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Analog Devices Inc. AD7709BRU-REEL
- Part No.:
- AD7709BRU-REEL
- Manufacturer:
- Analog Devices Inc.
- Category:
- Analog to Digital Converters (ADC)
- Package:
- 24-TSSOP (0.173", 4.40mm Width)
- Datasheet:
-
AD7709BRU-REEL.pdf
- Description:
- IC ADC 16BIT SIGMA-DELTA 24TSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:2,351
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Product details
Overview
AD7709BRU-REEL from Analog Devices is a 16-bit sigma-delta ADC with integrated programmable gain amplifier (PGA), three switchable matched excitation current sources (200 µA, 200 µA, and 25 µA), low-side power switches, and a 4-bit digital I/O port - designed for precision sensor front-end applications including RTD, thermocouple, and bridge transducer measurement. It supports ±20 mV to ±2.56 V input ranges, simultaneous 50/60 Hz rejection at 19.79 Hz update rate, and operates from single 3 V or 5 V supply.
For engineers reviewing the AD7709BRU-REEL datasheet, AD7709BRU-REEL pinout, AD7709BRU-REEL application, or AD7709BRU-REEL equivalent, key selection criteria include its 13-bit p-p resolution at ±20 mV/20 Hz, rail-to-rail buffered analog inputs, 3-wire SPI-compatible serial interface, and integrated excitation current matching (±2.5% between IEXC1/IEXC2) for ratiometric VBE measurements in portable instrumentation and smart transmitters.
Technical Context
The AD7709BRU-REEL implements a chopper-stabilized sigma-delta modulator with Sinc³ digital filtering, enabling 16-bit no-missing-codes performance and <±30 ppm FSR integral nonlinearity. Its on-chip PLL locks to a 32.768 kHz crystal to generate internal clocks, supporting programmable output data rates from 5.35 Hz to 105 Hz via an 8-bit filter register (SF × 8 decimation).
It features dual reference inputs (REFIN1/REFIN2), configurable as fully differential (AIN1/AIN2, AIN3/AIN4) or pseudo-differential (AIN1–AINCOM, etc.), with rail-to-rail input buffering and PGA gain settings from 1 to 128. The device integrates low-side power switches (SW1/SW2, RON = 3 Ω typ @ 5 V) and a 4-bit I/O port usable as general-purpose digital I/O or excitation control signals.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Resolution | 16-bit no missing codes; 13-bit p-p @ ±20 mV/20 Hz enables high-resolution microvolt-level strain gauge readings |
| Update Rate | 5.35 Hz to 105 Hz; software-selectable via SF register for trade-off between noise rejection and throughput |
| Excitation Currents | IEXC1/IEXC2 = 200 µA ±10% (200 ppm/°C drift); IEXC3 = 25 µA ±5%; matched within ±2.5% for ratiometric RTD/VBE sensing |
| Input Range | ±20 mV to ±2.56 V full-scale; selectable via PGA gain (1–128) and reference voltage (1 V to VDD) |
| Power Consumption | 1.25 mA typ @ 3 V normal mode; 7 µA typ @ 3 V power-down with crystal running - suitable for battery-powered weigh scales |
| Common-Mode Rejection | 110 dB typ @ DC and 50/60 Hz (±2.56 V range); critical for rejecting ground-loop noise in industrial sensor nodes |
| Normal-Mode Rejection | 100 dB min @ 50 Hz & 60 Hz simultaneously using 19.79 Hz update rate - eliminates mains interference without external notch filters |
Pinout & Package
AD7709BRU-REEL is housed in a 24-lead TSSOP (RU-24) package with exposed pad for thermal management. Pin functions are validated per Analog Devices' official pin configuration diagram (Rev. A, p.8) and pin function descriptions (p.9).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| IOUT1 / IOUT2 | Excitation current outputs | Switchable routing points for IEXC1/IEXC2/IEXC3; enable 3-wire RTD excitation with matched current sourcing |
| AIN1–AIN4 / AINCOM | Analog input multiplexer terminals | Support two fully differential or four pseudo-differential channels; AINCOM serves as common-mode reference for all pseudo-diff inputs |
| P1/SW1 / P2/SW2 | Dual-function pins | Configurable as GPIO bits or low-side power switches (RON = 3 Ω typ) to drive external load resistors or heater elements |
| REFIN1(±) / REFIN2(±) | Reference input pairs | Independent reference inputs allow absolute (REFIN1) and ratiometric (REFIN2) measurement modes - essential for sensor self-calibration |
| SCLK / DIN / DOUT / CS / RDY | 3-wire SPI-compatible interface | Schmitt-triggered SCLK enables opto-isolated communication; RDY indicates data-ready status for deterministic polling |
