Texas Instruments LM3814M-1.0/NOPB

Overview

LM3814M-1.0/NOPB from Texas Instruments is a high-side current gauge IC with integrated ultra-low-loss sense element (0.004 Ω typical), ΔΣ-based precision current measurement, and PWM output encoding ±1 A magnitude and direction. It operates from 2 V to 5.25 V, delivers ±3.5% room-temperature accuracy, and averages current over 6 ms for spike immunity-used in battery charge/discharge monitoring and smart fuse applications.

For engineers reviewing the LM3814M-1.0/NOPB datasheet, LM3814M-1.0/NOPB pinout, LM3814M-1.0/NOPB application, or LM3814M-1.0/NOPB equivalent, key selection criteria include high-side sensing topology, PWM duty-cycle–to-current linearity, shutdown quiescent current (2.5 µA), thermal drift behavior, and SO-8 package compatibility with PCB layout constraints for sense-path copper area.

Technical Context

The LM3814M-1.0/NOPB implements a delta-sigma analog-to-digital converter to digitize sensed current, followed by digital filtering and comparison against a digital ramp generator to produce a PWM waveform. The duty cycle (range 4.5%–95.5%) linearly encodes average current over the prior 6 ms sampling interval, with 50% representing zero current, >50% indicating positive flow, and <50% indicating reverse flow.

It features internal power-on reset, on-chip anti-aliasing filter inputs (FLTR+, FLTR−), and shutdown control via SD pin that reduces quiescent current to 2.5 µA. The internal sense element's 2600 ppm/°C temperature coefficient is compensated digitally, and quantization resolution is 128 levels (±0.5-bit offset).

Key Specifications

Pinout & Package

LM3814M-1.0/NOPB uses an SO-8 surface-mount package (TI package code M08A) with exposed pad not electrically connected. Pin 1 is SENSE+/VDD; pins 7 and 8 are GND; pin 5 is active-low shutdown; pin 6 is PWM output. Layout requires dedicated copper area under pins 1 and 2 for thermal stability in high-current operation.

Key Features

Applications

Equivalent & Alternatives

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

Compared with INA219 and MAX4009, LM3814M-1.0/NOPB uniquely combines zero-shunt loss, direction-aware PWM output, and hardware-averaged 6 ms sampling-reducing firmware burden and PCB area at the cost of digital bus flexibility and analog output versatility.

Availability

LM3814M-1.0/NOPB is available at Aetrix Electronics and suitable for battery management, motion control diagnostics, and smart fuse applications requiring stable component supply and long-term design continuity.

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

The LM3814 product line was designed specifically for high-accuracy, low-insertion-loss bidirectional current sensing in space-constrained and thermally sensitive applications-targeting battery-powered and safety-critical load monitoring systems.

FAQ

What is the sensing topology supported by LM3814M-1.0/NOPB?

The LM3814M-1.0/NOPB is configured exclusively for high-side current sensing. Its pin 1 serves as both SENSE+ and VDD, connecting directly to the positive supply rail, while pin 2 is SENSE−-enabling measurement of current flowing into a load without grounding disruption. This differs from the LM3815 family, which is low-side only.

How does the PWM output of LM3814M-1.0/NOPB encode current magnitude and direction?

The LM3814M-1.0/NOPB PWM output uses duty cycle to encode signed current: 50% duty cycle = 0 A; >50% (up to 95.5%) = positive current; <50% (down to 4.5%) = negative current. For LM3814M-1.0/NOPB, 95.5% corresponds to +1 A and 4.5% to −1 A, with linear interpolation between-enabling MCU firmware to compute current using D = [I_SENSE/(2.2 × 1 A)] + 0.5.

What is the accuracy specification of LM3814M-1.0/NOPB and under what conditions does it apply?

LM3814M-1.0/NOPB guarantees ±3.5% average current accuracy at room temperature (25°C), including contributions from its internal sense element and ΔΣ conversion. This specification applies under VDD = 5.0 V, with recommended 1 µF bypass and 0.1 µF filter capacitors, and assumes proper PCB layout with adequate copper area under sense pins to manage thermal gradients.

Can LM3814M-1.0/NOPB operate from a 3.3 V supply?

Yes, LM3814M-1.0/NOPB operates across 2.0 V to 5.25 V, making it fully compatible with 3.3 V systems. At 3.3 V, PWM logic levels remain valid (VOH ≥ VDD − 0.2 V, VOL ≤ 0.2 V), and quiescent current stays within 160 µA max. However, accuracy and noise performance are characterized at 5.0 V-designers should verify duty-cycle linearity and jitter in their specific 3.3 V application.

Is LM3814M-1.0/NOPB still in production or marked obsolete?

LM3814M-1.0/NOPB is marked OBSOLETE in its official TI datasheet (SNVS045D, Rev D, April 2013). While functional and available through authorized legacy distributors and Aetrix Electronics' extended inventory program, it is not recommended for new designs. Customers should evaluate TI's newer alternatives such as the INA2xx or TMCS1100 families for enhanced performance and active support.