Texas Instruments LM3812M-1.0/NOPB

Overview

LM3812M-1.0/NOPB from Texas Instruments is a precision high-side current gauge IC featuring an integrated 0.004 Ω sense element, ±2% room-temperature accuracy (−1 A to +1 A range), PWM output encoding magnitude and direction, and 50 ms sampling interval. It operates from 2 V to 5.25 V and delivers ultra-low insertion loss for battery charge/discharge monitoring in portable power systems.

For engineers reviewing the LM3812M-1.0/NOPB datasheet, LM3812M-1.0/NOPB pinout, LM3812M-1.0/NOPB application, or LM3812M-1.0/NOPB equivalent, key selection criteria include high-side sensing capability, PWM-based current-to-digital interface compatibility with microcontrollers, thermal stability over −40°C to +125°C, and shutdown quiescent current of 2.5 µA.

Technical Context

The LM3812M-1.0/NOPB implements a delta-sigma analog-to-digital converter with internal anti-aliasing filtering (via FLTR+/FLTR− pins) to digitize sensed current, followed by digital averaging over 50 ms intervals. Its PWM output encodes current as duty cycle relative to 50% zero-current baseline, supporting bidirectional measurement from −1 A to +1 A.

It integrates internal power-on-reset (POR), low-temperature-coefficient sense element (2600 ppm/°C), and shutdown control via SD pin-pulling SD low reduces quiescent current to 2.5 µA while disabling PWM output. The device requires no external sense resistor and rejects transient spikes via digital filtering.

Key Specifications

Pinout & Package

LM3812M-1.0/NOPB uses an 8-pin SOIC (D0008A) package with exposed pad for thermal enhancement. Pin 1 is SENSE+/VDD (high-side sense input and supply), Pin 2 is SENSE− (low-side sense return), Pins 3–4 are differential filter inputs (FLTR+/FLTR−), Pin 5 is SD (active-low shutdown), Pin 6 is PWM (open-drain output), and Pins 7–8 are GND.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar high-side current gauge applications.

Compared with LM3812M-1.0/NOPB, MAX40056ASA+T offers faster response but adds external component cost and analog signal conditioning complexity, while INA226AIDGST provides higher resolution and digital configurability at the expense of MCU firmware overhead and external shunt dependency.

Availability

LM3812M-1.0/NOPB is available at Aetrix Electronics and suitable for battery management systems, motion control subsystems, and power supply telemetry requiring stable component supply, long-term lifecycle support, and traceable sourcing.

Supply support for LM3812M-1.0/NOPB 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

Texas Instruments is a global semiconductor leader specializing in analog, embedded processing, and power management technologies, with decades of expertise in precision sensing and industrial-grade IC design.

The LM3812 product line was developed specifically for high-accuracy, low-loss current measurement in space-constrained, battery-sensitive applications-emphasizing integration, thermal stability, and direct microcontroller interfacing via PWM.

FAQ

What is the sensing topology supported by LM3812M-1.0/NOPB?

The LM3812M-1.0/NOPB is designed exclusively for high-side current sensing. Its pinout (SENSE+ tied to VDD, SENSE− as return) and internal architecture route current through the IC's integrated 0.004 Ω element on the power rail side-enabling ground-referenced load monitoring without disturbing the system ground plane. This differs fundamentally from low-side alternatives like LM3813.

How does the PWM output of LM3812M-1.0/NOPB encode current direction and magnitude?

The LM3812M-1.0/NOPB PWM output uses duty cycle to encode both parameters: 50% duty cycle indicates zero current; values above 50% represent positive current flow (e.g., 95.5% = +1.0 A); values below 50% indicate reverse current (e.g., 4.5% = −1.0 A). The relationship is linear per ISENSE = 2.2 × (D − 0.5) × IMAX, where IMAX = 1 A for LM3812M-1.0/NOPB.

What is the role of the FLTR+ and FLTR− pins on LM3812M-1.0/NOPB?

The FLTR+ and FLTR− pins form a differential input to the delta-sigma modulator's anti-aliasing filter. A 0.1 µF ceramic capacitor between them creates a low-pass filter that attenuates noise above ~10 Hz, ensuring sampled data integrity. This external RC network is mandatory-omitting it degrades accuracy and increases susceptibility to EMI-induced errors in the LM3812M-1.0/NOPB.

Can LM3812M-1.0/NOPB operate from a 3.3 V supply?

Yes, LM3812M-1.0/NOPB supports supply voltages from 2.0 V to 5.25 V, making 3.3 V operation fully compliant. At 3.3 V, the PWM output high-level voltage (VOH) remains ≥3.1 V (VDD − 0.2 V) with 1 mA sink, and logic thresholds (VTH = 1.2 V min, VTL = 0.7 V max) ensure reliable SD pin control and microcontroller interface compatibility.

What thermal considerations apply to LM3812M-1.0/NOPB accuracy?

LM3812M-1.0/NOPB features a 2600 ppm/°C sense element temperature coefficient, partially compensated internally. Accuracy remains ±2% from −40°C to +125°C junction temperature, but sustained high-current operation (>500 mA) requires adequate copper pour under pins 1 and 2 to minimize thermal gradient between sense element and die-otherwise, measurement drift may exceed spec due to localized heating.