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Analog Devices Inc. AD7894ARZ-3
- Part No.:
- AD7894ARZ-3
- Manufacturer:
- Analog Devices Inc.
- Category:
- Analog to Digital Converters (ADC)
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
AD7894ARZ-3.pdf
- Description:
- IC ADC 14BIT SAR 8SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:299
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Product details
Overview
AD7894ARZ-3 from Analog Devices is a 14-bit successive-approximation ADC with ±2.5 V bipolar input range, 5 µs conversion time in high-speed mode, single +5 V supply operation, and integrated track/hold amplifier - used in precision data acquisition systems for industrial process monitoring.
For engineers reviewing the AD7894ARZ-3 datasheet, AD7894ARZ-3 pinout, AD7894ARZ-3 application, or AD7894ARZ-3 equivalent, key selection considerations include its SO-8 package, twos-complement serial output, 77 dB SNR at 70 kHz, ±2 LSB relative accuracy (A-grade), and automatic power-down mode for low-power sampling.
Technical Context
The AD7894ARZ-3 implements a laser-trimmed internal clock driving a 14-bit R-2R ladder SAR core, with on-chip track/hold enabling full-scale sine wave digitization up to 100 kHz. Its analog front-end uses resistor-scaling networks (R1 = R2 = 2 kΩ, R3 open) to condition ±2.5 V inputs while maintaining high input impedance and <1.5 mA max input current.
It operates in two modes: Mode 1 delivers 5 µs conversion with continuous active operation; Mode 2 enables auto-sleep after conversion completion, reducing IDD to 20 µA max and power dissipation to 100 µW max - activated by holding CONVST low post-conversion and waking via rising edge.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Resolution | 14 bits - guarantees no missing codes over full operating temperature range (–40°C to +85°C) |
| Conversion Time | 5 µs max (Mode 1) - enables 160 kHz maximum throughput when paired with 16 MHz SCLK and 250 ns quiet time |
| Analog Input Range | ±2.5 V - supports bipolar sensor signals (e.g., strain gauges, accelerometers) without external level-shifting |
| Relative Accuracy | ±2 LSB max (A-grade) - defines worst-case deviation from ideal transfer curve endpoints |
| Signal-to-(Noise+Distortion) | 77 dB min at 70 kHz - ensures >12.8 effective bits for dynamic signal capture in noisy environments |
| Power Dissipation | 20 mW typical - achieved with 5 V supply and internal clock; drops to 15 µW typical in auto-sleep mode |
| Reference Input | +2.5 V ±5% buffered - requires external precision reference (e.g., AD780); 1 µA max input current minimizes loading error |
Pinout & Package
AD7894ARZ-3 is housed in an 8-lead narrow-body SOIC (SO-8) package with standard JEDEC MS-012AC footprint (5.3 mm × 4.4 mm, 1.27 mm pitch). Thermal resistance θJA = 170°C/W; rated for 450 mW max power dissipation.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 - REF IN | Voltage reference input | Accepts +2.5 V ±5% buffered reference; 1 µA max input current ensures minimal gain error contribution |
| 2 - VIN | Analog input channel | ±2.5 V bipolar input with 1.5 mA max input current; resistor-scaling network enables direct connection to transducer outputs |
| 3 - GND | Analog ground reference | Common return for track/hold, comparator, DAC, and digital logic - must be star-connected to minimize noise coupling |
| 4 - SCLK | Serial clock input | Accepts up to 16 MHz external clock; falling edge clocks out 16-bit serial data (2 leading zeros + 14-bit twos-complement result) |
| 5 - SDATA | Serial data output | Three-state output providing conversion result; data valid for 10 ns after SCLK falling edge; disabled after 16th clock |
| 6 - BUSY | Conversion status indicator | Active-high open-drain signal - goes high on CONVST falling edge, returns low 5 µs later to signal data readiness |
| 7 - CONVST | Edge-triggered conversion start | Falling edge initiates track→hold transition and conversion; low hold duration determines Mode 1 vs. Mode 2 operation |
