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Analog Devices Inc. AD7661AST
- Part No.:
- AD7661AST
- Manufacturer:
- Analog Devices Inc.
- Category:
- Analog to Digital Converters (ADC)
- Package:
- 48-LQFP
- Datasheet:
-
AD7661AST.pdf
- Description:
- IC ADC 16BIT W/REF 48-LQFP
- Quantity:
- Payment:
- Shipping:
Inventory:5,713
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Product details
Overview
AD7661AST from Analog Devices is a 16-bit, 100 kSPS unipolar successive approximation register (SAR) analog-to-digital converter with integrated 2.5 V reference, ±2.5 LSB INL, and parallel/serial 5 V/3 V interface - designed for precision data acquisition in medical instruments and spectrum analysis systems.
For engineers reviewing the AD7661AST datasheet, AD7661AST pinout, AD7661AST application, or AD7661AST equivalent, this page delivers verified specs including 88 dB S/(N+D) at 20 kHz, 3 ppm/°C reference drift, no pipeline delay, 48-lead LQFP package mapping, and confirmed alternative options for high-resolution DC/AC measurement systems.
Technical Context
The AD7661AST implements a charge redistribution SAR architecture with factory-calibrated error correction circuitry, enabling guaranteed 16-bit no-missing-codes performance and simultaneous AC/DC accuracy over –40°C to +85°C. Its internal conversion clock eliminates external timing dependencies.
It supports dual-mode digital interfacing: parallel 16-bit bus with BYTEWAP/OB/2C control, and SPI/QSPI/MICROWIRE-compatible serial mode with programmable clock division (DIVSCLK[1:0]), active-low SYNC framing, and configurable SDOUT edge alignment via INVSCLK and EXT/INT.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Resolution | 16-bit with no missing codes - ensures monotonicity and full-scale code coverage for precision measurement. |
| Throughput Rate | 100 kSPS maximum - enables real-time sampling of signals up to 45 kHz (Nyquist-limited) without aliasing. |
| S/(N+D) | 88 dB min @ 20 kHz - supports >14.3 ENOB for high-fidelity signal reconstruction in spectrum analysis. |
| INL | ±2.5 LSB max - corresponds to ±0.0038% FSR linearity error, critical for calibration-grade instrumentation. |
| Reference Drift | ±3 ppm/°C typical - guarantees <1 LSB drift over 85°C temperature range when using internal 2.5 V reference. |
| Analog Input Range | 0 V to 2.5 V unipolar - matches internal reference output, eliminating external scaling for single-supply designs. |
| Power Dissipation | 16 mW typ @ 100 kSPS without REF - enables low-power operation in battery-powered data loggers. |
Pinout & Package
AD7661AST is housed in a 48-lead LQFP (ST-48) package with exposed pad, rated for –40°C to +85°C operation. Pin 1 identifier located at top-left corner; AGND pins (1, 36, 41, 42) provide dedicated analog ground return paths.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| IN (Pin 43) | Analog input | Primary unipolar input node referenced to INGND; accepts 0 V to 2.5 V full-scale range. |
| REF (Pin 37) | Reference output | 2.5 V buffered reference source; used directly as ADC reference or external buffer input. |
| CNVST (Pin 35) | Conversion start | Falling-edge-triggered sample/hold control; supports low-jitter synchronous sampling. |
| BUSY (Pin 29) | Status output | Active-high indicates conversion in progress; falling edge signals valid data ready. |
| SER/PAR (Pin 8) | Interface mode select | LOW = parallel 16-bit mode; HIGH = serial mode using D8–D11 as SDOUT/SCLK/SYNC/RDERROR. |
| PDREF (Pin 47) | Reference enable | LOW enables internal 2.5 V reference; HIGH disables it for external reference use. |
Key Features
| Feature | Design Value |
|---|---|
| Internal 2.5 V reference | Guaranteed ±15 ppm/°C max drift - reduces BOM count and layout complexity vs. discrete reference ICs. |
| No pipeline delay | Immediate data availability after BUSY goes LOW - enables deterministic real-time control loops. |
| Parallel + serial interface | Single device supports both 16-bit parallel bus and SPI-compatible 2-wire serial - simplifies migration between microcontroller platforms. |
| Temperature sensor output | TEMP pin provides 300 mV @ 25°C with 1 mV/°C slope - enables on-chip thermal monitoring without external sensors. |
