RT4539A

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is a registered trademark of Richtek Technology Corporation

DS4539A-01

December 2022

www.richtek.com

27

26KHz Mode Division Frequency

The 26KHz mode division frequency can be set by the I2C interface, as shown in Table 15.

Table 15. 26KHz Mode Division Frequency

Address

Bit

Name

Default Value

Description

Resolution

R/W

08h

[7: 5]

26KHz mode

division

frequency

26KHz

(B000)

PWMO frequency

B000: 26KHz

B001: 26KHz/2

B010: 26KHz/4

B011: 26KHz/8

B1xx: 26KHz/16

--

R/W

The 26kHz mode division frequency can be controlled by address 08h[7: 5], there are five division frequencies

including 26KHz, 26KHz/2, 26KHz/4, 26KHz/8 and 26KHz/16. Moreover, this function can only be used at PWM

input control, if input control interface is I2C mode, the address 08h[7: 5] must write B000.

Control CLK PFM Function Enable and Lowest Switching Frequency for PFM

The Boost converter integrates a PFM function for high efficiency at light load. This function can be enabled or

disabled by address 0x09h [0: 0]. Moreover, PFM frequency can be set to different values by the desirable

applications. More setting details are shown in Table 16.

Table 16. Control CLK PFM Function Enable

Address Bit

Name

Default Value

Description

R/W

09h

[0:

0]

Control CLK PFM

function enable

off

(B0)

Control CLK PFM function enable

B0: Off

B1: On

R/W

[6:

1]

Lowest Switching

Frequency

for PFM

31.15KHz

(0x3Ch)

Lowest switching frequency setting

Formula:

16000/{(16000/Fsw)+(8*Code)+7}

R/W

The CLK PFM function enable can be controlled by address 09h[0: 0]. If the bit equals to 0, it means the boost

switching frequency just depends on the switching frequency setting. Otherwise, if the bit equals to 1, the boost

switching frequency will be decreased, when the boost on time is lower than the minimum on-time.