Texas Instruments LP3947ISD-09

Overview

LP3947ISD-09 from Texas Instruments is a single-cell Li-ion battery charger IC with integrated pass transistor, supporting both USB (100/500 mA) and AC adaptor (500 mA default) charging modes. It delivers 4.1 V battery regulation voltage, features I²C programmability for charge current and EOC threshold, and includes real-time temperature monitoring via Ts pin for safe charging in portable electronics.

For engineers reviewing the LP3947ISD-09 datasheet, LP3947ISD-09 pinout, LP3947ISD-09 application, or LP3947ISD-09 equivalent, this page provides verified technical context, validated pin functions, confirmed charging profiles, thermal performance data for WSON-14 package, and two field-validated alternative parts with documented functional differences.

Technical Context

The LP3947ISD-09 implements a four-phase charge algorithm-pre-qualification (≤70 mA), constant-current (CC), constant-voltage (CV), and maintenance-with automatic transition at 3.0 V (VBATT rise) and 3.9–4.02 V (VBATT fall). Its internal 120 mΩ current-sense resistor enables analog charge-current monitoring via Diff-Amp output (0.583–1.790 V over 50–750 mA range).

Thermal safety is enforced by continuous Ts-pin voltage monitoring against dual thresholds (1.39 V low, 2.427 V high); violation halts charging and resets the 5.6-hour safety timer. LDO mode activates when Ts ≥ 2.7 V, sourcing up to 1.2 A at 4.1 V regulated output without battery connection.

Key Specifications

Pinout & Package

LP3947ISD-09 uses a 14-pin WSON (NHL0014B) package with exposed thermal pad. The package supports ≤1.21 W continuous dissipation at 80 °C ambient and requires soldering the thermal pad to a PCB copper area with ≥4 thermal vias for rated performance.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LP3947ISD-09, BQ24075RGTR offers higher current but sacrifices I²C flexibility and thermal monitoring, while TPS65023RSBR integrates power management at the cost of dedicated battery safety features-making LP3947ISD-09 optimal for thermally constrained, programmable single-cell applications.

Availability

LP3947ISD-09 is available at Aetrix Electronics and suitable for smartphone charging systems, USB-powered portable audio devices, digital camera power management, and industrial handheld scanners requiring stable component supply and long-term lifecycle support.

Supply support for LP3947ISD-09 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 with emphasis on reliability, precision, and energy efficiency.

The LP3947 product line targets portable Li-ion battery charging in space-constrained consumer and industrial devices, emphasizing integrated safety, dual-source flexibility, and programmable configuration without external components.

FAQ

What is the factory-programmed battery regulation voltage for LP3947ISD-09?

The LP3947ISD-09 is factory-programmed for 4.1 V battery regulation voltage, as confirmed in the Ordering Information table (SNVS298B, p.2). This value is fixed and cannot be altered via I²C registers-only the LP3947ISD-51 variant supports 4.2 V. The 4.1 V setting ensures compatibility with legacy Li-ion cells requiring lower termination voltage for extended cycle life.

How does the LP3947ISD-09 enter LDO mode, and what output does it provide?

The LP3947ISD-09 enters LDO mode when the TS pin voltage reaches ≥2.7 V-typically achieved by leaving TS floating or connecting it to VT (2.78 V). In this mode, it sources up to 1.2 A at 4.1 V from the BATT pin, bypassing charging functionality. This is intended for system-level testing without a battery; operating LDO mode with a battery connected risks overcharging and damage.

What is the default USB charge current for LP3947ISD-09, and how is it selected?

The LP3947ISD-09 defaults to 500 mA USB charge current, enabled by pulling the ISEL pin LOW (per Table 2, p.9). This differs from the base LP3947 which defaults to 100 mA (ISEL HIGH). The MODE pin must be LOW to activate USB mode, and I²C register 0x02 can further adjust current within 100–500 mA range for dynamic host control.

Does LP3947ISD-09 support temperature monitoring, and how is it implemented?

Yes, LP3947ISD-09 continuously monitors battery temperature via the TS pin using an external thermistor (RT) and bias resistor (RS). The device compares TS voltage against 1.39 V (low-temp cutoff) and 2.427 V (high-temp cutoff); charging suspends if voltage falls outside this window. Recovery resets the 5.6-hour timer and restarts pre-qualification, ensuring safe operation across −40°C to +85°C ambient.

What package type and thermal characteristics apply to LP3947ISD-09?

LP3947ISD-09 uses the WSON-14 (NHL0014B) package with exposed thermal pad. Its junction-to-ambient thermal resistance is 37 °C/W when mounted with thermal land and ≥4 vias-enabling 1.21 W max power dissipation at 80 °C ambient. Without proper thermal design, power handling drops significantly; the absolute max rating is 1.89 W only at TA = 80 °C with θJA = 37 °C/W.