Datasheet LTC4008 (Analog Devices)

LTC4008 4A, High Efficiency, Multi-Chemistry Battery Charger
FEATURES DESCRIPTION
n
General Purpose Charger Controller
The LTC®4008 is a constant-current/constant-voltage n
High Conversion Efficiency: Up to 96%
charger controller. The PWM controller uses a synchro- n
Output Currents Exceeding 4A
nous, quasi-constant frequency, constant off-time archi- n
±0.8% Voltage Accuracy
tecture that will not generate audible noise even when n
AC Adapter Current Limiting Maximizes
using ceramic capacitors. Charging current is program-
Charge Rate*
mable with a sense resistor and programming resistor to n Thermistor Input for Temperature Qualified Charging ±4% typical accuracy. Charging current can be monitored n Wide Input Voltage Range: 6V to 28V as a voltage across the programming resistor. An external n Wide Output Voltage: 3V to 28V resistor divider and precision internal reference set the n 0.5V Dropout Voltage; Maximum Duty Cycle: 98% final float voltage. n Programmable Charge Current: ±4% Accuracy The LTC4008 includes a thermistor sensor input that will n Indicator Outputs for Charging, C/10 Current suspend charging if an unsafe temperature condition is Detection, AC Adapter Present, Input Current detected and will automatically resume charging when Limiting and Faults battery temperature returns to within safe limits; a FAULT n Charging Current Monitor Output pin indicates this condition. A FLAG pin indicates when n Available in a 20-Pin Narrow SSOP Package charging current has decreased below 10% of the pro-
APPLICATIONS
grammed current. An external sense resistor programs AC adapter current limiting. The ICL pin indicates when the n Notebook Computers charging current is being reduced by input current limiting n Portable Instruments so that the charging algorithm can adapt. n Battery Backup Systems All registered trademarks and trademarks are the property of their respective owners. Protected by U.S. Patents including 5723970.
TYPICAL APPLICATION 12.3V, 4A Li-Ion Charger
DCIN INPUT SWITCH 0V TO 28V 0.1µF 140k* LTC4008 VLOGIC BATMON DCIN 100k 100k VFB INFET 0.1µF 0.02Ω SYSTEM ICL ICL CLP 4.99k LOAD ACP ACP/SHDN CLN 20µF FAULT FAULT TGATE Q1 10µH 0.025Ω FLAG FLAG BGATE 32.4k Li-Ion NTC PGND Q2 20µF BATTERY RT CSP 15k* I 3.01k TH BAT THERMISTOR 150k 6.04k GND PROG 3.01k 10k CHARGING NTC CURRENT 0.47µF 0.12µF MONITOR 0.0047µF 26.7k Q1: Si4431BDY Q2: FDC645N NOTE: * 0.25% TOLERANCE 4008 TA01 ALL OTHER RESISTORS ARE 1% TOLERANCE Rev C Document Feedback For more information www.analog.com 1 Document Outline Description Typical Application Absolute Maximum Ratings Typical Performance Characteristics Pin Functions Block Diagram Operation Applications Information Package Description Typical Application Related Parts Features Applications Typical Application Description Absolute Maximum Ratings Pin Configuration Order Information Electrical Characteristics Typical Performance Characteristics Pin Functions Block Diagram Test Circuit Operation Applications Information Package Description Revision History Related Parts