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Analog Devices Inc. AD7908BRU-REEL
- Part No.:
- AD7908BRU-REEL
- Manufacturer:
- Analog Devices Inc.
- Category:
- Analog to Digital Converters (ADC)
- Package:
- 20-TSSOP (0.173", 4.40mm Width)
- Datasheet:
-
AD7908BRU-REEL.pdf
- Description:
- IC ADC 8BIT 8CH W/SEQ 20TSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:2,255
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Product details
Overview
AD7908BRU-REEL from Analog Devices is an 8-bit, 8-channel, successive approximation ADC with integrated channel sequencer, operating at up to 1 MSPS throughput on a single 2.7 V to 5.25 V supply. It features 8 single-ended analog inputs, SPI-compatible serial interface, 0 V to 2.5 V or 0 V to 5 V input range selection, and consumes only 6 mW max at 3 V/1 MSPS. It is used in industrial data acquisition systems requiring compact, low-power multichannel sampling.
For engineers reviewing the AD7908BRU-REEL datasheet, AD7908BRU-REEL pinout, AD7908BRU-REEL application, or AD7908BRU-REEL equivalent, key selection considerations include its 8-bit resolution, 1 MSPS conversion rate, TSSOP-20 package, sequencer-controlled channel cycling, and VDRIVE-enabled 3 V/5 V logic compatibility-critical for microcontroller interfacing in space-constrained embedded systems.
Technical Context
The AD7908BRU-REEL implements a standard SAR architecture with no pipeline delay, where sampling is triggered on the falling edge of CS and conversion is clocked entirely by SCLK (up to 20 MHz). Its internal track-and-hold supports >8 MHz input bandwidth and maintains 49 dB SINAD at 50 kHz.
It uses a programmable control register to configure input range (0 V to REFIN or 0 V to 2 × REFIN), output coding (straight binary or twos complement), and sequencer behavior. The eight VINx inputs are multiplexed via ADD2–ADD0 bits, and DOUT delivers MSB-first serial data with leading zero, 3-bit channel address, 8-bit result, and four trailing zeros.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Resolution | 8 bits - defines quantization step size (≈9.8 mV at 2.5 V reference) and limits dynamic range to ~49 dB SNR. |
| Throughput Rate | 1 MSPS maximum - enables real-time sampling of signals up to 500 kHz (Nyquist-limited) without aliasing in high-speed monitoring. |
| Input Channels | 8 single-ended - allows simultaneous connection of eight independent sensors (e.g., temperature, voltage, current) without external MUX. |
| Supply Range | AVDD = 2.7 V to 5.25 V - supports direct integration into both 3 V and 5 V system rails without level-shifting. |
| Power Dissipation | 6 mW max at 3 V/1 MSPS - reduces thermal load and extends battery life in portable instrumentation. |
| SINAD | 49 dB min at 50 kHz - ensures usable signal fidelity for medium-bandwidth sensor interfaces like motor control feedback loops. |
| VDRIVE | Independent 2.7 V to 5.25 V logic supply - permits direct connection to 3 V or 5 V microcontrollers regardless of AVDD voltage. |
Pinout & Package
AD7908BRU-REEL is housed in a 20-lead TSSOP package (4.4 mm × 6.5 mm, 0.65 mm pitch), qualified for automotive applications and compatible with standard surface-mount reflow profiles.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| SCLK | Serial clock input | Master clock for both data transfer and internal conversion timing; supports up to 20 MHz operation. |
| DIN | Control register data input | Accepts configuration bits (RANGE, CODING, SEQ) on falling SCLK edges to set input range and sequencer mode. |
| CS | Chip select / conversion trigger | Active-low signal that initiates sampling on falling edge and frames serial communication window. |
| DOUT | Serial data output | Delivers 12-bit frame (1 leading zero + 3 address bits + 8 data bits + 4 trailing zeros) MSB-first for unambiguous channel identification. |
| VIN0–VIN7 | Analog input channels | Eight single-ended inputs referenced to AGND; unused pins must be tied to AGND to prevent noise coupling. |
| REFIN | External reference input | Accepts 2.5 V ±1% precision reference to define full-scale range; impedance ≈36 kΩ at 1 MSPS. |
| AVDD | Analog power supply | Supplies core analog circuitry; must be ≥4.75 V for 0 V to 2 × REFIN operation. |
