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Analog Devices Inc. AD7894ARZ-2
- Part No.:
- AD7894ARZ-2
- Manufacturer:
- Analog Devices Inc.
- Category:
- Analog to Digital Converters (ADC)
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
AD7894ARZ-2.pdf
- Description:
- IC ADC 14BIT SAR 8SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:103
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Product details
Overview
AD7894ARZ-2 from Analog Devices is a 14-bit, single-supply successive-approximation ADC with 5 µs conversion time in Mode 1, ±2 LSB relative accuracy, 0 V to +2.5 V unipolar input range, and straight binary output coding - designed for precision data acquisition in industrial sensor interfaces and portable instrumentation.
For engineers reviewing the AD7894ARZ-2 datasheet, AD7894ARZ-2 pinout, AD7894ARZ-2 application, or AD7894ARZ-2 equivalent, this page delivers verified technical context, SO-8 package mapping, real-world use-value per application, and two confirmed alternative parts with documented functional and interface differences.
Technical Context
The AD7894ARZ-2 integrates an on-chip track/hold amplifier, laser-trimmed internal clock, and high-speed serial interface (SCLK/SDATA) in an 8-lead SOIC. It operates exclusively in unipolar mode with 0 V to +2.5 V analog input, requiring an external +2.5 V reference applied to REF IN.
It supports two operating modes: Mode 1 (5 µs conversion, continuous sampling) and Mode 2 (10 µs total cycle including 5 µs wake-up, auto power-down). Its 0.35 µs track/hold acquisition time and 7.5 MHz small-signal bandwidth enable accurate digitization of fast-rising sensor signals without external signal conditioning.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Resolution | 14 bits - guarantees no missing codes over full input range; enables 0.15 mV LSB step size with 2.5 V reference. |
| Conversion Time | 5 µs (Mode 1) - allows up to 160 kHz sustained sampling rate when paired with 16 MHz SCLK and proper timing margins. |
| Analog Input Range | 0 V to +2.5 V - unipolar configuration optimized for single-supply systems like battery-powered sensors and PLC analog inputs. |
| Relative Accuracy | ±2 LSB max - ensures monotonicity and ≤0.03% full-scale linearity error across –40°C to +85°C. |
| Power Dissipation | 20 mW typical - achieved via automatic power-down between conversions, critical for low-duty-cycle remote monitoring. |
| Output Coding | Straight (natural) binary - simplifies firmware parsing vs. two's complement; eliminates sign-extension logic in microcontroller drivers. |
| Reference Input | +2.5 V ±5% at REF IN - buffered input accepts low-current sources (≤1 µA); gain error directly tracks reference stability. |
Pinout & Package
AD7894ARZ-2 is housed in an 8-lead narrow-body SOIC (SO-8) package with standard JEDEC MS-012AC dimensions (4.9 mm × 3.9 mm × 1.75 mm), RoHS-compliant lead finish, and thermal resistance θJA = 170°C/W.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 - REF IN | Voltage reference input | Buffered, high-impedance node accepting +2.5 V ±5%; reference errors directly scale full-scale gain error. |
| 2 - VIN | Analog input channel | High-Z unipolar input (0 V to +2.5 V); input current ≤500 nA - eliminates need for external driver op-amp in most sensor applications. |
| 3 - GND | Analog ground reference | Common return for track/hold, DAC, comparator, and digital logic; must be star-connected to minimize noise coupling. |
| 4 - SCLK | Serial clock input | Asynchronous edge-triggered clock (max 16 MHz); falling edge clocks out 16-bit SDATA (2 leading zeros + 14-bit result). |
| 5 - SDATA | Serial data output | Three-state CMOS output; provides straight binary code; data valid ≥10 ns after SCLK falling edge. |
| 6 - BUSY | Conversion status indicator | Active-high open-drain output; goes high on CONVST falling edge, returns low 5 µs later - used for hardware handshaking. |
| 7 - CONVST | Conversion start trigger | Edge-sensitive input; falling edge initiates track-to-hold transition and conversion; low hold enables auto power-down. |
| 8 - VDD | Positive supply | +5 V ±5% supply; powers analog and digital sections; IDD ≤5.5 mA during conversion; drops to 20 µA in power-down. |
Key Features
| Feature | Design Value |
|---|---|
| On-chip track/hold amplifier | Acquires input to 14-bit accuracy in ≤0.35 µs - eliminates external sample-and-hold IC and associated layout complexity. |
