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Analog Devices Inc. AD7781CRZ-REEL
- Part No.:
- AD7781CRZ-REEL
- Manufacturer:
- Analog Devices Inc.
- Category:
- Analog to Digital Converters (ADC)
- Package:
- 14-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
AD7781CRZ-REEL.pdf
- Description:
- IC ADC 20BIT SIGMA-DELTA 14SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:4,508
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Product details
Overview
AD7781CRZ-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 - deployed in high-precision weigh scales and pressure transducers.
For engineers reviewing the AD7781CRZ-REEL datasheet, AD7781CRZ-REEL pinout, AD7781CRZ-REEL application, or AD7781CRZ-REEL equivalent, key selection criteria include RMS noise (44 nV @ 10 Hz, gain=128, C grade), settling time (300 ms at 10 Hz), on-chip oscillator, independent DVDD/AVDD supplies, and SOIC-14 package compatibility with industrial temperature range (−40°C to +105°C).
Technical Context
The AD7781CRZ-REEL implements a fully differential 20-bit Σ-Δ modulator with on-chip programmable gain amplifier (PGA) and digital filter, supporting ratiometric bridge measurements via unbuffered REFIN(±) inputs. Its pin-controlled architecture eliminates register programming overhead.
Filter response is selected via FILTER pin (10 Hz high-rejection or 16.7 Hz fast-settling), while GAIN pin configures PGA gain (1 or 128), directly determining full-scale input range (±5 V or ±39 mV). The DOUT/RDY pin delivers 20-bit conversion data plus 8 status bits in offset binary format over a 2-wire SPI-compatible interface.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Resolution | 20-bit sigma-delta ADC with no missing codes guaranteed |
| Update Rate | 10 Hz (300 ms settling, >−45 dB stop-band attenuation) or 16.7 Hz (120 ms settling, superior dynamic performance) |
| RMS Noise | 44 nV typical (C grade, gain=128, 10 Hz); enables sub-μV signal resolution in load cell interfaces |
| Power Consumption | 330 μA typical (gain=128, AVDD=3 V); supports battery-operated instrumentation |
| Input Range | Differential ±VREF/gain: ±5 V (gain=1) or ±39 mV (gain=128) with VREF = AVDD nominal |
| Common-Mode Rejection | 110 dB at 50/60 Hz; critical for rejecting mains-induced interference in industrial sensors |
| Operating Temp | −40°C to +105°C; qualified for harsh industrial and weigh scale environments |
Pinout & Package
AD7781CRZ-REEL is housed in a 14-lead, narrow-body SOIC package (package code CRZ), RoHS-compliant and rated for surface-mount reflow.
| Pin | Circuit Role | Design Meaning |
|---|---|---|
| SCLK | Serial clock input | Schmitt-triggered; controls timing of 32-bit read cycles (20-bit data + 8 status bits) |
| DOUT/RDY | Dual-function output | Active-low data-ready flag and serial data output; tristated during power-down |
| GAIN | PGA configuration input | Low = gain 128 (±39 mV FS); high = gain 1 (±5 V FS); resets modulator on change |
| FILTER | Digital filter select | Low = 16.7 Hz update (120 ms settling); high = 10 Hz update (300 ms settling) |
| PDRST | Power-down/reset control | Low = full power-down (10 μA), opens BPDSW, resets logic; high = active conversion |
| BPDSW | Bridge power-down switch terminal | Connects to load cell low-side; closed when PDRST high (RON ≤ 9 Ω, 30 mA rating) |
| AIN(+), AIN(−) | Differential analog input | High-impedance inputs optimized for direct connection to strain gages and Wheatstone bridges |
| REFIN(+), REFIN(−) | Differential reference input | Unbuffered; accepts 0.5 V to AVDD; enables ratiometric operation with bridge excitation |
| AVDD, DVDD | Independent power rails | AVDD (2.7–5.25 V) powers analog core; DVDD (2.7–5.25 V) sets digital logic levels |
| GND | Analog ground reference | Single ground pin; requires star-point layout for optimal noise performance |
Key Features
| Feature | Design Value |
|---|---|
| Pin-programmable gain & filter | Eliminates firmware configuration; gain (1/128) and update rate (10/16.7 Hz) set by hardwired logic levels |
| Simultaneous 50 Hz/60 Hz rejection | 63–90 dB rejection at both update rates; removes mains interference without external notch filters |
| Integrated bridge power-down switch | 9 Ω RON switch controlled by PDRST; reduces system current by disconnecting load cell during idle |
| Internal clock oscillator | 64 kHz ±3% oscillator; removes need for external crystal or clock source in space-constrained designs |
| Offset binary output coding | Direct mapping: 0x00000 = −FS, 0x80000 = 0 V, 0xFFFFF = +FS; simplifies host MCU arithmetic |
Applications
| Weigh Scales | Pressure Measurement |
|---|---|
Use Scenario: High-accuracy platform scales measuring 0–300 kg with 1 g resolution under varying ambient EMI. IC Role / Device Role / Timing Role: Front-end ADC digitizing mV-level output from 350 Ω strain-gauge load cells; provides 20-bit resolution and 50/60 Hz rejection. Use Value: Enables 17.6-bit peak-to-peak resolution (C grade, 10 Hz) and eliminates need for external anti-aliasing or notch filters. |
Use Scenario: Industrial pressure transmitters operating in 4–20 mA loop-powered systems with wide temperature swings. IC Role / Device Role / Timing Role: Low-power ADC interfacing to piezoresistive pressure sensors; uses BPDSW to minimize quiescent current during sleep cycles. Use Value: 330 μA typical supply current (gain=128) extends battery life; −40°C to +105°C rating ensures reliability in field deployments. |
| Industrial Process Control | Portable Instrumentation |
Use Scenario: DIN-rail mounted flow meter controllers requiring EMC robustness and long-term calibration stability. IC Role / Device Role / Timing Role: Precision ADC capturing slow-varying bridge outputs; leverages internal oscillator and independent DVDD/AVDD for noise isolation. Use Value: 110 dB common-mode rejection at 50/60 Hz suppresses ground-loop interference in factory-floor wiring. |
Use Scenario: Handheld torque analyzers powered by single Li-ion cell with <100 μA standby current target. IC Role / Device Role / Timing Role: Core signal conditioner enabling ultra-low-power wake-on-event operation via PDRST-controlled power-down. Use Value: 10 μA power-down current and 1 ms oscillator startup enable rapid measurement bursts without energy waste. |
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 programmable output rate, SPI register interface, higher power (380 μA) | Requires microcontroller firmware for configuration; suited for multi-channel or variable-rate systems | Select AD7190BRUZ when higher resolution and flexible data rate control outweigh simplicity and ultra-low power needs. |
| ADS1232IPW | 20-bit, 10/80 Hz fixed rates, internal oscillator, 16-pin TSSOP only, no BPDSW, lower noise (27 nV @ 10 Hz) | Lacks bridge power-down switch and independent DVDD; limited to single-supply digital interface | Choose ADS1232IPW where lowest possible noise is critical and bridge power management is handled externally. |
Compared with AD7781CRZ-REEL, AD7190BRUZ offers greater configurability at the cost of firmware dependency and higher current draw, while ADS1232IPW delivers lower noise but omits the integrated BPDSW and dual-supply flexibility essential for portable battery systems.
