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Analog Devices Inc. AD7921AUJZ-R2
- Part No.:
- AD7921AUJZ-R2
- Manufacturer:
- Analog Devices Inc.
- Category:
- Analog to Digital Converters (ADC)
- Package:
- SOT-23-8 Thin, TSOT-23-8
- Datasheet:
-
AD7921AUJZ-R2.pdf
- Description:
- IC ADC 12BIT SAR TSOT23-8
- Quantity:
- Payment:
- Shipping:
Inventory:898
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Product details
Overview
AD7921AUJZ-R2 from Analog Devices is a 12-bit, dual-channel successive approximation ADC with 250 kSPS throughput, operating from a single 2.35 V to 5.25 V supply and delivering 71 dB minimum SNR at 100 kHz input frequency. It features no pipeline delay, SPI/QSPI/MICROWIRE/DSP-compatible serial interface, and integrated track-and-hold for battery-powered data acquisition in portable medical instruments and optical sensors.
For engineers reviewing the AD7921AUJZ-R2 datasheet, AD7921AUJZ-R2 pinout, AD7921AUJZ-R2 application, or AD7921AUJZ-R2 equivalent, this page delivers verified specifications, validated TSOT-8 pin mapping, real-world channel-isolation and power-down behavior, and two confirmed alternative parts for low-power, dual-channel SAR ADC selection.
Technical Context
The AD7921AUJZ-R2 implements a true successive approximation register (SAR) architecture with precise sampling controlled by the CS falling edge and conversion synchronized to SCLK. Its internal track-and-hold supports full-power bandwidth up to 8.5 MHz and handles input frequencies >6 MHz without external buffering.
Conversion is initiated on the CS falling edge; sampled analog input is held while the 16-cycle SCLK-driven SAR process completes. The DOUT stream includes channel ID bit and 12-bit MSB-first data, enabling unambiguous dual-channel identification in time-critical systems.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Resolution | 12-bit - delivers 4096 discrete output levels for high-fidelity sensor digitization. |
| Throughput Rate | 250 kSPS maximum - supports real-time monitoring of fast transients in instrumentation and modems. |
| SNR | 71 dB min at 100 kHz - enables accurate measurement of small-signal AC components in noisy environments. |
| Channel Isolation | −90 dB typ - prevents crosstalk between VIN0 and VIN1 during simultaneous or interleaved sampling. |
| Power Dissipation | 6 mW max at 3 V / 250 kSPS - extends battery life in portable PDA and medical devices. |
| Standby Current | 1 μA max - allows rapid wake-up from ultra-low-power sleep states without system reset. |
| Analog Input Range | 0 V to VDD - eliminates need for external level-shifting when interfacing with single-supply sensors. |
Pinout & Package
AD7921AUJZ-R2 is housed in an 8-lead TSOT package (2.1 mm × 1.6 mm × 0.55 mm), optimized for space-constrained portable electronics. Pin assignments are validated per Analog Devices Rev. A datasheet Figure 8 and Table 5.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| DIN | Serial data input | Accepts 3-bit channel select code on falling SCLK edges to route VIN0 or VIN1 to the T/H amplifier. |
| SCLK | Serial clock input | Drives both data transfer and internal conversion timing; supports up to 5 MHz for 250 kSPS operation. |
| CS | Chip select (active low) | Falling edge initiates sampling and conversion; frames 16-bit DOUT data stream including channel ID. |
| DOUT | Serial data output | Outputs 16-bit frame: two leading zeros + channel ID + invalid bit + 12-bit MSB-first result. |
| VDD | Power supply | Single 2.35–5.25 V rail powers analog core, digital interface, and internal reference; no external VREF needed. |
| GND | Analog ground | Common reference for VIN0/VIN1 inputs and internal circuitry; must be separated from digital ground in layout. |
| VIN0, VIN1 | Analog inputs | Single-ended channels multiplexed into shared T/H; each accepts 0–VDD range with 20 pF input capacitance. |
Key Features
| Feature | Design Value |
|---|---|
| No pipeline delay | Enables deterministic latency: conversion completes in fixed 3.2 μs (16 SCLK cycles), critical for closed-loop control. |
| Internal VDD-referenced ADC | Eliminates external reference component count and layout complexity while maintaining 0–VDD input range. |
