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Analog Devices Inc. AD7985BCPZ-RL7
- Part No.:
- AD7985BCPZ-RL7
- Manufacturer:
- Analog Devices Inc.
- Category:
- Analog to Digital Converters (ADC)
- Package:
- 20-WFQFN Exposed Pad, CSP
- Datasheet:
-
AD7985BCPZ-RL7.pdf
- Description:
- IC ADC 16BIT SAR 20LFCSP
- Quantity:
- Payment:
- Shipping:
Inventory:1,116
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Product details
Overview
AD7985BCPZ-RL7 from Analog Devices is a 16-bit, 2.5 MSPS successive approximation ADC (SAR ADC) with integrated reference buffer and SPI-compatible serial interface. It delivers ±0.7 LSB typical INL, 88.5 dB SNR with internal reference, and operates from −40°C to +85°C in battery-powered data acquisition systems.
For engineers reviewing the AD7985BCPZ-RL7 datasheet, AD7985BCPZ-RL7 pinout, AD7985BCPZ-RL7 application, or AD7985BCPZ-RL7 equivalent, this page provides verified technical context, real-world timing behavior, power trade-offs between turbo/normal modes, and validated alternative options for high-speed precision sampling.
Technical Context
The AD7985BCPZ-RL7 uses a charge redistribution capacitive DAC architecture with on-chip track-and-hold, delivering zero pipeline delay and 100 ns transient response to full-scale steps. Its conversion core is clocked internally - SCK is used only for data readout, not conversion timing.
It supports dual operation modes: TURBO = high enables 2.5 MSPS throughput with continuous power, while TURBO = low reduces throughput to 2.0 MSPS and powers down between conversions. The device accepts pseudo-differential inputs from 0 V to VREF (up to 5.0 V) and features separate analog/digital/reference power domains (AVDD/DVDD/BVDD/VIO).
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Resolution | 16-bit with no missing codes - guarantees monotonicity and full code coverage across temperature. |
| Throughput | 2.5 MSPS (TURBO high), 2.0 MSPS (TURBO low) - defines maximum sample rate and corresponding power state transitions. |
| INL | ±0.7 LSB typical, ±1.5 LSB max - determines end-point linearity error affecting calibration accuracy in precision measurement. |
| SNR | 88.5 dB (internal 4.096 V ref), 90 dB (external 5.0 V ref) - sets dynamic range limit for small-signal detection in noisy environments. |
| Power Dissipation | 15.5 mW at 2.5 MSPS with external reference - enables thermal budget planning in compact, battery-constrained designs. |
| Analog Input Range | 0 V to VREF (VREF ≤ 5.0 V) - allows flexible scaling for sensor outputs without external level-shifting. |
| Reference Options | Internal 4.096 V ±10 ppm/°C drift or external 2.4–5.1 V - supports either self-contained operation or higher-accuracy system-level referencing. |
Pinout & Package
AD7985BCPZ-RL7 is housed in a 20-lead, 4 mm × 4 mm LFCSP package with exposed pad (EP) recommended to be soldered to system ground for thermal and EMI performance.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1, 2 REF | Reference Output/Input | Delivers 4.096 V when PDREF = low; accepts external reference up to 5.0 V when PDREF = high - requires 10 µF decoupling to REFGND. |
| 3, 4 REFGND | Analog Reference Ground | Isolated ground return for reference circuitry - must be connected separately from AGND/DGND to minimize noise coupling. |
| 5 IN− | Analog Input Sense | Ground reference point for pseudo-differential input - connects to remote sensor ground or local analog plane to reject common-mode noise. |
| 6 IN+ | Analog Input | Differential input referenced to IN− - accepts 0 V to VREF range with 250 nA leakage, enabling direct connection to low-output-impedance sensors. |
| 7 PDREF | Reference Power-Down Control | Digital input controlling internal reference enable/disable - low = internal reference active; high = external reference required. |
