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Analog Devices Inc. AD7705BRU-REEL7
- Part No.:
- AD7705BRU-REEL7
- Manufacturer:
- Analog Devices Inc.
- Category:
- Analog to Digital Converters (ADC)
- Package:
- 16-TSSOP (0.173", 4.40mm Width)
- Datasheet:
-
AD7705BRU-REEL7.pdf
- Description:
- IC ADC 16BIT SIGMA-DELTA 16TSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:1,538
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Product details
Overview
AD7705BRU-REEL7 from Analog Devices is a 16-bit sigma-delta analog-to-digital converter with two fully differential input channels, programmable gain (1–128), 3-wire SPI-compatible serial interface, and 1 mW max power dissipation at 3 V - designed for precision low-frequency transducer signal acquisition in industrial sensor systems.
For engineers reviewing the AD7705BRU-REEL7 datasheet, AD7705BRU-REEL7 pinout, AD7705BRU-REEL7 application, or AD7705BRU-REEL7 equivalent, key selection criteria include unipolar/bipolar input range support (±20 mV to ±2.5 V), on-chip self-calibration, 0.003% integral nonlinearity, and TSSOP-16 packaging for space-constrained PCB layouts.
Technical Context
The AD7705BRU-REEL7 employs a charge-balancing sigma-delta modulator followed by an on-chip digital filter with programmable first-notch frequency, enabling configurable output update rates and high-rejection filtering for 50/60 Hz line interference. Its analog front end integrates a programmable-gain amplifier (PGA) and optional input buffer, allowing direct connection to low-level transducers without external signal conditioning.
It operates from a single 2.7 V to 3.3 V supply, supports differential reference inputs (REF IN(+) and REF IN(−)), and features Schmitt-triggered SCLK for noise immunity. The device implements register-based configuration via a 3-wire serial interface compatible with SPI, QSPI, MICROWIRE, and DSP controllers.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Resolution | 16 bits with no missing codes - guarantees monotonicity and full code coverage across full-scale range. |
| Integral Nonlinearity | ±0.003% of FSR - ensures high accuracy in precision measurement applications such as load cells and RTDs. |
| Input Channels | 2 fully differential analog inputs - supports simultaneous high-accuracy acquisition from dual transducers or bridge sensors. |
| Programmable Gain | 1 to 128 - enables direct interfacing with microvolt-level outputs (e.g., strain gauges) without external amplification. |
| Power Dissipation | 1 mW max at 3 V - suitable for battery-powered instrumentation and portable data loggers. |
| Reference Input | Differential (REF IN(+)/REF IN(−)) - allows ratiometric measurement and rejection of common-mode reference drift. |
| Output Data Rate | Configurable via digital filter notch - supports 50/60 Hz rejection and update rates from ~10 Hz to 1 kHz depending on gain and clock. |
Pinout & Package
AD7705BRU-REEL7 is housed in a 16-lead thin shrink small outline package (TSSOP), 4.4 mm × 5.0 mm body, 0.65 mm pitch, with exposed pad for thermal enhancement (not electrically connected). Pin 1 marked by dot; pin numbering follows standard TSSOP convention.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| SCLK | Serial Clock Input | Schmitt-triggered input accepting 3-wire SPI-compatible clock; enables synchronous read/write access to internal registers. |
| MCLK IN | Master Clock Input | Accepts external CMOS clock (400 kHz–2.5 MHz) or crystal/resonator connection; drives internal sigma-delta modulator and digital filter. |
| MCLK OUT | Master Clock Output | Inverted copy of MCLK IN when external clock used; can drive one CMOS load or be disabled via CLKDIS bit to reduce power. |
| CS | Chip Select | Active-low enable for serial interface; allows 3-wire operation when hardwired low, eliminating need for separate address lines. |
| RESET | Hardware Reset | Active-low signal that resets all registers, calibration coefficients, digital filter state, and analog modulator to power-on defaults. |
| AIN1(+), AIN1(−) | Differential Channel 1 Input | Primary fully differential analog input pair; accepts bipolar (±20 mV to ±2.5 V) or unipolar (0–2.5 V) signals referenced to AIN1(−). |
| AIN2(+), AIN2(−) | Differential Channel 2 Input | Secondary fully differential analog input pair; independent of Channel 1, supporting dual-sensor or differential reference configurations. |
| REF IN(+), REF IN(−) | Differential Reference Inputs | Set full-scale range; support ratiometric operation; REF IN(+) must exceed REF IN(−) and may range from GND to VDD. |
| DIN | Serial Data Input | Accepts command and configuration data (e.g., setup register writes, calibration triggers) synchronized to SCLK. |
