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Analog Devices Inc. AD7708BRUZ
- Part No.:
- AD7708BRUZ
- Manufacturer:
- Analog Devices Inc.
- Category:
- Analog to Digital Converters (ADC)
- Package:
- 28-TSSOP (0.173", 4.40mm Width)
- Datasheet:
-
AD7708BRUZ.pdf
- Description:
- IC ADC 16BIT SIGMA-DELTA 28TSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:1,410
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Product details
Overview
AD7708BRUZ from Analog Devices is a 16-bit, 8-/10-channel Σ-Δ analog-to-digital converter (ADC) with integrated programmable gain amplifier (PGA), rail-to-rail input buffer, and on-chip 32.768 kHz crystal oscillator/PLL. It supports pseudo-differential or fully-differential inputs, simultaneous 50 Hz/60 Hz rejection, and operates from single 3 V or 5 V supplies. It is used in industrial process control systems for direct transducer signal digitization without external conditioning.
For engineers reviewing the AD7708BRUZ datasheet, AD7708BRUZ pinout, AD7708BRUZ application, or AD7708BRUZ equivalent, key selection considerations include its 16-bit resolution with up to 13-bit peak-to-peak noise performance, CHOP mode vs. non-CHOP trade-offs in throughput vs. noise, VREF Select™ capability for ratiometric/absolute measurement, and pin compatibility with the 24-bit AD7718 for upgrade paths.
Technical Context
The AD7708BRUZ implements a sigma-delta modulation architecture with a 3rd-order modulator and digital filter, supporting software-programmable output data rates from 5.4 Hz (CHOP enabled) to 1.365 kHz (CHOP disabled). Its on-chip PGA offers gains of 1 to 128, enabling direct conversion of signals from ±20 mV to ±2.56 V full-scale.
It features dual reference inputs (REFIN1 and REFIN2), configurable as analog inputs or reference sources, and includes a 2-bit digital I/O port. The device uses a 3-wire SPI-compatible serial interface with Schmitt-triggered SCLK and supports unipolar/bipolar coding, self-calibration, and power-down modes consuming as low as 1 µA (AVDD) and 2 µA (DVDD).
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Resolution | 16-bit no-missing-codes; 13-bit peak-to-peak at ±20 mV range with 20 Hz update rate |
| Input Channels | 8 pseudo-differential or 4 fully-differential channels; AIN1–AIN8 + AINCOM, plus REFIN2(±) configurable as AIN9/AIN10 |
| PGA Gain Range | 1 to 128; enables direct digitization of low-level transducer outputs (e.g., 20 mV) without external amplification |
| Power Consumption | 1.28 mA typical at 3 V (normal mode); 2 µA DVDD + 1 µA AVDD in power-down with oscillator off |
| AC Performance | 100 dB normal-mode rejection at 50/60 Hz; 90–110 dB common-mode rejection depending on range and chop mode |
| Reference Input | 2.5 V nominal (1 V to AVDD range); supports ratiometric or absolute measurements via VREF Select™ |
| Operating Supply | AVDD = 2.7–3.6 V or 4.75–5.25 V; DVDD independent and matched; AGND–DGND offset ≤ ±50 mV |
Pinout & Package
AD7708BRUZ is housed in a 28-lead TSSOP package (RU-28), lead-free and RoHS-compliant, with 0.65 mm pitch and exposed pad for thermal enhancement.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| AIN1–AIN8 | Analog input channels | Programmable-gain buffered inputs; support pseudo-differential (vs. AINCOM) or fully-differential (paired) configurations |
| AINCOM | Common analog input reference | Return node for pseudo-differential operation; voltage range: AGND –30 mV to AVDD +30 mV (NEGBUF=0) |
| REFIN1(+), REFIN1(–) | Primary reference inputs | Dedicated 2.5 V nominal reference pair; common-mode range extends from AGND –30 mV to AVDD +30 mV |
| REFIN2(+), REFIN2(–) | Secondary reference / auxiliary analog inputs | Configurable as reference inputs or as AIN9/AIN10; same electrical specs as REFIN1 |
| AVDD, AGND | Analog power and ground | Separate analog supply domain; requires low-noise decoupling; AGND–DGND differential ≤ ±50 mV |
| DVDD, DGND | Digital power and ground | Independent digital supply; supports 3 V or 5 V logic; Schmitt-triggered SCLK eases timing margin |
| DIN, DOUT, SCLK, CS, RDY | 3-wire serial interface | SPI/QSPI/MICROWIRE/DSP-compatible; RDY indicates data ready; CS enables frame synchronization |
| XTAL1, XTAL2 | Crystal oscillator terminals | Accepts 32.768 kHz crystal; internal buffer eliminates need for external load capacitors |