| 8 - VDD | Positive supply | +5 V ±5% supply rail powering all analog and digital circuitry; 5.5 mA max IDD supports stable operation under full load |
Key Features
| Feature | Design Value |
|---|---|
| Integrated track/hold amplifier | Acquires input to ±1/2 LSB in ≤0.35 µs - eliminates need for external sample-and-hold in high-speed DAQ designs |
| Two-wire high-speed serial interface | 16 MHz max SCLK with guaranteed timing margins (t4 ≤ 60 ns, t5 ≥ 10 ns) - simplifies microcontroller interfacing with minimal GPIO usage |
| Auto-sleep power management | Reduces IDD to 20 µA max between conversions - extends battery life in portable instrumentation without firmware overhead |
| Bipolar ±2.5 V input scaling | Resistor network (R1=R2=2 kΩ) enables direct connection to ±2.5 V sensors - avoids external op-amp gain stages and associated drift errors |
| On-chip laser-trimmed oscillator | Eliminates external clock components - ensures consistent 5 µs conversion time across temperature and voltage variations |
Applications
| Industrial Process Monitoring | Portable Test Equipment |
|---|---|
|
Use Scenario: Continuous digitization of 4–20 mA loop signals conditioned to ±2.5 V via precision resistors in PLC I/O modules. IC Role / Device Role / Timing Role: Primary ADC capturing analog sensor outputs at 100 kHz with 14-bit resolution and low THD (–86 dB). Use Value: Enables detection of sub-millivolt-level process deviations without external amplification, improving fault diagnosis accuracy. |
Use Scenario: Battery-powered handheld multimeter acquiring AC/DC voltage and current measurements with autoranging. IC Role / Device Role / Timing Role: High-accuracy ADC operating in auto-sleep mode between manual trigger events to conserve energy. Use Value: Achieves >10-hour battery life while maintaining 14-bit linearity and 77 dB SNR during active measurement cycles. |
| Motor Control Feedback | Medical Sensor Interface |
|
Use Scenario: Sampling current-sense amplifier outputs (±2.5 V) for real-time FOC (Field-Oriented Control) in servo drives. IC Role / Device Role / Timing Role: Low-latency ADC with 5 µs conversion time synchronized to PWM carrier edges via CONVST timing. Use Value: Supports 20 kHz current loop bandwidth with deterministic timing, reducing torque ripple in high-performance motors. |
Use Scenario: Digitizing outputs from MEMS accelerometers and piezoelectric pressure sensors in portable patient monitors. IC Role / Device Role / Timing Role: Low-noise ADC with high input impedance (>10⁹ Ω effective) preserving signal integrity from high-Z sources. Use Value: Maintains 12.8 ENOB at 10 kHz input frequency - sufficient for Class II medical device compliance per IEC 60601-2-51. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar 14-bit SAR ADC applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| AD7894BRZ-3 | B-grade: ±1.5 LSB relative accuracy (vs. ±2 LSB for AD7894ARZ-3), same SO-8 package and pinout | Preferred where tighter DC accuracy is required at higher ambient temperatures (–40°C to +85°C) | Select AD7894BRZ-3 if system-level calibration budget allows tighter gain/offset tolerances |
| ADS8325IPW | 16-bit SAR ADC, 2.7–5.5 V supply, SPI-compatible interface, no integrated track/hold, 500 kSPS max | Requires external track/hold for >100 kHz inputs; better resolution but higher power (15 mW @ 100 kSPS) | Choose ADS8325IPW only when 16-bit resolution is mandatory and board space permits external THA |
Compared with AD7894BRZ-3, the AD7894ARZ-3 trades 0.5 LSB accuracy for lower cost and broader availability; versus ADS8325IPW, it offers integrated track/hold and lower system-level BOM count at the expense of resolution and sampling rate.
Availability
AD7894ARZ-3 is available at Aetrix Electronics and suitable for industrial process monitoring, portable test equipment, motor control feedback, medical sensor interface, and precision instrumentation requiring stable component supply across extended temperature ranges.
