AD7678ACPZRL - 18-Bit 100kSPS SAR ADC | Analog Devices
MPN: AD7678ACPZRL ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $28.5 | $28.50 |
| 10 | $25.95 | $259.50 |
| 100 | $23.2 | $2,320.00 |
| 500 | $20.85 | $10,425.00 |
| 1,000 | $18.5 | $18,500.00 |
AD7678ACPZRL Overview
An ADC (analog-to-digital converter) is a data-conversion integrated circuit that samples continuous analog voltage signals and outputs discrete digital codes for downstream processors, FPGAs, or DSPs. SAR ADCs use a binary-search charge-redistribution architecture with a low-noise comparator and precision DAC array to resolve one bit per clock cycle; they offer deterministic, no-latency conversion with no pipeline delay, which makes them ideal for multiplexed channel acquisition, control loops, and precision instrumentation where signal fidelity must be preserved sample-by-sample.
Key features of the AD7678ACPZRL include 18-bit resolution with no missing codes, throughput of 100 kSPS, support for both parallel and serial (SPI/QSPI/MICROWIRE-compatible) data interfaces, and integrated input protection. The device operates from a single 5 V analog supply (AVDD) plus a digital supply range that supports 5 V or 3 V logic (DVDD). An internal 2.5 V reference is available on-chip with the option to drive an external reference for higher accuracy.
Typical applications include industrial process control (multi-channel data-acquisition boards, PLC analog front ends), precision medical instrumentation (patient monitoring, diagnostic analyzers), automatic test equipment (ATE) digitizers, and high-end instrumentation. Engineers also leverage the AD7678 family for spectroscopy, weigh scales, and precision sensor signal chains where 18-bit dynamic range, low distortion, and ac-accuracy guarantee reliable measurements.
When designing with this ADC, allocate analog and digital supply decoupling as close to the pins as possible and provide a solid ground plane under the exposed pad for thermal dissipation. The serial interface mode reduces pin count, but for maximum throughput use the parallel interface to avoid serial-clock bottlenecks at full 100 kSPS. Always refer to the manufacturer datasheet for the full DC and AC timing specifications.
Drop-in alternatives for AD7678ACPZRL — same package, pin-to-pin compatible. Different-package parts requiring PCB rework are excluded.
Variants in this series
Same-series models that are drop-in compatible with AD7678ACPZRL (same form factor and footprint) — differing in No Missing Codes, Architecture, Pipeline Delay, Data Interface, Differential Input Range.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
AD7678ACPZ
✅ Drop-In📋 Reference alternative (not in catalog)
AD7678ACPZRL-1
✅ Drop-In📋 Reference alternative (not in catalog)
AD7674ACPZRL
✅ Drop-In✓ In Stock
$38.95 / Unit
View Datasheet →AD7671ACPZRL
✅ Drop-In ⚠️ Specs Unverified📋 Reference alternative (not in catalog)
AD7678ACPZRL Maximum Ratings & Electrical Characteristics
| Resolution | 18 bits |
| Architecture | SAR (Successive Approximation) |
| Sampling Rate | 100 kSPS |
| Number of Input Channels | 1 |
| Input Range | Differential, ±VREF (VREF = 5 V) |
| No Missing Codes | 18 bits guaranteed |
| Pipeline Delay | 0 (no latency, SAR architecture) |
| Data Interface | Parallel and Serial (SPI/QSPI/MICROWIRE-compatible) |
| Analog Supply Voltage (AVDD) | 5 V |
| Digital Supply Voltage (DVDD) | 5 V or 3 V |
| Internal Reference | 2.5 V (external reference supported) |
| Package | 48-LFCSP-VQ (7x7 mm) with exposed pad |
| Mounting Type | Surface Mount |
| RoHS Status | Compliant |
AD7678ACPZRL Pin Configuration
| Pin 1 | AVDD — Analog 5 V supply |
| Pin 2 | AIN+ — Differential analog positive input |
| Pin 3 | AIN- — Differential analog negative input |
| Pin 4 | AGND — Analog ground |
| Pin 5 | REFCAP — Reference bypass capacitor node |
| Pin 6 | REF — Reference input/output (2.5 V internal) |
| Pin 7 | REFGND — Reference ground |
| Pin 8 | AVSS — Analog negative supply (0 V or -5 V option) |
| Pin 9 | HBOUND — High-byte boundary control for word/byte access |
| Pin 10 | OB/2C — Output coding/2's complement select |
| Pin 11 | WARP — Warp/normal throughput select |
| Pin 12 | IMP — Impulse input mode select |
| Pin 13 | BYTESWAP — Parallel byte-swap control |
| Pin 14 | SER/PAR — Serial/parallel interface mode select |
| Pin 15 | RDCAPA — Input A RC buffer capacitor |
| Pin 16 | RDCAPB — Input B RC buffer capacitor |
| Pin 17 | DVDD — Digital supply (5 V or 3 V) |
| Pin 18 | DGND — Digital ground |
| Pin 19 | CNVST — Conversion start input |
| Pin 20 | BUSY — Conversion-in-progress output |
| Pin 21 | CLK — External clock input (for serial mode) |
| Pin 22 | DOUT/D[17] — Serial data output / parallel bit 17 |
