3

RT4532

DS4532-01 August 2015

www.richtek.com

©

Copyright 2015 Richtek Technology Corporation. All rights reserved.

is a registered trademark of Richtek Technology Corporation.

Functional Block Diagram

PWM

Current

Source Gen.

PWM

Logic

Digital

Control

EA

VSLOPE

PWM2DC

VOUT

LX

FB1

FB2

GND

SCL

SDA

EN

VIN

+

-

OCP

OVP

OTP

LEDs

Operation

The RT4532 is a high efficiency solution with 24 WLEDs

in 4 parallels 6 series for backlight applications. The

RT4532 optimizes the feedback regulation voltage to

provide up to 85% high efficiency with as high as 8bits

resolution application.

Linear Brightness Dimming

control with maximum 20mA/40mA selection.

Reg0x02<3> corresponds to full-scale LED current control.

Reg0x04 sets 8bits resolution brightness dimming.

PWM Brightness Dimming

control, the RT4532 features a built-in PWM dimming

current control by setting Reg0x02<6> to 1, offering a

linear current dimming by external clock source. In order

to guarantee the PWM dimming resolution, recommending

dimming frequency have to be operated at range of 400Hz

to 20kHz.

OCP Protection

The RT4532 features a 1.2A current limitation. Once

detecting current level over current limitation, the RT4532's

LX witching will be forced off to avoid large current damage.

OTP Protection

The over-temperature protection function will be latched

at shutdown status when the junction temperature

exceeds 140

°C for 2ms. After re-power on sequence, the

converter will automatically resume switching.

OVP Protection

The over-voltage protection function monitors the output

voltage via the VOUT pin voltage. The OVP threshold

voltage is 24V/16V by selecting Reg0x02<7>. Once the

LED is open, the output voltage reaches the OVP

threshold, the driver will be shut down.