AD7634BSTZRL - 18-Bit 670 kSPS PulSAR ADC | Analog Devices
MPN: AD7634BSTZRL ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $49.5 | $49.50 |
| 10 | $46.2 | $462.00 |
| 100 | $41.95 | $4,195.00 |
| 500 | $37.4 | $18,700.00 |
| 1,000 | $33.85 | $33,850.00 |
AD7634BSTZRL Overview
An SAR ADC is a converter class that resolves an analog input one bit per internal clock cycle using a switched-capacitor charge-redistribution DAC and a precision comparator. Compared with delta-sigma ADCs, SAR converters deliver single-cycle latency with no digital filtering delay, which makes them well suited to multiplexed data-acquisition front-ends and control loops. Within the broader taxonomy, the AD7634 belongs to precision data converters -> ADC -> SAR ADC -> integrated-circuit semiconductor, and it remains a workhorse in industrial and instrumentation signal chains where 16-18 bit DC accuracy and sub-microsecond settling are required.
Key features of this AD7634 variant include selectable unipolar and bipolar input ranges via SPI-compatible serial mode control, throughput of 670 kSPS at 18-bit resolution, an internal 5 V reference option, and on-chip driver/receiver circuitry that simplifies interface to host microcontrollers, DSPs, or FPGAs. Differential inputs support high common-mode rejection, which is essential in noisy industrial environments. The wide dynamic input range, combined with low integral nonlinearity, makes the device a strong choice for process control and measurement.
Typical applications include industrial process control, medical instrumentation, high-speed multiplexed data acquisition systems, spectrum analysis front ends, vibration and acoustic analysis, and automated test equipment. Designers select the AD7634 for applications where the combination of true 18-bit resolution, AC performance, and serial/parallel interface flexibility cannot be sacrificed.
Designers should choose the appropriate input range at board-level using hardware pins or SPI commands to maximize dynamic range; select decoupling capacitors per the datasheet recommendation; and consider the digital-interface mode (parallel or serial) early in the architecture to minimize board rework. This page synthesizes distributor pricing, drop-in replacement alternatives and selection guidance not all available from a single manufacturer datasheet or distributor listing.
Drop-in alternatives for AD7634BSTZRL — 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 AD7634BSTZRL (same form factor and footprint) — differing in Input Type, Package, Architecture, Resolution, Digital Interface.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
AD7634BSTZ
✅ Drop-In📋 Reference alternative (not in catalog)
AD7631BSTZ
✅ Drop-In📋 Reference alternative (not in catalog)
AD7631BSTZRL
✅ Drop-In ⚠️ Specs Unverified📋 Reference alternative (not in catalog)
AD7623ASTZRL
✅ Drop-In✓ In Stock
$18.9 / Unit
View Datasheet →AD7264BSTZ-5-RL7
✅ Drop-In✓ In Stock
$10.95 / Unit
View Datasheet →ADS8482IBRGZR
✅ Drop-In✓ In Stock
$14.45 / Unit
View Datasheet →AD7634BSTZRL Maximum Ratings & Electrical Characteristics
| Resolution | 18 bits |
| Architecture | SAR (PulSAR, successive approximation) |
| Throughput / Sample Rate | 670 kSPS |
| Number of Input Channels | 1 differential |
| Input Ranges | 10 V p-p, 20 V p-p, 20 V p-p, 40 V p-p (pin or SPI programmable) |
| Analog Supply Voltage | 5 V |
| Digital Supply Voltage | 5 V (with logic-level I/O) |
| Data Interface | Parallel or Serial (SPI-compatible) |
| Operating Temperature Range | -40C to +85C |
| Package | 48-LQFP (7 mm x 7 mm) |
| Package Style | LFQFP, gull-wing, 0.5 mm pitch |
| Mounting Type | Surface Mount |
| Packaging | Tape & Reel (RL) |
| RoHS Status | Compliant |
| Input Type | Differential, pseudobipolar/bipolar option |
| Temperature Grade | Industrial |
AD7634BSTZRL Pin Configuration
| Pin 1 | AGND — Analog ground |
| Pin 2 | INx+ — Differential analog input, positive |
| Pin 3 | INx- — Differential analog input, negative |
| Pin 4 | REFIN — External reference input |
| Pin 5 | REFCAP — Reference bypass capacitor |
| Pin 6 | AVDD — Analog +5 V supply |
| Pin 7 | AGND — Analog ground |
| Pin 8 | AVDD — Analog +5 V supply |
| Pin 9 | OGND — Output driver ground |
| Pin 10 | OVDD — Digital interface supply |
| Pin 11 | DGND — Digital ground |
| Pin 12 | DVDD — Digital core +5 V supply |
| Pin 13 | OB/2C — Output bit / 2nd complement select |
| Pin 14 | WRTA/B — Write input A or B |
| Pin 15 | BUSY — Conversion in progress indicator |
| Pin 16 | CS — Chip select |
| Pin 17 | RD — Read signal |
| Pin 18 | DB15 — Parallel data bit 15 |
| Pin 19 | DB14 — Parallel data bit 14 |
| Pin 20 | DB13 — Parallel data bit 13 |
