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Analog Devices Inc. AD7781BRUZ-REEL
- Part No.:
- AD7781BRUZ-REEL
- Manufacturer:
- Analog Devices Inc.
- Category:
- Analog to Digital Converters (ADC)
- Package:
- 16-TSSOP (0.173", 4.40mm Width)
- Datasheet:
-
AD7781BRUZ-REEL.pdf
- Description:
- IC ADC 20BIT SIGMA-DELTA 16TSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:3,650
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Product details
Overview
AD7781BRUZ-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 across −40°C to +105°C in weigh scale and pressure measurement systems.
For engineers reviewing the AD7781BRUZ-REEL datasheet, AD7781BRUZ-REEL pinout, AD7781BRUZ-REEL application, or AD7781BRUZ-REEL equivalent, key selection criteria include its pin-controlled filter/gain configuration, 115–500 μA supply current scalability, 2-wire SPI-compatible interface, and on-chip oscillator eliminating external timing components.
Technical Context
The AD7781BRUZ-REEL implements a 20-bit sigma-delta modulator with programmable digital filter selecting either 10 Hz (300 ms settling, >−45 dB stop-band attenuation) or 16.7 Hz (120 ms settling, superior dynamic performance). Its PGA provides fixed gain options of 1 or 128, enabling full-scale differential inputs of ±5 V or ±39 mV respectively, with input common-mode range ≥0.5 V and absolute voltage limits dependent on gain and FILTER setting.
It integrates a bridge power-down switch (RON ≤ 9 Ω, 30 mA continuous) controlled via PDRST, an internal 64 kHz ±3% clock oscillator, and a 2-wire serial interface where DOUT/RDY serves dual roles: data-ready indicator and 32-bit output (20-bit conversion + 8 status bits), with Schmitt-triggered SCLK supporting DVDD-independent logic levels.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Resolution | 20-bit sigma-delta ADC with no missing codes; peak-to-peak resolution up to 19.4 bits (C grade, AVDD = 5 V, gain = 1, 16.7 Hz). |
| Update Rate | Pin-selectable 10 Hz (300 ms settling) or 16.7 Hz (120 ms settling); enables trade-off between noise rejection and response speed. |
| RMS Noise | 44 nV typical (C grade, gain = 128, 10 Hz, AVDD = 3 V); supports high-precision bridge measurements below 1 μV RMS. |
| Power Supply | AVDD: 2.7–5.25 V; DVDD: 2.7–5.25 V (independent rails); enables mixed-voltage system integration without level shifters. |
| Input Range | Differential: ±VREF/gain → ±5 V (gain = 1) or ±39 mV (gain = 128); accommodates both high-level and microvolt-level sensor outputs. |
| Common-Mode Rejection | 110 dB at 50/60 Hz; ensures robust operation in electrically noisy industrial environments with AC line interference. |
| Operating Temp | −40°C to +105°C; qualified for industrial and automotive under-hood sensor signal conditioning applications. |
Pinout & Package
AD7781BRUZ-REEL is supplied in a 16-lead TSSOP package (JEDEC MO-153, 5 mm × 4.4 mm × 1.2 mm), optimized for space-constrained industrial PCBs and compatible with standard reflow profiles (260°C peak).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| SCLK | Serial clock input | Schmitt-triggered; controls data read timing; supports noncontinuous clocking for low-power burst reads. |
| DOUT/RDY | Dual-function output | Active-low data-ready flag and 32-bit serial data output (20-bit result + 8 status bits); usable as interrupt source. |
| GAIN | Gain select control | Logic low = gain 128 (±39 mV FS); logic high = gain 1 (±5 V FS); resets modulator/filter on change. |
| FILTER | Filter select control | Logic low = 16.7 Hz fast settling; logic high = 10 Hz high-rejection; resets modulator/filter on change. |
| PDRST | Power-down/reset | Active-low; powers down ADC and opens BPDSW; tristates DOUT/RDY; requires ≥100 ns pulse width. |
| BPDSW | Bridge power-down switch | Internal NMOS switch to GND; RON ≤ 9 Ω; handles 30 mA continuous; reduces load cell current during idle. |
| AIN(+), AIN(−) | Differential analog input | High-impedance inputs; support direct connection to strain gages/load cells; CM voltage ≥ 0.5 V required. |
