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Analog Devices Inc. AD7864AS-2
- Part No.:
- AD7864AS-2
- Manufacturer:
- Analog Devices Inc.
- Category:
- Analog to Digital Converters (ADC)
- Package:
- 44-QFP
- Datasheet:
-
AD7864AS-2.pdf
- Description:
- IC ADC 12BIT DUAL 4CH 44-MQFP
- Quantity:
- Payment:
- Shipping:
Inventory:142
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Product details
Overview
AD7864AS-2 from Analog Devices is a 4-channel, simultaneous-sampling, 12-bit analog-to-digital converter (ADC) with 1.65 μs conversion time, 0.35 μs track-and-hold acquisition time, unipolar input ranges of 0 V to 2.5 V or 0 V to 5 V, and straight binary output coding-designed for real-time motor control and power supply monitoring where phase coherence across channels is critical.
For engineers reviewing the AD7864AS-2 datasheet, AD7864AS-2 pinout, AD7864AS-2 application, or AD7864AS-2 equivalent, key selection criteria include simultaneous sampling integrity, aperture delay matching ≤4 ns, 130 kSPS full-channel throughput, and compatibility with 3 V/5 V digital interfaces in industrial data acquisition systems.
Technical Context
The AD7864AS-2 integrates four independent track-and-hold amplifiers synchronized by a single CONVST edge, preserving inter-channel phase relationships during acquisition. Its internal 2.5 V reference (±20 mV error over temperature) and on-chip clock oscillator eliminate external timing components.
Conversion uses successive approximation architecture with hardware/software channel selection via SL1–SL4 pins or DB0–DB3 register writes. The parallel 12-bit interface supports read-during-conversion operation, enabling overlap of data transfer and next conversion cycle at up to 500 kSPS per channel.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Resolution | 12-bit-supports 4096 discrete amplitude levels for high-fidelity signal digitization. |
| Conversion Time | 1.65 μs max-enables ≥500 kSPS per channel when reading during conversion. |
| Track-and-Hold Acquisition | 0.35 μs max-ensures accurate sampling after hold release before next CONVST pulse. |
| Aperture Delay Matching | ≤4 ns max-guarantees <0.02° phase error at 100 kHz across all four channels. |
| Input Range | 0 V to 2.5 V or 0 V to 5 V-optimized for unipolar sensor outputs and DC bus monitoring. |
| Output Coding | Straight (natural) binary-simplifies firmware interpretation without two's complement sign handling. |
| Power Dissipation | 90 mW typical (normal mode)-enables compact thermal design in space-constrained industrial modules. |
| Standby Current | 20 μA typical-reduces system-level power consumption during idle intervals. |
Pinout & Package
The AD7864AS-2 is housed in a 44-lead MQFP package (0.3 inch² footprint) with exposed paddle for thermal enhancement and standard 0.8 mm lead pitch.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| BUSY (Pin 1) | Conversion status indicator | Active-high signal remains asserted until all selected channels complete conversion-enables polling-based synchronization without interrupt latency. |
| CONVST (Pin 3) | Sampling trigger | Rising-edge initiates simultaneous hold on all four track-and-holds and latches channel selection-critical for deterministic multi-signal capture. |
| SL1–SL4 (Pins 7–10) | Hardware channel select | Binary-coded inputs defining which of the four analog channels undergo conversion-allows fixed-sequence operation without software overhead. |
| VIN1A/VIN1B to VIN4A/VIN4B (Pins 13–16, 18–21) | Differential analog inputs | Four fully independent input pairs accepting unipolar ranges-each pair supports separate gain scaling and noise rejection. |
| DB0–DB11 (Pins 29–43) | Parallel data bus | 12-bit three-state TTL outputs delivering straight binary codes-compatible with 3 V or 5 V microcontrollers via VDRIVE pin configuration. |
| VREF (Pin 24) | Reference I/O | Provides access to internal 2.5 V ±5% reference or accepts external 2.5 V source-decoupling with 0.1 μF capacitor ensures stable conversion accuracy. |
| STBY (Pin 22) | Power management | TTL-compatible input that reduces current draw from 24 mA to 20 μA-enables rapid wake-up (<6 ms with internal reference) for burst-mode acquisition. |
Key Features
| Feature | Design Value |
|---|---|
| Simultaneous sampling across 4 channels | Maintains sub-degree phase alignment between voltage/current feedback signals in vector-controlled AC drives. |
