ST AN2726 Application note
AN2726
Application note
Evaluation board user guidelines for the STw4102 single Li-Ion cell battery charger including gas gauge
1 Introduction
This application note describes the STEVAL-ISB006V1, an evaluation board specifically designed for the STw4102 battery management integrated circuit.
This document provides:
●a brief description of the STw4102
●a description of the evaluation board
●a detailed bill of materials of the evaluation board
●the layout of the evaluation board.
Figure 1. STw4102 evaluation board
July 2008 |
Rev 1 |
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www.st.com
About the STw4102 |
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2 About the STw4102
The STw4102 is a standalone constant-current, constant-voltage (CCCV) linear charger dedicated to Li-Ion batteries. The device has a dual charging capability that uses the main input adaptor (wall or car adapter) or a USB cable with no external component.
The STw4102 offers a programmable fast-charge current using an external resistor. The thermal regulation circuitry limits the charge current so that the die junction temperature never exceeds the maximum specified value. An end-of-charge output pin indicates the charge termination when the fast charge current drops below 10% of the programmed current value.The STw4102 contains an accurate gas-gauge based on a 13-bit AD converter. An external resistor is used between the battery and ground pin to sense a charge/discharge current. With a typical 30 mΩresistor, the current can be up to 2.5 A and the 24-bit accumulator system provides a capacity of up to 914 mA.h.
The STw4102 has the following key features.
■Constant-current constant-voltage (CCCV) linear charger.
■Common or separate USB/wall adapter inputs.
■Fast-charge current control up to 1 A for wall adapters and up to 500 mA for USB.
■Support for currents higher than 1 A using external components.
■Programmable charge voltage (4.1 V, 4.2 V, 4.3 V, 4.35 V) with 1% accuracy.
■Thermal regulation.
■Trickle-charge mode at low battery voltage.
■Wall adapter voltage up to 13 V.
■Battery over-voltage protection at 4.7 V.
■Gas gauge with 13-bit AD converter.
■Battery voltage monitor with 7- to 12-bit AD converter.
■I²C interface for device monitoring and control.
■Charge status output pin.
■Power detection output pin.
■Programmable watchdog security timer.
■4.7 V LDO regulator (with external power MOSFET).
Figure 2 describes the application schematics, with the typical connections and peripheral components surrounding the charger IC.
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About the STw4102 |
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Figure 2. Typical application for the STw4102
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Refer to the datasheet for more detailed information on the STw4102.
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