| VDRIVE | Digital I/O power supply | Defines logic threshold levels independently of AVDD-enables mixed-voltage system interfacing. |
| AGND | Analog ground reference | Common return for all analog signals and reference; four dedicated pins minimize ground bounce in multichannel operation. |
Key Features
| Feature | Design Value |
|---|---|
| No pipeline delay | Sampling instant precisely controlled by CS falling edge-enables deterministic timing for synchronized multi-sensor capture. |
| Programmable input range | Select 0 V to REFIN (2.5 V) or 0 V to 2 × REFIN (5 V) via RANGE bit-supports both low-voltage sensors and rail-to-rail industrial signals. |
| Channel sequencer | Preprogrammed cycling through up to 8 channels using ADD2–ADD0 and SEQ bit-eliminates host CPU overhead for round-robin acquisition. |
| Low-power shutdown | 0.5 μA max quiescent current in full shutdown-ideal for battery-powered devices requiring periodic wake-up sampling. |
| SPI/QSPI/MICROWIRE/DSP compatibility | Standard 4-wire serial interface with no protocol translation needed-reduces firmware development time across MCU platforms. |
Applications
| Industrial PLC Analog Input Module | Automotive Battery Monitoring Unit |
|---|---|
Use Scenario: Sampling of eight thermocouple, RTD, or voltage outputs in a programmable logic controller rack. IC Role / Device Role / Timing Role: Central 8-channel ADC providing synchronized, sequenced conversions with minimal host intervention. Use Value: Reduces component count versus discrete ADC + MUX solutions while maintaining 1 MSPS aggregate throughput across all channels. | Use Scenario: Real-time monitoring of individual cell voltages and pack temperature sensors in a 12S Li-ion battery management system. IC Role / Device Role / Timing Role: High-speed, low-drift sampling front-end with built-in channel sequencing for periodic cell balancing decisions. Use Value: Enables sub-100 µs per-cell measurement cycle time, supporting fast fault detection and thermal runaway prevention. |
| Portable Medical Vital Signs Monitor | Motor Drive Current Feedback System |
Use Scenario: Simultaneous acquisition of ECG, SpO₂, respiration, and temperature signals in handheld diagnostic equipment. IC Role / Device Role / Timing Role: Low-power, 8-bit multichannel converter interfaced directly to an ARM Cortex-M0+ MCU via SPI. Use Value: 6 mW max power at 3 V extends battery runtime beyond 8 hours while meeting IEC 60601-1 leakage current requirements. | Use Scenario: Sampling phase currents and DC bus voltage in a three-phase inverter for field-oriented control (FOC). IC Role / Device Role / Timing Role: High-bandwidth analog front-end delivering timely current samples to the PWM timer's trigger input. Use Value: 8.2 MHz full-power bandwidth and <300 ns acquisition time support accurate current reconstruction at switching frequencies up to 20 kHz. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar multichannel SAR ADC applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| AD7918BRU-REEL | 10-bit resolution, 61 dB SINAD min, same pinout and interface | Higher precision required for vibration analysis or audio pre-processing | Select when 10-bit accuracy and improved SNR justify higher cost and code depth handling. |
| ADS8320EB/2K5 | 16-bit, 100 kSPS, SPI interface, SOIC-8 package | Lower speed but higher resolution for precision DC measurements (e.g., weigh scales) | Choose for static or slow-varying signals where resolution outweighs speed; not pin-compatible. |
Compared with AD7908BRU-REEL, AD7918BRU-REEL offers 2 extra bits and 12 dB better SINAD at identical speed and footprint, while ADS8320EB/2K5 trades 10× lower throughput for 8× higher resolution in a smaller 8-pin package-making AD7908BRU-REEL optimal for cost-sensitive, medium-accuracy, high-channel-count real-time systems.
Availability
AD7908BRU-REEL is available at Aetrix Electronics and suitable for industrial PLC analog input modules, automotive battery monitoring units, portable medical vital signs monitors, and motor drive current feedback systems requiring stable component supply and long-term production continuity.
Supply support for AD7908BRU-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 Norwood, MA.
