Analog Devices Inc. LTC2422CMS#PBF

Overview

LTC2422CMS#PBF from Analog Devices (formerly Linear Technology) is a 2-channel, 20-bit micropower delta-sigma ADC in MSOP-10 package, operating from 2.7V to 5.5V supply. It delivers 8ppm INL, 1.2ppm RMS noise, and no-latency digital filtering with single-cycle settling-enabling precise, real-time digitization of bridge sensor outputs in industrial weight scales and strain gauge transducers.

For engineers reviewing the LTC2422CMS#PBF datasheet, LTC2422CMS#PBF pinout, LTC2422CMS#PBF application, or LTC2422CMS#PBF equivalent, key selection criteria include its pseudo-differential bridge digitizer architecture, 50Hz/60Hz ±2% notch rejection via FO pin control, extended input range (–12.5% to +112.5% VREF), and automatic ping-pong channel selection between CH0 and CH1.

Technical Context

The LTC2422CMS#PBF employs a proprietary decimating FIR filter synchronized to an integrated oscillator, eliminating latency by settling fully within one conversion cycle. Its architecture supports both internal oscillator modes (FO = GND for 60Hz rejection; FO = VCC for 50Hz rejection) and external clock operation (f_EOSC = 2.56–307.2 kHz), enabling user-defined notch frequencies at f_EOSC/2560.

It features continuous auto-calibration of offset and full-scale every conversion cycle, ensuring stability against temperature drift (0.04 ppm/°C offset drift) and supply variation. The 24-bit serial output includes 4 status bits (EOC, channel, sign, extended range) followed by 20-bit resolution data, compatible with SPI and MICROWIRE protocols using 2- or 3-wire interface.

Key Specifications

Pinout & Package

Package: 10-lead plastic MSOP (MS10), 3 mm × 3 mm × 1.1 mm, exposed pad not electrically connected.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar 20-bit delta-sigma ADC applications.

Compared with LTC2422IMS#PBF, the LTC2422CMS#PBF trades extended temperature range for lower cost and same performance in commercial environments; versus LTC2402CGN#PBF, it provides pin-compatibility, lower power, and configurable notch frequency at the expense of 12 fewer output bits.

Availability

LTC2422CMS#PBF is available at Aetrix Electronics and suitable for weight scales, industrial process control, and portable instrumentation requiring stable component supply, long-term lifecycle assurance, and RoHS-compliant packaging.

Supply support for LTC2422CMS#PBF 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 acquired Linear Technology in 2017 and maintains its precision analog portfolio, emphasizing high-resolution signal conditioning for demanding industrial and instrumentation markets.

The LTC2422CMS#PBF belongs to the LTC24xx family of micropower delta-sigma ADCs, designed specifically for direct sensor digitization in low-power, high-accuracy applications such as bridge-based transducers and precision temperature sensing.

FAQ

What is the function of the FO pin on the LTC2422CMS#PBF?

The FO pin on the LTC2422CMS#PBF selects the line-frequency rejection mode: tied to GND enables 60Hz ±2% notch filtering, tied to VCC enables 50Hz ±2% rejection, and driven by an external clock (2.56–307.2 kHz) sets the notch at f_EOSC/2560. This eliminates need for external notch filters or software-based digital filtering in noisy AC environments. The LTC2422CMS#PBF uses this pin to configure its internal digital filter null without changing hardware or firmware.

Does the LTC2422CMS#PBF require external components for oscillator operation?

No, the LTC2422CMS#PBF integrates a precision internal oscillator and requires no external crystals, capacitors, or resistors for basic 50Hz or 60Hz rejection operation. When FO is connected to GND or VCC, the device self-configures for corresponding notch frequency with no external timing components. Only external clock mode (for custom rejection frequencies) requires a clean square-wave source applied to FO. The LTC2422CMS#PBF thus reduces BOM count and layout complexity in space-constrained designs.

How does the LTC2422CMS#PBF handle input signals outside the nominal 0–VREF range?

The LTC2422CMS#PBF supports an extended input range of –12.5% VREF to +112.5% VREF, allowing valid conversion of signals below zero scale (ZSSET) or above full scale (FSSET). Inputs beyond this range are clamped, but remain within absolute maximum ratings (–0.3V to VCC + 0.3V). This capability resolves common system-level issues like sensor offset, amplifier saturation, or wiring-induced common-mode shifts - all without external level-shifting circuitry. The LTC2422CMS#PBF reports extended-range condition via the EXR status bit in its 24-bit output frame.

Is the LTC2422CMS#PBF pin-compatible with earlier Linear Technology ADCs?

Yes, the LTC2422CMS#PBF is pin-compatible with the LTC2402CGN#PBF in the same MSOP-10 package, sharing identical pin functions and mechanical footprint. While the LTC2422CMS#PBF outputs 24 bits (4 status + 20 data) versus 32 bits for the LTC2402, its timing and interface behavior match closely - including optional 32-bit mode where last 8 bits are logic HIGH for drop-in replacement. This allows legacy designs using LTC2402 to migrate to LTC2422CMS#PBF with minimal layout or firmware changes.

What is the significance of the "ping-pong" channel selection in the LTC2422CMS#PBF?

The LTC2422CMS#PBF implements automatic ping-pong channel selection between CH0 and CH1, alternating conversions without host intervention. After each completed conversion, the device internally switches to the other channel and begins the next acquisition. This ensures synchronized, time-aligned sampling of two related signals - such as strain and temperature in a compensated transducer - with deterministic inter-channel timing. The channel ID is reported in Bit 22 of the 24-bit output frame, enabling real-time correlation in the host processor. The LTC2422CMS#PBF performs this switching autonomously, reducing MCU overhead and jitter compared to software-controlled multiplexing.