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Analog Devices Inc. AD7821KRZ-REEL
- Part No.:
- AD7821KRZ-REEL
- Manufacturer:
- Analog Devices Inc.
- Category:
- Analog to Digital Converters (ADC)
- Package:
- 20-SOIC (0.295", 7.50mm Width)
- Datasheet:
-
AD7821KRZ-REEL.pdf
- Description:
- IC ADC 8BIT PIPELINED 20SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:844
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Product details
Overview
AD7821KRZ-REEL from Analog Devices is a high-speed, 8-bit LC2MOS analog-to-digital converter with integrated track-and-hold, 660 ns conversion time (WR-RD mode), ±1 LSB total unadjusted error over –40°C to +85°C, and support for both unipolar (0 V to +5 V) and bipolar (±2.5 V) input ranges. It interfaces directly to microprocessor buses using standard CS/WR/RD/INT signals and targets real-time data acquisition in industrial control and DSP systems.
For engineers reviewing the AD7821KRZ-REEL datasheet, AD7821KRZ-REEL pinout, AD7821KRZ-REEL application, or AD7821KRZ-REEL equivalent, key selection considerations include its 100 kHz signal bandwidth, ratiometric reference capability, no-external-clock operation, 20-lead SOIC package, and compatibility with 5 V single-supply or ±5 V dual-supply configurations.
Technical Context
The AD7821KRZ-REEL employs a half-flash conversion architecture with two 4-bit flash ADCs and an internal DAC to generate 8-bit results without requiring an external clock. Its sampling instant is precisely defined on the falling edge of WR (WR-RD mode) or RD (RD mode), enabling deterministic timing for DSP applications.
It features latched three-state data outputs (DB0–DB7), dedicated overflow (OFL) and interrupt (INT) outputs, and MODE pin-selectable interface modes - supporting both WAIT-state microprocessors (RD mode) and non-WAIT systems (WR-RD mode). The VSS pin enables true bipolar operation at ±5 V supplies.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Resolution | 8 bits - delivers 256 discrete output codes with natural binary (unipolar) or offset binary (bipolar) encoding. |
| Conversion Time | 660 ns max (WR-RD mode) - enables 1 MHz sampling rate, suitable for real-time waveform digitization up to 100 kHz. |
| Total Unadjusted Error | ±1 LSB max - ensures monotonicity and no missing codes across full temperature range (–40°C to +85°C). |
| Signal-to-Noise Ratio | 45 dB min - measured at 99.85 kHz full-scale sine wave, supporting voice and sensor signal fidelity in DSP front-ends. |
| Slew Rate (Tracking) | 1.6 V/µs max - allows accurate digitization of 5 VPP, 100 kHz sine waves without external track-and-hold. |
| Power Dissipation | 50 mW typ - low power consumption enables use in thermally constrained embedded systems. |
| Reference Input | Ratiometric - VREF(+) and VREF(–) define full-scale span; supports supply-referenced measurements and flexible input scaling. |
Pinout & Package
AD7821KRZ-REEL is housed in a 20-lead SOIC (Small Outline Integrated Circuit) package, RoHS-compliant and tape-and-reel formatted (REEL suffix). Pin count, lead pitch (1.27 mm), and thermal profile align with JEDEC MS-013AC standards.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VIN (Pin 1) | Analog Input | Accepts differential input voltage between VREF(–) and VREF(+); supports ±2.5 V bipolar or 0–5 V unipolar ranges. |
| DB0–DB7 (Pins 2–5, 14–17) | Digital Output Bus | Latched, three-state outputs delivering 8-bit result; compatible with 5 V TTL/CMOS logic and high-speed data buses. |
| WR/RDY (Pin 6) | Mode-Dependent Control | In WR-RD mode: write strobe initiating conversion; in RD mode: ready status output (open-drain) for WAIT-state interfacing. |
| MODE (Pin 7) | Interface Configuration | Selects WR-RD (high) or RD (low) operation; internally pulled low (50 µA), allowing default RD-mode operation if left unconnected. |
| RD (Pin 8) | Read Strobe | Enables output data transfer when low; also initiates conversion in RD mode when asserted with CS. |
| INT (Pin 9) | Interrupt Output | Active-low signal indicating conversion completion; resets on rising edge of CS or RD. |
| GND (Pin 10) | Ground Reference | Common return for digital and analog sections; requires low-impedance connection to minimize noise coupling. |
| VREF(–) (Pin 11) | Reference Lower Bound | Defines negative end of reference span; supports ratiometric operation and bipolar offset configuration. |
| VREF(+) (Pin 12) | Reference Upper Bound | Defines positive end of reference span; accepts up to VDD; sets full-scale range with VREF(–). |