Key Features
| Feature | Design Value |
|---|---|
| VREF Select™ | Enables seamless switching between absolute (fixed reference) and ratiometric (sensor-excitation-referenced) measurement modes without hardware change |
| ISOURCE Select™ | Hardware-selectable excitation current routing (IEXC1/IEXC2/IEXC3 → IOUT1/IOUT2) simplifies 2-/3-/4-wire RTD and thermistor biasing |
| Chopped sigma-delta architecture | Reduces offset drift to ±10 nV/°C and enables stable 13-bit p-p resolution over temperature in uncalibrated systems |
| Rail-to-rail input buffer + PGA | Accepts high-impedance sensor outputs (e.g., thermocouples) directly; supports gain up to 128 for microvolt-level signals without external op-amps |
| Simultaneous 50/60 Hz rejection | Eliminates need for external line-frequency notch filters in global industrial deployments - achieved at 19.79 Hz update rate with Sinc³ filter notches |
Applications
| Pressure Measurement | Temperature Measurement |
|---|---|
Use Scenario: High-accuracy pressure transducers (e.g., silicon piezoresistive bridges) in HVAC and medical devices requiring <0.1% FS accuracy over –40°C to +85°C. IC Role / Device Role / Timing Role: Primary ADC front-end with integrated excitation, PGA, and digital filtering - digitizes bridge output while rejecting EMI and 50/60 Hz noise. Use Value: Eliminates external current sources and anti-aliasing filters; 13-bit p-p resolution at ±20 mV enables sub-Pa pressure resolution in battery-operated handheld gauges. | Use Scenario: 3-wire RTD (Pt100/Pt1000) circuits in industrial process control where lead-wire resistance compensation and long-term stability are critical. IC Role / Device Role / Timing Role: Precision ratiometric ADC with matched IEXC1/IEXC2 sourcing and REFIN2-based reference - performs true 4-wire-equivalent measurement using 3 wires. Use Value: ±2.5% initial current matching and 20 ppm/°C drift matching between IEXC1/IEXC2 minimize RTD self-heating errors and improve temperature accuracy to ±0.05°C. |
| Weigh Scales | Smart Transmitters |
Use Scenario: Portable and platform weigh scales using load cells with mV/V output, requiring low-noise acquisition and battery life >1 year. IC Role / Device Role / Timing Role: Low-power sigma-delta ADC with 7 µA power-down mode and integrated buffer - acquires microvolt-level signals while minimizing quiescent current. Use Value: 1.25 mA typical supply current @ 3 V and 300 ms startup time enable rapid wake-up sampling cycles, extending coin-cell battery life beyond 2 years. | Use Scenario: HART-enabled 4–20 mA smart transmitters needing local sensor digitization, diagnostics, and digital I/O for valve control or alarm signaling. IC Role / Device Role / Timing Role: Integrated analog front-end with 4-bit I/O port (P1–P4), low-side switches (SW1/SW2), and SPI interface - replaces discrete ADC + GPIO + driver ICs. Use Value: Reduces BOM count by 4 components; P1/SW1 and P2/SW2 drive 20 mA loads directly, enabling local solenoid or LED control without external drivers. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar precision sigma-delta ADC applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| AD7190BRUZ | 24-bit resolution, 4.7 Hz to 4.8 kHz update rate, internal PGA (1–128), but no integrated excitation current sources | Requires external current sources for RTD; better suited for ultra-high-resolution applications where excitation is handled separately | Select AD7190BRUZ when >16-bit resolution is mandatory and external excitation circuitry already exists |
| ADS1248IPWR | 24-bit delta-sigma ADC, integrated 200 µA excitation current, but only one current source and no low-side switches or I/O port | Lacks dual excitation matching and power-switch functionality; limited to single-sensor configurations without local actuation | Select ADS1248IPWR for cost-sensitive, single-channel RTD systems where GPIO and switching are unnecessary |
Compared with AD7709BRU-REEL, AD7190BRUZ offers higher resolution but requires external excitation and adds system complexity, while ADS1248IPWR reduces integration by omitting matched dual currents and power switches - making AD7709BRU-REEL uniquely suited for compact, self-contained 3-wire RTD or multi-sensor front-ends with local control.