| DOUT | Serial Data Output | Provides conversion results and register contents; tri-state when CS is high; supports daisy-chain configurations. |
| DRDY | Data Ready Output | Open-drain logic-low pulse indicates valid conversion result in data register; used for interrupt-driven or polled read timing. |
| GND | Analog/Digital Ground | Single ground pin serving both analog and digital sections; requires low-impedance PCB connection to minimize noise coupling. |
| VDD | Supply Voltage | 2.7 V to 3.3 V operation only for this variant; powers analog modulator, digital filter, and interface logic with <1 mW total dissipation. |
Key Features
| Feature | Design Value |
|---|---|
| On-chip self-calibration | Eliminates zero-scale and full-scale errors without external components; reduces system-level calibration effort and cost. |
| Programmable digital filter notch | Enables precise 50 Hz or 60 Hz line-frequency rejection by setting first filter notch - critical for industrial AC-noise environments. |
| Buffered analog input option | Configurable input buffer (via BUF bit) supports high-impedance sources (e.g., thermocouples) while maintaining specified INL and noise performance. |
| Low-power standby mode | Reduces current to ≤8 μA at 3 V - extends battery life in portable measurement devices without losing register state. |
| 3-wire serial interface | Minimizes interconnect count and opto-isolator requirements in isolated systems; compatible with microcontrollers lacking dedicated SPI peripherals. |
Applications
| Pressure Measurement | Temperature Monitoring |
|---|---|
Use Scenario: High-accuracy pressure sensing in HVAC control panels using silicon piezoresistive bridge sensors with mV-level output. IC Role / Device Role / Timing Role: ADC front end performing PGA gain scaling, sigma-delta conversion, and digital filtering to reject 50/60 Hz ambient noise. Use Value: Enables direct digitization of ±15 mV bridge outputs at 16-bit resolution without external op-amps or anti-aliasing filters. |
Use Scenario: Multi-point temperature logging in industrial ovens using PT100 RTD sensors with 4-wire Kelvin connections. IC Role / Device Role / Timing Role: Dual-channel differential ADC acquiring ratiometric voltage ratios from constant-current-excited RTDs. Use Value: Delivers <0.003% INL and <600 nV rms noise - sufficient for ±0.1°C accuracy over −40°C to +85°C. |
| Smart Transmitter | Battery Monitoring |
Use Scenario: 4–20 mA loop-powered field transmitter converting process variable (e.g., flow rate) to HART-modulated output. IC Role / Device Role / Timing Role: Precision ADC digitizing conditioned sensor output while operating from limited loop power budget. Use Value: 1 mW max power at 3 V and 8 μA standby allow continuous operation within 3.5 mA loop limit during sleep cycles. |
Use Scenario: State-of-charge estimation in lithium-ion battery packs using cell voltage and current shunt monitoring. IC Role / Device Role / Timing Role: Simultaneous acquisition of voltage (unipolar) and current-sense (bipolar) channels with programmable gain. Use Value: Supports ±10 mV to ±2.5 V input ranges and on-chip calibration - eliminates offset drift errors affecting long-term SoC accuracy. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar sigma-delta ADC applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| AD7706BRU-REEL7 | 3-channel pseudo-differential input vs. AD7705BRU-REEL7's 2-channel fully differential input; identical core architecture, register map, and power specs. | Supports three single-ended or pseudo-differential inputs referenced to COMMON pin - better suited for multi-sensor systems with shared reference. | Select AD7706BRU-REEL7 when needing >2 input channels and can accept pseudo-differential topology instead of true differential pairs. |
| ADS1220IPWR | 24-bit resolution, integrated PGA (1–128), VREF buffered output, and enhanced diagnostics; higher power (~1.3 mW) and different serial protocol (4-wire SPI). | Offers higher resolution and built-in temperature sensor; targets applications requiring <0.0005% INL and system health monitoring. | Choose ADS1220IPWR when 24-bit resolution, on-chip temperature sensing, or enhanced fault detection outweighs AD7705BRU-REEL7's lower power and simpler interface. |
Compared with AD7705BRU-REEL7, AD7706BRU-REEL7 adds a third channel at identical power and accuracy but sacrifices true differential input capability per channel; ADS1220IPWR delivers 8 extra bits and diagnostics at higher power and interface complexity - making AD7705BRU-REEL7 optimal for cost-sensitive, dual-channel, ultra-low-power 16-bit measurement tasks.
