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Analog Devices Inc. AD7678ACPZ
- Part No.:
- AD7678ACPZ
- Manufacturer:
- Analog Devices Inc.
- Category:
- Analog to Digital Converters (ADC)
- Package:
- 48-VFQFN Exposed Pad, CSP
- Datasheet:
-
AD7678ACPZ.pdf
- Description:
- IC ADC 18BIT SAR 48LFCSP
- Quantity:
- Payment:
- Shipping:
Inventory:4,264
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Product details
Overview
AD7678ACPZ from Analog Devices is an 18-bit, 100 kSPS charge redistribution SAR analog-to-digital converter with ±2.5 LSB INL, differential ±VREF input (up to 5 V), and dual serial/parallel interface. It operates on a single 5 V supply, delivers 103 dB dynamic range at 5 V reference, and targets high-accuracy data acquisition in medical CT scanners and geophone sensor systems.
For engineers reviewing the AD7678ACPZ datasheet, AD7678ACPZ pinout, AD7678ACPZ application, or AD7678ACPZ equivalent, this page provides verified technical context, real-world interface timing constraints, package-specific thermal behavior, and validated alternative options for precision SAR ADC selection in industrial and medical instrumentation.
Technical Context
The AD7678ACPZ implements a fully differential switched-capacitor SAR architecture with no pipeline delay, enabling immediate conversion result availability after CNVST assertion. Its internal calibration circuitry corrects for capacitor mismatch, achieving ±2.5 LSB INL across –40°C to +85°C without missing codes.
It supports three parallel bus widths (18-/16-/8-bit) and SPI/QSPI/MICROWIRE-compatible serial modes via MODE0/MODE1 configuration. The on-chip reference buffer accepts 2.5 V at REFBUFIN and outputs 4.096 V at REF, eliminating external buffer requirements for precision applications.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Resolution | 18-bit with no missing codes - guarantees monotonicity and full-scale code coverage for metrology-grade measurement. |
| Throughput Rate | 100 kSPS - enables real-time capture of 45 kHz bandwidth signals per Nyquist criterion with margin. |
| INL | ±2.5 LSB max (±9.5 ppm FS) - ensures <0.001% absolute linearity error over full temperature range. |
| Differential Input Range | ±VREF, VREF up to 5 V - supports direct connection to precision voltage references or transformer-coupled sensors. |
| Dynamic Range | 103 dB typ @ VREF = 5 V - allows detection of 105:1 signal amplitude ratios, critical for seismic and medical imaging. |
| Power Dissipation | 18 mW @ 100 kSPS, 180 µW @ 1 kSPS - enables low-power operation in battery-backed or thermally constrained systems. |
| Aperture Jitter | 5 ps rms - limits SNR degradation to <0.1 dB at 10 kHz input, preserving ENOB >16.2 bits. |
Pinout & Package
AD7678ACPZ is available in a 48-lead LFCSP (CP-48-4) package with exposed pad internally connected to AGND. Thermal resistance θJA = 26°C/W enables high-density PCB layouts without forced airflow.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| IN+, IN– | Differential analog inputs | Accept ±VREF fully differential signal; CMRR ≥65 dB at 100 kHz reduces common-mode noise coupling. |
| REF, REFGND | Reference input terminals | Support external 3–5.25 V reference or internal buffered 4.096 V output; REFGND must be star-connected to AGND. |
| CNVST | Conversion start trigger | Falling-edge sensitive; initiates sample/hold hold phase and conversion-timing-critical for synchronous sampling. |
| BUSY | Conversion status indicator | Active-HIGH pulse (1.5 µs min) signals ongoing conversion; falling edge serves as hardware data-ready strobe. |
| MODE0, MODE1 | Interface mode select | Configure 18-bit/16-bit/8-bit parallel or serial mode; determines D[0:17] pin function and bus timing protocol. |
| PDBUF | Reference buffer enable | LOW enables internal 4.096 V buffer from 2.5 V REFBUFIN; HIGH disables buffer for external reference use. |
| SDOUT, SCLK, SYNC | Serial interface outputs | Support master/slave SPI-compatible readout; SDOUT outputs MSB-first 18-bit data synchronized to SCLK edges. |
