LTC4055/LTC4055-1
USB Power Controller
and Li-Ion Charger
FEATURES DESCRIPTION n The LTCВ®4055/LTC4055-1 are USB power manager and
Li-Ion battery chargers designed to work in portable
battery-powered applications. The parts manage and limit
the total current used by the USB peripheral for operation
and battery charging. Depending on the state of the current
select pin (HPWR), total input current can be limited to
either 100mA or 500mA. The voltage drop from the USB
supply or battery to the USB peripheral is typically less than
100mV at 400mA and 20mV at 80mA. Other management
features include: automatic switchover to battery when
input is removed, inrush current limiting, reverse current
blocking, undervoltage lockout and thermal shutdown. n APPLICATIONS
n Portable USB Devices: Cameras, MP3 Players, PDAs L, LT, LTC and LTM are registered trademarks of Linear Technology Corporation.
PowerPath is a trademark of Linear Technology Corporation. All other trademarks are the
property of their respective owners. *Protected by U.S. Patent, including 6522118. The LTC4055/LTC4055-1 include a complete constantcurrent/constant-voltage linear charger for single-cell
Li-ion batteries. The float voltage applied to the battery
is held to a tight 0.8% tolerance, and charge current is
programmable using an external resistor to ground. Fully
discharged cells are automatically trickle charged at 10%
of the programmed current until the cell voltage exceeds …