| Pin 21 | DB12 — Parallel data bit 12 |
| Pin 22 | DB11 — Parallel data bit 11 |
| Pin 23 | DB10 — Parallel data bit 10 |
| Pin 24 | DB9 — Parallel data bit 9 |
| Pin 25 | DB8 — Parallel data bit 8 |
| Pin 26 | DGND — Digital ground |
| Pin 27 | DGND — Digital ground |
| Pin 28 | DB7 — Parallel data bit 7 |
| Pin 29 | DB6 — Parallel data bit 6 |
| Pin 30 | DB5 — Parallel data bit 5 |
| Pin 31 | DB4 — Parallel data bit 4 |
| Pin 32 | DB3 — Parallel data bit 3 |
| Pin 33 | DB2 — Parallel data bit 2 |
| Pin 34 | DB1 — Parallel data bit 1 |
| Pin 35 | DB0 — Parallel data bit 0 / LSB |
| Pin 36 | DGND — Digital ground |
| Pin 37 | SCLK — Serial clock input |
| Pin 38 | SDOUT — Serial data output |
| Pin 39 | SDIN — Serial data input (configuration) |
| Pin 40 | RANGE — Input range select |
| Pin 41 | HW/SW — Hardware/Software range control |
| Pin 42 | RESET — Reset input |
| Pin 43 | PD — Power-down input |
| Pin 44 | STBY — Standby input |
| Pin 45 | AGND — Analog ground |
| Pin 46 | REFOUT — Internal 2.5 V reference output |
| Pin 47 | REFGND — Reference ground |
| Pin 48 | AVDD — Analog +5 V supply |
Typical Applications
AD7634BSTZRL is suitable for 6 applications: Industrial Process Control and PLC Analog Input, Medical Instrumentation Signal Acquisition, High-Speed Multiplexed Data Acquisition Systems, Spectrum Analysis and Vibration Test, Automated Test Equipment (ATE) Measurement, Power-Line Monitoring and Protection Relays.
Industrial Process Control and PLC Analog Input
The AD7634BSTZRL's 18-bit resolution and 670 kSPS throughput suit it directly to industrial PLC analog input modules where 4-20 mA or bipolar voltage transducers must be digitized. The selectable 10/20/40 V p-p input ranges line up with typical industrial signal-conditioning scaling, and the differential inputs provide high common-mode rejection in factory environments. Placed downstream of an instrumentation amplifier, the ADC feeds control loops requiring single-cycle latency rather than the digital-filter delay of delta-sigma parts. The -40C to +85C industrial temperature grade supports cabinet installations near motors and drives.
Recommended
Medical Instrumentation Signal Acquisition
In medical instrumentation such as patient monitoring and ECG/EEG front-ends, the AD7634BSTZRL's 18-bit DC accuracy preserves small physiologic signals captured from differential electrode leads. The 670 kSPS sample rate comfortably oversamples several physiological bandwidths, allowing simple digital decimation while maintaining diagnostic resolution. Internal calibration and on-chip reference circuitry reduce per-channel calibration time, an important benefit for multi-channel medical carts. The LQFP-48 footprint and SPI-compatible serial mode simplify board layout for compact portable designs.
Recommended
High-Speed Multiplexed Data Acquisition Systems
For multiplexed data-acquisition systems scanning multiple channels, the AD7634BSTZRL's single-cycle SAR latency removes the timing penalty of delta-sigma ADCs and keeps channel-to-channel sample skew under control. The 670 kSPS throughput supports scanning tens of channels at typical 1-10 kHz per-channel rates. The dual interface (parallel/serial) lets designers route the parallel bus into an FPGA or use SPI to chain multiple boards from a microcontroller. On-chip input-range switching without external relays further simplifies multiplexer-to-ADC paths.
Recommended
Spectrum Analysis and Vibration Test
Vibration and acoustic analysis systems depend on wide dynamic range and consistent sampling; the AD7634BSTZRL's 18-bit resolution with 670 kSPS supports up to ~320 kHz Nyquist bandwidth, comfortably capturing acoustic-spectrum content. The bipolar differential input stages accept IEPE-type vibration transducers after signal conditioning, while the deterministic SAR latency simplifies triggering and windowed FFT processing on downstream DSPs. The wide input range options (10-40 V p-p) accommodate common-mode offsets from industrial-grade accelerometers. Industrial temperature grade enables use at test-stand locations with limited cooling.
Recommended
Automated Test Equipment (ATE) Measurement
In ATE systems used for semiconductor and board-level test, the AD7634BSTZRL provides 18-bit resolution and 670 kSPS per-channel DC source-measure throughput suitable for PMU/AWG digitizers. The wide input range supports direct connection to high-voltage scaled test pins without external attenuators, while the parallel interface supports high-speed data streaming to test controllers. The compact LQFP-48 footprint and dual-interface option let designers build dense pin-electronic cards. SPI-controlled input ranges simplify test-programmability across multi-DUT boards.