| Low-power scaling | 160 µW @ 1 kSPS - extends battery life in portable instrumentation without sacrificing resolution. |
Applications
| Medical Instrumentation | Spectrum Analysis |
|---|---|
Use Scenario: High-accuracy ECG/EEG front-end digitization with DC-coupled analog conditioning. IC Role / Device Role / Timing Role: Primary SAR ADC capturing bio-potential waveforms at 100 kSPS with <1 LSB INL for diagnostic fidelity. Use Value: Internal reference and no-missing-codes guarantee eliminate post-acquisition calibration for FDA-submission-ready designs. |
Use Scenario: Real-time FFT-based spectral monitoring in handheld RF analyzers. IC Role / Device Role / Timing Role: Unipolar ADC feeding FPGA-based DFT engine; 88 dB S/(N+D) preserves dynamic range for weak-signal detection. Use Value: 45 kHz usable bandwidth and 5 ps rms aperture jitter minimize frequency-domain smearing in narrowband analysis. |
| Data Acquisition Systems | Battery-Powered Test Equipment |
Use Scenario: Modular DAQ modules for industrial process control with multi-channel synchronized sampling. IC Role / Device Role / Timing Role: Precision ADC with CNVST-triggered acquisition and BUSY-driven readout for deterministic multi-device timing. Use Value: Pin-to-pin compatibility with AD7660/AD7651 allows scalable channel-count upgrades without PCB redesign. |
Use Scenario: Portable power quality meters requiring 16-bit resolution and >10-hour runtime on Li-ion cells. IC Role / Device Role / Timing Role: Low-power ADC operating at 1–10 kSPS with PD and PDREF control for adaptive power management. Use Value: 160 µW standby power and internal reference reduce quiescent current by >40% vs. external-ref alternatives. |
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 |
|---|---|---|---|
| AD7660AST | Same 48-lead LQFP package, identical pinout, but 16-bit/100 kSPS with external reference only (no internal REF). | Lacks integrated 2.5 V reference - requires external REF IC and additional decoupling, increasing board area and cost. | Select AD7660AST only if system already uses a higher-precision external reference or needs tighter drift spec than ±15 ppm/°C. |
| AD7651AST | 16-bit/100 kSPS pseudo-differential SAR ADC; supports ±2.5 V input range with internal reference. | Accepts bipolar inputs - suitable for AC-coupled sensor interfaces where offset rejection is required. | Choose AD7651AST when measuring bidirectional transducer outputs (e.g., accelerometers), not unipolar signals like thermocouples or strain gauges. |
Compared with AD7661AST, AD7660AST removes reference integration to lower cost and power but increases design complexity, while AD7651AST shifts to pseudo-differential topology to support bipolar measurement - neither offers the same combination of unipolar simplicity, internal reference stability, and LQFP pin compatibility.
Availability
AD7661AST is available at Aetrix Electronics and suitable for medical instrumentation, spectrum analysis, and battery-powered test equipment requiring stable component supply across extended temperature ranges and long production lifecycles.
Supply support for AD7661AST 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 is a global leader in high-performance analog, mixed-signal, and digital signal processing semiconductors, headquartered in Norwood, MA, with R&D and manufacturing facilities worldwide.
The AD7661AST belongs to Analog Devices' PulSAR® family of precision SAR ADCs, engineered specifically for applications demanding high DC accuracy, excellent AC performance, and flexible digital interfacing in space-constrained industrial and medical systems.
FAQ
What is the maximum sampling rate supported by the AD7661AST?
The AD7661AST supports a maximum throughput rate of 100 kSPS, corresponding to a minimum conversion cycle time of 10 µs. This rate is achievable in both parallel and serial interface modes, with BUSY signal indicating completion. At this speed, the AD7661AST maintains full 16-bit no-missing-codes performance and specified AC parameters including 88 dB S/(N+D) at 20 kHz. The AD7661AST does not require external clocking for conversion timing due to its integrated conversion clock.
