Texas Instruments LP3947ISD-09/NOPB

Overview

LP3947ISD-09/NOPB from Texas Instruments is a single-cell Li-ion battery charger IC with integrated pass transistor, I²C programmability, and dual-mode (USB/AC) input selection. It delivers 500 mA charge current, regulates battery voltage to 4.1 V ±1%, and features 5.6-hour safety timer, temperature monitoring via Ts pin, and LDO mode operation up to 1.2 A. It targets portable USB-powered devices requiring safe, flexible charging control.

For engineers reviewing the LP3947ISD-09/NOPB datasheet, LP3947ISD-09/NOPB pinout, LP3947ISD-09/NOPB application, or LP3947ISD-09/NOPB equivalent, key selection considerations include its factory-default 4.1 V regulation, 500 mA AC adaptor charge current, I²C-configurable EOC thresholds (0.1C–0.2C), and thermal shutdown at 160 °C - all validated for WSON-14 package operation across −40 °C to +85 °C ambient.

Technical Context

The LP3947ISD-09/NOPB implements a four-phase charge algorithm (pre-qualification, constant-current, constant-voltage, maintenance) with automatic transition based on VBATT and ICHG. Its internal 120 mΩ current-sense resistor enables analog charge current monitoring via Diff-Amp output, while Ts pin voltage thresholds (1.39 V–2.427 V) directly enable/disable charging and trigger LDO mode above 2.7 V.

It supports dual-input source arbitration via MODE pin (HIGH = AC adaptor, LOW = USB), and USB power-class selection via ISEL pin (HIGH = 100 mA, LOW = 500 mA). All programmable parameters - including charge current, battery voltage, and EOC threshold - are stored in nonvolatile registers accessible over standard 400 kHz I²C interface with slave address 0x47.

Key Specifications

Pinout & Package

LP3947ISD-09/NOPB uses a 14-pin WSON (NHL0014B) package with 3.0 mm × 4.0 mm footprint and exposed thermal pad. Pin 1 is top-left corner (EN), pin 14 is bottom-right (CHG-IN); orientation matches TI's top-side marking "L00061B".

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar Li-ion battery charger applications.

Compared with LP3947ISD-09/NOPB, BQ24075RGTR offers higher current but lacks 4.1 V support and I²C flexibility, while MAX1555ESA+ simplifies interface at the expense of adaptive thermal and timing control - making LP3947ISD-09/NOPB optimal for programmable, dual-input, temperature-aware portable chargers.

Availability

LP3947ISD-09/NOPB is available at Aetrix Electronics and suitable for cellular handsets, USB-powered portable devices, digital cameras, and PDAs requiring stable component supply, long-term lifecycle support, and consistent parametric performance across production batches.

Supply support for LP3947ISD-09/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 experience in battery management IC design.

The LP3947ISD-09/NOPB belongs to TI's dedicated battery charger product line, engineered specifically for single-cell Li-ion applications in space-constrained, dual-input portable electronics where programmability, thermal safety, and seamless USB/AC transition are critical.

FAQ

What is the factory-default battery regulation voltage for LP3947ISD-09/NOPB?

The LP3947ISD-09/NOPB is factory-programmed for 4.1 V battery regulation voltage, as indicated by its "-09" suffix in the ordering code. This value is stored in Register-1 (bit 0 = 0) and remains active unless modified via I²C. The 4.1 V setting aligns with lithium-ion cells optimized for longer cycle life and reduced stress versus 4.2 V variants.

How does the LP3947ISD-09/NOPB handle USB versus AC adaptor input selection?

The LP3947ISD-09/NOPB uses the MODE pin to distinguish inputs: HIGH selects AC adaptor mode (default 500 mA charge current), LOW selects USB mode (default 100 mA). In USB mode, the ISEL pin further configures current - HIGH = 100 mA, LOW = 500 mA. This dual-pin scheme avoids ambiguity and ensures correct current limiting per USB specification.

Can LP3947ISD-09/NOPB operate without a battery connected?

Yes - when the Ts pin is left floating or pulled to VT (≥2.7 V), the LP3947ISD-09/NOPB enters LDO mode and sources up to 1.2 A at 4.1 V from the BATT pin. This mode is intended for system-level testing without battery insertion, but TI explicitly warns against using LDO mode with a battery connected due to risk of damage.

What is the function of the Diff-Amp pin on LP3947ISD-09/NOPB?

Diff-Amp is the differential amplifier output that converts charge current through the internal 120 mΩ sense resistor into a voltage (0.583 V at 50 mA, scaling linearly to 1.79 V at 750 mA). This analog signal enables real-time current monitoring during both charging and LDO modes, supporting diagnostics and remaining-charge estimation in host firmware.

Does LP3947ISD-09/NOPB require external components for basic operation?

Yes - LP3947ISD-09/NOPB requires a minimum of two external capacitors: 1 µF ceramic on CHG-IN to GND and 10 µF ceramic on BATT to GND. Additionally, a thermistor network (RT + RS) is mandatory for Ts-based temperature monitoring, and pull-up resistors on SCL/SDA are needed for I²C communication. No external current-setting resistor is required.