| REFIN(+), REFIN(−) | Differential reference input | Unbuffered; accepts 0.5–AVDD reference; ratiometric operation eliminates excitation source noise sensitivity. |
Key Features
| Feature | Design Value |
|---|---|
| Pin-programmable gain & filter | Eliminates firmware configuration overhead; enables hardware-only adaptation to sensor type and environmental noise profile. |
| Simultaneous 50 Hz/60 Hz rejection | Guaranteed >63 dB normal-mode rejection at both 10 Hz and 16.7 Hz update rates; no external notch filters needed. |
| Integrated bridge power-down switch | Reduces system standby current by disconnecting load cell excitation; extends battery life in portable instrumentation. |
| Independent AVDD/DVDD supplies | Allows 3 V digital interface with 5 V analog rail (or vice versa); simplifies power domain partitioning in mixed-signal designs. |
| On-chip 64 kHz oscillator | Removes need for external crystal/clock source; reduces BOM count and layout area while ensuring timing consistency. |
Applications
| Weigh Scales | Pressure Measurement |
|---|---|
|
Use Scenario: High-accuracy platform scales measuring 0.1 g increments over 30 kg range using 350 Ω strain-gage load cells. IC Role / Device Role / Timing Role: Primary sigma-delta ADC front end; digitizes mV-level bridge output with 20-bit resolution and 50/60 Hz line rejection. Use Value: Enables <10 ppm total error (INL ±6 ppm, offset ±6 μV) and 17.6+ bit p-p resolution without external amplification or filtering. |
Use Scenario: Industrial pressure transmitters monitoring hydraulic systems with ±100 kPa range and 0.05% FS accuracy requirement. IC Role / Device Role / Timing Role: Bridge sensor signal conditioner; converts differential pressure-induced voltage with programmable gain and temperature-stable offset. Use Value: Delivers ±10 nV/°C offset drift and ±2 ppm/°C gain drift, meeting long-term stability requirements in unattended installations. |
| Industrial Process Control | Portable Instrumentation |
|
Use Scenario: DIN-rail mounted flow meter controller acquiring sensor data in factory automation networks with EMI exposure. IC Role / Device Role / Timing Role: Low-noise ADC subsystem; interfaces to Wheatstone bridge sensors while rejecting conducted and radiated 50/60 Hz noise. Use Value: Achieves 110 dB common-mode rejection and 90 dB normal-mode rejection, maintaining accuracy in electrically hostile plant floors. |
Use Scenario: Handheld multimeter with battery life target >200 hours per charge, requiring ultra-low quiescent current in active and sleep states. IC Role / Device Role / Timing Role: Power-optimized ADC core; uses PDRST-driven power-down and BPDSW to minimize average current draw. Use Value: Reduces typical supply current to 115 μA (gain = 1) or 330 μA (gain = 128), extending runtime without sacrificing resolution. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar sigma-delta ADC applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| AD7190BRUZ | 24-bit resolution, 4.7 Hz–4.8 kHz update rate, PGA gain 1–128, but consumes 4.65 mA typical (vs. 115–500 μA for AD7781BRUZ-REEL). | Targeted at high-precision laboratory instruments; lacks integrated bridge power-down switch and pin-programmable filter. | Choose AD7190BRUZ only when higher resolution and wider bandwidth outweigh power and integration constraints. |
| ADS1232IPW | 20-bit resolution, 10/80 Hz update rates, integrated oscillator, but requires external reference and offers no simultaneous 50/60 Hz rejection guarantee. | Designed for weigh scale ASICs; lacks independent DVDD/AVDD and has lower CMRR (100 dB vs. 110 dB). | Prefer ADS1232IPW for cost-sensitive consumer scales where 100 dB CMRR suffices and external reference is acceptable. |
Compared with AD7781BRUZ-REEL, AD7190BRUZ trades ultra-low power and integrated bridge switching for higher resolution and flexibility, while ADS1232IPW sacrifices guaranteed 50/60 Hz rejection and dual-supply independence to reduce system cost-making AD7781BRUZ-REEL optimal for battery-powered industrial sensors demanding precision, noise immunity, and minimal external components.
