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ADP2291
Datasheet
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Analog Devices ADP2291 Datasheet

Compact, 1.5 A Linear Charger
4

FEATURES

Simple, safe linear charger for single cell lithium battery
4.5 V to 12 V input voltage range Adjustable charging current up to 1.5 A Low cost PNP external pass element Automatic reverse isolation with no external blocking diode Output overshoot protection Deep discharge precharge mode Thermal shutdown Automatic recharge Programmable termination timer LED charging status indicator
4.2 V output voltage with ±1% accuracy over line and temperature
1 µA shutdown supply current Small, 8-pin MSOP and 3 × 3 mm LFCSP packages

APPLICATIONS

Wireless handsets Smart handhelds and PDAs Digital cameras Single cell lithium ion-powered systems Cradle chargers
for Single-Cell Li+ Battery
ADP2291

GENERAL DESCRIPTION

The ADP2291 is a constant-current/constant-voltage linear charger for a single cell lithium ion battery, requiring just a few components to provide a simple and safe charging system that operates from a wide 4.5 V to 12 V input voltage range. It features an internally controlled, multistep charging cycle that improves battery life.
An external, low cost, PNP provides the charging current to the battery and an external resistor sets the maximum charge current. A small external capacitor programs the maximum charge time. The controller includes an LED driver to indicate the battery charging status.
Safety features include charging stop mode for battery faults, output overshoot protection, and thermal shutdown. The ADP2291 also features automatic reverse isolation, which does not require an additional blocking diode.
The multistep charge cycle optimizes the battery charging time in a safe manner. It features a trickle charge mode for a deeply discharged cell and a fast charging mode with a maximum current of 1.5 A. The ADP2291 controls the end of charge with a 4.2 V output voltage that is 1% accurate over line and temp­erature. 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 µA.

TYPICAL OPERATING CIRCUIT

INPUT
.6V–12V
Rev. 0
CIN
CTIMER
Figure 1. Basic Circuit Configuration
The ADP2291 is available in both a small, 8-pin MSOP package and a 3 × 3 mm LFCSP package that is ideally suited for small, portable applications.
RS Q1
CS DRV
IN
ADP2291
CHG
TIMER ADJ
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A. Tel: 781.329.4700 Fax: 781.326.8703 © 2004 Analog Devices, Inc. All rights reserved.
+
COUT
BAT
GND
SHUTDOWN
04873-0-001
www.analog.com
ADP2291
TABLE OF CONTENTS
Specifications..................................................................................... 3
Absolute Maximum Ratings............................................................ 5
ESD Caution.................................................................................. 5
Pin Configuration And Functional Descriptions......................... 6
Typical Performance Characteristics............................................. 7
Theory of Operation ...................................................................... 10
Precharge Mode.......................................................................... 10
End-of-Charge Mode................................................................. 10
Shutdown Mode.......................................................................... 10
Charge Restart............................................................................. 10
Programmable Timer................................................................. 10
Charge Status Indicator ............................................................. 10
Automatic Reverse Isolation ..................................................... 10
Overshoot Protection................................................................. 10
Power Supply Checks ................................................................. 10
Thermal Shutdown .................................................................... 11
Application Information................................................................ 12
Setting the Maximum Charge Current.................................... 12
Setting the Maximum Charge Time ........................................ 12
External Capacitors.................................................................... 12
Reverse Input Protection ........................................................... 12
External Pass Transistor ............................................................ 13
Typical Application Circuit ....................................................... 14
EOC Terminates Charging........................................................ 14
Selectable Charge Current......................................................... 14
Thermal Protection .................................................................... 14
Printed Circuit Board Layout Considerations........................ 16
LFSCP Layout Considerations.................................................. 16
Outline Dimensions....................................................................... 18
Ordering Guide .......................................................................... 18
REVISION HISTORY
10/04—Initial Version: Revision 0
Rev. 0 | Page 2 of 20
ADP2291