| 8 VIO | I/O Interface Supply | Independent 1.8 V/2.5 V/2.7 V supply for digital interface - isolates logic voltage from AVDD/DVDD to support mixed-voltage host systems. |
| 9 SDO | Serial Data Output | MSB-first 16-bit straight-binary output synchronized to SCK falling edge - supports daisy-chain mode with 16-cycle delay. |
| 10 DGND | Digital Ground | Return path for DVDD and digital I/O - must be tied to system digital ground plane with low-inductance connection. |
| 11 DVDD | Digital Power Supply | 2.5 V ±62.5 mV supply for digital core - decoupling required close to pin to suppress switching noise. |
| 12 SCK | Serial Clock Input | Edge-triggered clock for data readout - minimum period 9 ns (CS mode), 11 ns (chain mode); timing independent of conversion clock. |
| 13 CNV | Convert Input / Mode Select | Rising edge initiates sampling; level during CNV edge selects CS vs. chain mode - also enables busy indicator in CS mode when low. |
| 14 SDI | Serial Data Input / Mode Select | Configures interface mode on CNV rising edge - low = chain mode; high = CS mode; in chain mode, relays upstream ADC data with 16-cycle offset. |
| 15 TURBO | Conversion Speed Control | High = 2.5 MSPS continuous operation; low = 2.0 MSPS with inter-conversion power-down - directly scales power vs. speed trade-off. |
| 16 AVDD | Analog Power Supply | 2.5 V ±62.5 mV supply for analog front-end - requires dedicated low-noise decoupling to AGND. |
| 17, 18 AGND | Analog Ground | Return path for AVDD and analog inputs - must be partitioned from DGND/REFGND and connected at single point to avoid ground loops. |
| 19 BVDD | Reference Buffer Power | 5.0 V supply for internal reference buffer - required when using internal reference; connects to external buffer if using 5 V external reference. |
| 20 REFIN | Reference Buffer Input/Output | Outputs 1.2 V bandgap when PDREF = low; accepts 1.2 V input when PDREF = high - requires 0.1 µF decoupling for stability. |
| Exposed Pad (EP) | Thermal & Mechanical Anchor | Not electrically connected - must be soldered to system ground plane to improve thermal dissipation and mechanical reliability. |
Key Features
| Feature | Design Value |
|---|---|
| No pipeline delay | Enables true real-time sampling in multiplexed channel systems - conversion result available immediately after tCONV (320 ns in turbo mode). |
| Dual conversion modes | TURBO/normal selection allows dynamic adaptation: 2.5 MSPS for burst capture or 2.0 MSPS with 30% lower power for continuous monitoring. |
| Flexible reference architecture | Switchable internal 4.096 V ±10 ppm/°C reference or external 2.4–5.1 V input - eliminates need for external reference IC in many portable applications. |
| 1.8 V/2.5 V/2.7 V logic interface | VIO supply enables direct interfacing with low-voltage FPGAs, microcontrollers, and DSPs without level shifters - reduces BOM count and layout complexity. |
| Daisy-chain capability | SDI-to-SDO chaining of multiple AD7985BCPZ-RL7 devices on single 3-wire bus - simplifies multi-channel synchronization and reduces host GPIO usage. |
Applications
| Battery-Powered Data Loggers | Medical Patient Monitoring |
|---|---|
Use Scenario: Continuous acquisition of ECG, EEG, or blood pressure waveforms from low-power wearable sensors. IC Role / Device Role / Timing Role: Precision SAR ADC capturing 16-bit waveform samples at 2.0 MSPS in normal mode to extend battery life. Use Value: 15.5 mW power at 2.5 MSPS and 12 mW at 2.0 MSPS enables >72-hour runtime on coin-cell batteries in clinical-grade portable monitors. |
Use Scenario: High-fidelity digitization of ultrasound transducer signals in handheld diagnostic equipment. IC Role / Device Role / Timing Role: Zero-latency ADC acquiring fast transient echoes with 100 ns step response and 88.5 dB SNR. Use Value: Pseudo-differential input and ±0.7 LSB INL ensure accurate amplitude reconstruction of weak echo returns critical for image contrast resolution. |
