features

• activepathtm system power selection of best
available input supply
• 40mω battery switch for highest efficiency
• dynamic control of charging current allowing
system to draw maximum load from ac/usb
input
• ±0.5% battery voltage accuracy
• up to 12v input
• thermal regulation for charge control
• charge status outputs for led or system
interface
• battery voltage level indication
• programmable fast charge current
• programmable charging timer
• low reverse leakage current
• short-circuit and thermal protection
• preconditioning for deeply depleted battery
• low quiescent current standby mode
• space-saving, thermally-enhanced tqfn44-20
or tdfn3545-20 packages

applications
• personal navigation devices
• smart mobile phones
• blue-tooth devices
• portable media players
• portable devices

general description
the act3780 is a complete battery charging and
management solution for one cell lithium-ion or lithium-
polymer battery. the act3780 incorporates the
activepath architecture which automatically selects
the best available input supply for the system.
when an external power source such as an ac
adapter or a usb port is connected in, the act3780
regulates the system voltage to 4.8v in addition to
providing charging current to the battery. if the external
input source is not present or the system load
current is more than the input source can provide,
the activepath supplies additional current from the
battery to the system.
the act3780 charger is a complete, thermally
regulated, stand-alone single cell linear li+ charger
that integrates an internal power 12v mosfet. the
battery regulation voltage is ±0.5% accurate, and is
factory programmed from 4.2v (other voltages available
upon request).
the act3780 is available in an thermally enhanced
4mm x 4mm thin-qfn and 3.5mm × 4.5mm thin-
dfn 20-pin packages.