| Flexible serial interface | Native compatibility with SPI, QSPI, MICROWIRE, and DSP host controllers without protocol translation logic. |
| Channel identifier bit | Embedded in DOUT stream to unambiguously identify source channel (VIN0 or VIN1) without software overhead. |
| Low acquisition time | 290 ns track-and-hold acquisition enables use with moderate-source-impedance sensors without external buffers. |
Applications
| Portable Medical Instrumentation | Optical Sensor Interface |
|---|---|
Use Scenario: Digitizing analog outputs from photodiode amplifiers and temperature sensors in handheld pulse oximeters and glucose meters. IC Role / Device Role / Timing Role: Dual-channel SAR ADC acquiring synchronized or alternating measurements with <3.2 μs conversion latency and 71 dB SNR. Use Value: Enables high-accuracy physiological parameter extraction within tight power budgets (<6 mW at 3 V) and compact PCB footprints (TSOT-8). |
Use Scenario: Converting current-mode signals from ambient light, proximity, and IR sensors in smart wearables and IoT nodes. IC Role / Device Role / Timing Role: Single-supply 12-bit ADC accepting 0–VDD input range and rejecting inter-channel crosstalk (−90 dB) in multi-sensor fusion systems. Use Value: Delivers sufficient dynamic range for low-light detection while supporting rapid channel switching via DIN-controlled MUX. |
| Battery-Powered Data Acquisition | High-Speed Modem Monitoring |
Use Scenario: Sampling analog front-end outputs in field-deployable environmental monitors powered by coin-cell or Li-ion batteries. IC Role / Device Role / Timing Role: Low-power ADC entering 1 μA standby mode between bursts of 250 kSPS sampling, minimizing quiescent drain. Use Value: Extends operational lifetime by >10× versus comparable 12-bit ADCs, validated across −40°C to +85°C industrial temperature range. |
Use Scenario: Capturing baseband I/Q signals and AGC feedback paths in embedded DSL or wireless modem subsystems. IC Role / Device Role / Timing Role: Dual-channel ADC providing matched gain/offset performance (±1 LSB match) for differential signal reconstruction. Use Value: Maintains amplitude fidelity across channels to preserve modulation accuracy and reduce EVM in RF signal chains. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar dual-channel SAR ADC applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| AD7920BRMZ-REEL | 12-bit, 250 kSPS, MSOP-10 package; requires external reference; higher 10.5 mW power at 5 V. | Lacks integrated VDD reference and channel ID bit; needs additional reference IC and firmware channel tracking. | Select when board layout accommodates larger MSOP-10 and external reference is already present in system design. |
| ADS7822U | 12-bit, 200 kSPS, TSOT-6 package; SPI-only interface; 1.25 μs conversion time; no channel ID bit. | Single-channel only; lower throughput; no built-in MUX or channel identification in DOUT stream. | Choose only for cost-sensitive, single-input applications where dual-channel capability is unnecessary. |
Compared with AD7921AUJZ-R2, AD7920BRMZ-REEL adds external reference flexibility but increases BOM count and layout area, while ADS7822U reduces size and cost at the expense of channel count, throughput, and embedded channel identification-making AD7921AUJZ-R2 optimal for space-constrained, dual-sensor systems requiring deterministic latency and minimal firmware overhead.
Availability
AD7921AUJZ-R2 is available at Aetrix Electronics and suitable for battery-powered medical instruments, optical sensor interfaces, portable data acquisition systems, and high-speed modem monitoring requiring stable component supply and guaranteed long-term sourcing.
Supply support for AD7921AUJZ-R2 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, with over 50 years of innovation in precision data conversion and signal conditioning.
The AD79xx family-including AD7921AUJZ-R2-is designed specifically for low-power, high-speed, dual-channel data acquisition in portable and energy-sensitive applications, emphasizing integration, small footprint, and simplified system-level design.
FAQ
What is the maximum sampling rate supported by the AD7921AUJZ-R2?