| P1, P2 | 2-bit digital I/O port | Configurable as inputs or outputs; referenced to AVDD/AGND; usable for status signaling or control |
Key Features
| Feature | Design Value |
|---|---|
| VREF Select™ technology | Enables seamless switching between ratiometric (e.g., bridge sensor) and absolute (e.g., temperature) measurement modes using same hardware |
| Simultaneous 50 Hz/60 Hz rejection | Guaranteed ≥100 dB rejection at both line frequencies without external notch filters-critical for industrial AC environments |
| Factory-calibrated, self-calibrating architecture | Eliminates need for system-level calibration; offset and full-scale errors reduced to noise floor after self-calibration |
| CHOP mode (CHOP = 0) vs. non-CHOP (CHOP = 1) | CHOP improves offset drift (10 nV/°C typ) and PSR (100 dB typ) at cost of lower throughput; non-CHOP enables 1.365 kHz max update rate |
| Pin-for-pin compatibility with AD7718 | Allows hardware-reuse migration path from 16-bit to 24-bit resolution without PCB redesign or layout changes |
Applications
| Industrial Process Control | Smart Pressure Transmitters |
|---|---|
Use Scenario: Monitoring flow, level, and temperature in distributed control systems (DCS) with 4–20 mA loop integration. IC Role / Device Role / Timing Role: Primary ADC front-end converting conditioned sensor outputs (e.g., strain gauge bridges) into digital data for microcontroller processing. Use Value: Direct ratiometric measurement capability eliminates reference drift errors; 100 dB line-frequency rejection ensures stable readings in electrically noisy plant environments. |
Use Scenario: High-accuracy pressure sensing in hazardous-area field instruments with intrinsic safety requirements. IC Role / Device Role / Timing Role: Signal conditioner and digitizer for piezoresistive or capacitive pressure elements, interfacing to low-power wireless MCU. Use Value: Ultra-low power consumption (≤1.28 mA @ 3 V) extends battery life; CHOP mode reduces offset drift to 10 nV/°C for long-term stability over temperature. |
| Portable Data Acquisition | Programmable Logic Controllers (PLCs) |
Use Scenario: Handheld multimeters and portable analyzers requiring high resolution, low power, and compact size. IC Role / Device Role / Timing Role: Core ADC capturing multi-channel sensor data (voltage, current, thermocouple) with on-the-fly gain switching. Use Value: Integrated PGA and 8-channel multiplexer reduce BOM count; TSSOP-28 package enables dense, low-profile PCB layouts. |
Use Scenario: Modular I/O modules in DIN-rail mounted PLCs handling analog inputs from factory-floor sensors. IC Role / Device Role / Timing Role: Isolated analog input channel IC, typically paired with digital isolators and microcontrollers for real-time monitoring. Use Value: Simultaneous 50/60 Hz rejection and >90 dB CMRR ensure immunity to motor drives and variable frequency inverters in industrial settings. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar precision ADC applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| AD7718BRUZ | 24-bit resolution, identical pinout and register map; higher noise performance (18-bit p-p at ±2.56 V), improved CMRR (110 dB typ) | Required where ultra-high resolution (e.g., weigh scales, precision metrology) outweighs cost and power constraints | Select AD7718BRUZ when 24-bit resolution and enhanced DC accuracy are mandatory; retains full hardware compatibility |
| ADS124S08IPW | Texas Instruments 24-bit delta-sigma ADC; 12-channel, integrated PGA, but no on-chip oscillator; SPI interface only (no QSPI/MICROWIRE) | Used in TI-centric designs with existing MSP430/C2000 ecosystems; lacks VREF Select™ and simultaneous 50/60 Hz rejection guarantee | Choose ADS124S08IPW if leveraging TI's design tools and require more input channels; verify external clock sourcing and line-rejection validation |
Compared with AD7718BRUZ, the AD7708BRUZ trades resolution and drift performance for lower cost and power; compared with ADS124S08IPW, it offers guaranteed line-frequency rejection and flexible interface compatibility but fewer channels and no integrated temperature sensor.
Availability
AD7708BRUZ is available at Aetrix Electronics and suitable for industrial process control, smart transmitter development, and portable instrumentation requiring stable component supply, long-term lifecycle support, and traceable sourcing.
Supply support for AD7708BRUZ 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.
