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Analog Devices Inc. AD7705BRZ-REEL
- Part No.:
- AD7705BRZ-REEL
- Manufacturer:
- Analog Devices Inc.
- Category:
- Analog to Digital Converters (ADC)
- Package:
- 16-SOIC (0.295", 7.50mm Width)
- Datasheet:
-
AD7705BRZ-REEL.pdf
- Description:
- IC ADC 16BIT SIGMA-DELTA 16SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:774
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Product details
Overview
AD7705BRZ-REEL 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 operation at 2.7–3.3 V or 4.75–5.25 V. It delivers 0.003% integral nonlinearity, <600 nV rms noise, and 1 mW max power dissipation at 3 V - enabling direct transducer interfacing in low-power industrial sensor systems.
For engineers reviewing the AD7705BRZ-REEL datasheet, AD7705BRZ-REEL pinout, AD7705BRZ-REEL application, or AD7705BRZ-REEL equivalent, key selection criteria include its dual-channel differential architecture, on-chip calibration support, 50/60 Hz notch filter programmability, and compatibility with microcontroller-based data acquisition where precision, low power, and minimal external signal conditioning are required.
Technical Context
The AD7705BRZ-REEL employs a charge-balancing sigma-delta modulator followed by an on-chip digital filter with programmable first-notch frequency (20 Hz to 60 Hz), enabling precise rejection of line-frequency interference. Its analog front end integrates a programmable-gain amplifier (PGA) and optional input buffer, supporting unipolar (0 mV to 1.225 V) or bipolar (±10 mV to ±1.225 V) input ranges when using a 1.225 V reference at 3 V supply.
It features a Schmitt-triggered SCLK input, DRDY status flag for data-ready synchronization, and supports self-calibration and system calibration via dedicated registers. The device operates with either an external master clock (400 kHz–2.5 MHz) or a crystal/resonator across MCLK IN/OUT pins, and includes standby mode with ≤8 μA current draw at 3 V.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Resolution | 16 bits, no missing codes - guarantees monotonicity and full code coverage over temperature and supply range. |
| INL | ±0.003% of FSR - ensures high-end measurement fidelity for calibrated sensor interfaces. |
| Input Channels | 2 fully differential - enables simultaneous high-accuracy measurement of two isolated transducer outputs without shared reference crosstalk. |
| PGA Gain Range | 1 to 128 - allows direct connection of low-level sensors (e.g., strain gauges, RTDs) without external amplification. |
| Power Dissipation | 1 mW max @ 3 V - supports battery-powered or thermally constrained embedded systems. |
| Reference Input | Differential (REF IN(+) − REF IN(−)) - permits ratiometric measurement and eliminates reference drift impact on accuracy. |
| Serial Interface | 3-wire SPI/QSPI/MICROWIRE/DSP-compatible - reduces MCU GPIO count and simplifies isolation in noisy industrial environments. |
Pinout & Package
AD7705BRZ-REEL is supplied in a 16-lead SOIC package (wide-body, 0.3 inch). Pin assignments match the AD7705 functional configuration, distinct from AD7706's pseudo-differential layout.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| SCLK | Serial clock input | Schmitt-triggered - tolerates slow-rising/noisy clock edges; synchronizes all serial read/write operations. |
| MCLK IN | Master clock input | Accepts external CMOS clock (400 kHz–2.5 MHz) or crystal/resonator leg - determines conversion throughput and filter timing. |
| CS | Chip select | Active-low enable - allows multi-device sharing of DIN/DOUT/SCLK lines in daisy-chain or bus configurations. |
| AIN1(+), AIN1(−) | Channel 1 differential analog input | High common-mode rejection (>130 dB at gain ≥8) - rejects noise coupled equally to both inputs in sensor wiring. |
| AIN2(+), AIN2(−) | Channel 2 differential analog input | Independent channel path - supports dual-sensor monitoring (e.g., pressure + temperature) with separate gain/offset settings. |
| REF IN(+), REF IN(−) | Differential reference input | Defines full-scale range - enables ratiometric operation where reference tracks supply or sensor excitation voltage. |
| DIN/DOUT | Serial data I/O | Half-duplex 3-wire mode - eliminates need for separate read/write control lines, reducing PCB routing complexity. |
| DRDY | Data ready output | Open-drain logic low - signals valid conversion result; used for interrupt-driven sampling or polling synchronization. |
Key Features
| Feature | Design Value |
|---|---|
| Programmable 50/60 Hz notch filter | First digital filter notch configurable to 20 Hz, 25 Hz, 50 Hz, or 60 Hz - eliminates mains interference without external analog filters. |
