Analog Devices Inc. LTC1865CMS#PBF

Overview

LTC1865CMS#PBF from Analog Devices (formerly Linear Technology) is a 16-bit, 250ksps successive approximation ADC with integrated 2-channel software-selectable multiplexer and adjustable reference input, housed in a 10-lead MSOP package. It operates on a single 5V supply, draws only 850μA at full speed, and auto-shuts down between conversions to reduce current to 2μA at 1ksps. Its high-impedance differential analog inputs and 1V–5V reference range enable direct connection to low-output-impedance sensors in portable instrumentation.

For engineers reviewing the LTC1865CMS#PBF datasheet, LTC1865CMS#PBF pinout, LTC1865CMS#PBF application, or LTC1865CMS#PBF equivalent, key selection criteria include its 10-lead MSOP footprint, SPI/MICROWIRE-compatible 3-wire serial interface, guaranteed operation from 0°C to 70°C, true differential input architecture, and support for ratiometric or external reference configurations in space-constrained, battery-powered data acquisition systems.

Technical Context

The LTC1865CMS#PBF implements a switched-capacitor SAR architecture with internal sample-and-hold, enabling precise 16-bit conversion at up to 250ksps. Its 2-channel MUX is configured via a 2-bit word shifted into SDI during the CONV low phase, supporting four modes: single-ended CH0/GND, CH1/GND, or differential CH0–CH1 and CH1–CH0.

It features separate AGND and DGND pins for noise isolation, requires external bypassing of VCC and VREF with ≥1μF tantalum capacitors, and uses a falling-edge–clocked SDO output synchronized to SCK - with data captured on the rising edge by the host controller. Conversion timing is controlled by the CONV signal, with tCONV = 3.2μs (max) and automatic sleep entry when CONV remains high post-conversion.

Key Specifications

Pinout & Package

Package: 10-Lead Plastic MSOP (3mm × 3mm), exposed pad not electrically connected; thermal resistance θ_JA = 210°C/W.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar 16-bit SAR ADC applications.

Compared with ADS8860IDRCT and AD7682BRMZ, the LTC1865CMS#PBF uniquely combines software-configurable 2-channel differential MUX, 1V–5V reference adaptability, and ultra-low 850μA active current in a 10-lead MSOP - making it optimal for compact, battery-sensitive, multi-sensor measurement systems requiring analog noise immunity.

Availability

LTC1865CMS#PBF is available at Aetrix Electronics and suitable for portable instrumentation, industrial sensor interfaces, and isolated remote monitoring requiring stable component supply, long-term lifecycle support, and consistent parametric performance across production batches.

Supply support for LTC1865CMS#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 LTC1865CMS#PBF belongs to ADI's legacy Linear Technology precision data acquisition product line, designed specifically for low-power, high-resolution measurement in space- and energy-constrained embedded systems.

FAQ

What is the maximum clock frequency supported by the LTC1865CMS#PBF for reliable SPI communication?

The LTC1865CMS#PBF supports a maximum SCK frequency of 20MHz for H-grade versions and 16.7MHz for standard-grade units like the LTC1865CMS#PBF. At 5V supply and 25°C, timing parameters such as t_WHCLK and t_WLCLK require ≥40% duty cycle, and setup/hold times (e.g., t_suDI = 15ns) must be met. The LTC1865CMS#PBF achieves full 250ksps throughput only when SCK is operated within these limits and CONV timing constraints are satisfied.

Does the LTC1865CMS#PBF require an external reference, or can it operate with VCC as reference?

The LTC1865CMS#PBF in the MSOP package (including LTC1865CMS#PBF) requires an external reference applied to the VREF pin, which accepts 1V to 5V. Unlike the SO-8 version, the MSOP variant does not internally tie VREF to VCC. Using VCC directly as reference is not supported for LTC1865CMS#PBF; doing so risks violating the specified VREF input range and degrading INL/SNR performance. The LTC1865CMS#PBF must be used with a clean, low-noise external reference source.

How does the LTC1865CMS#PBF handle channel selection, and what are the valid MUX configurations?

The LTC1865CMS#PBF uses a 2-bit word shifted into SDI during the CONV low phase to select among four MUX modes: single-ended CH0/GND, CH1/GND, or differential CH0–CH1 and CH1–CH0. These are defined in Table 1 of the datasheet. The LTC1865CMS#PBF does not support simultaneous sampling or hardware-triggered channel sequencing - each conversion requires explicit SDI configuration prior to the next CONV assertion. The MUX state persists until reprogrammed.

What is the purpose of separate AGND and DGND pins on the LTC1865CMS#PBF, and how should they be connected?

The LTC1865CMS#PBF provides separate AGND and DGND pins to isolate analog and digital return currents, minimizing noise coupling into the sensitive SAR core. AGND must connect directly to a dedicated analog ground plane; DGND should connect to the digital ground plane *at a single point*, typically near the VCC bypass capacitor. This separation preserves the 87dB SNR and prevents digital switching noise from modulating the conversion result. Improper grounding violates the LTC1865CMS#PBF's specified AC performance.

Can the LTC1865CMS#PBF achieve 16-bit no-missing-codes performance across its full operating temperature range?

Yes - the LTC1865CMS#PBF guarantees no missing codes at 14 bits over the full 0°C to 70°C range, and 15 bits for the A-grade variant. While full 16-bit monotonicity is specified at T_A = 25°C, the device maintains ±8 LSB INL (max) across temperature, ensuring functional 16-bit resolution in most precision applications. For critical metrology use cases demanding guaranteed 16-bit no-missing-codes behavior over temperature, the LTC1865CMS#PBF datasheet recommends verifying system-level performance with actual sensor inputs and reference sources.