SPECIFICATIONS

VIN = 5.5 V, V
= 4.2 V, R
BAT
open, TA = –40°C to +85°C, typical values are at 25°C unless otherwise noted.
ADJ
Table 1. Electrical Characteristics
Parameter Conditions Min Typ Max Unit
Power Supply, IN
Input Voltage 4.5 12 V Current Draw
Fast charge/precharge/end-of-charge modes Timeout/shutdown/battery fault
Battery Voltage, BAT
Voltage Accuracy, End-of-charge (V
Load Regulation, No Battery VIN – VCS = 0 to VRS Current Draw
Current Draw
Reverse Leakage Current
BAT, EOC
)
= 0°C to +50°C
T
A
= 4.5 V to 12 V
V
IN
V
– VCS = VRS/10
IN
Timeout mode
= 4.5 V to 12 V
V
IN
Battery fault/shutdown mode
= 4.5 V to 12 V
V
IN
Power-down mode
= float, V
V
IN
BAT
= 4.2 V
Fast Charge Mode
Sense Voltage Setpoint (VRS)
Sense Voltage Setpoint (VRS)
Current Regulation Adjustment per V of (3 V – V
– VCS, R
V
IN
V
IN
V
BAT
V
IN
V
IN
V
BAT
ADJ
= 4.5 V to 12 V
= 3.6 V
– VCS, R
ADJ
= 4.5 V to 12 V
= 3.6 V
= open
= 100 kΩ
) 67 mV/V
ADJ
Precharge Mode
Sense Voltage Setpoint (VRS)
Sense Voltage Setpoint (VRS)
BAT Precharge Threshold V
– V
V
IN
= 4.5 V to 12 V
V
IN
V
= 2 V
BAT
– VCS, R
V
IN
V
= 4.5 V to 12 V
IN
= 2 V
V
BAT
rising 2.65 2.85 V
BAT
CS, RADJ
ADJ
= open
= 100 kΩ
Hysteresis 70 mV
Shutdown Mode
ADJ Shutdown Threshold V
falling, VIN = 4.5 V 0.30 0.45 V
ADJ
Hysteresis 40 mV Pullup current from ADJ V
= 0 40 µA
ADJ
Power-Down Mode
VIN Powerdown Threshold VIN rising 3.6 4 V Hysteresis 220 mV
VIN_Good Comparator
Threshold (VIN > V
) VIN rising 125 170 220 mV
BAT
Hysteresis 110 mV
EOC Comparator
Current Threshold VIN – VCS falling, R Current Threshold VIN – VCS falling, R
= open, relative to VRS 7 10 13 %
ADJ
= 100 kΩ, relative to VRS 6 10 16 %
ADJ
Hysteresis 12 mV
Restart Comparator
BAT Restart Threshold VIN > 4.5 V, V
falling, relative to V
BAT
BAT, EOC
1
6
1.4 9 1.8
mA mA
4.158 4.2 4.242 V
–80 mV 45 µA
0.1 1 µA
0.1 µA
140 150 160 mV
40 50 60 mV
10 15 20 mV
5 10 15 mV
–170 mV
Rev. 0 | Page 3 of 20
ADP2291
Parameter Conditions Min Typ Max Unit
Battery Charge Timer
Charge/Discharge TIMER Current 21.0 24.0 27.0 µA
Low Threshold 1.2 V
High Threshold 2.0 V
High-Low Threshold Delta Overshoot Protection
BAT Threshold 4.7 5 5.3 V
Current Sink <2 ms duration 1.5 A CHG Output
Output Voltage Low Current = 20 mA 0.45 V
Output Leakage Current V
Base Drive Capability
Max Base Drive Current 40 mA Thermal Shutdown
Shutdown Threshold TA rising 135 °C
Hysteresis 35 °C
1
All limits at temperature extremes are guaranteed via correlation using standard statistical quality control (SQC). Typical values are at TA = 25° C.
2
Guaranteed by design, not tested in production.
2
750 850 mV
= 5 V 0.1 1 µA
CHG
Rev. 0 | Page 4 of 20
ADP2291

ABSOLUTE MAXIMUM RATINGS

Table 2.
Parameter Rating
IN, DRV1, CS, CHG, to GND BAT, ADJ, TIMER to GND −0.3 V to (VIN + 0.3 V) Operating Ambient Temperature −40°C to +85°C Operating Junction Temperature −40°C to +125°C
θJA, 2-layer MSOP-8 220ºC/W θJA, 4-layer MSOP-8 158ºC/W θJA, 2-layer LFCSP-8 62ºC/W
θJA, 4-layer LFCSP-8 48ºC/W Storage Temperature −65°C to +150°C Lead Temperature Range Soldering
(10 sec)
−0.3 V to +13.5 V
300°C

ESD CAUTION

ESD (electrostatic discharge) sensitive device. Electrostatic charges as high as 4000 V readily accumulate on the human body and test equipment and can discharge without detection. Although this product features proprietary ESD protection circuitry, permanent damage may occur on devices subjected to high energy electrostatic discharges. Therefore, proper ESD precautions are recommended to avoid performance degradation or loss of functionality.
Stresses above those listed under Absolute Maximum Ratings may cause permanent damage to the device. This is a stress rating only and functional operation of the device at these or any other condition s above those indicated in the operational section of this specification is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. Absolute maximum ratings apply individually only, not in combination. Unless otherwise specified all other voltages referenced to GND.
1
Pulling current from the DRV pin by driving it below ground, while VIN is
applied, may cause permanent damage to the device.
Rev. 0 | Page 5 of 20
ADP2291

PIN CONFIGURATION AND FUNCTIONAL DESCRIPTIONS

DRV
1
CS
ADP2291
2
TOP VIEW
3
(Not to Scale)
4
GND BAT
Figure 2. 8-Lead MSOP
Table 3. Pin Function Descriptions
Pin No. Mnemonic Description
1 DRV Base Driver Output. Controls the base of an external PNP pass transistor. 2 GND Ground. 3 BAT Battery Voltage Sense Input. 4 CS Current Sense Resistor Negative Input. 5 ADJ Charging Current Adjust and Charger Shutdown Input.
6 IN Power Input and Current-Sense Resistor Positive Input. 7 TIMER Timer Programming Input/Disable. 8
CHG
CHG
8
TIMER
7 6
IN ADJ
5
04873-0-002
LED Charge-Status Indicator. This is an open-collector output.
PIN 1
1DRV
INDICATOR
2GND
ADP2291
3BAT
TOP VIEW
(Not to Scale)
4CS
Figure 3. 8-Lead LFCSP
8 CHG 7 TIMER 6IN 5 ADJ
04873-0-003
Rev. 0 | Page 6 of 20
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