The AD7708BRUZ belongs to Analog Devices' precision Σ-Δ ADC product line, designed specifically for low-frequency, high-accuracy measurement applications including industrial automation, sensor conditioning, and portable test equipment.
FAQ
What is the maximum output data rate of the AD7708BRUZ in non-CHOP mode?
The AD7708BRUZ achieves a maximum output data rate of 1.365 kHz in non-CHOP mode (CHOP = 1), optimized for high channel throughput. This setting disables chopping to minimize conversion latency, making it suitable for applications requiring faster sampling-such as dynamic sensor monitoring-while maintaining 16-bit no-missing-codes performance. The AD7708BRUZ supports programmable update rates across this full range via its Mode Register.
Does the AD7708BRUZ require an external crystal or oscillator?
No, the AD7708BRUZ integrates a crystal input buffer and PLL circuit that accepts a standard 32.768 kHz tuning-fork crystal directly on XTAL1/XTAL2 pins-no external oscillator or load capacitors are needed. This simplifies board design and improves timing stability. The AD7708BRUZ uses this clock to generate all internal operating frequencies, including the modulator and filter clocks required for Σ-Δ conversion.
Can the AD7708BRUZ measure both ratiometric and absolute voltage signals?
Yes, the AD7708BRUZ implements VREF Select™ technology, allowing runtime selection between ratiometric (using sensor excitation as reference) and absolute (using stable external reference) measurement modes. This is achieved by configuring REFIN1 or REFIN2 as either reference inputs or auxiliary analog inputs-enabling a single AD7708BRUZ design to serve multiple sensor types without hardware modification.
What is the purpose of the P1 and P2 pins on the AD7708BRUZ?
The P1 and P2 pins on the AD7708BRUZ form a 2-bit general-purpose digital I/O port, configurable as inputs or outputs via the I/O Control Register. They are referenced to AVDD/AGND-not DVDD/DGND-making them suitable for analog-domain signaling, such as driving LED indicators, reading switch states near analog sections, or synchronizing with external analog circuitry. Their design avoids digital noise coupling into sensitive analog domains.
How does the AD7708BRUZ handle power supply separation between AVDD and DVDD?
The AD7708BRUZ supports independent operation of AVDD and DVDD supplies-each can be set to 3 V or 5 V-and specifies strict limits on AGND–DGND potential difference (±50 mV max) to prevent ground-loop errors. This separation allows noise-sensitive analog sections to be powered from clean LDOs while digital interfaces run from noisy SMPS rails, provided proper partitioning and decoupling are implemented per the AD7708BRUZ layout guidelines.
AD7708BRUZ Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 28-TSSOP (0.173", 4.40mm Width)
- Packaging:
- Tube
- Product Status:
- Active
- Number of Bits:
- 16
- Sampling Rate (Per Second):
- 1.37k
- Number of Inputs:
- 4, 8
- Input Type:
- Differential, Pseudo-Differential, Single Ended
- Data Interface:
- SPI, DSP
- Configuration:
- MUX-PGA-ADC
- Ratio - S/H:ADC:
- -
- Number of A/D Converters:
- 1
- Architecture:
- Sigma-Delta
- Reference Type:
- External
- Voltage - Supply, Analog:
- 2.7V ~ 3.3V, 5V
- Voltage - Supply, Digital:
- 2.7V ~ 3.3V, 5V
- Features:
- PGA
- Operating Temperature:
- -40°C ~ 85°C
- Supplier Device Package:
- 28-TSSOP
- Mounting Type:
- Surface Mount
- Grade:
- -
- Qualification:
- -
AD7708BRUZ FAQ
1.How can I place an order for AD7708BRUZ through Aetrix?
Please submit a Request for Quotation (RFQ) for AD7708BRUZ 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 AD7708BRUZ reliable?
The price and inventory of AD7708BRUZ are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for AD7708BRUZ is usually 5 days.
3.What payment methods are accepted for AD7708BRUZ?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for AD7708BRUZ transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for AD7708BRUZ?
AD7708BRUZ orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your AD7708BRUZ 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 AD7708BRUZ?
For technical support, including AD7708BRUZ datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your AD7708BRUZ requirements.
6.How does Aetrix verify that AD7708BRUZ is sourced from the original manufacturer or authorized distributors?
All AD7708BRUZ 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 AD7708BRUZ meets industry standards.
7.What is the process for return or replacement of AD7708BRUZ?
All AD7708BRUZ units undergo pre-shipment inspection (PSI). If there is an issue with AD7708BRUZ, 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 AD7708BRUZ part is unused and in its original packaging.
Return procedure for AD7708BRUZ:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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