RT5021 datasheet(34/67 Pages) RICHTEK

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RT5021

DS5021-01 April 2013

www.richtek.com

is a registered trademark of Richtek Technology Corporation.

CH8 : Low Voltage LDO

CH8 is a low voltage LDO and its output voltage is controlled by I2C interface. It supplies for multiple purpose power. The

output voltage of CH8 can be adjusted by the I2C interface in the range of 1.1V to 3.3V.

CH8 regulation voltage can be selected by I

C interface. The default voltage is 2.8V.

Code

Voltage

Code

Voltage

Code

Voltage

Code

Voltage

0000

Switch

0001

1.1V

0010

1.2V

0011

1.3V

0100

1.4V

0101

1.5V

0110

1.6V

0111

1.7V

1000

1.8V

1001

1010

2.2V

1011

2.5V

VOUT8 [3:0]

1100

2.8V

1101

3.1V

1110

3.2V

1111

3.3V

RTC_LDO : Accuracy 3.05V LDO Output.

The RT5021 provides a 3.05V output LDO for real-time clock. The LDO features low quiescent current (3

μA), reverse

leakage prevention from output node and high output voltage accuracy. This LDO is always on, even when the system is

shut down. For better stability, it is recommended to connect a 0.1

μF capacitor to the RTCPWR pin. The RTC LDO

includes pass transistor body diode control to avoid the RTCPWR node from back-charging into the input node VDDI.

Switching Frequency

The converters of CH1, CH3, CH4 and CH5 operate in PWM mode with 2MHz switching frequency. The converters of

CH2 and CH7 operates in PWM mode with 1MHz switching frequency.

Power On/Off Sequence and deglitch function for CH1 to CH4

SEQ pull down resistance RSEQ Defines power on/off sequence.

RSEQ (kΩ) Range

SEQ#

M in

Typ

Max

SEQ #0

Short to Power (>0.2V)

SEQ #1

SEQ #2

6.25

SEQ #3

1.56

2.5

SEQ #4

0.63

SEQ #5

100

160

SEQ # 0 : CH2

CH3

CH4

(CH1 is decided by register A4 bit3.)

SEQ # 1 : CH1 → CH3 → CH2 → CH4

SEQ # 2 : CH1 → CH3 → CH4 → CH2

SEQ # 3 : CH1 → CH2 → CH4 → CH3

SEQ # 4 : CH1 → CH4 → CH3 → CH2

SEQ # 5 : CH1 → CH4 → CH2 → CH3

Floating = resistance greater than 160k

Ω = SEQ#5

The power on sequence of CH1 to CH4 is shown below :

(Using SEQ #3 : CH1 → CH2 → CH4 → CH3 to explain)

When EN1234 goes high, CH1 will be turned on first then CH2 will be turned on after CH1 turn on for 10msec, likewise,

CH4 will be turned on after CH2 turns on for 10msec. Finally, CH3 is turned on after CH4 turns on for 10msec. The soft-

start time is 4msec for each channel.

The power off sequence of CH1 to CH4 is :

When EN1234 goes low, CH3 will turn off first and internally discharge output via LX3 pin. When FB3 < 0.1V, CH4 will

turn off and also internally discharge output via the LX4 pin. When FB4 < 0.1V, CH2 will turn off and internally discharge

output via the LX2 pin. Likewise, when FB2 < 0.1V, CH1 will turn off and discharge output. After FB1 < 0.1V, CH1 to CH4

shutdown sequence is completed.

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