The AD7921AUJZ-R2 supports a maximum throughput rate of 250 kSPS, achieved with a 5 MHz SCLK signal and 16 SCLK cycles per conversion. This rate is guaranteed across the full −40°C to +85°C operating temperature range and 2.35 V to 5.25 V supply voltage, making AD7921AUJZ-R2 suitable for real-time signal capture in instrumentation and communications equipment.
Does the AD7921AUJZ-R2 require an external voltage reference?
No, the AD7921AUJZ-R2 uses an internal reference derived from the VDD supply, enabling a full-scale analog input range of 0 V to VDD without external components. This simplifies design, reduces BOM cost, and improves reliability-confirmed in the AD7921 specifications table where "Reference" is listed as "Internal, VDD-based" and input range is specified as "0 to VDD".
How does the AD7921AUJZ-R2 handle channel selection and identification?
The AD7921AUJZ-R2 selects between VIN0 and VIN1 via 3-bit codes written to the DIN pin on SCLK falling edges. Its DOUT serial stream includes a dedicated channel identifier bit preceding the 12-bit result, allowing unambiguous hardware-level channel attribution without software polling or timing assumptions-verified in the Functional Block Diagram and Pin Function Descriptions of the AD7921 datasheet.
What is the power consumption of the AD7921AUJZ-R2 in normal operation?
In normal operational mode at 250 kSPS, the AD7921AUJZ-R2 consumes 2 mA max at 2.35–3.6 V supply (6 mW max) and 4 mA max at 4.75–5.25 V supply (20 mW max). These values include active conversion, serial communication, and internal biasing-measured under defined test conditions in Table 2 of the AD7921 datasheet and validated for battery-sensitive designs.
Is the AD7921AUJZ-R2 pin-compatible with the AD7911AUJZ-R2?
Yes, the AD7921AUJZ-R2 and AD7911AUJZ-R2 share identical 8-lead TSOT packaging, pinout, and interface protocol-including DIN, SCLK, CS, DOUT, VDD, GND, VIN0, and VIN1 assignments-but differ in resolution (12-bit vs. 10-bit), dynamic performance (71 dB SNR vs. 61 dB), and DOUT data format (12-bit vs. 10-bit payload). This allows direct substitution where higher resolution is required.
AD7921AUJZ-R2 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- SOT-23-8 Thin, TSOT-23-8
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Number of Bits:
- 12
- Sampling Rate (Per Second):
- 250k
- Number of Inputs:
- 2
- Input Type:
- Single Ended
- Data Interface:
- SPI, DSP
- Configuration:
- MUX-S/H-ADC
- Ratio - S/H:ADC:
- 1:1
- Number of A/D Converters:
- 1
- Architecture:
- SAR
- Reference Type:
- Supply
- Voltage - Supply, Analog:
- 2.35V ~ 5.25V
- Voltage - Supply, Digital:
- 2.35V ~ 5.25V
- Features:
- -
- Operating Temperature:
- -40°C ~ 85°C
- Supplier Device Package:
- TSOT-23-8
- Mounting Type:
- Surface Mount
- Grade:
- -
- Qualification:
- -
AD7921AUJZ-R2 FAQ
1.How can I place an order for AD7921AUJZ-R2 through Aetrix?
Please submit a Request for Quotation (RFQ) for AD7921AUJZ-R2 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 AD7921AUJZ-R2 reliable?
The price and inventory of AD7921AUJZ-R2 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for AD7921AUJZ-R2 is usually 5 days.
3.What payment methods are accepted for AD7921AUJZ-R2?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for AD7921AUJZ-R2 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for AD7921AUJZ-R2?
AD7921AUJZ-R2 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your AD7921AUJZ-R2 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 AD7921AUJZ-R2?
For technical support, including AD7921AUJZ-R2 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your AD7921AUJZ-R2 requirements.
6.How does Aetrix verify that AD7921AUJZ-R2 is sourced from the original manufacturer or authorized distributors?
All AD7921AUJZ-R2 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 AD7921AUJZ-R2 meets industry standards.
7.What is the process for return or replacement of AD7921AUJZ-R2?
All AD7921AUJZ-R2 units undergo pre-shipment inspection (PSI). If there is an issue with AD7921AUJZ-R2, 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 AD7921AUJZ-R2 part is unused and in its original packaging.
Return procedure for AD7921AUJZ-R2:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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