LTC2945CMS#PBF

Analog Devices (Linear Technology) · Wide range I2C power monitor, 0 V to 80 V · MSOP-12 (MS12)

LTC2945CMS#PBF is the commercial-temperature (0 C to 70 C), MSOP-12 version of ADI's LTC2945: a rail-to-rail system monitor that measures current, voltage and power. A 12-bit delta-sigma ADC reads the voltage across an external sense resistor (102.4 mV full scale) at any common mode from 0 V to 80 V, the supply or SENSE+ voltage (102.4 V full scale) and an auxiliary input ADIN (2.048 V full scale); an internal multiplier turns current and voltage into a 24-bit power value, minimum and maximum values are stored, and an open-drain ALERT pin flags programmable limits. The part runs from 2.7 V to 80 V and has a shunt regulator mode for higher supplies. The I2C interface has separate data input and output pins (SDAI, SDAO) for opto-isolated buses (datasheet Rev. D p.1).

Key specifications

Values from the LTC2945 data sheet Rev. D; over the full operating range unless noted.

Pinout (top view)

Pin numbers, names and functions from the MS package pin configuration (p.3) and pin functions (p.9).

All twelve pins have functions; the MSOP has no exposed pad and no NC pins. The QFN version (UD package) numbers the pins differently and is a different footprint.

Ordering variants

All MS12 versions are marked 2945 (29451 for the -1) on the package (p.4). The 3D model here carries a virtual mark, see 3D models.

Design notes

• Kelvin-connect SENSE+ and SENSE- to the sense resistor pads; the datasheet's recommended layout is Figure 19 on p.21 (the pin function text on p.9 calls it Figure 17).
• For a non-isolated bus tie SDAI to SDAO. SCL and SDAI are clamped at about 6.4 V, so pull-ups can go to VDD through a resistor or to INTVCC (p.9).
• The address pins are three-state; "open" must leak less than 7 uA (p.6).
• When INTVCC supplies other parts from the internal regulator, treat it as a supply output in your schematic (the library pin type is power input).

CAD

Footprint

Pads follow ADI's recommended solder pad layout for the MS12 package (p.32, drawing 05-08-1668 Rev A): 0.42 x 0.889 mm rectangles on a 0.65 mm pitch. The drawing gives the gap between the pad rows as 3.20 to 3.45 mm and the overall length as 5.10 mm minimum; this footprint uses the middle of the range, 3.325 mm, so the pad centres are at x = +-2.107 mm and the overall length is 5.103 mm. Pad 1 is top left. KiCad's generic MSOP-12_3x4.039mm_P0.65mm uses longer IPC pads (1.45 x 0.40 at +-2.15) that reach 0.24 mm further under the body and 0.32 mm further out; the pad-by-pad comparison is in provenance/footprint-check.json.

3D models

ADI's own STEP sits behind a third-party CAD portal that refused a plain request, so this page uses KiCad's library model MSOP-12_3x4.039mm_P0.65mm unchanged. It was checked against ADI's drawing: body 4.039 x 3.00 mm, tip to tip 4.90 mm, height 0.95 mm (1.10 max), standoff 0.10 mm, lead width 0.30 mm, lead thickness 0.18 mm, foot length at the gauge plane 0.446 mm (0.53 +-0.152), with radiused gull-wing bends; every value is inside the drawing (provenance/3d-model.json). The overlay below puts the model on the drawing; the drawing is marked not to scale, so each axis is calibrated on its own printed dimension lines.

The part number on the top of the model (LTC2945 / CMS#PBF) is a virtual identification mark added with adom-chip-laser, not ADI's real marking (2945). The page's 3D viewer shows a hero model with the footprint's pad outlines, pin names and silkscreen drawn under the chip; boards should use ltc2945cms-pbf-etched.glb or the STEP.

Detail levels for board and digital-twin viewers

Four clean board-use GLBs (no footprint artwork): high and medium keep the mark, low is a coarser mesh of the same model, super-low is a box stand-in with all twelve leads.

Symbol chip outline

The chip drawing in the symbol body is the outline of the etched 3D model (artwork/LTC2945CMS-PBF-3d-outline-dark-named.svg).

Sourcing

Checked 2026-10-21.

Mouser also listed the tape-and-reel LTC2945CMS#TRPBF (584-LTC2945CMS#TRPBF, 2140 in stock) the same day. Unit price about 12.40 USD at both.

Manufacturer and resources

Open items

• ADI's own STEP model was not compared (not reachable with a plain HTTP request).
• The libraries were checked by parsing them, not by opening them in KiCad, Fusion or Altium.
• Not yet reviewed by a person.

Provenance

Library content written for this page is CC-BY-4.0. The data sheet and package drawing remain Analog Devices documents; the KiCad model and footprint keep their CC-BY-SA 4.0 license with the KiCad library exception.