| CS (Pin 13) | Chip Select | Active-low enable; must be low for any read/write operation or status access. |
| OFL (Pin 18) | Overflow Flag | Active-low open-collector output signaling input > (VREF(+) – ½ LSB); used to cascade multiple AD7821 devices for higher resolution. |
| VSS (Pin 19) | Negative Supply | Required for bipolar operation (–5 V); grounded for unipolar (+5 V only) mode. |
| VDD (Pin 20) | Positive Supply | +5 V ±5% supply; powers analog core and digital interface; decoupling recommended near pin. |
Key Features
| Feature | Design Value |
|---|---|
| No external clock required | Half-flash architecture eliminates need for CLK generation circuitry, reducing BOM count and layout complexity. |
| Built-in track-and-hold | Supports 100 kHz full-scale sine wave inputs without external THS, simplifying front-end design and lowering system cost. |
| Ratiometric reference inputs | VREF(+) and VREF(–) allow direct connection to supply rails or precision references, enabling supply-voltage-insensitive measurements. |
| Microprocessor-compatible interface | Standard CS/WR/RD/INT signals and three-state outputs enable plug-in integration with 68000-, 80x86-, and Z80-based systems. |
| Extended temperature range | Specified from –40°C to +85°C (K version), supporting deployment in industrial automation and outdoor instrumentation. |
Applications
| Industrial Data Acquisition | DSP-Based Signal Processing |
|---|---|
Use Scenario: Real-time monitoring of motor current, temperature, and vibration in PLC-controlled factory equipment. IC Role / Device Role / Timing Role: ADC front-end capturing analog sensor outputs at up to 1 MHz sample rate with deterministic sampling edges on WR/RD falling edges. Use Value: ±1 LSB accuracy and 100 kHz bandwidth ensure faithful representation of fast transients (e.g., bearing fault signatures) without external track-and-hold. | Use Scenario: Digitizing audio or ultrasonic sensor signals in adaptive filtering or echo cancellation algorithms. IC Role / Device Role / Timing Role: High-fidelity sampling engine providing 45 dB SNR and –50 dB THD at 99.85 kHz, synchronized to DSP clock via WR strobe. Use Value: Built-in track-and-hold and precise sampling edge eliminate aperture jitter, preserving phase coherence critical for FIR/IIR filter stability. |
| Test & Measurement Equipment | Medical Sensor Interfaces |
Use Scenario: Portable oscilloscope or waveform analyzer capturing transient events in field service tools. IC Role / Device Role / Timing Role: Core ADC converting conditioned analog inputs into 8-bit samples for display or storage; operates in WR-RD mode for minimal CPU overhead. Use Value: 660 ns conversion time and OFL flag enable rapid multi-channel sampling and overflow detection during burst capture. | Use Scenario: ECG or pulse oximetry front-end digitizing low-amplitude biopotential signals. IC Role / Device Role / Timing Role: Bipolar-input ADC accepting ±2.5 V signals referenced to isolated patient ground, powered from ±5 V supplies. Use Value: VSS pin enables true bipolar operation and ratiometric referencing improves common-mode rejection against supply ripple. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar 8-bit, high-speed ADC applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| AD7820KN | Slower conversion (1.36 µs), no VSS pin, unipolar-only, no built-in track-and-hold. | Requires external THS for >6.4 kHz signals; limited to single-supply systems. | Select AD7821KRZ-REEL when 100 kHz bandwidth, bipolar input, or reduced BOM count is required. |
| MAX1112CPE+ | Serial SPI interface, 2.7–5.25 V supply, 1.5 µs conversion, ±0.5 LSB INL. | Lower pin count, but serial interface increases CPU load and adds timing constraints vs. parallel DB0–DB7. | Choose AD7821KRZ-REEL for high-throughput parallel bus systems needing deterministic latency and microprocessor-native timing. |
Compared with AD7820KN and MAX1112CPE+, the AD7821KRZ-REEL uniquely combines parallel 8-bit output, 660 ns conversion, integrated track-and-hold, and dual-supply bipolar operation - making it optimal for space-constrained, high-speed industrial DAQ where timing predictability and analog flexibility are critical.
Availability
AD7821KRZ-REEL is available at Aetrix Electronics and suitable for industrial automation, test equipment, and medical sensor interfaces requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.
Supply support for AD7821KRZ-REEL 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 Wilmington, MA.
