Datasheet LTC1980 (Analog Devices)

LTC1980 Combination Battery Charger and DC/DC Converter
U FEATURES DESCRIPTIO
■
Single Controller IC Includes Battery Charger
The LTC®1980 integrates PWM power control for charg-
Plus DC/DC Converter
ing a battery and converting the battery voltage to a ■
Wall Adapter Voltage May be Above or Below
regulated output or simultaneously charging the battery
Battery Voltage
while powering a system load from an unregulated AC wall ■
LDO Controller Allows Simultaneous Charging
adapter. Combining these features into a single IC pro-
and Regulating from Wall Adapter Input
duces a smaller area and lower cost solution compared to ■
Standalone Li-Ion Battery Charger Including Charge
presently available multi-IC solutions. The LTC1980 shares the discrete components for both the battery charger and
Termination, Overvoltage Protection, Shorted-Cell
the DC/DC converter thus minimizing size and cost relative
Detection and Battery Recharge
■ to dual controller solutions. Both the battery charger and Selectable 4.1V, 4.2V, 8.2V and 8.4V Float Voltages ■ DC/DC converter use a current mode flyback topology for Simple NiMH and NiCd Battery Charger ■ high efficiency and excellent transient response. Optional Pin Programmable Regulator Burst Mode® Operation Burst Mode operation and power-down mode allow power and Shutdown for High Efficiency density, efficiency and output ripple to be tailored to the ■ High Efficiency Current Mode 300kHz PWM application. ■ Reduced Component Architecture ■ Undervoltage Protection and Soft-Start Ensures The LTC1980 provides a complete Li-Ion battery charger Start-Up with Current Limited Wall Adapter with charge termination timer, preset Li-Ion battery volt- ■ Small 24-Pin SSOP Package ages, overvoltage and undervoltage protection, and user-
U
programmable constant-current charging. Automatic bat-
APPLICATIO S
tery recharging, shorted-cell detection, and open-drain C/10 and wall plug detect outputs are also provided. User ■ Digital Cameras programming allows NiMH and NiCd battery chemistries ■ Handheld Computers to be charged as well. ■ Personal Digital Assistants , LTC and LT are registered trademarks of Linear Technology Corporation. ■ 1W to 10W Uninterruptable Power Supplies Burst Mode is a registered trademark of Linear Technology Corporation. Patents Pending.
U TYPICAL APPLICATIO Li-Ion Charger and DC/DC Converter Using One IC 3.3V Regulator Efficiency vs Load Current
POWER FLOW 90 CHARGING BATTERY OPERATION UNREGULATED 85 Li-Ion WALL ADAPTER • BATTERY INPUT (3V TO 10V) SYSTEM 80 POWER BAT-FET • REG-FET 75 LDO/ SWITCH EFFICIENCY (%) 70 3.3V 65 V SYSTEM LOAD BAT = 3.6V T DC/DC 1.8V A = 25°C FIGURE 5 CONVERTERS 1.5V 60 10 100 1000 LTC1980 LOAD CURRENT (mA) 1980 TA01 1980 G04 1980f 1