Key Features
| Feature | Design Value |
|---|---|
| No pipeline delay | SAR architecture delivers conversion result immediately post-BUSY LOW-enables deterministic latency for closed-loop control. |
| On-board reference buffer | Fixed-gain buffer accepts 2.5 V at REFBUFIN and outputs stable 4.096 V at REF, reducing BOM count and layout sensitivity. |
| Flexible digital interface | Configurable 18-/16-/8-bit parallel or 2-wire serial (SPI/QSPI/MICROWIRE) supports legacy microcontrollers and modern FPGAs. |
| Low power scaling | 180 µW at 1 kSPS enables duty-cycled operation in portable instrumentation without sacrificing resolution. |
| High CMRR | 65 dB at 100 kHz suppresses EMI-induced errors in noisy industrial environments with long sensor cables. |
Applications
| CT Scanners | Geophone Sensor Arrays |
|---|---|
Use Scenario: Digitizing X-ray detector current outputs in multi-slice computed tomography systems requiring sub-0.001% linearity over temperature. IC Role / Device Role / Timing Role: Primary SAR ADC capturing 100 kSPS differential signals from low-noise transimpedance amplifiers with precise aperture timing. Use Value: 103 dB dynamic range resolves weak tissue contrast against strong bone signals; ±2.5 LSB INL ensures quantitative Hounsfield unit accuracy. |
Use Scenario: High-channel-count seismic data acquisition where 18-bit resolution captures microvolt-level ground motion across wide bandwidth. IC Role / Device Role / Timing Role: Precision ADC front-end in distributed sensor nodes, interfacing directly to piezoelectric geophone outputs with differential input rejection. Use Value: 5 ps aperture jitter preserves SNR at 45 kHz bandwidth; low 18 mW power enables dense channel packing in remote field units. |
| Medical Instrumentation | Spectrum Analysis Equipment |
Use Scenario: Electroencephalography (EEG) and electrophysiology systems demanding ultra-low THD (–118 dB) and missing-code-free operation. IC Role / Device Role / Timing Role: High-fidelity signal digitizer for biopotential amplifiers, using internal reference buffer to eliminate external op-amp drift sources. Use Value: –118 dB THD at 2 kHz prevents harmonic contamination of neural waveforms; 18-bit no-missing-codes guarantees diagnostic integrity. |
Use Scenario: Real-time RF spectrum analyzers requiring 100 dB SFDR and fast throughput to resolve adjacent-channel interference. IC Role / Device Role / Timing Role: Baseband ADC in IF sampling architectures, leveraging parallel 18-bit interface for DMA-driven high-speed data streaming to FPGA. Use Value: 120 dB SFDR at 2 kHz rejects spurious tones from local oscillators; 100 kSPS throughput supports 50 kHz analysis bandwidth with oversampling. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar high-resolution SAR ADC applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| AD7679ACPZ | Same 18-bit/100 kSPS SAR core but with extended –40°C to +105°C operating range and improved gain error drift (±1.2 ppm/°C vs. ±1.6 ppm/°C). | Required for automotive under-hood or industrial high-temp environments where AD7678ACPZ's +85°C limit is insufficient. | Select AD7679ACPZ when ambient temperature exceeds +85°C; otherwise AD7678ACPZ offers identical performance at lower cost. |
| AD7674ACPZ | Pin-to-pin compatible predecessor with identical 48-lead LFCSP package but higher 3.5 LSB INL (vs. 2.5 LSB) and 105 mW power at 100 kSPS. | Legacy designs where minor linearity degradation is acceptable and existing layout cannot accommodate newer thermal profile. | Choose AD7674ACPZ only for backward compatibility; AD7678ACPZ provides superior linearity and 43% lower power with no PCB changes. |
Compared with AD7679ACPZ, AD7678ACPZ trades extended temperature range for lower cost and identical core accuracy; versus AD7674ACPZ, it delivers tighter INL and 43% power reduction while maintaining pin compatibility-making it the optimal upgrade path for new designs targeting medical and test equipment.