Availability
AD7709BRU-REEL is available at Aetrix Electronics and suitable for pressure measurement, temperature sensing, weigh scales, and smart transmitter designs requiring stable component supply, long-lifecycle support, and guaranteed traceable sourcing.
Supply support for AD7709BRU-REEL 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 AD7709BRU-REEL belongs to Analog Devices' precision sigma-delta ADC product line, engineered specifically for low-frequency sensor signal conditioning in industrial, instrumentation, and portable measurement systems.
FAQ
What is the maximum update rate of the AD7709BRU-REEL, and how is it configured?
The AD7709BRU-REEL supports a maximum update rate of 105 Hz, achieved by programming the filter register (SF) to decimal 13. This sets the Sinc³ decimation factor to 104 (13 × 8), yielding an output data rate of fMOD/(SF × 8 × 3) = 32.768 kHz/(13 × 8 × 3) ≈ 105 Hz. The update rate is software-configurable via the 8-bit Filter Register, with increments of 0.732 ms per SF step.
Does the AD7709BRU-REEL support both 3 V and 5 V operation, and what are the typical supply currents?
Yes, the AD7709BRU-REEL is specified for single-supply operation at either 3 V (2.7–3.6 V) or 5 V (4.75–5.25 V). At 3 V, typical supply current is 1.25 mA in normal mode and 7 µA in power-down mode with the 32.768 kHz crystal active. At 5 V, typical current is 1.45 mA normal and 6.5 µA power-down. These values are confirmed in the Rev. A datasheet Table "POWER REQUIREMENTS".
How does the AD7709BRU-REEL achieve simultaneous 50 Hz and 60 Hz rejection?
The AD7709BRU-REEL achieves simultaneous 50 Hz and 60 Hz rejection through its Sinc³ digital filter architecture when operated at a 19.79 Hz update rate (SF = 69). At this rate, the filter's first notches fall at 52.5 Hz and 60 Hz, providing ≥100 dB rejection for both frequencies without external hardware. This capability is explicitly documented in the "NORMAL-MODE REJECTION" section of the datasheet.
What are the key differences between the AD7709BRU-REEL and the AD7709ARU variant?
The AD7709BRU-REEL and AD7709ARU share identical pinout, functionality, and package (24-lead TSSOP), differing only in grade specification: AD7709BRU-REEL is the B-grade version with ±0.75 LSB full-scale error (typical), while AD7709ARU is A-grade with ±0.2% of FS full-scale error (typical). Both operate across –40°C to +85°C and use the same REEL packaging format.
Can the AD7709BRU-REEL's digital I/O port be used for both input and output functions?
Yes - pins AIN3/P3 and AIN4/P4 are configurable as either analog inputs or general-purpose digital input bits, while P1/SW1 and P2/SW2 can operate as digital output bits or low-side power switches. All four I/O lines support weak internal pull-ups and tolerate voltages from GND to VDD, enabling flexible system-level control and monitoring without additional GPIO expanders.
AD7709BRU-REEL Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 24-TSSOP (0.173", 4.40mm Width)
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Obsolete
- Number of Bits:
- 16
- Sampling Rate (Per Second):
- 105
- Number of Inputs:
- 2, 4
- Input Type:
- Differential, Pseudo-Differential
- 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:
- 24-TSSOP
- Mounting Type:
- Surface Mount
- Grade:
- -
- Qualification:
- -
AD7709BRU-REEL FAQ
1.How can I place an order for AD7709BRU-REEL through Aetrix?
Please submit a Request for Quotation (RFQ) for AD7709BRU-REEL 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 AD7709BRU-REEL reliable?
The price and inventory of AD7709BRU-REEL are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for AD7709BRU-REEL is usually 5 days.
3.What payment methods are accepted for AD7709BRU-REEL?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for AD7709BRU-REEL transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for AD7709BRU-REEL?
AD7709BRU-REEL orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your AD7709BRU-REEL 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 AD7709BRU-REEL?
For technical support, including AD7709BRU-REEL datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your AD7709BRU-REEL requirements.
6.How does Aetrix verify that AD7709BRU-REEL is sourced from the original manufacturer or authorized distributors?
All AD7709BRU-REEL 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 AD7709BRU-REEL meets industry standards.
7.What is the process for return or replacement of AD7709BRU-REEL?
All AD7709BRU-REEL units undergo pre-shipment inspection (PSI). If there is an issue with AD7709BRU-REEL, 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 AD7709BRU-REEL part is unused and in its original packaging.
Return procedure for AD7709BRU-REEL:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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