The AD7908BRU-REEL belongs to the AD7908/AD7918/AD7928 family of high-speed, low-power, multichannel SAR ADCs designed for space-constrained industrial, automotive, and medical data acquisition where sequenced sampling and flexible power management are essential.
FAQ
What is the maximum sample rate supported by the AD7908BRU-REEL?
The AD7908BRU-REEL supports a maximum throughput rate of 1 MSPS, achieved with a 20 MHz SCLK and 16 clock cycles per conversion. This corresponds to a minimum conversion time of 800 ns. At lower SCLK frequencies, the throughput scales linearly-for example, 10 MHz SCLK yields 500 kSPS-making it adaptable to bandwidth-constrained microcontroller interfaces.
Does the AD7908BRU-REEL require an external reference voltage?
Yes, the AD7908BRU-REEL requires an external reference voltage applied to the REFIN pin. For specified performance, REFIN must be 2.5 V ±1%. The device supports two input ranges: 0 V to REFIN (2.5 V) or 0 V to 2 × REFIN (5 V), selectable via the RANGE bit in the control register. No internal reference is provided.
Can the AD7908BRU-REEL interface directly with a 3.3 V microcontroller while operating from a 5 V analog supply?
Yes. The AD7908BRU-REEL's VDRIVE pin allows independent logic-level setting: connect VDRIVE to 3.3 V while AVDD is at 5 V. This configures DIN and DOUT thresholds to 3.3 V logic levels, enabling seamless SPI communication with 3.3 V MCUs without level shifters-even when the analog section runs at higher voltage for extended input range.
How does the channel sequencer function in the AD7908BRU-REEL?
The AD7908BRU-REEL sequencer cycles through up to eight channels (VIN0–VIN7) in user-defined order using the SEQ bit and ADD2–ADD0 address bits in the control register. Once enabled, it automatically advances to the next channel after each conversion, eliminating continuous host polling. The DOUT stream includes a 3-bit channel address prefix, allowing firmware to identify source without additional register reads.
Is the AD7908BRU-REEL suitable for automotive applications?
Yes. The AD7908BRU-REEL is qualified for automotive applications per the datasheet, with guaranteed operation from −40°C to +125°C junction temperature and AEC-Q100 stress testing compliance. Its 20-lead TSSOP package, low EMI emissions, and robust 1.5 kV ESD rating make it appropriate for battery monitoring, cabin sensor hubs, and chassis control subsystems.
AD7908BRU-REEL Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- *
- Package/Case:
- 20-TSSOP (0.173", 4.40mm Width)
- Packaging:
- Bulk
- Product Status:
- Obsolete
- Number of Bits:
- 8
- Sampling Rate (Per Second):
- -
- Number of Inputs:
- -
- Input Type:
- -
- Data Interface:
- -
- Configuration:
- -
- Ratio - S/H:ADC:
- -
- Number of A/D Converters:
- -
- Architecture:
- -
- Reference Type:
- -
- Voltage - Supply, Analog:
- -
- Voltage - Supply, Digital:
- -
- Features:
- -
- Operating Temperature:
- -
- Supplier Device Package:
- 20-TSSOP
- Mounting Type:
- Surface Mount
- Grade:
- -
- Qualification:
- -
AD7908BRU-REEL FAQ
1.How can I place an order for AD7908BRU-REEL through Aetrix?
Please submit a Request for Quotation (RFQ) for AD7908BRU-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 AD7908BRU-REEL reliable?
The price and inventory of AD7908BRU-REEL are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for AD7908BRU-REEL is usually 5 days.
3.What payment methods are accepted for AD7908BRU-REEL?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for AD7908BRU-REEL transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for AD7908BRU-REEL?
AD7908BRU-REEL orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your AD7908BRU-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 AD7908BRU-REEL?
For technical support, including AD7908BRU-REEL datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your AD7908BRU-REEL requirements.
6.How does Aetrix verify that AD7908BRU-REEL is sourced from the original manufacturer or authorized distributors?
All AD7908BRU-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 AD7908BRU-REEL meets industry standards.
7.What is the process for return or replacement of AD7908BRU-REEL?
All AD7908BRU-REEL units undergo pre-shipment inspection (PSI). If there is an issue with AD7908BRU-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 AD7908BRU-REEL part is unused and in its original packaging.
Return procedure for AD7908BRU-REEL:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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