| On-chip self- and system calibration | Zero-scale and full-scale calibration registers eliminate offset/gain errors - removes need for manual trim components or factory calibration steps. |
| Buffered analog input option | BUF bit in setup register enables internal buffer - supports high-impedance sources (e.g., thermocouples) without external op-amps. |
| Low-power standby mode | 8 μA max current at 3 V - extends battery life in portable instrumentation while retaining register state and calibration coefficients. |
| CMOS process & rail-to-rail compatibility | Operates from 2.7–3.3 V or 4.75–5.25 V - interoperates with both modern low-voltage MCUs and legacy 5 V industrial controllers. |
Applications
| Pressure Measurement | Temperature Monitoring |
|---|---|
Use Scenario: High-accuracy bridge-based pressure sensor readout in HVAC or industrial process control. IC Role / Device Role / Timing Role: ADC front end performing PGA amplification, sigma-delta conversion, and digital filtering of millivolt-level Wheatstone bridge outputs. Use Value: Eliminates external instrumentation amplifier and anti-aliasing filter; achieves <0.01% FS accuracy with on-chip calibration and 50/60 Hz rejection. | Use Scenario: Multi-point RTD or thermocouple monitoring in building automation or lab equipment. IC Role / Device Role / Timing Role: Dual-channel digitizer acquiring cold-junction compensation and sensor voltage simultaneously with matched timing. Use Value: Enables true differential sensing per channel, minimizing thermal EMF errors and eliminating need for external multiplexers or gain-switching circuitry. |
| Smart Transmitter | Battery Voltage Monitoring |
Use Scenario: 4–20 mA loop-powered field transmitter with HART communication and local diagnostics. IC Role / Device Role / Timing Role: Precision ADC capturing sensor, supply, and diagnostic voltages under strict power budget constraints. Use Value: 1 mW max power at 3 V and 8 μA standby allow continuous background measurement without compromising loop compliance. | Use Scenario: Low-power battery fuel gauging in portable medical or IoT devices. IC Role / Device Role / Timing Role: High-resolution ADC measuring cell voltage and current-sense shunt with programmable gain for dynamic range optimization. Use Value: 16-bit no-missing-codes resolution and <600 nV rms noise enable detection of sub-100 μV changes in battery ESR or aging trends. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar sigma-delta ADC applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| AD7706BRZ | 3 pseudo-differential input channels vs. AD7705BRZ-REEL's 2 fully differential channels; identical core architecture, timing, and register map. | Supports three single-ended or pseudo-differential sensors referenced to COMMON; less suitable for true differential bridge sensors requiring independent AIN(+) and AIN(−) pairs. | Select AD7706BRZ when expanding channel count is prioritized over differential integrity per channel. |
| ADS1115IDGSR | 4-channel, 16-bit delta-sigma ADC with integrated PGA and I²C interface; higher data rate (860 sps vs. ~120 sps at 50 Hz notch); no built-in 50/60 Hz notch programming. | Requires external notch filtering or DSP post-processing for line-frequency rejection; better suited for general-purpose multichannel logging than precision industrial transducers. | Choose ADS1115IDGSR for cost-sensitive, I²C-based designs needing more channels and faster updates, accepting trade-offs in inherent line-noise immunity. |
Compared with AD7706BRZ and ADS1115IDGSR, the AD7705BRZ-REEL uniquely balances dual fully differential inputs, hardware-programmable 50/60 Hz rejection, and ultra-low power - making it optimal for standalone, calibration-critical transducer interfaces where channel independence and noise immunity outweigh raw channel count or interface flexibility.
Availability
AD7705BRZ-REEL is available at Aetrix Electronics and suitable for pressure measurement, temperature monitoring, smart transmitter design, and battery voltage monitoring requiring stable component supply, long-term lifecycle support, and traceable sourcing.
Supply support for AD7705BRZ-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 is a global leader in high-performance analog, mixed-signal, and digital signal processing semiconductors, serving industrial, automotive, communications, and healthcare markets since 1965.
The AD7705/AD7706 product line was designed specifically for low-frequency, high-accuracy sensor signal conditioning in resource-constrained embedded systems - integrating PGA, sigma-delta conversion, digital filtering, and calibration into a single 16-pin IC.
FAQ
What is the maximum sample rate of the AD7705BRZ-REEL at 50 Hz notch filter setting?