The AD7821KRZ-REEL belongs to Analog Devices' legacy high-speed ADC product line, designed specifically for cost-sensitive, real-time data acquisition systems demanding sub-microsecond latency and microprocessor-native parallel interfacing.
FAQ
What is the maximum analog input frequency supported by the AD7821KRZ-REEL without external track-and-hold?
The AD7821KRZ-REEL supports analog input frequencies up to 100 kHz without external track-and-hold, enabled by its inherent sampled-data comparator architecture and 1.6 V/µs tracking slew rate. This corresponds to a 5 VPP sine wave and is validated per the datasheet's dynamic specifications under fSAMPLE = 500 kHz conditions. The AD7821KRZ-REEL achieves this performance while maintaining ±1 LSB total unadjusted error across its full operating temperature range.
Does the AD7821KRZ-REEL require an external clock signal to operate?
No, the AD7821KRZ-REEL does not require an external clock signal. It uses a half-flash conversion technique that generates internal timing for both the most-significant and least-significant 4-bit conversions, eliminating the need for CLK input. All timing is controlled by WR, RD, and CS signals - making the AD7821KRZ-REEL ideal for systems where clock distribution noise or routing complexity must be minimized.
Can the AD7821KRZ-REEL operate from a single +5 V supply?
Yes, the AD7821KRZ-REEL can operate from a single +5 V supply when configured for unipolar input mode: tie VSS (Pin 19) to GND, set VREF(–) = GND and VREF(+) = +5 V. In this configuration, the AD7821KRZ-REEL delivers 0 V to +5 V full-scale range with natural binary output coding and maintains all specified performance including 660 ns conversion time and ±1 LSB accuracy.
What is the function of the MODE pin on the AD7821KRZ-REEL?
The MODE pin (Pin 7) selects between two digital interface modes: when low, the AD7821KRZ-REEL operates in RD mode (WR/RDY functions as READY output); when high, it operates in WR-RD mode (WR/RDY functions as WRITE input). The pin is internally pulled low (50 µA), so leaving it unconnected defaults the AD7821KRZ-REEL to RD mode - simplifying designs targeting WAIT-state-capable microprocessors.
How does the OFL (overflow) output of the AD7821KRZ-REEL function in cascaded configurations?
The OFL output of the AD7821KRZ-REEL is an active-low, non-three-state signal that goes low when VIN exceeds (VREF(+) – ½ LSB), indicating overflow. In cascaded configurations, OFL from a lower-order AD7821KRZ-REEL can drive the CS or WR of a higher-order device to extend resolution beyond 8 bits - for example, enabling 16-bit acquisition by chaining two AD7821KRZ-REEL units with shared timing control.
AD7821KRZ-REEL Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 20-SOIC (0.295", 7.50mm Width)
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Number of Bits:
- 8
- Sampling Rate (Per Second):
- 1M
- Number of Inputs:
- 1
- Input Type:
- Single Ended
- Data Interface:
- Parallel
- Configuration:
- S/H-ADC
- Ratio - S/H:ADC:
- 1:1
- Number of A/D Converters:
- 1
- Architecture:
- Pipelined
- Reference Type:
- External
- Voltage - Supply, Analog:
- 5V
- Voltage - Supply, Digital:
- 5V
- Features:
- -
- Operating Temperature:
- -40°C ~ 85°C
- Supplier Device Package:
- 20-SOIC
- Mounting Type:
- Surface Mount
- Grade:
- -
- Qualification:
- -
AD7821KRZ-REEL FAQ
1.How can I place an order for AD7821KRZ-REEL through Aetrix?
Please submit a Request for Quotation (RFQ) for AD7821KRZ-REEL 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 AD7821KRZ-REEL reliable?
The price and inventory of AD7821KRZ-REEL are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for AD7821KRZ-REEL is usually 5 days.
3.What payment methods are accepted for AD7821KRZ-REEL?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for AD7821KRZ-REEL transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for AD7821KRZ-REEL?
AD7821KRZ-REEL orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your AD7821KRZ-REEL 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 AD7821KRZ-REEL?
For technical support, including AD7821KRZ-REEL datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your AD7821KRZ-REEL requirements.
6.How does Aetrix verify that AD7821KRZ-REEL is sourced from the original manufacturer or authorized distributors?
All AD7821KRZ-REEL 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 AD7821KRZ-REEL meets industry standards.
7.What is the process for return or replacement of AD7821KRZ-REEL?
All AD7821KRZ-REEL units undergo pre-shipment inspection (PSI). If there is an issue with AD7821KRZ-REEL, 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 AD7821KRZ-REEL part is unused and in its original packaging.
Return procedure for AD7821KRZ-REEL:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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