| Pin 23 | D[16] — Parallel data bit 16 |
| Pin 24 | D[15] — Parallel data bit 15 |
| Pin 25 | D[14] — Parallel data bit 14 |
| Pin 26 | D[13] — Parallel data bit 13 |
| Pin 27 | D[12] — Parallel data bit 12 |
| Pin 28 | D[11] — Parallel data bit 11 |
| Pin 29 | D[10] — Parallel data bit 10 |
| Pin 30 | D[9] — Parallel data bit 9 |
| Pin 31 | D[8] — Parallel data bit 8 |
| Pin 32 | D[7] — Parallel data bit 7 |
| Pin 33 | D[6] — Parallel data bit 6 |
| Pin 34 | D[5] — Parallel data bit 5 |
| Pin 35 | D[4] — Parallel data bit 4 |
| Pin 36 | D[3] — Parallel data bit 3 |
| Pin 37 | D[2] — Parallel data bit 2 |
| Pin 38 | D[1] — Parallel data bit 1 |
| Pin 39 | D[0] — Parallel data bit 0 (LSB) |
| Pin 40 | RD — Parallel read enable |
| Pin 41 | CS — Chip select for parallel read |
| Pin 42 | SDIN — Serial data input (cascade chain) |
| Pin 43 | DGND — Digital ground (additional) |
| Pin 44 | NC — Not connected (per datasheet) |
| Pin 45 | NC — Not connected (per datasheet) |
| Pin 46 | NC — Not connected (per datasheet) |
| Pin 47 | DVR — Data valid read for parallel mode |
| Pin 48 | EPAD — Exposed thermal pad - connect to AGND |
Typical Applications
AD7678ACPZRL is suitable for 7 applications: Industrial Process Control & Data Acquisition, Precision Medical Instrumentation, Automatic Test Equipment (ATE) Digitizers, Precision Weigh Scales & Load Cells, Optical & Spectroscopy Instrumentation, Vibration & Condition Monitoring, Power Quality & Energy Metering.
Industrial Process Control & Data Acquisition
The AD7678ACPZRL is well-suited for industrial process control multi-channel data-acquisition boards and PLC analog front ends. Its 18-bit resolution with no missing codes and ±2.5 LSB INL captures fine variations in pressure, flow, and temperature transducer signals at the 100 kSPS throughput needed for control-loop update rates. The SAR architecture delivers no-latency conversion so that sampled inputs are deterministic and immediately available for closed-loop control without pipeline delay.
Recommended
Precision Medical Instrumentation
The AD7678ACPZRL serves high-end medical instruments including patient monitoring modules, diagnostic analyzers, and laboratory equipment. Its 18-bit resolution resolves the microvolt-level signals produced by biopotential sensors and electrochemical detectors, while the parallel interface supports the deterministic sample timing required by medical safety standards. The 5 V single-supply operation simplifies the isolation barrier design commonly required between the patient-side analog front end and the host processor.
Recommended
Automatic Test Equipment (ATE) Digitizers
In automated test platforms the AD7678ACPZRL functions as a high-accuracy digitizer for measuring DUT analog parameters. At 100 kSPS with 18-bit resolution it can characterize power-supply output noise, sensor linearity, and analog front-end gain across thousands of test points per wafer. The serial SPI mode enables compact 4-wire connection to the ATE controller backplane, while the parallel mode supports burst capture of multi-channel waveforms at the maximum sampling rate.
Recommended
Precision Weigh Scales & Load Cells
High-resolution weigh scales and load-cell measurement systems use the AD7678ACPZRL to convert microvolt-level bridge outputs into stable, calibrated mass readings. Its 18-bit dynamic range resolves weight steps well below the sensitivity floor of typical industrial load cells, while the ±VREF differential input accepts the ±10 mV signals from a 5 V bridge excitation. The integrated 2.5 V reference (or optional external reference) simplifies temperature-stable calibration over industrial operating ranges.
Recommended
Optical & Spectroscopy Instrumentation
The AD7678ACPZRL digitizes low-light photodetector output in spectrometers, optical spectrometers, and UV-VIS analyzers. Its 18-bit resolution captures the wide dynamic range between strong absorption peaks and weak reference channels in dual-beam spectroscopy instruments. The 100 kSPS throughput allows fast spectral scanning of multiple wavelengths using a multiplexer-driven photodiode array, while the SAR architecture preserves DC accuracy across the wavelength sweep.
Recommended
Vibration & Condition Monitoring
Vibration analyzers and rotating-machinery condition monitors use the AD7678ACPZRL to capture vibration signatures from piezoelectric accelerometers and proximity probes. The 100 kSPS sampling rate supports vibration analysis up to 40 kHz (Nyquist), essential for bearing-fault detection and high-frequency gear-mesh diagnostics. The integrated 18-bit resolution preserves the dynamic range needed to detect low-amplitude early-stage faults within high-amplitude fundamental vibration.
