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Analog Devices Inc. AD7858LARZ
- Part No.:
- AD7858LARZ
- Manufacturer:
- Analog Devices Inc.
- Category:
- Analog to Digital Converters (ADC)
- Package:
- 24-SOIC (0.295", 7.50mm Width)
- Datasheet:
-
AD7858LARZ.pdf
- Description:
- IC ADC 12BIT SAR 24SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:3,888
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Product details
Overview
AD7858LARZ from Analog Devices is a 12-bit, 100 kSPS successive approximation register (SAR) analog-to-digital converter optimized for low-power operation. It features eight single-ended or four pseudo-differential analog inputs, on-chip 2.5 V reference, system/self-calibration, and SPI/QSPI/µP-compatible serial interface. Designed for battery-powered instrumentation and portable medical devices operating from 3 V to 5.5 V.
For engineers reviewing the AD7858LARZ datasheet, AD7858LARZ pinout, AD7858LARZ application, or AD7858LARZ equivalent, key selection considerations include its 100 kSPS throughput, 4.5 mW typical power at 3 V, ±1 LSB integral nonlinearity, 24-lead SOIC package, and support for automatic power-down after conversion.
Technical Context
The AD7858LARZ implements a charge redistribution DAC architecture with integrated track-and-hold, calibrated internal reference, and flexible serial interface supporting Mode 2 (SPI-compatible) timing. Its conversion cycle begins on CONVST rising edge, completes in ≤10 µs (at 1.8 MHz CLKIN), and asserts BUSY high until data is ready.
Calibration is performed via dedicated CAL pin or software command, enabling system offset/gain correction with defined voltage spans (±0.05 × VREF offset, ±0.025 × VREF gain). Input range is 0 V to VREF (up to AVDD), with leakage current ≤±1 µA and input capacitance 20 pF across all eight channels.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Resolution | 12-bit SAR ADC with straight binary output coding |
| Throughput Rate | 100 kSPS maximum - defines real-time sampling capability for continuous sensor monitoring |
| Power Dissipation | 4.5 mW typical at 3 V - enables >100-hour operation in coin-cell–powered systems |
| Integral Nonlinearity | ±1 LSB max - ensures monotonicity and <0.025% full-scale error without external trimming |
| Analog Input Range | 0 V to VREF (1.2 V to AVDD) - supports direct interfacing with unbuffered sensors and rail-to-rail op-amps |
| Reference Source | Internal 2.5 V ±20 ppm/°C REFOUT with external CREF1/CREF2 decoupling - eliminates need for external reference IC |
| Serial Interface | SPI/QSPI/8051-compatible Mode 2 - interoperates with common microcontrollers without level-shifting |
Pinout & Package
AD7858LARZ is housed in a 24-lead SOIC (R-24) package with 0.3-inch body width and standard JEDEC MS-013 footprint. Pin 1 is marked by a beveled corner; pin numbering proceeds counterclockwise.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| CONVST (Pin 1) | Convert Start trigger | Rising-edge–initiated conversion start; can be omitted if software-controlled via control register |
| BUSY (Pin 2) | Conversion status indicator | Active-high open-drain output signaling conversion completion or calibration progress |
| SLEEP (Pin 3) | Low-power mode enable | Logic 0 powers down all circuitry including internal reference while retaining calibration data |
| REFIN/REFOUT (Pin 4) | Reference I/O node | Provides 2.5 V reference output; accepts external reference up to AVDD; requires CREF1 (0.1 µF) and CREF2 (0.01 µF) to AGND |
| AIN1–AIN8 (Pins 9–16) | Configurable analog inputs | Support eight single-ended (vs. AGND) or four pseudo-differential pairs; channel selection via control register |
| CAL (Pin 17) | Calibration initiation | Rising-edge–triggered self/system calibration; optional 10 nF capacitor to DGND enables auto-cal on power-up |
| DOUT/DIN/SCLK/SYNC (Pins 20–24) | Serial interface signals | Full-duplex SPI-compatible port with frame sync; supports read-after/write-during conversion for 100 kSPS sustained rate |
Key Features
| Feature | Design Value |
|---|---|
| Autocalibration on power-up | Eliminates manual calibration step during system boot; retains accuracy over temperature via on-chip memory |
