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Analog Devices Inc. AD7781BRZ-REEL
- Part No.:
- AD7781BRZ-REEL
- Manufacturer:
- Analog Devices Inc.
- Category:
- Analog to Digital Converters (ADC)
- Package:
- 14-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
AD7781BRZ-REEL.pdf
- Description:
- IC ADC 20BIT SIGMA-DELTA 14SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:1,190
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Product details
Overview
AD7781BRZ-REEL from Analog Devices is a 20-bit, low-power sigma-delta ADC optimized for bridge sensor front ends, featuring pin-programmable gain (1 or 128), dual update rates (10 Hz / 16.7 Hz), simultaneous 50 Hz/60 Hz rejection, and integrated bridge power-down switch. It delivers 17.6–19.4 bits peak-to-peak resolution with RMS noise as low as 44 nV (C grade, gain = 128, 10 Hz) and operates from 2.7 V to 5.25 V across −40°C to +105°C - enabling high-accuracy weigh scale and pressure measurement systems.
For engineers reviewing the AD7781BRZ-REEL datasheet, AD7781BRZ-REEL pinout, AD7781BRZ-REEL application, or AD7781BRZ-REEL equivalent, this page provides verified technical context, exact pin functions, real-world noise and resolution data, confirmed filter settling behavior, and validated alternative options for load-cell signal conditioning designs.
Technical Context
The AD7781BRZ-REEL implements a single-channel, differential-input sigma-delta modulator with on-chip programmable gain amplifier (PGA), digital filter, and internal 64 kHz oscillator. Its two-pin-configurable filter modes deliver either fast settling (120 ms at 16.7 Hz) or high stop-band attenuation (>−45 dB at 10 Hz), both supporting simultaneous 50/60 Hz rejection without external notch filters.
Gain selection (GAIN pin) and filter selection (FILTER pin) directly reset the modulator and digital filter, requiring full settling time before valid data appears on DOUT/RDY. The device uses offset binary coding, supports ratiometric operation via unbuffered REFIN(±), and includes a 9 Ω bridge power-down switch controlled by PDRST - enabling true zero-current sensor biasing during idle periods.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Resolution | 20-bit no-missing-codes; 17.1–19.4 bits peak-to-peak resolution depending on gain, filter, and supply voltage. |
| Update Rate | 10 Hz (300 ms settling) or 16.7 Hz (120 ms settling); selected via FILTER pin, not software. |
| RMS Noise | 44 nV (C grade, gain=128, 10 Hz, 3 V ref); enables sub-10 ppm measurement precision in low-drift weigh scales. |
| PGA Gain | Pin-selectable 1 or 128; supports ±5 V (gain=1) or ±39 mV (gain=128) differential input range with same reference. |
| Power Consumption | 115 μA typical (gain=1, 3 V AVDD); 330 μA typical (gain=128, C grade, 3 V AVDD); drops to 10 μA in power-down. |
| Common-Mode Rejection | 110 dB at 50/60 Hz; ensures stable readings in electrically noisy industrial environments with shared ground paths. |
| Operating Temperature | −40°C to +105°C; qualified for embedded industrial process control and automotive cabin-sensor applications. |
Pinout & Package
AD7781BRZ-REEL is supplied in a 14-lead, narrow-body SOIC package (package code BRZ). Pin assignments are fixed per Analog Devices' official pinout and not variant-dependent.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| SCLK | Serial clock input | Schmitt-triggered; controls timing of 32-bit read cycles (20-bit data + 8 status bits); noncontinuous clocking supported. |
| DOUT/RDY | Dual-function output | Active-low data-ready flag and serial data output; falling edge serves as interrupt; tristated during power-down. |
| GAIN | Gain select control | Low = gain 128 (±39 mV FS); high = gain 1 (±5 V FS); change resets modulator and requires full filter settling. |
| FILTER | Filter response select | Low = 16.7 Hz update (120 ms settling); high = 10 Hz update (300 ms settling); change resets filter and sets DOUT/RDY high. |
| PDRST | Power-down/reset control | Low = full power-down (ADC + clock + BPDSW open); high = active conversion; 100 ns pulse minimum for reset. |
| BPDSW | Bridge power-down switch terminal | Connects to GND; closed when PDRST high; 9 Ω RON, 30 mA continuous rating; eliminates sensor bias current in sleep mode. |
| AIN(+), AIN(−) | Differential analog input | High-impedance inputs; support direct connection to strain gages/load cells; common-mode voltage ≥0.5 V required. |