| Automated Test Equipment (ATE) | Communications Baseband Sampling |
Use Scenario: Multi-channel voltage/current measurement in benchtop ATE systems requiring traceable accuracy. IC Role / Device Role / Timing Role: High-speed SAR ADC operating in turbo mode (2.5 MSPS) with daisy-chained configuration for synchronized channel capture. Use Value: Pin compatibility with AD7986 allows seamless upgrade path to 18-bit resolution without PCB redesign when higher ENOB is required. |
Use Scenario: Digitizing IF signals in software-defined radio (SDR) front-ends with wide dynamic range requirements. IC Role / Device Role / Timing Role: ADC providing 90 dB SNR with external 5 V reference and 19 MHz input bandwidth for clean baseband sampling. Use Value: 103 dB SFDR ensures spurious-free reception of adjacent channels in LTE/WiFi coexistence testing environments. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar high-speed precision SAR ADC applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| AD7986BCPZ-RL7 | 18-bit resolution, same 20-lead LFCSP package and pinout; 2.5 MSPS throughput; ±1.0 LSB max INL; 92 dB SNR with external reference. | Higher resolution required for metrology-grade instrumentation where 16-bit quantization noise limits dynamic range. | Select AD7986BCPZ-RL7 when ENOB > 14.5 bits is mandatory and board space/layout reuse is prioritized over cost. |
| AD7980BRMZ-REEL7 | 16-bit, 1 MSPS max throughput; 2.5 mm × 3 mm MSOP-10 package; 7 mW at 1 MSPS; ±0.5 LSB max INL; no internal reference. | Lower-speed, space-constrained applications like IoT sensor nodes where 2.5 MSPS is unnecessary and ultra-low power dominates. | Choose AD7980BRMZ-REEL7 for sub-1 MSPS sampling with 60% lower power and 40% smaller footprint, accepting reduced speed and external reference dependency. |
Compared with AD7985BCPZ-RL7, AD7986BCPZ-RL7 offers two additional bits of resolution in identical packaging for seamless upgrade, while AD7980BRMZ-REEL7 trades speed and integration for minimal size and power - making each suitable for distinct tiers of performance and integration requirements.
Availability
AD7985BCPZ-RL7 is available at Aetrix Electronics and suitable for battery-powered equipment, medical instruments, automated test equipment, and communications systems requiring stable component supply with guaranteed long-term sourcing.
Supply support for AD7985BCPZ-RL7 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 AD7985BCPZ-RL7 belongs to the PulSAR® family of precision SAR ADCs designed for applications demanding high speed, low power, and excellent ac/dc accuracy - especially where zero latency and flexible reference options are critical.
FAQ
What is the maximum sampling rate of the AD7985BCPZ-RL7 and how is it controlled?
The AD7985BCPZ-RL7 achieves a maximum sampling rate of 2.5 MSPS in TURBO mode (TURBO pin = high). In normal mode (TURBO = low), the maximum rate drops to 2.0 MSPS. This mode selection is hardware-controlled via the TURBO pin and directly governs both throughput and inter-conversion power-down behavior - no register writes or firmware configuration is needed to switch modes. The AD7985BCPZ-RL7 maintains full 16-bit accuracy and timing specifications across both modes.
Does the AD7985BCPZ-RL7 require an external clock for conversion?
No, the AD7985BCPZ-RL7 contains an internal conversion clock and does not require an external clock source for the sampling or conversion process. The SCK signal is used solely for serial data readout and has no effect on conversion timing. Conversion is initiated by the rising edge of the CNV signal, and the result becomes available after a fixed tCONV delay (320 ns in turbo mode). This architecture eliminates clock distribution challenges and jitter sensitivity in high-precision systems using the AD7985BCPZ-RL7.
