LTC1980_15 Datasheet, PDF (1/16 Pages) Linear Technology – Combination Battery Charger and DC/DC Converter

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