| REFIN(+), REFIN(−) | Differential reference input | Unbuffered; accepts 0.5 V to AVDD; ratiometric operation cancels excitation noise; avoid high-impedance sources. |
Key Features
| Feature | Design Value |
|---|---|
| Pin-programmable filter | Selects between 10 Hz (high-rejection) and 16.7 Hz (fast-settling) modes without register writes or firmware overhead. |
| Integrated bridge power-down | 9 Ω switch controlled by PDRST pin enables true zero-bias current for battery-powered load cells between measurements. |
| Simultaneous 50 Hz/60 Hz rejection | Hardware-filtered at both update rates - eliminates need for external notch filters or digital post-processing in AC-line-noise environments. |
| Status-embedded serial output | Each 32-bit read includes 20-bit conversion + 8 status bits (pattern sequence) for automatic validity checking of serial transfers. |
| Independent interface supply | DVDD (2.7–5.25 V) powers logic pins separately from AVDD - allows mixed-voltage system interfacing (e.g., 3.3 V MCU with 5 V analog rail). |
Applications
| Weigh Scales | Pressure Measurement |
|---|---|
|
Use Scenario: High-resolution digital weighing platform using 350 Ω strain-gauge load cell with 5 V excitation in factory floor environment. IC Role / Device Role / Timing Role: Front-end ADC with integrated PGA and bridge power switch; performs synchronized 10 Hz conversions with 300 ms settling to reject mechanical vibration and line noise. Use Value: Achieves 17.6-bit p-p resolution and <±6 ppm INL without calibration, enabling Class III legal-for-trade accuracy with minimal BOM count. |
Use Scenario: Industrial pressure transducer with Wheatstone bridge output in oil & gas monitoring cabinet operating at 70°C ambient. IC Role / Device Role / Timing Role: Precision analog front end; uses 16.7 Hz update rate and gain = 128 to resolve microvolt-level bridge imbalances while rejecting 60 Hz EMI. Use Value: Delivers 44 nV RMS noise and 110 dB CMRR at 60 Hz, ensuring stable 0.05% FS repeatability over full temperature range. |
| Industrial Process Control | Portable Instrumentation |
|
Use Scenario: DIN-rail mounted flow meter controller acquiring bridge sensor data in 24/7 operation with 4–20 mA loop power constraints. IC Role / Device Role / Timing Role: Low-power sigma-delta converter with pin-controlled power-down; activates only during scheduled 10 Hz sampling bursts to minimize average current draw. Use Value: Draws just 115 μA (gain = 1) and supports independent DVDD/AVDD rails - simplifies isolated power design and extends system lifetime. |
Use Scenario: Handheld torque tester powered by two AA batteries, requiring >100-hour runtime and millivolt-level strain detection. IC Role / Device Role / Timing Role: Battery-optimized ADC; uses PDRST to fully disconnect bridge and shut down internal clock between readings, reducing quiescent current to 10 μA. Use Value: Enables 330 μA active current (gain = 128) + zero-bias sensor current, extending battery life by >3× versus always-on alternatives. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar bridge-sensor ADC applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| AD7190BRUZ | 24-bit, 4.8 kSPS max, SPI interface, programmable registers, higher power (4.6 mA), no pin-programmable filter. | Used in high-speed, multi-channel industrial DAQ where software configurability outweighs ultra-low power needs. | Choose AD7190BRUZ when resolution >20 bits and channel count >1 are required; not drop-in due to different pinout, interface, and power profile. |
| ADS1232IPW | 20-bit, 80 SPS max, pin-programmable gain (1/2/64/128), 50/60 Hz rejection, 380 μA typical (gain=128), 16-TSSOP only. | Targeted at cost-sensitive weigh scale OEMs needing identical pin-programmable simplicity but with wider gain options. | ADS1232IPW offers same core functionality in TSSOP; differs in REF pin configuration, lack of BPDSW, and lower CMRR (100 dB vs 110 dB). |
Compared with AD7781BRZ-REEL, AD7190BRUZ trades ultra-low power and pin simplicity for higher resolution and flexibility, while ADS1232IPW matches the pin-programmable philosophy but omits the integrated bridge switch and delivers lower noise rejection performance.
Availability
AD7781BRZ-REEL is available at Aetrix Electronics and suitable for weigh scales, pressure transducers, and portable instrumentation requiring stable component supply, long-term industrial lifecycle support, and guaranteed traceable sourcing.