Does the AD7661AST require an external reference voltage?
No, the AD7661AST includes a factory-trimmed 2.5 V internal reference with ±3 ppm/°C typical drift and ±15 ppm/°C maximum drift over –40°C to +85°C. The internal reference is enabled by pulling PDREF (Pin 47) LOW. An external reference can be used by setting PDREF HIGH and applying 2.3 V to AVDD – 1.85 V to REFBUFIN (Pin 46); however, the AD7661AST's internal reference eliminates the need for external components in most unipolar 0 V to 2.5 V applications.
What digital interface options does the AD7661AST support?
The AD7661AST supports both parallel and serial digital interfaces via the SER/PAR (Pin 8) control. In parallel mode (SER/PAR = LOW), it outputs 16-bit data on D0–D15 with RD/CS handshaking and BUSY status. In serial mode (SER/PAR = HIGH), it operates as an SPI/QSPI/MICROWIRE-compatible slave or master, using D8–D11 as SDOUT/SCLK/SYNC/RDERROR. Clock division (DIVSCLK[1:0]) and edge alignment (INVSCLK) are configurable to match host controller timing requirements.
How is the AD7661AST powered, and what are its supply requirements?
The AD7661AST operates from three independent supplies: AVDD (4.75–5.25 V, analog core), DVDD (4.75–5.25 V, digital logic), and OVDD (2.7–5.25 V, I/O interface). AGND, DGND, and OGND must be separated and tied at a single point. Typical power dissipation is 16 mW at 100 kSPS without reference, 40 mW with reference enabled. Power-down (PD pin) reduces consumption to 160 µW at 1 kSPS, making the AD7661AST suitable for battery-powered systems.
What is the function of the TEMP pin on the AD7661AST?
The TEMP (Pin 45) provides an analog voltage output proportional to die temperature: 300 mV at 25°C with a sensitivity of 1 mV/°C. This on-chip temperature sensor enables real-time thermal monitoring without external components. The output impedance is 4.3 kΩ, and it is intended for ratiometric or calibrated reading - not for precision temperature measurement - but suffices for thermal derating, fault detection, and ambient compensation in medical and industrial ADC applications using the AD7661AST.
AD7661AST Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- PulSAR®
- Package/Case:
- 48-LQFP
- Packaging:
- Bag
- Product Status:
- Obsolete
- Number of Bits:
- 16
- Sampling Rate (Per Second):
- 100k
- Number of Inputs:
- -
- Input Type:
- -
- Data Interface:
- -
- Configuration:
- -
- Ratio - S/H:ADC:
- -
- Number of A/D Converters:
- 1
- Architecture:
- -
- Reference Type:
- -
- Voltage - Supply, Analog:
- -
- Voltage - Supply, Digital:
- -
- Features:
- -
- Operating Temperature:
- -40°C ~ 85°C
- Supplier Device Package:
- 48-LQFP (7x7)
- Mounting Type:
- Surface Mount
- Grade:
- -
- Qualification:
- -
AD7661AST FAQ
1.How can I place an order for AD7661AST through Aetrix?
Please submit a Request for Quotation (RFQ) for AD7661AST 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 AD7661AST reliable?
The price and inventory of AD7661AST are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for AD7661AST is usually 5 days.
3.What payment methods are accepted for AD7661AST?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for AD7661AST transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for AD7661AST?
AD7661AST orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your AD7661AST 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 AD7661AST?
For technical support, including AD7661AST datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your AD7661AST requirements.
6.How does Aetrix verify that AD7661AST is sourced from the original manufacturer or authorized distributors?
All AD7661AST 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 AD7661AST meets industry standards.
7.What is the process for return or replacement of AD7661AST?
All AD7661AST units undergo pre-shipment inspection (PSI). If there is an issue with AD7661AST, 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 AD7661AST part is unused and in its original packaging.
Return procedure for AD7661AST:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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