Analog Devices Inc. DC2222A-B

Overview

LTC2508-32 from Analog Devices is a 32-bit oversampling successive approximation register (SAR) analog-to-digital converter with integrated configurable digital filter, operating from a single 2.5V supply and supporting ±VREF differential input range up to 5.1V reference. It delivers dual simultaneous outputs: a 32-bit low-noise filtered code (145dB DR at 61sps) and a 22-bit no-latency composite code (14-bit differential + 8-bit common mode), targeting high-precision DC and low-frequency measurement systems in seismology and energy exploration.

For engineers reviewing the LTC2508-32 datasheet, LTC2508-32 pinout, LTC2508-32 application, or LTC2508-32 equivalent, key selection considerations include its 24-lead DFN package, pin-strappable down-sampling factors (256–16384), guaranteed 32-bit no-missing-codes performance, ±0.5ppm INL, and dual SPI-compatible serial interfaces (SDOA/SDOB) with independent clocking and data-ready signaling.

Technical Context

The LTC2508-32 employs a 32-bit charge redistribution SAR core followed by a programmable decimating lowpass digital filter, enabling dynamic range scaling from 131dB at 3.9ksps to 145dB at 61sps via four pin-selectable down-sampling ratios. Its dual-output architecture separates high-precision filtered data (SDOA) from real-time 22-bit composite data (SDOB), each with dedicated serial interface (SCKA/SCKB), read-enable (RDLA/RDLB), and data-ready (DRL/BUSY) signals.

It supports wide analog input common-mode range (0V to VREF), operates with VREF from 2.5V to 5.1V, and features 1.8V–5V SPI-compatible I/O (OVDD). Synchronization across multiple devices is achieved via the SYNC pin, while anti-aliasing requirements are relaxed by the on-chip digital filtering.

Key Specifications

Pinout & Package

24-lead (7mm × 4mm) plastic DFN package (DKD) with exposed pad (Pin 25) soldered to PCB ground plane for thermal and electrical integrity.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar high-precision SAR ADC applications.

Compared with AD7177-2 and ADS1282, the LTC2508-32 uniquely combines guaranteed 32-bit no-missing-codes performance, dual independent SPI outputs, pin-strappable digital filtering, and ±0.5ppm INL-making it irreplaceable in applications demanding both metrology-grade DC accuracy and real-time 1Msps composite data for control or diagnostics.

Availability

LTC2508-32 is available at Aetrix Electronics and suitable for seismology sensor arrays, energy exploration logging tools, and automated test equipment requiring stable component supply, long-term lifecycle support, and traceable sourcing for mission-critical instrumentation.

Supply support for LTC2508-32 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 technologies, serving industrial, automotive, communications, and healthcare markets.

The LTC2508-32 belongs to Analog Devices' Linear Technology precision ADC product line, designed specifically for ultra-high-resolution, low-noise DC and low-frequency measurement applications where missing codes, INL, and long-term stability are critical.

FAQ

What is the maximum sampling rate of the LTC2508-32?

The LTC2508-32 supports a maximum sampling rate of 1Msps. At this rate, the no-latency 22-bit composite output (SDOB) is available every conversion cycle, while the 32-bit filtered output (SDOA) data rate depends on the selected down-sampling factor - ranging from 3.9ksps (DF=256) down to 61sps (DF=16384). The SAR core completes each conversion in under 652ns.

Does the LTC2508-32 require external anti-aliasing filters?

The LTC2508-32 significantly relaxes analog anti-aliasing requirements due to its integrated configurable digital lowpass filter. While a minimal RC filter (e.g., 10Ω + 3300pF) is recommended before the input buffer to limit noise and transient coupling, a traditional multi-pole analog anti-aliasing filter is not required - especially at lower output data rates (e.g., 61sps), where the digital filter provides >140dB stopband attenuation.

How is the down-sampling factor configured on the LTC2508-32?

The down-sampling factor (DF) on the LTC2508-32 is set using two logic inputs: SEL0 (Pin 11) and SEL1 (Pin 12). These pins are pin-strapped to OVDD or GND to select one of four fixed DF values: 00 → DF=256, 01 → DF=1024, 10 → DF=4096, 11 → DF=16384. Configuration is static at power-up and remains fixed until reset or power cycle; no SPI register writes are needed.

What is the purpose of the dual serial outputs (SDOA and SDOB) on the LTC2508-32?

The LTC2508-32 provides SDOA for the 32-bit digitally filtered, high-precision output (optimized for accuracy and noise rejection) and SDOB for the 22-bit no-latency composite output (14-bit differential + 8-bit common mode), available every 1µs at 1Msps. This dual-path architecture enables simultaneous high-fidelity measurement recording and real-time system control or diagnostics without latency-induced timing errors.

Is the LTC2508-32 suitable for operation at 85°C?

Yes - the LTC2508I-32 grade is fully specified and guaranteed for operation from –40°C to +85°C. Key parameters including ±0.5ppm INL (typ), 145dB dynamic range, and 32-bit no-missing-codes performance are maintained across this extended industrial temperature range, making the LTC2508-32 suitable for downhole, outdoor, and high-ambient industrial environments.