The LTC?3553 is a micropower, highly integrated power management and battery charger IC for single-cell Li-Ion/Polymer battery applications. It includes a PowerPath manager with automatic load prioritization, a battery charger, an ideal diode and numerous internal
protection features. Designed specifi cally for USB applications,
the LTC3553 power manager automatically limits
input current to a maximum of either 100mA or 500mA.
Battery charge current is automatically reduced such that
the sum of the load current and the charge current does
not exceed the selected input current limit. The LTC3553
also includes a synchronous buck regulator, a low dropout
linear regulator (LDO), and a pushbutton controller. With
all supplies enabled in standby mode, the quiescent current
drawn from the battery is only 12μA. The LTC3553
is available in an ultrathin (0.55mm) 3mm × 3mm 20-pin UTQFN package.