Availability
AD7705BRU-REEL7 is available at Aetrix Electronics and suitable for pressure transducers, RTD temperature sensors, smart 4–20 mA transmitters, and battery-monitoring circuits requiring stable component supply, long-lifecycle availability, and traceable sourcing.
Supply support for AD7705BRU-REEL7 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 and manufacturing operations worldwide.
The AD7705/AD7706 product line was engineered specifically for low-frequency, high-accuracy sensor signal acquisition in industrial, instrumentation, and process control systems - emphasizing low power, integrated signal conditioning, and robust noise rejection.
FAQ
What is the maximum input voltage range supported by AD7705BRU-REEL7?
The AD7705BRU-REEL7 supports unipolar input ranges from 0 mV to 2.5 V and bipolar ranges from ±20 mV to ±2.5 V when operating at 5 V supply with a 2.5 V reference. At 3 V supply with 1.225 V reference, it handles 0–1.225 V unipolar or ±10 mV to ±1.225 V bipolar inputs. Absolute input voltage must stay within GND − 100 mV to VDD + 30 mV for specified performance.
Does AD7705BRU-REEL7 require an external reference voltage?
No - AD7705BRU-REEL7 accepts an external differential reference (REF IN(+) and REF IN(−)), but it does not include an internal reference. A stable external reference (e.g., 2.5 V or 1.225 V) must be supplied to achieve specified accuracy. The device supports ratiometric operation, where reference voltage tracks supply or sensor excitation for improved system-level stability.
Can AD7705BRU-REEL7 perform self-calibration without external components?
Yes - AD7705BRU-REEL7 includes on-chip self-calibration for zero-scale and full-scale errors. Writing to the appropriate calibration registers initiates internal calibration sequences that adjust internal coefficients without requiring external voltage sources or precision references. This feature is accessible via the serial interface and preserves calibration across power cycles when stored in nonvolatile memory (if used with external controller).
What serial interface protocols is AD7705BRU-REEL7 compatible with?
AD7705BRU-REEL7 supports 3-wire SPI-compatible communication, including native compatibility with SPI, QSPI, MICROWIRE, and generic DSP serial ports. It uses DIN, DOUT, and SCLK pins with active-low CS; no additional control lines are required. The Schmitt-triggered SCLK input enhances noise immunity in electrically noisy industrial environments.
Is AD7705BRU-REEL7 pin-compatible with other packages of the same part number?
Yes - AD7705BRU-REEL7 (TSSOP-16) shares identical pinout and electrical behavior with AD7705BN (PDIP-16) and AD7705BR (SOIC-16). All variants use the same pin numbering, function mapping, and timing specifications. PCB layout changes are only needed for footprint adaptation; no schematic or firmware modifications are required when migrating between packages.
AD7705BRU-REEL7 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 16-TSSOP (0.173", 4.40mm Width)
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Obsolete
- Number of Bits:
- 16
- Sampling Rate (Per Second):
- 500
- Number of Inputs:
- 2
- Input Type:
- 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:
- 16-TSSOP
- Mounting Type:
- Surface Mount
- Grade:
- -
- Qualification:
- -
AD7705BRU-REEL7 FAQ
1.How can I place an order for AD7705BRU-REEL7 through Aetrix?
Please submit a Request for Quotation (RFQ) for AD7705BRU-REEL7 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 AD7705BRU-REEL7 reliable?
The price and inventory of AD7705BRU-REEL7 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for AD7705BRU-REEL7 is usually 5 days.
3.What payment methods are accepted for AD7705BRU-REEL7?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for AD7705BRU-REEL7 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for AD7705BRU-REEL7?
AD7705BRU-REEL7 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your AD7705BRU-REEL7 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 AD7705BRU-REEL7?
For technical support, including AD7705BRU-REEL7 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your AD7705BRU-REEL7 requirements.
6.How does Aetrix verify that AD7705BRU-REEL7 is sourced from the original manufacturer or authorized distributors?
All AD7705BRU-REEL7 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 AD7705BRU-REEL7 meets industry standards.
7.What is the process for return or replacement of AD7705BRU-REEL7?
All AD7705BRU-REEL7 units undergo pre-shipment inspection (PSI). If there is an issue with AD7705BRU-REEL7, 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 AD7705BRU-REEL7 part is unused and in its original packaging.
Return procedure for AD7705BRU-REEL7:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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