RT5021 Datasheet, PDF (33/67 Pages) Richtek Technology Corporation – Channels DC/DC PMU with Li-ion Battery Charger

RT5021
CH5 : Step-Down Synchronous DC/ DC Converter
The step-down synchronous DC/ DC converter includes internal power MOSFETs and compensation network. They can
be operated at 100% maximum duty cycle to extend battery operating voltage range. When the input voltage is close to
the output voltage, the converter enters low dropout mode with low output ripple. The output voltage can be selected as
the following list or set by external feedback network.
CH5 regulation voltage can be selected by I²C interface. The default voltage is 1.8V.
Code Voltage Code Voltage Code Voltage Code Voltage
0000
REF
0001
1.1V
0010
1.2V
0011
1.3V
VOUT5 [3:0]
0100
1000
1.4V
1.8V
0101
1001
1.5V
2V
0110
1010
1.6V
2.2V
0111
1011
1.7V
2.3V
1100
2.5V
1101
2.6V
1110
2.7V
1111
2.8V
Note : VOUT5 [3:0] = 0000 (REF) means using external feedback network and FB5
regulation target is 0.8V ± 1.5%
CH6 : Low Voltage LDO
CH6 is a low voltage LDO and its output voltage is controlled by I²C interface. This supplies the multiple purpose power.
The output voltage of CH6 can be adjusted by the I²C interface in the range of 1.1V to 3.3V.
CH6 regulation voltage can be selected by I²C interface. The default voltage is 1.3V.
Code Voltage Code Voltage Code Voltage Code Voltage
VOUT6 [3:0]
0000
0100
Switch
1.4V
0001
0101
1.1V
1.5V
0010
0110
1.2V
1.6V
0011
0111
1.3V
1.7V
1000
1.8V
1001
2V
1010
2.2V
1011
2.5V
1100
2.8V
1101
3.1V
1110
3.2V
1111
3.3V
CH7 : Current Source/Step-Up WLED Driver
The WLED drivers operating in either current source mode or synchronous step-up mode include internal power MOSFET
and compensation network. The operation mode is determined by setting I²C. The P-MOSFET in step-up mode can be
controlled to disconnect the output loading.
When CH7 works in current source mode, it likes a LDO and regulates the current by FB7 voltage. The LED current is
defined by the FB7 voltage as well as the external resistor between FB7 and GND. The FB7 regulation voltage can be set
in 31 steps from 8mV to 250mV. If CH7 works in synchronous step-up mode, it can support an output voltage up to 15V
or 21V controlled by I²C interface. The LED current is also set via an external resistor and FB7 regulation voltage.
The WLED current can be set by the following equation :
ILED (mA) = [250mV / R (Ω)] x EN7_DIM7 [4:0] / 31
Where R is the current sense resistor from FB7 to GND and EN7_DIM7 [4:0] / 31 ratio refers to the I²C control register
file.
Copyright ©2013 Richtek Technology Corporation. All rights reserved.
DS5021-01 April 2013
is a registered trademark of Richtek Technology Corporation.
www.richtek.com
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