Compact, 1.5 A Linear Charger for Single-Cell Li+ Battery ADP2291 FEATURES GENERAL DESCRIPTION Simple, safe linear charger for single-cell lithium battery The ADP2291 is a constant-current/constant-voltage linear 4.5 V to 12 V input voltage range charger for a single-cell, lithium ion battery, requiring just a few Adjustable charging current up to 1.5 A components to provide a simple and safe charging system that Low cost PNP external pass element operates from a wide 4.5 V to 12 V input voltage range. It Automatic reverse isolation with no external blocking diode features an internally controlled, multistep charging cycle that Output overshoot protection improves battery life. Deep discharge precharge mode An external, low cost PNP provides the charging current to the Thermal shutdown battery, and an external resistor sets the maximum charge Automatic recharge current. A small, external capacitor programs the maximum Programmable termination timer charge time. The controller includes an LED driver to indicate LED charging status indicator the battery charging status. 4.2 V output voltage with 1% accuracy over line and temperature Safety features include charging stop mode for battery faults, 1 A shutdown supply current output overshoot protection, and thermal shutdown. The Small, 8-lead MSOP and 3 3 mm LFCSP packages ADP2291 also features automatic reverse isolation, which does not require an additional blocking diode. APPLICATIONS The multistep charge cycle optimizes the battery charging time Wireless handsets in a safe manner. It features a trickle charge mode for a deeply Smart handhelds and PDAs discharged cell and a fast charging mode with a maximum Digital cameras current of 1.5 A. The ADP2291 controls the end of charge with Single-cell, lithium ion-powered systems a 4.2 V output voltage that is 1% accurate over line and tem- Cradle chargers perature. It automatically recharges the battery if the cell voltage drops. When the input supply is removed, the part enters a low current state and reduces the current drawn from the battery to below 1 A. The ADP2291 is available in both a small, 8-lead MSOP package and a 3 3 mm LFCSP package that is ideally suited for small, portable applications. TYPICAL OPERATING CIRCUIT RS Q1 INPUT 4.6V12V + CIN COUT CS DRV IN BAT ADP2291 CHG GND TIMER ADJ CTIMER SHUTDOWN Figure 1. Rev. A Information furnished by Analog Devices is believed to be accurate and reliable. However, no responsibility is assumed by Analog Devices for its use, nor for any infringements of patents or other One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A. rights of third parties that may result from its use. Specifications subject to change without notice. No Tel: 781.329.4700 www.analog.com license is granted by implication or otherwise under any patent or patent rights of Analog Devices. Fax: 781.461.3113 2005 Analog Devices, Inc. All rights reserved. Trademarks and registered trademarks are the property of their respective owners. 04873-001ADP2291 TABLE OF CONTENTS Features .............................................................................................. 1 Overshoot Protection................................................................. 10 Applications....................................................................................... 1 Power Supply Checks................................................................. 10 General Description ......................................................................... 1 Thermal Shutdown .................................................................... 11 Typical Operating Circuit................................................................ 1 Application Information................................................................ 12 Specifications..................................................................................... 3 Setting the Maximum Charge Current.................................... 12 Absolute Maximum Ratings............................................................ 5 Setting the Maximum Charge Time ........................................ 12 ESD Caution.................................................................................. 5 External Capacitors.................................................................... 12 Pin Configurations and Function Descriptions ........................... 6 Reverse Input Protection........................................................... 12 Typical Performance Characteristics ............................................. 7 External Pass Transistor ............................................................ 13 Theory of Operation ...................................................................... 10 Typical Application Circuit....................................................... 14 Precharge Mode.......................................................................... 10 Charge Termination................................................................... 14 End-of-Charge Mode................................................................. 10 Selectable Charge Current......................................................... 14 Shutdown Mode.......................................................................... 10 Thermal Protection.................................................................... 14 Charge Restart............................................................................. 10 Printed Circuit Board Layout Considerations ....................... 16 Programmable Timer................................................................. 10 LFSCP Layout Considerations.................................................. 16 Charge Status Indicator ............................................................. 10 Outline Dimensions ....................................................................... 17 Automatic Reverse Isolation ..................................................... 10 Ordering Guide .......................................................................... 17 REVISION HISTORY 11/05Rev. 0 to Rev. A Changes to Equation 7 ................................................................... 13 Changes to Figure 26...................................................................... 15 Changes to Table 7.......................................................................... 16 Changes to Ordering Guide .......................................................... 17 Updated Outline Dimensions ....................................................... 17 10/04Initial Version: Revision 0 Rev. A Page 2 of 20