Supply support for AD7894ARZ-3 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 semiconductor company specializing in high-performance analog, mixed-signal, and digital signal processing technologies for precision measurement and control.
The AD7894 product line delivers compact, single-supply 14-bit SAR ADCs with integrated track/hold and serial interfaces - designed specifically for space-constrained, low-power industrial and instrumentation applications.
FAQ
What is the absolute maximum analog input voltage for AD7894ARZ-3?
The absolute maximum analog input voltage for AD7894ARZ-3 is ±7 V referenced to GND, as specified in the Absolute Maximum Ratings table. Exceeding this limit risks permanent damage. The functional input range remains ±2.5 V; operation beyond ±2.5 V violates the specified performance and may cause clipping or code anomalies. Always use input protection circuitry (e.g., series resistors + clamping diodes) if transient overvoltage exposure is possible in the end application.
Does AD7894ARZ-3 require an external reference voltage?
Yes, AD7894ARZ-3 requires an external +2.5 V reference applied to the REF IN pin. The device includes an on-chip buffer with 1 µA max input current, but provides no internal reference. Precision references such as the AD780 or ADR421 are recommended to maintain the specified ±2 LSB relative accuracy and 77 dB SNR. Using a non-precision or unregulated source introduces proportional gain error directly into the conversion result.
How does the auto-sleep mode function in AD7894ARZ-3?
In auto-sleep mode (Mode 2), AD7894ARZ-3 enters low-power state automatically after conversion completes - triggered by holding the CONVST pin low when BUSY goes low. It "wakes up" on the rising edge of the next CONVST pulse, with a typical 5 µs wake-up delay before conversion begins. During sleep, IDD drops to 20 µA max and power dissipation falls to 100 µW max, making AD7894ARZ-3 suitable for battery-operated systems with intermittent sampling requirements.
What is the serial data format output by AD7894ARZ-3?
AD7894ARZ-3 outputs 16-bit serial data on the SDATA pin, clocked out on the falling edge of SCLK. The format consists of two leading zero bits followed by 14 bits of conversion result in twos-complement format (e.g., 00DDDDDDDDDDDDDD). After the 16th clock, SDATA enters three-state mode. Data is valid for 10 ns after each SCLK falling edge, and the entire read cycle must complete at least 250 ns before the next CONVST falling edge to ensure track/hold settling.
Can AD7894ARZ-3 interface directly with a 3.3 V microcontroller?
AD7894ARZ-3 is not 3.3 V logic-compatible: its digital inputs require VIH ≥ 2.4 V and VIL ≤ 0.8 V with VDD = 5 V, and outputs drive VOH ≥ 4.0 V (ISOURCE = 400 µA) and VOL ≤ 0.4 V (ISINK = 1.6 mA). Direct connection to a 3.3 V MCU may violate input voltage limits and cause reliability issues. Level translation (e.g., TXB0104 or discrete MOSFET buffers) is required for safe interfacing - especially for SCLK and SDATA lines.
AD7894ARZ-3 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-3 FAQ
1.How can I place an order for AD7894ARZ-3 through Aetrix?
Please submit a Request for Quotation (RFQ) for AD7894ARZ-3 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-3 reliable?
The price and inventory of AD7894ARZ-3 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for AD7894ARZ-3 is usually 5 days.
3.What payment methods are accepted for AD7894ARZ-3?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for AD7894ARZ-3 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for AD7894ARZ-3?
AD7894ARZ-3 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your AD7894ARZ-3 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-3?
For technical support, including AD7894ARZ-3 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your AD7894ARZ-3 requirements.
6.How does Aetrix verify that AD7894ARZ-3 is sourced from the original manufacturer or authorized distributors?
All AD7894ARZ-3 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-3 meets industry standards.
7.What is the process for return or replacement of AD7894ARZ-3?
All AD7894ARZ-3 units undergo pre-shipment inspection (PSI). If there is an issue with AD7894ARZ-3, 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-3 part is unused and in its original packaging.
Return procedure for AD7894ARZ-3:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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