Availability
AD7781BRUZ-REEL is available at Aetrix Electronics and suitable for weigh scales, pressure transmitters, industrial process controllers, and portable instrumentation requiring stable component supply, long-term lifecycle support, and guaranteed traceable sourcing.
Supply support for AD7781BRUZ-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, communications, automotive, and healthcare markets since 1965.
The AD7781BRUZ-REEL belongs to Analog Devices' precision sigma-delta ADC product line, engineered specifically for low-power, high-accuracy bridge sensor signal conditioning in harsh industrial environments.
FAQ
What is the maximum allowable analog input voltage range for AD7781BRUZ-REEL?
The AD7781BRUZ-REEL supports a differential input voltage range of ±VREF/gain. With VREF = AVDD and gain = 1, this yields ±5 V (for AVDD = 5 V); with gain = 128, it yields ±39 mV. Absolute input 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 performance.
How does the AD7781BRUZ-REEL achieve simultaneous 50 Hz and 60 Hz rejection?
The AD7781BRUZ-REEL achieves simultaneous 50 Hz and 60 Hz rejection through its digital filter architecture, which provides >63 dB normal-mode rejection at both 10 Hz and 16.7 Hz update rates. This is inherent to the sigma-delta modulator's notch placement and does not require external filtering or software calibration-ensuring consistent rejection regardless of mains frequency variation across global deployments.
Can AD7781BRUZ-REEL operate with separate analog and digital supply voltages?
Yes, AD7781BRUZ-REEL supports independent AVDD (2.7–5.25 V) and DVDD (2.7–5.25 V) supplies. This allows AVDD to be set at 5 V for optimal analog performance while DVDD runs at 3 V to interface with low-voltage microcontrollers-eliminating level-shifting circuitry and reducing system complexity without compromising ADC accuracy or timing integrity.
What is the function of the BPDSW pin on AD7781BRUZ-REEL?
The BPDSW terminal on AD7781BRUZ-REEL is an internal NMOS bridge power-down switch connected to GND, controlled by the PDRST pin. When PDRST is high, BPDSW closes to enable excitation current to the load cell; when PDRST is low, BPDSW opens, cutting off current flow. With RON ≤ 9 Ω and 30 mA continuous rating, it minimizes power loss while enabling rapid bridge disconnection in battery-powered AD7781BRUZ-REEL systems.
Does AD7781BRUZ-REEL require an external clock source?
No, AD7781BRUZ-REEL includes an internal 64 kHz ±3% oscillator, eliminating the need for external crystals, resonators, or clock generators. This reduces bill-of-materials cost, PCB area, and potential timing failure modes-making AD7781BRUZ-REEL ideal for compact, high-reliability industrial sensor nodes where component count and layout simplicity are critical design priorities.
AD7781BRUZ-REEL 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:
- 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:
- 16-TSSOP
- Mounting Type:
- Surface Mount
- Grade:
- -
- Qualification:
- -
AD7781BRUZ-REEL FAQ
1.How can I place an order for AD7781BRUZ-REEL through Aetrix?
Please submit a Request for Quotation (RFQ) for AD7781BRUZ-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 AD7781BRUZ-REEL reliable?
The price and inventory of AD7781BRUZ-REEL are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for AD7781BRUZ-REEL is usually 5 days.
3.What payment methods are accepted for AD7781BRUZ-REEL?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for AD7781BRUZ-REEL transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for AD7781BRUZ-REEL?
AD7781BRUZ-REEL orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your AD7781BRUZ-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 AD7781BRUZ-REEL?
For technical support, including AD7781BRUZ-REEL datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your AD7781BRUZ-REEL requirements.
6.How does Aetrix verify that AD7781BRUZ-REEL is sourced from the original manufacturer or authorized distributors?
All AD7781BRUZ-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 AD7781BRUZ-REEL meets industry standards.
7.What is the process for return or replacement of AD7781BRUZ-REEL?
All AD7781BRUZ-REEL units undergo pre-shipment inspection (PSI). If there is an issue with AD7781BRUZ-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 AD7781BRUZ-REEL part is unused and in its original packaging.
Return procedure for AD7781BRUZ-REEL:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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