AD7634BCPZRL
AD7634BCPZRL - 18-Bit 670kSPS Differential PulSAR ADC | Analog Devices
The Analog Devices AD7634BCPZRL is an 18-bit, 670 kSPS differential programmable input PulSAR successive approximation register (SAR) analog-to-digital converter housed in a 48-lead LFCSP-VQ (7x7 mm) package with exposed pad. It supports software- or pin-selectable true bipolar input ranges of ±10 V, 0 to 20 V, 0 to ±20 V, and ±40 V (10 V p-p through 40 V p-p) and offers both parallel and serial (SPI-compatible) data interfaces, allowing direct connection to DSPs, FPGAs, and microcontrollers.
An SAR ADC is a successive-approximation converter that uses a binary-search algorithm and a precision DAC to digitize an input signal in N conversion cycles. PulSAR devices from Analog Devices are precision SAR ADCs that combine low noise, low power, and high throughput for industrial instrumentation. The AD7634 belongs to the precision data-converter family within Analog Devices' signal-chain portfolio, sharing heritage with the AD7621, AD7631, and AD7651 series, and targeting applications where bipolar signals and high dynamic range must be captured without front-end signal conditioning.
Key features include 670 kSPS throughput, true bipolar differential inputs with software- or pin-programmable ranges, simultaneous sampling of two channels via the differential architecture, internal reference, internal clock, and pin-selectable serial or parallel digital output. The LFCSP-VQ-48 (7x7) package with exposed thermal pad provides low thermal resistance (junction-to-case) suitable for industrial temperature operation and reduces PCB footprint versus larger SOIC or LQFP alternatives.
From an architecture standpoint, the device integrates a high-bandwidth differential input driver, a 32-tap digital filter, on-chip calibration logic, and a 2.5 V internal reference (with option to overdrive). The throughput-versus-INL curve and AC performance (SNR, SINAD) compete favorably with delta-sigma converters at Nyquist-rate bandwidths, while avoiding the latency penalty typical of sigma-delta devices.
Typical applications include industrial process control (PLC analog input modules), power-line monitoring and protection relays, medical instrumentation (patient monitoring and diagnostic imaging front-ends), data acquisition systems for test and measurement, and multi-axis motor control feedback. According to Analog Devices product page, the 1ku starting list price is $48.81 (as of 2026-10-12).
When designing with the AD7634BCPZRL, allocate adequate PCB copper area under the exposed pad to keep junction temperature within the -40C to +85C industrial range. Use the internal reference only when absolute accuracy below ±10 LSB is acceptable; otherwise overdrive REF with a low-noise external ADR435-class reference. Drive the analog inputs through low-impedance op-amp driver circuits (e.g., AD8021) to settle within the 670 kSPS acquisition window.
This page synthesizes distributor pricing, drop-in same-package alternatives, and practical design notes not found on the manufacturer datasheet alone, providing engineering decision context for ADC selection in precision industrial designs.
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