RT4539AWSC datasheet(5/39 Pages) RICHTEK

5 / 39 page

RT4539A

is a registered trademark of Richtek Technology Corporation

DS4539A-01

December 2022

www.richtek.com

Operation

Enable Control

When VIN is higher than the UVLO voltage and the EN

pin input voltage is higher than rising threshold, the

VCP will be regulated around 3.4V if VIN is higher than

3.4V.

Switching Frequency

The boost converter switching frequency is adjusted by

the I2C interface. The switching frequency range is

from 300kHz to 1.6MHz.

PWM Controller

This controller can control LX N-MOSFET on/off

according to error amplifier signal. This block controls

the minimum on- time and max duty of LX. The

RT4539A PWM controller is a current mode Boost

converter integrated with a 250mΩ, 39V power switch

and can cover a wide VIN range from 2.7V to 24V and

contains I2C interface.

OCP

When LX N-MOSFET peak current is higher than 2.5A

(typically), the LX N-MOSFET is turned off immediately

and resumes again at next clock pulse.

OTP

The RT4539A equips an Over Temperature Protection

(OTP) circuitry to prevent overheating due to excessive

power dissipation. The OTP will shut down switching

operation when junction temperature exceeds 150°C.

Once the junction temperature cools down by

approximately 30°C, the boost converter will resume

operation. To maintain continuous operation maximum,

the junction temperature should be prevented from

rising above 125°C.

OVP

The RT4539A integrates over-voltage protection. The

over-voltage protection could be set by the I2C, When

the OVP pin voltage is higher than 40V, the LX

N-MOSFET is turned off immediately to protect the LX

N-MOSFET.

Minimum LED Selection

This block detects all LEDx voltage and selects a

minimum voltage to EA (Error Amplifier). This function

can guarantee that the lowest voltage of the LED pin is

around 400mV and VOUT can be boosted to the highest

forward voltage of LED strings.

LED Open Detection

If the voltage at LEDx pin is lower than 100mV, this

channel is defined as open channel and the Minimum

LED Selection function will discard it to regulate other

used channels in proper voltage.

LED String Short Detection

If CHx pin voltages exceed the threshold of

approximately 5.6V during normal operation, the

channels will be turned off and it can be reset by EN or

VIN UVLO.

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