Analog Devices Inc. DC1009A-A

Overview

LTC2492 from Analog Devices (formerly Linear Technology) is a 24-bit, 4-channel delta-sigma ADC with Easy Drive input current cancellation, integrated temperature sensor, and programmable 50/60Hz rejection. It supports up to 2 differential or 4 single-ended inputs, delivers 0.6 µV_RMS noise, 2 ppm INL, and operates from 2.7V to 5.5V supply. It is used in precision industrial data acquisition systems requiring direct digitization of high-impedance sensors and on-chip temperature compensation.

For engineers reviewing the LTC2492 datasheet, LTC2492 pinout, LTC2492 application, or LTC2492 equivalent, key selection considerations include its rail-to-rail input common-mode range (GND to V_CC), zero-differential-input-current architecture, integrated oscillator, 2× speed mode (7.5 Hz output rate), and 14-lead DFN package with exposed pad.

Technical Context

The LTC2492 employs a third-order delta-sigma modulator with decimating FIR filter and auto-calibration circuitry, enabling true no-latency operation-filter settles in one cycle even after channel reconfiguration. Its patented Easy Drive sampling scheme cancels dynamic input current errors by balancing charge injection across differential inputs.

It features dual conversion modes: normal speed (15 Hz output rate with 80 µA typical current) and 2× speed mode (30 Hz output rate with higher noise floor of 0.85 µV_RMS). Input common-mode rejection exceeds 140 dB DC and at 50/60 Hz, while reference common-mode rejection reaches 140 dB.

Key Specifications

Pinout & Package

The LTC2492 is housed in a 14-lead (4 mm × 3 mm) plastic DFN package with exposed pad (Pin 15 = GND), requiring soldering to PCB ground plane for thermal and electrical performance.

Key Features

Applications

Equivalent & Alternatives

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

Compared with ADS124S08 and MAX11206, the LTC2492 uniquely combines ultra-low noise (0.6 µV_RMS), integrated ±2°C temperature sensor, and GND-to-V_CC input common-mode range-making it optimal for single-point, high-stability industrial measurements where thermal drift dominates error budget.

Availability

LTC2492 is available at Aetrix Electronics and suitable for industrial process control, precision weighing systems, and portable environmental monitoring requiring stable component supply, long-term lifecycle support, and traceable sourcing.

Supply support for LTC2492 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 LTC2492 belongs to ADI's precision delta-sigma ADC product line, designed specifically for high-accuracy, low-power, multi-channel data acquisition in harsh industrial environments with strong EMI and wide temperature variation.

FAQ

What is the maximum input impedance the LTC2492 can directly digitize without external buffering?

The LTC2492 uses Easy Drive technology to cancel differential input current, enabling direct digitization of source impedances up to 1 MΩ while maintaining full 24-bit accuracy and 0.6 µV_RMS noise. This eliminates the need for op-amp buffers in high-impedance sensor interfaces like thermistors, RTDs, and piezoresistive bridges-reducing thermal drift, power consumption, and board space. The LTC2492 achieves this without compromising DC accuracy or linearity.

Does the LTC2492 require an external reference voltage, or can it operate with an internal reference?

The LTC2492 does not include an internal reference; it requires an external differential reference applied to REF+ and REF– pins. The reference voltage (V_REF) must be between 0.1 V and V_CC, and for on-chip temperature measurements, V_REF must be ≥2 V. Reference common-mode rejection exceeds 140 dB, allowing flexible reference sourcing-including ratiometric connections to sensor excitation supplies. The LTC2492 itself provides no internal reference voltage generation.

How does the LTC2492 achieve "no latency" in its delta-sigma architecture?

The LTC2492 achieves no-latency operation through a unique decimating FIR filter that settles fully within one conversion cycle-even after changing input channels or configuration settings. Unlike conventional delta-sigma ADCs requiring multiple cycles to settle after reconfiguration, the LTC2492 guarantees the first output after any channel or mode change is valid and accurate. This behavior is enabled by its auto-calibrating modulator and optimized digital filter structure, making it ideal for dynamic multi-channel scanning applications. The LTC2492 delivers deterministic timing without hidden latency penalties.

Can the LTC2492 measure its own die temperature, and what is the accuracy?

Yes, the LTC2492 integrates a high-accuracy PTAT temperature sensor with 1/30 °C resolution and ±2 °C absolute accuracy across –40°C to +85°C. The sensor output is digitized alongside analog inputs and appears as a dedicated conversion result. It is factory-trimmed and does not require external calibration. This on-chip thermal measurement enables real-time compensation of sensor gain/offset drift in precision systems. The LTC2492 uses this sensor internally for self-compensation and exposes it as a user-accessible channel.

What are the power consumption characteristics of the LTC2492 in sleep and active modes?

In sleep mode (CS HIGH), the LTC2492 draws just 1 µA typical, reducing power by two orders of magnitude versus active operation. In normal-speed active mode (15 Hz output), it consumes 160 µA typical; in 2× speed mode (30 Hz), it draws 200 µA typical. Conversion current is independent of output data rate-only the sleep duration changes. All modes operate from 2.7 V to 5.5 V. The LTC2492's ultra-low sleep current makes it suitable for battery-powered applications where wake-on-event or periodic sampling is used.