RT5021
Operation
The RT5021 is an integrated power solution for digital still
cameras and other small handheld devices. It includes
six DC/DC converters, a WLED driver, a RTC LDO, and a
fully integrated single-cell Li-ion battery charger.
CH1 : Step-Up DC/DC Converter
CH1 is a step-up converter for motor driver power. The
converter operates at PFM or PWM current mode which
can be set by I
2
C interface.
CH2 : Step-Up/Down DC/DC Converter
CH2 is a step-up/down converter for I/O power. The
converter operates at PFM or PWM current mode which
can be set by I
2
C interface.
CH3 : Step-Down DC/DC Converter
CH3 is a step-down converter for core power. The converter
operates at PFM or PWM current mode which can be set
by I
2
C interface.
CH4 : Step-Down DC/DC Converter
CH4 is a step-down converter for memory power. The
converter operates at PFM or PWM current mode which
can be set by I
2
C interface.
CH5 : Step-Down DC/DC Converter
CH5 is a step-down converter. The converter operates at
PFM/PWM current mode.
CH6 : Generic LDO
CH6 is a generic low voltage LDO for multiple purpose
power.
CH7 : WLED Driver
CH7 is a WLED driver that can operate in either current
source mode or synchronous step-up mode which is
determined by I
2
C interface control signal.
Constant Voltage Mode
When the output voltage is near 4.2V and the charging
current falls below the termination current for a deglitch
time of 25ms, the charger will be turned off and CHG will
go to high.
Re-Charge Mode
When the chip is in charge termination mode, the charging
current gradually goes down to zero. Once the battery
voltage drops to below 4.1V for 100ms, the charger will
resume charging operation.
Fast-Charge Mode
When the output voltage is higher than 3V, the charging
current will be equal to the fast-charge current set by
A8.ISETA [3:0].
Pre-Charge Mode
When the output voltage is lower than 2.8V, the charging
current will be reduced to a ratio of fast-charge current
set by A8.ISETA [3:0] to protect the battery life-time.
CH8 : Generic LDO
CH8 is a generic low voltage LDO for multiple purpose
power.
CH9 : Keep Alive LDO and RTC
CH9 is a LDO providing a 3.05V output for real time clock.
Charger Unit
A Li-ion battery charger with automatic power path
management is designed to operate in below modes.
Copyright
©
2013 Richtek Technology Corporation. All rights reserved.
is a registered trademark of Richtek Technology Corporation.
DS5021-01 April 2013
www.richtek.com
7
RICHTEK [ RICHTEK TECHNOLOGY CORPORATION ]