| Flexible power management | Three modes: normal (4.5 mW), partial power-down (400 µA), full power-down (5 µA) - selectable via PMGT bits |
| Pseudo-differential input architecture | Enables noise rejection in noisy environments without external instrumentation amplifiers |
| Wide supply range | Operates from 3.0 V to 5.5 V AVDD/DVDD - compatible with Li-ion, USB, and industrial 3.3 V/5 V rails |
| Channel-to-channel isolation | –90 dB typical - prevents crosstalk between multiplexed sensor inputs in multi-channel systems |
Applications
| Portable Medical Monitoring | Battery-Powered Data Loggers |
|---|---|
Use Scenario: Continuous acquisition of ECG, temperature, and SpO₂ signals in handheld patient monitors. IC Role / Device Role / Timing Role: Primary 12-bit ADC digitizing multiple analog sensor outputs with synchronized sampling and low-latency serial output. Use Value: 100 kSPS throughput captures transient cardiac events; 4.5 mW power extends battery life beyond 72 hours on two AA cells. | Use Scenario: Environmental sensing in remote field deployments using solar-charged batteries. IC Role / Device Role / Timing Role: Low-power SAR ADC managing periodic wake-up, multi-channel sampling, and SPI-based data transfer to MCU. Use Value: Automatic power-down between conversions reduces average current to <10 µA; on-chip calibration maintains accuracy across –40°C to +85°C. |
| Industrial Sensor Hubs | Pen-Based Human-Machine Interfaces |
Use Scenario: Signal conditioning and digitization of pressure, humidity, and vibration sensors in factory automation nodes. IC Role / Device Role / Timing Role: High-isolation ADC front-end multiplexing eight transducer outputs into a single serial stream. Use Value: –90 dB channel-to-channel isolation prevents cross-talk in dense sensor arrays; 24-lead SOIC simplifies PCB layout and thermal management. | Use Scenario: Digitizing analog stylus position and pressure in pen computers and digital notepads. IC Role / Device Role / Timing Role: Fast-acquisition ADC capturing pen movement at >100 Hz with minimal latency for real-time rendering. Use Value: 500 ns track/hold acquisition time ensures accurate position capture during rapid strokes; SPI interface enables direct connection to ARM Cortex-M host. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar 12-bit SAR ADC applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| ADS7822U | 8-bit, 200 kSPS, 3-V-only, no internal reference, 8-pin SOIC | Limited resolution and missing calibration; suited only for low-accuracy control loops | Select AD7858LARZ when 12-bit precision, on-chip reference, and system calibration are required. |
| MAX11131ETE+ | 12-bit, 500 kSPS, 2.7–3.6 V supply, internal reference, 16-pin TQFN | Higher speed and smaller package but lacks pseudo-differential mode and operates only below 3.6 V | Choose AD7858LARZ for wider supply range (3–5.5 V), pseudo-differential inputs, and proven reliability in industrial temperature range. |
Compared with ADS7822U and MAX11131ETE+, the AD7858LARZ uniquely combines 12-bit accuracy, 100 kSPS throughput, 3–5.5 V operation, on-chip 2.5 V reference, and pseudo-differential input flexibility in a standard 24-lead SOIC - making it optimal for cost-sensitive, battery-powered instrumentation requiring long-term stability.
Availability
AD7858LARZ is available at Aetrix Electronics and suitable for portable medical devices, battery-powered data loggers, industrial sensor hubs, and pen-based human-machine interfaces requiring stable component supply across extended temperature ranges and multi-year production cycles.
Supply support for AD7858LARZ 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, Inc. is a global leader in high-performance analog, mixed-signal, and digital signal processing semiconductors, headquartered in Norwood, MA.
The AD7858LARZ belongs to the AD7858 family of low-power, high-accuracy SAR ADCs designed specifically for portable and battery-constrained measurement systems where precision, calibration integrity, and supply flexibility are critical.
FAQ
What is the maximum sampling rate supported by the AD7858LARZ?
