Datasheet

Data Sheet ADP5065
Rev. D | Page 15 of 40
THEORY OF OPERATION
INTRODUCTION
The ADP5065 is a fully I
2
C-programmable charger for single-
cell lithium-ion or lithium-polymer batteries suitable for a wide
range of portable applications.
The highly efficient switcher dc-to-dc architecture enables higher
charging currents as well as a lower temperature charging
operation that results in faster charging times because of the
following features:
• 3 MHz switch mode charger.
• 1.25 A charge current from dedicated charger.
• Up to 680 mA of charging current from a 500 mA
USB host.
The ADP5065 operates from an input voltage from 4 V to 5.5 V
but is tolerant of voltages of up to 20 V. This alleviates the concern
about USB bus spiking during disconnection or connection
scenarios.
The ADP5065 features an internal FET between the dc-to-dc
charger output and the battery. This permits battery isolation
and, hence, system powering in a dead battery or no battery
scenario, which allows for immediate system function on
connection to a USB power supply.
The ADP5065 is fully compliant with the USB 3.0 battery charging
specification and enables charging via the mini USB VBUS pin
from a wall charger, car charger, or USB host port. Based on the
type of USB source, which is detected by an external USB
detection device, the ADP5065 can be set to apply the correct
current limit for optimal charging and USB compliance. The USB
charger permits correct operation under all USB compliant
sources such as, wall chargers, host chargers, hub chargers, and
standard hosts and hubs.
A processor is able to control the USB charger using the I
2
C to
program the charging current and numerous other parameters
including
• Trickle charge current level.
• Trickle charge voltage threshold.
• Weak charge (constant current) charge current level.
• Fast charge (constant current) charge current level.
• Fast charge (constant voltage) charge voltage level at 1%
accuracy.
• Fast charge safety timer period.
• Watchdog safety timer parameters.
• Weak battery threshold detection.
• Charge complete threshold.
• Recharge threshold.
• Charge enable/disable.
• Battery pack temperature detection and automatic charger
shutdown.