Can the AD7985BCPZ-RL7 operate with an external reference, and what are the voltage limits?
Yes, the AD7985BCPZ-RL7 supports external reference operation when PDREF is driven high. In this configuration, the REF pin accepts a reference voltage from 2.4 V to 5.1 V, and the REFIN pin must be driven to approximately 1.2 V. The device draws up to 500 µA from the external reference source. Using an external reference improves SNR to 90 dB and reduces drift dependency - critical for applications where the AD7985BCPZ-RL7 must maintain accuracy across wide temperature ranges or long-term deployments.
How does the daisy-chain interface work on the AD7985BCPZ-RL7?
The AD7985BCPZ-RL7 supports daisy-chain mode when SDI is low during the CNV rising edge. In this configuration, the SDO output of one AD7985BCPZ-RL7 drives the SDI input of the next device, allowing multiple converters to share a single SCK and CNV line. Each device shifts its 16-bit result onto the chain with a 16-SCK-cycle delay, enabling synchronized multi-channel capture without additional chip-select lines. The busy indicator is not available in chain mode, and all devices must use identical TURBO and VIO settings for reliable operation.
What is the purpose of the separate REFGND pins on the AD7985BCPZ-RL7?
The AD7985BCPZ-RL7 features dedicated REFGND (pins 3 and 4) to isolate reference circuitry ground return from analog and digital grounds. This separation prevents noise from AVDD switching or digital I/O activity from modulating the reference voltage - a key factor in maintaining ±0.7 LSB INL and 88.5 dB SNR. REFGND must be connected to a quiet ground plane and decoupled locally to REF with a 10 µF capacitor; mixing REFGND with AGND or DGND degrades ac performance and introduces code-dependent errors in the AD7985BCPZ-RL7.
AD7985BCPZ-RL7 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- PulSAR®
- Package/Case:
- 20-WFQFN Exposed Pad, CSP
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Number of Bits:
- 16
- Sampling Rate (Per Second):
- 2.5M
- Number of Inputs:
- 1
- Input Type:
- Pseudo-Differential
- Data Interface:
- SPI, DSP
- Configuration:
- S/H-ADC
- Ratio - S/H:ADC:
- 1:1
- Number of A/D Converters:
- 1
- Architecture:
- SAR
- Reference Type:
- External, Internal
- Voltage - Supply, Analog:
- 2.375V ~ 2.625V
- Voltage - Supply, Digital:
- 2.375V ~ 2.625V
- Features:
- -
- Operating Temperature:
- -40°C ~ 85°C
- Supplier Device Package:
- 20-LFCSP (4x4)
- Mounting Type:
- Surface Mount
- Grade:
- -
- Qualification:
- -
AD7985BCPZ-RL7 FAQ
1.How can I place an order for AD7985BCPZ-RL7 through Aetrix?
Please submit a Request for Quotation (RFQ) for AD7985BCPZ-RL7 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 AD7985BCPZ-RL7 reliable?
The price and inventory of AD7985BCPZ-RL7 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for AD7985BCPZ-RL7 is usually 5 days.
3.What payment methods are accepted for AD7985BCPZ-RL7?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for AD7985BCPZ-RL7 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for AD7985BCPZ-RL7?
AD7985BCPZ-RL7 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your AD7985BCPZ-RL7 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 AD7985BCPZ-RL7?
For technical support, including AD7985BCPZ-RL7 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your AD7985BCPZ-RL7 requirements.
6.How does Aetrix verify that AD7985BCPZ-RL7 is sourced from the original manufacturer or authorized distributors?
All AD7985BCPZ-RL7 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 AD7985BCPZ-RL7 meets industry standards.
7.What is the process for return or replacement of AD7985BCPZ-RL7?
All AD7985BCPZ-RL7 units undergo pre-shipment inspection (PSI). If there is an issue with AD7985BCPZ-RL7, 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 AD7985BCPZ-RL7 part is unused and in its original packaging.
Return procedure for AD7985BCPZ-RL7:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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