Supply support for AD7781BRZ-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 AD7781 belongs to Analog Devices' precision sigma-delta ADC product line, designed specifically for low-power, high-accuracy bridge sensor signal conditioning in demanding industrial and portable measurement applications.
FAQ
What is the maximum allowed analog input voltage range for AD7781BRZ-REEL?
The AD7781BRZ-REEL supports a differential input voltage range of ±VREF/gain. With VREF = 5 V and gain = 1, the range is ±5 V; with gain = 128, it is ±39 mV. Absolute voltage limits depend on gain and filter setting: for gain = 128 and FILTER = 0, AIN must stay between GND + 450 mV and AVDD − 1.1 V. Exceeding these violates specifications and degrades linearity and noise.
Does AD7781BRZ-REEL require an external crystal or clock source?
No, AD7781BRZ-REEL does not require an external clock. It contains a fully integrated 64 kHz ±3% internal oscillator, eliminating the need for crystals, capacitors, or clock distribution circuitry. This reduces BOM cost and board space while ensuring consistent timing behavior across temperature and voltage.
How does the bridge power-down switch (BPDSW) function in AD7781BRZ-REEL?
In AD7781BRZ-REEL, the BPDSW terminal connects to GND and is controlled by the PDRST pin. When PDRST is high, BPDSW closes (RON ≤ 9 Ω), enabling current flow to the bridge sensor. When PDRST is low, BPDSW opens, cutting off all bias current to the sensor - a critical feature for extending battery life in portable instrumentation.
Can AD7781BRZ-REEL reject both 50 Hz and 60 Hz interference simultaneously?
Yes, AD7781BRZ-REEL provides simultaneous 50 Hz and 60 Hz rejection at both 10 Hz and 16.7 Hz update rates - achieving 72–90 dB rejection depending on filter mode and grade. This hardware-based rejection is built into the digital filter architecture and requires no external components or firmware intervention.
What is the purpose of the 8 status bits appended to each AD7781BRZ-REEL data read?
Each 32-bit serial read from AD7781BRZ-REEL includes 20 bits of conversion data followed by 8 status bits containing a fixed pattern sequence. This sequence allows the host processor to verify the integrity of the serial transfer - confirming that the correct number of clock edges occurred and that no bit shifts or framing errors corrupted the data word.
AD7781BRZ-REEL Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 14-SOIC (0.154", 3.90mm Width)
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Number of Bits:
- 20
- Sampling Rate (Per Second):
- 16.7
- Number of Inputs:
- 1
- Input Type:
- Differential
- Data Interface:
- SPI
- Configuration:
- PGA-ADC
- Ratio - S/H:ADC:
- -
- Number of A/D Converters:
- 1
- Architecture:
- Sigma-Delta
- Reference Type:
- External
- Voltage - Supply, Analog:
- 2.7V ~ 5.25V
- Voltage - Supply, Digital:
- 2.7V ~ 5.25V
- Features:
- PGA
- Operating Temperature:
- -40°C ~ 105°C
- Supplier Device Package:
- 14-SOIC
- Mounting Type:
- Surface Mount
- Grade:
- -
- Qualification:
- -
AD7781BRZ-REEL FAQ
1.How can I place an order for AD7781BRZ-REEL through Aetrix?
Please submit a Request for Quotation (RFQ) for AD7781BRZ-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 AD7781BRZ-REEL reliable?
The price and inventory of AD7781BRZ-REEL are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for AD7781BRZ-REEL is usually 5 days.
3.What payment methods are accepted for AD7781BRZ-REEL?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for AD7781BRZ-REEL transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for AD7781BRZ-REEL?
AD7781BRZ-REEL orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your AD7781BRZ-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 AD7781BRZ-REEL?
For technical support, including AD7781BRZ-REEL datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your AD7781BRZ-REEL requirements.
6.How does Aetrix verify that AD7781BRZ-REEL is sourced from the original manufacturer or authorized distributors?
All AD7781BRZ-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 AD7781BRZ-REEL meets industry standards.
7.What is the process for return or replacement of AD7781BRZ-REEL?
All AD7781BRZ-REEL units undergo pre-shipment inspection (PSI). If there is an issue with AD7781BRZ-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 AD7781BRZ-REEL part is unused and in its original packaging.
Return procedure for AD7781BRZ-REEL:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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