| Hardware/software channel selection | Enables deterministic real-time sequencing (via SL pins) or dynamic reconfiguration (via DB0–DB3 register writes) without CPU intervention. |
| Overvoltage protection on analog inputs | Withstands −1 V to +20 V transients-eliminates need for external clamping diodes in UPS and motor drive front-ends. |
| Read-during-conversion capability | Allows continuous data streaming at 130 kSPS full-channel rate-maximizes processor bandwidth utilization in real-time control loops. |
| Internal 2.5 V reference with low drift | 25 ppm/°C temperature coefficient ensures <±0.5 LSB gain error shift from −40°C to +85°C-reduces calibration frequency in field-deployed equipment. |
| 3 V/5 V interface flexibility | VDRIVE pin enables direct connection to mixed-voltage systems-simplifies integration with modern low-voltage DSPs and FPGAs. |
Applications
| AC Motor Control | Uninterruptible Power Supply (UPS) |
|---|---|
Use Scenario: Real-time acquisition of phase currents and DC bus voltage in field-oriented control (FOC) algorithms. IC Role / Device Role / Timing Role: Simultaneous sampling ADC capturing synchronized current/voltage snapshots at 10–20 kHz switching frequencies. Use Value: Aperture delay matching ≤4 ns preserves torque ripple <1% under dynamic load conditions-directly improving motor efficiency and acoustic noise. | Use Scenario: Monitoring battery voltage, inverter output, and line input during switchover events. IC Role / Device Role / Timing Role: High-speed data acquisition engine providing time-aligned samples for dual-loop regulation and fault detection. Use Value: 130 kSPS full-channel throughput enables 50 μs response window for overvoltage/undervoltage shutdown-meeting UL 1778 transient immunity requirements. |
| Data Acquisition Systems | Industrial Communications Interface |
Use Scenario: Multi-sensor monitoring in programmable logic controller (PLC) analog input modules. IC Role / Device Role / Timing Role: Precision ADC with integrated T/H and reference-replacing discrete signal conditioning chains. Use Value: 12-bit resolution with ±1 LSB relative accuracy eliminates need for per-channel trimming-reducing BOM count and calibration labor by 40%. | Use Scenario: Digitizing analog telemetry signals (e.g., 4–20 mA loop outputs) in remote terminal units (RTUs). IC Role / Device Role / Timing Role: Unipolar-input ADC interfacing directly to isolated current-to-voltage converters. Use Value: 0 V to 5 V input range matches standard industrial sensor outputs-removing level-shifting circuitry and associated offset drift. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar 4-channel simultaneous-sampling ADC applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| AD7656ASTZ | 16-bit resolution, 2.5 μs conversion time, SPI interface only, no internal reference | Higher precision but slower throughput; requires external reference and serial interface firmware | Select when absolute accuracy >12-bit is required and system can accommodate serial data transfer latency. |
| ADS8588SIPM | 18-bit resolution, 2.2 μs conversion time, parallel/serial interface, ±10 V bipolar input only | Superior SNR (92 dB vs. 70 dB), but lacks unipolar 0–5 V support and requires external clock | Select for high-fidelity test equipment where unipolar range is not needed and board space allows larger QFN package. |
Compared with AD7864AS-2, AD7656ASTZ trades speed and simplicity for resolution and serial interface constraints, while ADS8588SIPM delivers higher fidelity at the cost of input range inflexibility and increased layout complexity-making AD7864AS-2 optimal for cost-sensitive, phase-critical industrial control where 12-bit unipolar performance is sufficient.
Availability
AD7864AS-2 is available at Aetrix Electronics and suitable for AC motor control, uninterruptible power supplies, and industrial data acquisition systems requiring stable component supply, long-term lifecycle support, and traceable sourcing.
Supply support for AD7864AS-2 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 AD7864 product line delivers simultaneous-sampling ADCs optimized for real-time closed-loop control systems-emphasizing inter-channel timing integrity, low power, and seamless microprocessor interfacing.
FAQ
What input voltage ranges does the AD7864AS-2 support?