The AD7858LARZ supports a maximum throughput rate of 100 kSPS, achieved with a 1.8 MHz master clock (CLKIN) at 0°C to +70°C or 1 MHz CLKIN at –40°C to +85°C. This rate is guaranteed across the full operating temperature range and supply voltage (3.0 V to 5.5 V), enabling reliable real-time acquisition in portable instrumentation. The AD7858LARZ achieves this performance while maintaining ±1 LSB integral nonlinearity and 71 dB SNR.
Does the AD7858LARZ require an external reference voltage?
No, the AD7858LARZ does not require an external reference voltage. It integrates a 2.5 V reference with ±20 ppm/°C drift, accessible via the REFIN/REFOUT pin. External decoupling capacitors (0.1 µF CREF1 and 0.01 µF CREF2 to AGND) are mandatory for stability. The part also accepts external references from 1.2 V to AVDD, but the internal reference is fully functional and calibrated out-of-box for the AD7858LARZ.
How does the AD7858LARZ handle power management in battery-operated systems?
The AD7858LARZ provides three distinct power states: normal mode (4.5 mW at 3 V), partial power-down (400 µA), and full power-down (5 µA with external clock off). Power state is controlled via PMGT1/PMGT0 bits in the control register or the SLEEP pin. Full power-down retains calibration data and allows wake-up in <1 µs, making it ideal for duty-cycled sensor nodes where the AD7858LARZ spends >99% of time in sleep.
Can the AD7858LARZ interface directly with an 8051 microcontroller?
Yes, the AD7858LARZ supports 8051-compatible serial interface timing (Mode 2), requiring only SYNC, SCLK, DIN, and DOUT connections. Its 3–5.5 V supply range matches standard 8051 I/O levels, eliminating level shifters. The AD7858LARZ's software-controlled conversion start and register-based channel selection allow seamless integration with 8051 firmware without hardware modifications.
What is the purpose of the CAL pin on the AD7858LARZ?
The CAL pin on the AD7858LARZ initiates on-chip calibration sequences: a rising edge triggers full self-calibration (typ. 31.25 ms), system offset calibration (3.47 ms), or system full-scale calibration (27.78 ms). Connecting a 10 nF capacitor from CAL to DGND enables automatic self-calibration on power-up. During calibration, BUSY remains high, and all other operations are suspended - ensuring the AD7858LARZ delivers traceable accuracy without host intervention.
AD7858LARZ Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 24-SOIC (0.295", 7.50mm Width)
- Packaging:
- Tube
- Product Status:
- Active
- Number of Bits:
- 12
- Sampling Rate (Per Second):
- 100k
- Number of Inputs:
- 4, 8
- Input Type:
- Pseudo-Differential, Single Ended
- Data Interface:
- SPI
- Configuration:
- MUX-S/H-ADC
- Ratio - S/H:ADC:
- 1:1
- Number of A/D Converters:
- 1
- Architecture:
- SAR
- Reference Type:
- External, Internal
- Voltage - Supply, Analog:
- 3V ~ 5.5V
- Voltage - Supply, Digital:
- 3V ~ 5.5V
- Features:
- -
- Operating Temperature:
- -40°C ~ 85°C
- Supplier Device Package:
- 24-SOIC
- Mounting Type:
- Surface Mount
- Grade:
- -
- Qualification:
- -
AD7858LARZ FAQ
1.How can I place an order for AD7858LARZ through Aetrix?
Please submit a Request for Quotation (RFQ) for AD7858LARZ 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 AD7858LARZ reliable?
The price and inventory of AD7858LARZ are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for AD7858LARZ is usually 5 days.
3.What payment methods are accepted for AD7858LARZ?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for AD7858LARZ transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for AD7858LARZ?
AD7858LARZ orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your AD7858LARZ 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 AD7858LARZ?
For technical support, including AD7858LARZ datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your AD7858LARZ requirements.
6.How does Aetrix verify that AD7858LARZ is sourced from the original manufacturer or authorized distributors?
All AD7858LARZ 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 AD7858LARZ meets industry standards.
7.What is the process for return or replacement of AD7858LARZ?
All AD7858LARZ units undergo pre-shipment inspection (PSI). If there is an issue with AD7858LARZ, 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 AD7858LARZ part is unused and in its original packaging.
Return procedure for AD7858LARZ:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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