The AD7705BRZ-REEL achieves approximately 120 samples per second when configured with a 50 Hz notch filter and 2.4576 MHz master clock. This update rate results from the digital filter's group delay and decimation ratio; actual throughput may vary slightly with gain setting and clock stability. The AD7705BRZ-REEL's filter notch and output rate are linked - selecting 50 Hz notch fixes the effective data rate unless the master clock frequency is adjusted. For higher rates, use 20 Hz or 25 Hz notch settings.
Does the AD7705BRZ-REEL support bipolar input ranges, and how is polarity configured?
Yes, the AD7705BRZ-REEL supports bipolar input ranges (e.g., ±10 mV to ±1.225 V) via the B/U bit in the Setup Register. When B/U = 0, the device interprets input as bipolar and centers the output code around mid-scale (0x8000 for 16-bit). The negative full-scale error is specified at ±0.003% of FSR. Bipolar operation requires proper referencing of AIN(−) inputs and matching the reference voltage polarity - the AD7705BRZ-REEL's differential reference architecture ensures accurate zero-crossing detection without external level-shifting.
Can the AD7705BRZ-REEL operate with a 3.3 V supply and a 2.5 V reference voltage?
No - the AD7705BRZ-REEL requires the reference voltage to scale with supply: at 3 V operation, the recommended reference is 1.225 V (±1%), not 2.5 V. Using 2.5 V with 3 V supply violates the REF IN(+) − REF IN(−) specification limit of 1/1.75 V (min/max) for 2.7–3.3 V VDD. Doing so risks saturation, reduced dynamic range, or invalid conversions. The AD7705BRZ-REEL's datasheet explicitly ties reference compliance to supply voltage - always pair 1.225 V ref with 3 V supply and 2.5 V ref with 5 V supply.
How does the DRDY pin behave during calibration sequences on the AD7705BRZ-REEL?
During on-chip self-calibration or system calibration, the DRDY pin goes low and remains asserted until calibration completes - typically within 128 × tCLKIN cycles. This provides hardware synchronization for firmware: software initiates calibration by writing to the appropriate register, then waits for DRDY to return high before reading results. The AD7705BRZ-REEL uses the same DRDY signal for both data-ready and calibration-complete indication, eliminating need for additional status polling. No DRDY assertion occurs during calibration unless the part is actively converting; calibration halts ongoing conversions.
Is the AD7705BRZ-REEL pin-compatible with other variants like AD7705BN or AD7705BR?
Yes - AD7705BRZ-REEL shares identical pinout and footprint with AD7705BN (PDIP) and AD7705BR (SOIC), as all belong to the AD7705 family and use the same 16-lead SOIC package outline. The "Z" suffix denotes lead-free finish, and "-REEL" indicates tape-and-reel packaging; electrical and mechanical compatibility is maintained across these variants. However, thermal characteristics differ: AD7705BRZ-REEL has θJA = 75°C/W (SOIC), while AD7705BN (PDIP) is 105°C/W - board layout and power dissipation must account for this in high-density designs.
AD7705BRZ-REEL Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 16-SOIC (0.295", 7.50mm Width)
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- 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-SOIC
- Mounting Type:
- Surface Mount
- Grade:
- -
- Qualification:
- -
AD7705BRZ-REEL FAQ
1.How can I place an order for AD7705BRZ-REEL through Aetrix?
Please submit a Request for Quotation (RFQ) for AD7705BRZ-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 AD7705BRZ-REEL reliable?
The price and inventory of AD7705BRZ-REEL are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for AD7705BRZ-REEL is usually 5 days.
3.What payment methods are accepted for AD7705BRZ-REEL?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for AD7705BRZ-REEL transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for AD7705BRZ-REEL?
AD7705BRZ-REEL orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your AD7705BRZ-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 AD7705BRZ-REEL?
For technical support, including AD7705BRZ-REEL datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your AD7705BRZ-REEL requirements.
6.How does Aetrix verify that AD7705BRZ-REEL is sourced from the original manufacturer or authorized distributors?
All AD7705BRZ-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 AD7705BRZ-REEL meets industry standards.
7.What is the process for return or replacement of AD7705BRZ-REEL?
All AD7705BRZ-REEL units undergo pre-shipment inspection (PSI). If there is an issue with AD7705BRZ-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 AD7705BRZ-REEL part is unused and in its original packaging.
Return procedure for AD7705BRZ-REEL:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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