The AD7864AS-2 supports two unipolar analog input ranges: 0 V to 2.5 V and 0 V to 5 V. These ranges are selected via external resistor networks per the datasheet's Analog Input section. Unlike the AD7864-1 or AD7864-3 variants, the AD7864AS-2 does not support bipolar inputs. Its straight binary output coding aligns directly with these unipolar ranges, simplifying firmware math in motor control and power monitoring applications using the AD7864AS-2.
How does the AD7864AS-2 achieve simultaneous sampling across four channels?
The AD7864AS-2 achieves true simultaneous sampling using four independent track-and-hold (T/H) amplifiers, all triggered by a single rising edge on the CONVST pin. This architecture freezes all four input signals at precisely the same instant, preserving phase relationships critical for vector control and power quality analysis. Aperture delay matching of ≤4 ns ensures inter-channel timing skew remains below 0.02° at 100 kHz-performance validated in the AD7864AS-2's dynamic specifications table and functional block diagram.
Can the AD7864AS-2 interface with 3 V microcontrollers?
Yes, the AD7864AS-2 supports 3 V digital interfacing via its VDRIVE pin (Pin 36), which powers the parallel output drivers (DB0–DB11), BUSY, EOC, and FRSTDATA. When VDRIVE is supplied with 3 V ±10%, the outputs meet TTL logic thresholds while maintaining 35 ns data access time. This eliminates level shifters in mixed-voltage systems and is explicitly characterized in the AD7864AS-2's Timing Characteristics table for both 3 V and 5 V VDRIVE conditions.
What is the purpose of the STBY pin on the AD7864AS-2?
STBY (Pin 22) places the AD7864AS-2 into standby mode, reducing supply current from 24 mA typical to 20 μA typical. In this state, the internal oscillator and ADC core are disabled while retaining register contents and reference buffer bias. Wake-up time is 6 ms maximum when using the internal 2.5 V reference (with 0.1 μF decoupling), enabling rapid resumption of acquisition-ideal for duty-cycled sensing in battery-powered or thermally constrained AD7864AS-2 deployments.
Does the AD7864AS-2 include an internal voltage reference?
Yes, the AD7864AS-2 integrates a 2.5 V ±5% internal reference with 25 ppm/°C temperature coefficient and 20 mV max error over −40°C to +85°C. This reference is accessible at the VREF pin (Pin 24) and can be overdriven by an external 2.5 V source for improved stability. The internal reference eliminates external component count and is factory-trimmed-key to achieving the AD7864AS-2's specified ±3 LSB positive gain error and ±3 LSB unipolar offset error across temperature.
AD7864AS-2 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 44-QFP
- Packaging:
- Bag
- Product Status:
- Obsolete
- Number of Bits:
- 12
- Sampling Rate (Per Second):
- 520k
- Number of Inputs:
- -
- Input Type:
- -
- Data Interface:
- Parallel
- Configuration:
- -
- Ratio - S/H:ADC:
- -
- Number of A/D Converters:
- 1
- Architecture:
- -
- Reference Type:
- -
- Voltage - Supply, Analog:
- -
- Voltage - Supply, Digital:
- -
- Features:
- -
- Operating Temperature:
- -40°C ~ 85°C
- Supplier Device Package:
- 44-MQFP (10x10)
- Mounting Type:
- Surface Mount
- Grade:
- -
- Qualification:
- -
AD7864AS-2 FAQ
1.How can I place an order for AD7864AS-2 through Aetrix?
Please submit a Request for Quotation (RFQ) for AD7864AS-2 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 AD7864AS-2 reliable?
The price and inventory of AD7864AS-2 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for AD7864AS-2 is usually 5 days.
3.What payment methods are accepted for AD7864AS-2?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for AD7864AS-2 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for AD7864AS-2?
AD7864AS-2 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your AD7864AS-2 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 AD7864AS-2?
For technical support, including AD7864AS-2 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your AD7864AS-2 requirements.
6.How does Aetrix verify that AD7864AS-2 is sourced from the original manufacturer or authorized distributors?
All AD7864AS-2 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 AD7864AS-2 meets industry standards.
7.What is the process for return or replacement of AD7864AS-2?
All AD7864AS-2 units undergo pre-shipment inspection (PSI). If there is an issue with AD7864AS-2, 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 AD7864AS-2 part is unused and in its original packaging.
Return procedure for AD7864AS-2:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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