RT4539A

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DS4539A-01

December 2022

18

Table 4. Switching Frequency

Boost Switching Frequency [3: 0]

Frequency

0x00h

300kHz

0x01h

300kHz

0x02h

300kHz

0x03h

300kHz

0x04h

300kHz

0x05h

400kHz

0x06h

500kHz

0x07h

600kHz

0x08h

700kHz

0x09h

800kHz

0x0Ah

900kHz

0x0Bh

1000kHz

0x0Ch

1225kHz

0x0Dh

1335kHz

0x0Eh

1450kHz

0x0Fh

1600kHz

Current-Limit Protection

The RT4539A integrates current-limit protection and can limit the peak current to achieve over-current protection.

The RT4539A senses the inductor current that flows through the LX pin. During the “ON” period, the duty cycle

depends on the current signal, and internal slope compensation is compared with the error signal. The internal

switch of Boost converter will be turned off when the peak current value of inductor current is larger than the

over-current protection setting. In the “OFF” period, the inductor current will be decreased until the internal switch is

turned on by the oscillator.

Current-limit protection can be set by I2C interface and more details are shown in Table 5.

Table 5. Current-Limit Protection Setting

Address

Bit

Name

Default Value

Description

Resolution

R/W

01h

[4]

Switching Current

Limitation Selection

2.5A (B1)

B0: 1.5A

B1: 2.5A

--

R/W