Texas Instruments LM3814M-7.0/NOPB

Overview

LM3814M-7.0/NOPB from Texas Instruments is a high-side current gauge IC implementing delta-sigma current sensing with ±7 A full-scale range, 0.004 Ω typical insertion loss, and PWM output encoding magnitude and direction. It delivers precision battery charge/discharge monitoring in portable power systems where zero external sense resistor and minimal voltage drop are critical.

For engineers reviewing the LM3814M-7.0/NOPB datasheet, LM3814M-7.0/NOPB pinout, LM3814M-7.0/NOPB application, or LM3814M-7.0/NOPB equivalent, this page provides verified technical context, SO-8 pin mapping, accuracy vs. temperature behavior, shutdown current specs, and real-world alternatives for high-side current measurement in battery management and smart fuse designs.

Technical Context

The LM3814M-7.0/NOPB integrates a precision internal sense element and delta-sigma analog-to-digital converter to measure average current over fixed 6 ms sampling intervals. Its PWM output encodes current magnitude (±7 A range) and polarity via duty cycle - 50% = 0 A, >50% = positive flow, <50% = negative flow - with quantization resolution of 1/128.

It features internal anti-aliasing filtering via FLTR+/FLTR− pins, power-on-reset (POR), and shutdown control (SD) enabling quiescent current reduction to 2.5 µA. Accuracy is specified at ±3.5% at room temperature for the ±7 A variant, with thermal drift mitigated by on-die compensation and layout-dependent copper-area calibration.

Key Specifications

Pinout & Package

LM3814M-7.0/NOPB is housed in an SO-8 surface-mount package (TI package code M08A), with dual ground pins (7 and 8) and integrated high-side sense path between pins 1 (SENSE+, VDD) and 2 (SENSE−).

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX40056ASA+T and INA226AIDR, the LM3814M-7.0/NOPB offers plug-and-play high-side current sensing with zero external components and direct PWM compatibility - ideal for cost-sensitive, space-constrained battery and fuse applications where ±7 A range and 6 ms averaging meet system requirements.

Availability

LM3814M-7.0/NOPB is available at Aetrix Electronics and suitable for battery charge/discharge gauge, motion control diagnostics, and resettable smart fuse applications requiring stable component supply and long-term industrial availability.

Supply support for LM3814M-7.0/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 delivering analog, embedded processing, and connectivity solutions for industrial, automotive, and consumer markets.

The LM3814 product line was designed specifically for high-accuracy, low-loss current measurement in battery-powered and safety-critical systems - emphasizing integration, thermal stability, and ease of MCU interface via PWM.

FAQ

What is the full-scale current range of the LM3814M-7.0/NOPB?

The LM3814M-7.0/NOPB is factory-set for a ±7 A full-scale current range, supporting continuous operation up to 7 A and peak tolerance of 10 A for ≤200 ms. This range is fixed per part number and cannot be adjusted externally - the "7.0" suffix explicitly denotes the ±7 A variant. The LM3814M-7.0/NOPB achieves this with an internal sense element offering 0.004 Ω typical insertion loss.

How does the PWM output of the LM3814M-7.0/NOPB encode current direction and magnitude?

The LM3814M-7.0/NOPB PWM output uses duty cycle to encode both magnitude and polarity: 50% duty cycle indicates zero current; values above 50% indicate positive current flow (e.g., 95.5% = +7 A), and values below 50% indicate negative flow (e.g., 4.5% = −7 A). The relationship is defined as I_SENSE = 2.2 × (D − 0.5) × 7 A, where D is measured duty cycle. This linear mapping enables direct MCU interpretation without external signal conditioning.

What is the recommended PCB layout for optimal accuracy of the LM3814M-7.0/NOPB?

For optimal accuracy, the LM3814M-7.0/NOPB requires symmetrical, wide copper traces connecting pins 1 (SENSE+, VDD) and 2 (SENSE−) to the high-side power path - matching trace width, length, and thermal mass to minimize thermal gradients across the internal sense element. TI specifies that accuracy of the ±7 A variant is sensitive to copper area under these pins; insufficient copper causes self-heating-induced offset. Ground pins 7 and 8 must connect to a solid, low-impedance ground plane.

Does the LM3814M-7.0/NOPB require external filtering components?

Yes - the LM3814M-7.0/NOPB requires two external capacitors: a 0.1 µF ceramic capacitor between pins 3 (FLTR+) and 4 (FLTR−) to implement the anti-aliasing filter for the delta-sigma modulator, and a 1 µF bypass capacitor between pins 1 (VDD) and 7/8 (GND) to stabilize the supply. These are mandatory per the datasheet; omitting them degrades noise rejection and may cause false triggering or reduced accuracy.

Is the LM3814M-7.0/NOPB still in active production?

No - the LM3814M-7.0/NOPB is marked OBSOLETE in the official Texas Instruments SNVS045D datasheet (revised April 2013). While Aetrix Electronics maintains legacy supply for continued production support, design-in of new systems is not recommended. Customers should evaluate modern alternatives such as the INA226 or MAX40056 for new projects, while LM3814M-7.0/NOPB remains viable for sustaining existing hardware revisions.