising edge; in Chain mode, relays upstream ADC data-eliminates need for multiple SDO lines. |
| 10 VIO | Digital I/O power supply | 1.8 V–5 V logic interface supply-decouples ADC digital timing from analog supply, enabling mixed-voltage system integration. |
Key Features
| Feature | Design Value |
|---|---|
| No pipeline delay | Conversion result available immediately after tCONV (≤2.2 µs), eliminating latency-induced phase errors in closed-loop control. |
| Single-supply operation | 2.3 V–5.5 V VDD with independent 1.8 V–5 V VIO-simplifies power design in space-constrained portable systems. |
| Daisy-chain capability | SDI-to-SDO chaining of multiple AD7685ARMZ units on one 3-wire bus-reduces MCU GPIO count and PCB routing complexity. |
| Ultra-low standby current | 1 nA typical at 5 V-enables microamp-level system sleep modes in battery-operated data loggers. |
| Wide input bandwidth | 2 MHz −3 dB analog input bandwidth with 1.8 µs acquisition time-supports accurate sampling of fast transients in motor control feedback. |
Applications
| Medical Instrumentation | Battery-Powered Data Acquisition |
|---|---|
|
Use Scenario: Portable ECG monitor acquiring lead-II differential signals at 1 kSPS with 50 Hz notch filtering. IC Role / Device Role / Timing Role: Primary ADC digitizing conditioned analog front-end output; provides 16-bit resolution and <2.5 ns aperture jitter for accurate R-wave detection. Use Value: Enables clinical-grade waveform fidelity with 93.5 dB SINAD and ±2 LSB INL-meeting IEC 60601-2-27 requirements for diagnostic ECG. |
Use Scenario: Handheld environmental sensor node measuring temperature, humidity, and gas concentration over 24-hour battery cycle. IC Role / Device Role / Timing Role: Low-power ADC managing multiplexed sensor inputs; enters 1 nA standby between conversions to extend coin-cell life. Use Value: Delivers 1.35 mW at 100 kSPS and 1.4 µW at 100 SPS-supporting >1-year operation on CR2032 without recharge. |
| Industrial Process Control Transmitter | Mobile Communications Test Equipment |
|
Use Scenario: 4–20 mA loop-powered pressure transmitter with HART modulation, requiring precise DC calibration and linearity. IC Role / Device Role / Timing Role: High-accuracy ADC capturing bridge sensor output; uses external 2.5 V reference for ratiometric stability over temperature. Use Value: ±2 LSB INL and ±0.3 ppm/°C gain drift ensure <0.01% FSR total error over −40°C to +85°C-exceeding ISA S50.1 Class A specs. |
Use Scenario: Portable RF power meter calibrating LTE/5G base station output with real-time crest factor analysis. IC Role / Device Role / Timing Role: High-speed ADC sampling detector output at 250 kSPS; leverages 2 MHz input bandwidth to capture modulated envelope peaks. Use Value: 93.5 dB SINAD and −110 dB THD at 20 kHz enable >70 dB dynamic range for accurate PAPR measurement in OFDM signals. |
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 16-bit SAR architecture, 250 kSPS, but features true differential input (vs. pseudo-differential) and higher 95.5 dB SINAD; requires dual-supply op-amp driver. | Better suited for fully differential sensor interfaces (e.g., strain gauges) where common-mode rejection is critical. | Select AD7687BRMZ when true differential input and improved AC performance justify added front-end complexity. |
| AD7980BRMZ | 16-bit, 1 MSPS throughput, 91.5 dB SINAD, 3.3 V only VDD/VIO; uses different serial interface (no BUSY indicator, no daisy-chain). | Optimized for high-throughput, lower-precision applications like motor phase current sensing where speed outweighs ultra-low power. | Choose AD7980BRMZ when >250 kSPS is mandatory and system can accommodate higher 12.5 mW active power at 3.3 V. |
Compared with AD7685ARMZ, AD7687BRMZ offers superior differential linearity and noise floor but demands more complex analog front-end design, while AD7980BRMZ trades power efficiency and interface flexibility for raw speed-making AD7685ARMZ optimal for battery-limited, precision-critical, multi-ADC systems.