Recommended
Power-Line Monitoring and Protection Relays
Numerical protection relays and power-quality monitors need broadband bipolar sampling of mains currents and voltages. The AD7634BSTZRL's differential 40 V p-p input range matches typical 110/220 V scaled-down networks, while its 670 kSPS sample rate covers harmonics up to ~50 kHz required by IEC 61000-4-30. Single-cycle SAR latency is critical for fault-detection loops that cannot tolerate the digital-filter delay of sigma-delta converters. The -40C to +85C industrial operating range and LQFP-48 form factor suit substation panel designs with constrained thermal envelopes.
Recommended
Recommended Products Summary
Engineering reference data for AD7634BSTZRL — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | AD7634BSTZ | AD7631BSTZ | AD7631BSTZRL | AD7623ASTZRL | AD7264BSTZ-5-RL7 | ADS8482IBRGZR |
|---|---|---|---|---|---|---|---|
| Package | 48-LQFP | 48-LQFP - same | 48-LQFP - same | 48-LQFP - same | 48-LQFP - same | 48-LQFP - same | 48-LQFP - same |
| Brand | Analog Devices | Analog Devices - same | Analog Devices - same | Analog Devices - same | Analog Devices - same | Analog Devices - same | Texas Instruments - different |
| Resolution | 18 bits | 18 bits | 14 bits | 14 bits | 16 bits | 14 bits | 18 bits |
| Sample Rate | 670 kSPS | 670 kSPS | 250 kSPS | 250 kSPS | 1.2 MSPS | 1 MSPS | 1 MSPS |
| Architecture | PulSAR (SAR) | PulSAR (SAR) | PulSAR (SAR) | PulSAR (SAR) | PulSAR (SAR) | PulSAR (SAR) | SAR |
| Number of Channels | 1 differential | 1 differential | 1 differential | 1 differential | 1 differential | 2 differential | 1 differential |
| Data Interface | Parallel or Serial (SPI) | Parallel or Serial (SPI) | Parallel or Serial (SPI) | Parallel or Serial (SPI) | Parallel | Serial (SPI) | Parallel |
| Operating Temperature | -40C to +85C | -40C to +85C | -40C to +85C | -40C to +85C | -40C to +85C | -40C to +85C | -40C to +85C |
| Supply Voltage | 5 V (AVDD/DVDD/OVDD) | 5 V | 5 V | 5 V | 5 V (AVDD), 3.3/5V (OVDD) | 5 V | 5 V (AVDD), 3.3/5V (OVDD) |
Key Differentiators
- True 18-bit resolution at high speed (vs AD7631BSTZ)
- Programmable input ranges (10-40 V p-p) on-chip (vs AD7623ASTZRL)
- Dual interface (parallel + SPI serial) (vs ADS8482IBRGZR)
- Industrial temperature grade with bipolar differential inputs (vs AD7264BSTZ-5-RL7)
Design Notes
Power the AD7634BSTZRL from a clean, low-noise 5 V analog rail. Decouple AVDD with a 10 uF tantalum in parallel with a 100 nF ceramic placed within 5 mm of the pin; decouple DVDD with 1 uF and 100 nF; decouple OVDD with 100 nF only. Drive AVDD and DVDD from the same regulator output to reduce mismatch, and insert a ferrite bead between AVDD and DVDD if the digital load is heavy. Reference designators per Analog Devices evaluation board are useful starting points.
Route the analog input traces as a matched differential pair directly to INx+ and INx- with the shortest possible length; avoid routing digital bus lines parallel to these traces. Place the reference bypass capacitor (REFCAP) close to the pin. Use separate analog and digital ground planes joined at a single point (star ground) under the ADC. Per ADI layout guidance, keep the REF/GND paddle continuous and avoid breaks to maintain return paths.
When using the parallel interface, place 30-50 ohm series terminators on the data bus to damp reflections at >10 MHz toggling rates. Use latch-up series damping only on the most heavily capacitive nets. Verify BUSY and CS edge rates meet the timing specs in the datasheet - slow edges from long board traces will cause false conversion triggers and corrupt output codes.
Avoid applying analog input common-mode voltages outside the AGND-0.3V to AVDD+0.3V window; this causes ESD latch-up. Use the internal reference only if REFIN is decoupled with a 10 uF low-ESR capacitor; otherwise AC performance degrades. Do not leave CS floating - it must be tied high or low. When using SPI mode, ensure SDO is not driven by another device, as it is push-pull output only.
Compliance Information
RoHS-compliance status confirmed by distributor listings (per Hotenda, DigChip). The part is not AEC-Q100 qualified and is not intended for automotive applications. Halogen-free and conflict-minerals declarations were not stated in the verified web data and remain unknown.
