Analog Devices Inc. LTC2945CMS-1#PBF

Overview

LTC2945CMS-1#PBF from Analog Devices is a rail-to-rail I²C power monitor IC that measures current (via shunt), input voltage (0V–80V), and calculates 24-bit power. It features a 12-bit ΔΣ ADC with ±0.75% total unadjusted error, internal multiplier, min/max tracking, and programmable alert thresholds. Used in telecom power shelves and automotive battery monitoring systems.

For engineers reviewing the LTC2945CMS-1#PBF datasheet, LTC2945CMS-1#PBF pinout, LTC2945CMS-1#PBF application, or LTC2945CMS-1#PBF equivalent, key selection criteria include its 0V–80V sense range, split SDAI/SDAO pins for opto-isolation, -1 variant's inverted SDAO output, and MSOP-12 package compatibility with space-constrained high-voltage rails.

Technical Context

The LTC2945CMS-1#PBF integrates a 12-bit ΔΣ ADC that sequentially samples differential shunt voltage (∆SENSE), supply voltage (VDD/SENSE+), and auxiliary ADIN voltage - each with dedicated full-scale ranges (102.4mV, 102.4V, 2.048V) and confirmed resolution (25µV, 25mV, 0.5mV). Its onboard digital multiplier computes 24-bit power values without host CPU intervention.

It supports two operating modes: continuous scan (7.5Hz typical conversion rate) and snapshot mode (single-channel on-demand measurement). The -1 suffix denotes inverted SDAO output, enabling direct interface with inverting opto-isolators - a hardware-level distinction from the standard LTC2945CMS#PBF.

Key Specifications

Pinout & Package

Package: 12-Lead Plastic MSOP (0°C to 70°C operating range). Exposed pad not present in MSOP variant.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar power monitoring applications.

Compared with LTC2945CMS#PBF, the LTC2945CMS-1#PBF saves board space and component count in opto-isolated systems by integrating signal inversion; compared with INA226AIDGST, it delivers autonomous 24-bit power, min/max tracking, and wider 0V–80V sensing - critical for telecom and automotive high-voltage monitoring.

Availability

LTC2945CMS-1#PBF is available at Aetrix Electronics and suitable for telecom infrastructure, automotive battery management, and industrial PLC power diagnostics requiring stable component supply and long-lifecycle support.

Supply support for LTC2945CMS-1#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 is a global semiconductor company specializing in high-performance analog, mixed-signal, and digital signal processing technologies.

The LTC2945 product line delivers integrated power monitoring solutions for high-voltage DC systems, designed to simplify current/voltage/power telemetry in telecom, automotive, and industrial equipment without host processor burden.

FAQ

What is the key functional difference between LTC2945CMS-1#PBF and LTC2945CMS#PBF?

The LTC2945CMS-1#PBF features an inverted SDAO (I²C data output) pin, enabling direct interface with inverting optocouplers in isolated bus configurations. The standard LTC2945CMS#PBF has non-inverted SDAO. All other electrical specifications, pinout, package, and register map are identical between the two variants. This inversion is implemented at silicon level - no external components are needed to achieve opto-isolation compatibility in the LTC2945CMS-1#PBF.

Does LTC2945CMS-1#PBF support monitoring of negative supply rails?

Yes - the LTC2945CMS-1#PBF supports true rail-to-rail common-mode input from 0V to 80V, and its SENSE+ and SENSE– inputs are fully differential. When used in low-side current sensing with a negative supply (e.g., –48V telecom systems), the device derives power from the INTVCC shunt regulator and references measurements to its local ground. Figure 4 in the datasheet confirms operation with –4V to –80V supplies, maintaining ±0.75% TUE and 25µV current resolution.

How does the LTC2945CMS-1#PBF calculate power, and where is the result stored?

The LTC2945CMS-1#PBF performs 24-bit digital multiplication of its 12-bit current (∆SENSE) and 12-bit voltage (VDD or SENSE+) measurements internally. The resulting 24-bit power value is stored in dedicated POWER_MSB and POWER_LSB registers (addresses 0x0C and 0x0D), updated automatically after each conversion cycle. No host MCU computation is required - the value is ready for readback via I²C immediately after conversion completes.

Can LTC2945CMS-1#PBF operate from a supply above 80V?

Yes - the LTC2945CMS-1#PBF supports supplies above 80V using its INTVCC shunt regulator mode. Connect the high-voltage supply to INTVCC through an external shunt resistor sized per Equation 1 in the datasheet (e.g., 5.4kΩ for –36V to –72V telecom). The internal shunt clamps INTVCC at ~6.3V, powering the IC safely. VDD is left unconnected or tied to GND in this configuration, and SENSE+/SENSE– remain fully functional for current sensing.

What is the purpose of the ADR0 and ADR1 pins on LTC2945CMS-1#PBF?

The ADR0 and ADR1 pins on LTC2945CMS-1#PBF are I²C address configuration inputs. Each pin can be tied to INTVCC (logic high), GND (logic low), or left open (high-impedance), producing nine unique 7-bit I²C addresses (0x60–0x68). This allows up to nine LTC2945CMS-1#PBF devices on the same I²C bus without address conflict - essential in multi-rail power systems like server PDUs or telecom shelves where independent monitoring of multiple voltages is required.