Availability
AD7678ACPZ is available at Aetrix Electronics and suitable for CT scanner subsystems, geophone data loggers, and medical EEG equipment requiring stable component supply with guaranteed long-term manufacturability.
Supply support for AD7678ACPZ 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, headquartered in Norwood, MA.
The AD7678ACPZ belongs to Analog Devices' PulSAR® family of precision SAR ADCs, designed specifically for applications demanding high resolution, low latency, and excellent DC/AC accuracy without pipeline delay.
FAQ
What is the maximum recommended reference voltage for AD7678ACPZ?
The AD7678ACPZ supports an external reference voltage up to 5 V at the REF pin. When using the internal reference buffer, apply 2.5 V to REFBUFIN to generate a precise 4.096 V output at REF. Exceeding 5 V on REF risks violating absolute maximum ratings and may cause permanent damage to the AD7678ACPZ.
Does AD7678ACPZ require separate analog and digital ground planes?
Yes, AD7678ACPZ requires physically separated AGND and DGND planes, tied together at a single point near the device. The datasheet specifies ±0.3 V maximum ground potential difference between AGND, DGND, and OGND. Improper grounding causes increased noise and degrades the AD7678ACPZ's 103 dB dynamic range performance.
Can AD7678ACPZ operate with a 3 V digital interface while using 5 V analog supply?
Yes, AD7678ACPZ supports mixed-voltage operation: AVDD and DVDD at 5 V, while OVDD can be set to 3 V to interface with 3 V logic systems. The serial interface remains SPI-compatible, and the parallel bus operates correctly when MODE0/MODE1 configure appropriate data width-ensuring full functionality of the AD7678ACPZ in hybrid-voltage systems.
What is the purpose of the PDBUF pin on AD7678ACPZ?
The PDBUF pin on AD7678ACPZ controls the internal reference buffer: driving it LOW enables the buffer (outputting 4.096 V from 2.5 V at REFBUFIN), while driving it HIGH disables the buffer for direct external reference use. This flexibility allows the AD7678ACPZ to support both buffered and unbuffered reference configurations without external components.
How does the BUSY signal behave during conversion on AD7678ACPZ?
On AD7678ACPZ, the BUSY signal transitions HIGH upon CNVST assertion and remains HIGH for 1.5 µs minimum until conversion completes and data is latched. Its falling edge is synchronized to internal timing and can serve as a hardware data-ready strobe for DMA or FPGA capture-eliminating software polling overhead in time-critical applications.
AD7678ACPZ Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- PulSAR®
- Package/Case:
- 48-VFQFN Exposed Pad, CSP
- Packaging:
- Tray
- Product Status:
- Active
- Number of Bits:
- 18
- Sampling Rate (Per Second):
- 100k
- Number of Inputs:
- 1
- Input Type:
- Differential
- Data Interface:
- SPI, Parallel, 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:
- 5V
- Voltage - Supply, Digital:
- 5V
- Features:
- -
- Operating Temperature:
- -40°C ~ 85°C
- Supplier Device Package:
- 48-LFCSP-VQ (7x7)
- Mounting Type:
- Surface Mount
- Grade:
- -
- Qualification:
- -
AD7678ACPZ FAQ
1.How can I place an order for AD7678ACPZ through Aetrix?
Please submit a Request for Quotation (RFQ) for AD7678ACPZ 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 AD7678ACPZ reliable?
The price and inventory of AD7678ACPZ are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for AD7678ACPZ is usually 5 days.
3.What payment methods are accepted for AD7678ACPZ?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for AD7678ACPZ transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for AD7678ACPZ?
AD7678ACPZ orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your AD7678ACPZ 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 AD7678ACPZ?
For technical support, including AD7678ACPZ datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your AD7678ACPZ requirements.
6.How does Aetrix verify that AD7678ACPZ is sourced from the original manufacturer or authorized distributors?
All AD7678ACPZ 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 AD7678ACPZ meets industry standards.
7.What is the process for return or replacement of AD7678ACPZ?
All AD7678ACPZ units undergo pre-shipment inspection (PSI). If there is an issue with AD7678ACPZ, 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 AD7678ACPZ part is unused and in its original packaging.
Return procedure for AD7678ACPZ:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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