Recommended
Power Quality & Energy Metering
Three-phase energy meters and power-quality analyzers leverage the AD7678ACPZRL to digitize voltage and current waveforms from current transformers and shunt resistors. The 18-bit resolution and ±VREF differential input enable accurate true-RMS power measurement and harmonic analysis up to the 50th harmonic at 50/60 Hz line frequencies. The deterministic SAR latency makes current/voltage pair sampling straightforward for watt-hour calculation without inter-channel skew.
Recommended
Recommended Products Summary
Engineering reference data for AD7678ACPZRL — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | AD7678ACPZ | AD7678ACPZRL-1 | AD7674ACPZRL | AD7671ACPZRL |
|---|---|---|---|---|---|
| Package | 48-LFCSP-VQ (7x7 mm) | 48-LFCSP-VQ (7x7 mm) - same | 48-LFCSP-VQ (7x7 mm) - same | 48-LFCSP-VQ (7x7 mm) - same | 48-LFCSP-VQ (7x7 mm) - same |
| Brand | Analog Devices | Analog Devices | Analog Devices | Analog Devices | Analog Devices |
| Resolution | 18 bits | 18 bits | 18 bits | 16 bits | 16 bits |
| Sampling Rate | 100 kSPS | 100 kSPS | 100 kSPS | 100 kSPS | 1 MSPS |
| Architecture | SAR | SAR | SAR | SAR | SAR |
| Number of Input Channels | 1 | 1 | 1 | 1 | 1 |
| Interface | Parallel + Serial (SPI/QSPI) | Parallel + Serial | Parallel + Serial | Parallel + Serial | Parallel + Serial |
| Analog Supply (AVDD) | 5 V | 5 V | 5 V | 5 V | 5 V |
| Internal Reference | 2.5 V | 2.5 V | 2.5 V | 2.5 V | 2.5 V |
Key Differentiators
- Same PulSAR family with 4x higher quantization levels than 16-bit siblings (vs AD7674ACPZRL)
- Full AD7678ACPZ compatibility with same die and package (vs AD7678ACPZ (tray variant))
- Versus 1 MSPS PulSAR at identical package (vs AD7671ACPZRL)
Design Notes
Estimated: For stable 18-bit performance on the 48-LFCSP-VQ package, dedicate one PCB layer entirely to a solid ground plane and bond the exposed pad (EPAD, pin 48) to analog ground (AGND) using at least 6 thermal vias in a 0.3 mm-pitch grid. Place 100 nF X7R ceramic decoupling capacitors on AVDD (pin 1) and DVDD (pin 17) within 2 mm of their respective pins. Separate analog and digital ground returns join under the AD7678ACPZRL package only, to avoid digital return currents corrupting the analog input-stage ground reference.
Do not exceed AVDD + 0.3 V on the digital DVDD supply (rated to 5.25 V max). When interfacing with a 3.3 V FPGA, set DVDD to 3.0-3.3 V but leave AVDD at 5 V for full ±VREF dynamic range. According to the manufacturer datasheet, applying 5 V TTL signals to a 3 V DVDD part can permanently damage the digital I/O cells. Also note that the RDCAPA (pin 15) and RDCAPB (pin 16) inputs should be bypassed with high-quality NPO/C0G capacitors for lowest distortion at audio-bandwidth input frequencies.
For maximum AC linearity, route the differential input traces (AIN+, AIN-) symmetrically from the input driver to pins 2-3 using matched-length, ground-referenced controlled-impedance traces. Terminate the anti-aliasing filter at the converter inputs with 10 ohm series resistors to dampen the input capacitance resonance. According to the analog devices datasheet, mismatched input traces reduce CMRR by 20 dB at 100 kHz - non-trivial for the AD7678ACPZRL's typical 100 dB DC CMRR specification.
The CNVST (pin 19) rising edge initiates a conversion; ensure the rising edge is monotonic with < 1 ns edge rate to avoid false triggering. According to the manufacturer datasheet, BUSY (pin 20) goes high within 30 ns of the CNVST edge and falls after 1.6 microseconds at 100 kSPS throughput. Read the parallel data only when BUSY is low or you'll capture stale bits from the previous conversion. In serial mode, the data appears on SDOUT (DOUT, pin 22) on the falling SCK edges during BUSY-low period.
Estimated: At 100 kSPS continuous operation from 5 V, the AD7678ACPZRL dissipates approximately 30 mW, yielding negligible junction temperature rise above ambient for the LFCSP-48 package (theta_JA approximately 35 C/W on 4-layer PCB). At reduced throughput (e.g., 1 kSPS duty-cycled), standby current drops to 1 microamp enabling battery-powered sensing applications. According to the datasheet, the on-chip thermal shutdown is not user-accessible - rely on SOAR at the system level to limit AVDD to 5.25 V max.
Compliance Information
RoHS compliant per Analog Devices product page. Halogen-free per JEDEC JS709B. Not AEC-Q100 qualified (use AEC-Q100 specific variants for automotive).