| Auto power-down mode | Reduces IDD to 20 µA between conversions - extends battery life in intermittent-sampling applications like environmental loggers. |
| High-speed serial interface | Two-wire (SCLK/SDATA) with 16 MHz max clock - minimizes MCU GPIO usage and PCB routing vs. parallel bus alternatives. |
| Unipolar 0 V to +2.5 V input | Optimized for single-supply sensor front-ends (e.g., RTD, thermocouple amps, current-loop receivers) without level-shifting circuitry. |
| Low input bias current (≤500 nA) | Enables direct connection to high-impedance sources (e.g., piezoelectric sensors, pH electrodes) without signal degradation. |
Applications
| Industrial Sensor Interface | Portable Data Logger |
|---|---|
Use Scenario: Digitizing outputs from 4–20 mA loop-powered transmitters and bridge-based pressure sensors in factory automation cabinets. IC Role / Device Role / Timing Role: Primary ADC capturing analog sensor voltage after I/V conversion; synchronized to PLC scan cycle via CONVST edge triggering. Use Value: ±2 LSB linearity and 0.35 µs acquisition ensure <0.03% measurement error across temperature; SO-8 footprint saves board space in dense I/O modules. |
Use Scenario: Battery-operated environmental monitor logging temperature, humidity, and CO₂ over multi-day intervals with 100 ms sampling bursts. IC Role / Device Role / Timing Role: Low-power ADC activated by microcontroller wake-up interrupt; enters auto power-down after each 5 µs conversion. Use Value: 20 µA standby current and 20 mW active power extend AA battery life to >12 months; straight binary output reduces firmware overhead. |
| Medical Instrument Front-End | Test & Measurement Equipment |
Use Scenario: Signal conditioning stage in handheld ECG or pulse oximeter devices requiring DC-coupled, low-noise analog capture. IC Role / Device Role / Timing Role: High-Z unipolar ADC interfacing directly to instrumentation amplifier output; REF IN driven by AD780 precision reference. Use Value: 500 nA input current prevents loading of sensitive IA stages; 7.5 MHz track/hold bandwidth preserves signal integrity up to 100 kHz. |
Use Scenario: Embedded digitizer in benchtop multimeters and oscilloscope auxiliary channels needing fast, repeatable DC voltage measurements. IC Role / Device Role / Timing Role: Standalone ADC triggered by FPGA logic; BUSY signal used for precise timing alignment of serial read cycles. Use Value: 5 µs conversion + 1 µs serial read enables 160 kSPS throughput; ±2 LSB accuracy meets Class II DMM calibration requirements. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar 14-bit unipolar SAR ADC applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| ADS8325IPW | 16-bit resolution, SPI interface, 2.7–5.5 V supply; no integrated track/hold; requires external reference buffer. | Higher resolution but larger PCB footprint (TSSOP-20); lacks auto power-down - less suitable for battery operation. | Select when 16-bit precision outweighs power and space constraints; verify external REF buffer design for <1 µA leakage. |
| MAX11166ETK+ | 14-bit, 500 kSPS, SPI, internal reference; 2.7–3.6 V supply only; no unipolar-only variant - supports bipolar/unipolar via register config. | Requires level-shifting for 5 V MCU interfaces; internal reference limits flexibility vs. AD7894ARZ-2's external REF IN control. | Select for 3.3 V systems where internal reference simplifies BOM; avoid if system uses precision external reference like AD780. |
Compared with ADS8325IPW and MAX11166ETK+, the AD7894ARZ-2 uniquely combines 5 µs conversion, SO-8 packaging, unipolar-optimized architecture, and auto power-down - making it the only option that meets all three criteria: minimal board area, sub-20 mW active power, and guaranteed 0 V to +2.5 V input linearity without configuration overhead.
Availability
AD7894ARZ-2 is available at Aetrix Electronics and suitable for industrial sensor interfaces, portable data loggers, medical instrument front-ends, and test & measurement equipment requiring stable component supply across extended temperature ranges.
Supply support for AD7894ARZ-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, founded in 1965 and headquartered in Wilmington, MA.
The AD7894 product line was engineered for space-constrained, low-power precision data acquisition - delivering 14-bit accuracy in an SO-8 package with integrated track/hold and serial interface to replace multi-chip solutions in industrial and portable systems.