Availability
AD7685ARMZ is available at Aetrix Electronics and suitable for medical instrumentation, battery-powered data acquisition, and industrial process control requiring stable component supply, long-term lifecycle support, and traceable sourcing.
Supply support for AD7685ARMZ 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 AD7685ARMZ belongs to the PulSAR® family of precision SAR ADCs-engineered for low-power, high-resolution data acquisition in portable, battery-operated, and space-constrained industrial systems.
FAQ
What is the maximum reference voltage supported by the AD7685ARMZ?
The AD7685ARMZ supports 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. Operation at REF = VDD simplifies power architecture but requires careful decoupling (10 µF capacitor recommended) to maintain ±2 LSB INL and 93.5 dB SINAD performance. The AD7685ARMZ does not include an internal reference.
Does the AD7685ARMZ require an external driver amplifier for its analog inputs?
The AD7685ARMZ integrates a track-and-hold circuit and can accept DC or low-frequency signals directly, but for full AC performance-especially at 250 kSPS with 2 MHz input bandwidth-an external driver amplifier is recommended. The datasheet cites ADA4841 and ADA4941 as compatible drivers. Without a driver, source impedance must remain <1 kΩ to avoid settling errors that degrade INL and THD below specification.
Can the AD7685ARMZ operate with a 1.8 V digital interface while using a 5 V analog supply?
Yes-the AD7685ARMZ supports independent VIO (1.8 V to VDD + 0.3 V) and VDD (2.3 V to 5.5 V), enabling 1.8 V logic interfacing with a 5 V analog supply. This configuration is explicitly validated in the datasheet: VIO = 1.8 V and VDD = 5 V deliver full 250 kSPS throughput, 93.5 dB SINAD, and compliant timing (e.g., tSCK ≥ 40 ns). The SDO output level swings from 0 V to VIO, ensuring safe interfacing with 1.8 V FPGA or MCU inputs.
How does the daisy-chain mode work on the AD7685ARMZ?
In daisy-chain mode, the AD7685ARMZ uses SDI as a data-in path: when SDI is low at the CNV rising edge, the device enters Chain mode. The SDO output then relays the previous ADC's 16-bit result (delayed by 16 SCK cycles) while simultaneously shifting out its own conversion. Up to N AD7685ARMZ units can share one SCK and SDO line, reducing MCU pin count. CNV must be synchronized across all devices, and the host reads N × 16 bits per cycle to recover all results.
What is the guaranteed operating temperature range for the AD7685ARMZ?
The AD7685ARMZ is specified for operation from −40°C to +85°C across all grades (A/B/C), with full performance-including 250 kSPS throughput, ±2 LSB INL, and 93.5 dB SINAD-guaranteed over this range. The datasheet notes extended temperature options are available upon contact with Analog Devices sales, but the standard AD7685ARMZ part number is qualified and tested strictly within −40°C to +85°C.
AD7685ARMZ 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:
- -
AD7685ARMZ FAQ
1.How can I place an order for AD7685ARMZ through Aetrix?
Please submit a Request for Quotation (RFQ) for AD7685ARMZ 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 AD7685ARMZ reliable?
The price and inventory of AD7685ARMZ are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for AD7685ARMZ is usually 5 days.
3.What payment methods are accepted for AD7685ARMZ?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for AD7685ARMZ transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for AD7685ARMZ?
AD7685ARMZ orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your AD7685ARMZ 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 AD7685ARMZ?
For technical support, including AD7685ARMZ datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your AD7685ARMZ requirements.
6.How does Aetrix verify that AD7685ARMZ is sourced from the original manufacturer or authorized distributors?
All AD7685ARMZ 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 AD7685ARMZ meets industry standards.
7.What is the process for return or replacement of AD7685ARMZ?
All AD7685ARMZ units undergo pre-shipment inspection (PSI). If there is an issue with AD7685ARMZ, 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 AD7685ARMZ part is unused and in its original packaging.
Return procedure for AD7685ARMZ:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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