Availability
AD7781CRZ-REEL is available at Aetrix Electronics and suitable for weigh scales, pressure transducers, and industrial process controllers requiring stable component supply across extended product lifecycles.
Supply support for AD7781CRZ-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, headquartered in Norwood, MA.
The AD7781CRZ-REEL belongs to Analog Devices' precision sigma-delta ADC family designed specifically for low-frequency, high-resolution bridge sensor measurement - emphasizing ultra-low power, pin-configurable operation, and integrated system-level features like BPDSW and simultaneous AC-line rejection.
FAQ
What is the maximum allowable analog input voltage range for AD7781CRZ-REEL?
The AD7781CRZ-REEL supports a differential input voltage range of ±VREF/gain. With VREF = AVDD (nominal 5 V) and gain = 1, the range is ±5 V; with gain = 128, it is ±39 mV. Absolute voltage limits are GND + 450 mV to AVDD − 1.1 V (gain = 128, FILTER = 0) - exceeding these degrades linearity and noise performance. The common-mode voltage must remain ≥0.5 V.
How does the AD7781CRZ-REEL achieve simultaneous 50 Hz and 60 Hz rejection?
The AD7781CRZ-REEL achieves simultaneous 50 Hz/60 Hz rejection through its digital filter architecture, which provides 63–90 dB attenuation at both frequencies across both update rates (10 Hz and 16.7 Hz). This is intrinsic to the filter response design - no external components or configuration are required. The rejection is specified under normal mode conditions with AIN = 7.81 mV and applies regardless of gain or filter setting.
Can AD7781CRZ-REEL operate with separate analog and digital supply voltages?
Yes, AD7781CRZ-REEL supports independent analog (AVDD) and digital (DVDD) supplies, each ranging from 2.7 V to 5.25 V. This allows AVDD to be set at 5 V for optimal analog performance while DVDD runs at 3 V to interface with low-voltage MCUs - reducing digital switching noise coupling into the analog section and improving overall SNR.
What is the function of the BPDSW pin on AD7781CRZ-REEL?
The BPDSW pin on AD7781CRZ-REEL is the output terminal of an integrated low-side bridge power-down switch (RON ≤ 9 Ω, 30 mA rating). It is controlled by the PDRST pin: when PDRST is high, BPDSW connects to GND, enabling excitation current to flow through the load cell; when PDRST is low, BPDSW opens, cutting off bridge current to reduce system power consumption - critical for battery-powered instrumentation.
Does AD7781CRZ-REEL require an external clock source?
No, AD7781CRZ-REEL includes an internal 64 kHz ±3% oscillator, eliminating the need for external crystals or clock generators. This simplifies PCB layout, reduces BOM count, and improves reliability in space-constrained or cost-sensitive applications such as portable weigh scales and handheld test equipment.
AD7781CRZ-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:
- -
AD7781CRZ-REEL FAQ
1.How can I place an order for AD7781CRZ-REEL through Aetrix?
Please submit a Request for Quotation (RFQ) for AD7781CRZ-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 AD7781CRZ-REEL reliable?
The price and inventory of AD7781CRZ-REEL are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for AD7781CRZ-REEL is usually 5 days.
3.What payment methods are accepted for AD7781CRZ-REEL?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for AD7781CRZ-REEL transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for AD7781CRZ-REEL?
AD7781CRZ-REEL orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your AD7781CRZ-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 AD7781CRZ-REEL?
For technical support, including AD7781CRZ-REEL datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your AD7781CRZ-REEL requirements.
6.How does Aetrix verify that AD7781CRZ-REEL is sourced from the original manufacturer or authorized distributors?
All AD7781CRZ-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 AD7781CRZ-REEL meets industry standards.
7.What is the process for return or replacement of AD7781CRZ-REEL?
All AD7781CRZ-REEL units undergo pre-shipment inspection (PSI). If there is an issue with AD7781CRZ-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 AD7781CRZ-REEL part is unused and in its original packaging.
Return procedure for AD7781CRZ-REEL:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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