FAQ
What is the maximum sampling rate achievable with the AD7894ARZ-2?
The AD7894ARZ-2 achieves a maximum sustained sampling rate of 160 kHz in Mode 1 operation. This requires a 16 MHz SCLK, 5 µs conversion time, 1.0 µs serial read (16 clocks), and a mandatory 250 ns quiet period before the next CONVST falling edge - totaling 6.25 µs per sample. Exceeding this rate violates the track/hold acquisition timing and degrades linearity.
Does the AD7894ARZ-2 require an external reference voltage?
Yes, the AD7894ARZ-2 requires an external +2.5 V reference applied to the REF IN pin. The device features an on-chip buffer with ≤1 µA input current, enabling direct connection to precision references like the AD780 or AD680. Reference voltage accuracy and stability directly determine gain error and full-scale performance of the AD7894ARZ-2.
How does the auto power-down mode work in the AD7894ARZ-2?
In auto power-down mode (Mode 2), the AD7894ARZ-2 enters low-power state (IDD ≤20 µA) immediately after BUSY goes low post-conversion. It "wakes up" internally upon the rising edge of CONVST, with a typical 5 µs wake-up delay before the falling edge initiates conversion. This mode cuts average power in low-duty-cycle applications - e.g., a 1 Hz sampling rate reduces average current from 5.5 mA to ~30 µA.
What is the purpose of the two leading zero bits in the AD7894ARZ-2 serial output?
The AD7894ARZ-2 outputs 16 bits per conversion: two leading zeros followed by the 14-bit straight binary result. These zeros provide fixed-width framing for reliable synchronization with microcontroller SPI peripherals or FPGA shift registers - ensuring consistent bit alignment regardless of data value, simplifying firmware parsing and eliminating bit-shift logic.
Can the AD7894ARZ-2 interface directly with a 3.3 V microcontroller?
Yes, but with level-shifting for digital signals. The AD7894ARZ-2 operates from a 5 V supply (VDD = +5 V ±5%), so its SCLK and SDATA logic levels are 0 V / 4.0 V (VOH min) and 0.4 V (VOL max). To interface with a 3.3 V MCU, use bidirectional level translators on SCLK and SDATA lines; CONVST and BUSY also require translation since they are 5 V-tolerant inputs/outputs.
AD7894ARZ-2 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 8-SOIC (0.154", 3.90mm Width)
- Packaging:
- Tube
- Product Status:
- Active
- Number of Bits:
- 14
- Sampling Rate (Per Second):
- 200k
- Number of Inputs:
- 1
- Input Type:
- Single Ended
- Data Interface:
- SPI
- Configuration:
- S/H-ADC
- Ratio - S/H:ADC:
- 1:1
- Number of A/D Converters:
- 1
- Architecture:
- SAR
- Reference Type:
- External
- Voltage - Supply, Analog:
- 5V
- Voltage - Supply, Digital:
- 5V
- Features:
- -
- Operating Temperature:
- -40°C ~ 85°C
- Supplier Device Package:
- 8-SOIC
- Mounting Type:
- Surface Mount
- Grade:
- -
- Qualification:
- -
AD7894ARZ-2 FAQ
1.How can I place an order for AD7894ARZ-2 through Aetrix?
Please submit a Request for Quotation (RFQ) for AD7894ARZ-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 AD7894ARZ-2 reliable?
The price and inventory of AD7894ARZ-2 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for AD7894ARZ-2 is usually 5 days.
3.What payment methods are accepted for AD7894ARZ-2?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for AD7894ARZ-2 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for AD7894ARZ-2?
AD7894ARZ-2 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your AD7894ARZ-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 AD7894ARZ-2?
For technical support, including AD7894ARZ-2 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your AD7894ARZ-2 requirements.
6.How does Aetrix verify that AD7894ARZ-2 is sourced from the original manufacturer or authorized distributors?
All AD7894ARZ-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 AD7894ARZ-2 meets industry standards.
7.What is the process for return or replacement of AD7894ARZ-2?
All AD7894ARZ-2 units undergo pre-shipment inspection (PSI). If there is an issue with AD7894ARZ-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 AD7894ARZ-2 part is unused and in its original packaging.
Return procedure for AD7894ARZ-2:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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