Analog Devices Inc. LTC2421IMS#PBF

Overview

LTC2421IMS#PBF from Analog Devices (formerly Linear Technology) is a 1-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 that settles in a single conversion cycle. Designed for high-precision bridge digitization, it supports pseudo-differential inputs with extended range (–12.5% to +112.5% of VREF) and integrated 50Hz/60Hz notch rejection - ideal for strain gauge transducers and precision weight scales.

For engineers reviewing the LTC2421IMS#PBF datasheet, LTC2421IMS#PBF pinout, LTC2421IMS#PBF application, or LTC2421IMS#PBF equivalent, key selection criteria include its single-cycle settling filter architecture, live-zero input range accommodation, internal oscillator eliminating external timing components, and compatibility with SPI/MICROWIRE interfaces in resource-constrained industrial sensing systems.

Technical Context

The LTC2421IMS#PBF employs a proprietary delta-sigma modulator with a decimating FIR filter that achieves full settling in one conversion cycle - eliminating latency typical of conventional ∆Σ converters. Its digital filter nulls are programmable via the FO pin to deliver ≥110dB rejection at 50Hz or 60Hz ±2%, or user-defined frequencies from 1Hz to 120Hz using an external oscillator.

It features continuous auto-calibration of offset and full-scale every conversion cycle, ensuring stability over temperature, supply voltage, and time. Input range is defined by externally set FSSET and ZSSET pins, enabling flexible reference configuration (VREF = FSSET – ZSSET) from 0.1V to VCC, with analog input support from –12.5% to +112.5% of VREF.

Key Specifications

Pinout & Package

Package: 10-lead plastic MSOP (MS10), 3mm × 3mm × 1.1mm, exposed pad optional. Thermal resistance θJA = 130°C/W. Rated for –40°C to +85°C industrial temperature range (I-grade).

Key Features

Applications

Equivalent & Alternatives

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

Compared with ADS124S08IPWR and LTC2401CMS#PBF, the LTC2421IMS#PBF provides optimal balance of ultra-low noise (1.2ppm), true no-latency operation, and crystal-free 50/60Hz rejection - making it uniquely suited for space-constrained, battery-operated precision sensor nodes where layout simplicity and long-term stability are critical.

Availability

LTC2421IMS#PBF is available at Aetrix Electronics and suitable for weight scales, direct temperature measurement, strain gauge transducers, gas analyzers, and industrial process control requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for LTC2421IMS#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, Inc. (ADI) is a global leader in high-performance analog, mixed-signal, and digital signal processing technologies, serving industrial, automotive, communications, and healthcare markets.

The LTC2421IMS#PBF belongs to ADI's precision delta-sigma ADC product line, designed specifically for high-accuracy, low-power sensor digitization in harsh environments - emphasizing robustness, ease of use, and elimination of external timing components.

FAQ

What is the maximum recommended reference voltage range for the LTC2421IMS#PBF?

The LTC2421IMS#PBF accepts a reference voltage (VREF = FSSET – ZSSET) from 0.1V to VCC. While the absolute maximum input range extends to –0.3V to VCC + 0.3V, the recommended operating range for optimal INL and noise performance is 0.1V to VCC. Using VREF < 0.1V may degrade accuracy due to increased relative offset error and reduced SNR margin.

Does the LTC2421IMS#PBF require external passive components for its internal oscillator to function?

No, the LTC2421IMS#PBF does not require any external passive components for its internal oscillator. The oscillator is fully integrated and automatically configured when the FO pin is tied to VCC (for 50Hz rejection) or GND (for 60Hz rejection). This eliminates crystals, capacitors, or resistors - reducing BOM cost and PCB area while guaranteeing consistent 50/60Hz notch performance.

How does the LTC2421IMS#PBF handle input signals outside the nominal 0V to VREF range?

The LTC2421IMS#PBF supports an extended input range of –12.5% to +112.5% of VREF (i.e., ZSSET – 0.12VREF to FSSET + 0.12VREF). Inputs within this range are digitized linearly. Signals beyond this range are clamped: below –12.5% VREF yield the minimum code; above +112.5% VREF yield the maximum code - preventing overflow errors in systems with sensor offset or amplifier gain mismatch.

Can the LTC2421IMS#PBF interface directly with a standard SPI host controller?

Yes, the LTC2421IMS#PBF supports standard SPI-compatible 3-wire communication (CS, SCK, SDO) with no additional protocol translation. It operates in SPI Mode 0 (CPOL = 0, CPHA = 0) and outputs 24-bit data (4 status + 20 data bits) MSB-first on the falling edge of SCK. The SDO pin is three-state and controlled by CS, enabling direct connection to multi-device SPI buses.

What is the significance of the "no latency" claim for the LTC2421IMS#PBF?

"No latency" means the LTC2421IMS#PBF's digital filter settles completely within one conversion cycle - unlike conventional delta-sigma ADCs that require multiple cycles to settle after input changes or channel switching. This enables true real-time sampling, deterministic timing for multiplexed sensors, and simplified firmware - as each 24-bit output corresponds precisely to the immediately preceding analog input sample with no pipeline delay.