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RT4532 Evaluation Board

EVB_RT4532WSC

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The RT4532 is a high-efficiency LED driver for backlight applications. An asynchronous boost converter with an internal Schottky diode and a current source driver are designed to support 6LED/channel with wide input voltage range from 2.5V to 5.5V.


Purpose

The RT4532 is a high-efficiency LED driver for backlight applications with an internal schottky diode and current source driver.

It supports linear mappings with 256 steps to setup the brightness of backlight LEDs. It also supports PWM dimming to adjust the brightness. This document explains the function and use of the RT4532 evaluation board (EVB) and provides information to enable operation and modification of the evaluation board and circuit to suit individual requirements.


Introduction

General Product Information

The RT4532 is a high-efficiency LED driver for backlight applications. An asynchronous boost converter with an internal Schottky diode and a current source driver are designed to support 6LED/channel with wide input voltage range from 2.5V to 5.5V.

This document explains the function and use of the RT4532 evaluation board (EVB) and provides information to enable operation and modification of the evaluation board and circuit to suit individual requirements.

Product Feature

  • Input Voltage Range : 2.5V to 5.5V
  • Internal Schottky Diode
  • Fast-speed mode I2C Compatible Interface
  • Drive Up to 6 WLEDs in 4 String
  • External PWM Brightness Control
  • 550k/1.1MHz Switching Frequency
  • Built-in Internal Soft-Start
  • I2C Programmable 256 Steps Linear Current Regulation
  • Up to 85% Efficiency with Small Magnetics
  • Programmable 16V/24V OVP
  • Current Accuracy ±5% and Current Balance ±3%
  • UVLO, OVP, OCP, OTP Protection
  • Shutdown Current : < 1µA
  • Temperature Range : -40°C to 85°C


Key Performance Summary Table

Key Features

Evaluation Board Number : PCB015_V1

Default Input Voltage

2.5V~5.5V

Max Output Current

20mA/40mA

Default Output Voltage

17V

Default Marking & Package Type

RT4532

Operation Frequency

Steady 1.1MHz at all loads

Protection

UVLO

OVP

OCP

Thermal Shutdown


Bench Test Setup Conditions

Headers Description and Placement

Technical Document Image Preview

Please carefully inspect the EVB IC and external components, comparing them to the following Bill of Materials, to ensure that all components are installed and undamaged. If any components are missing or damaged during transportation, please contact the distributor or send e-mail to evb_service@richtek.com.


Test Points

The EVB is provided with the test points and pin names listed in the table below.

Pin No.

Pin Name

Comment (expected waveforms or voltage levels on test points)

A2

GND

Ground. The exposed pad must be soldered to a large PCB and connected to GND for maximum thermal dissipation.

B1

VOUT

Power Output of the Asynchronous Boost Converter for Backlight LEDs.

Connect a 1μF or larger ceramic capacitor from VOUT to ground.

B2

VIN

Power Input. Connect this pin to the input power supply voltage.

Connect a 10μF or larger ceramic capacitor from the VIN to ground.

C1

PWM

PWM Dimming Input for Backlight LED.

C2

EN

Enable Control Input (Active High). The chip is in shutdown mode when the EN pin is low.

D1

SDA

I2C Serial Data Input/Output. An external pull-up resistor is required.

D2

SCL

I2C Serial Data Input/Output. An external pull-up resistor is required.

E1

FB2

Single Output 2 for Backlight LED.

E2

FB1

Single Output 1 for Backlight LED.


Power-up & Measurement Procedure

1. Apply 3.6V nominal input power supply (2.5V < VIN < 5.5V) to the VIN and GND terminals.

2. The EN voltage is pulled to logic high by internal circuit to enable operation. Drive EN high (>1.05V) to enable operation or low (<0.4V) to disable operation. Pull EN pin to High pin that make EN voltage equal to VIN.

3. There is a 2-pin header JP2 “EN” for enable control. To use a jumper at “H” option to tie EN test pin to input power VIN for enabling the device. Inversely, to use a jumper at “L” option to tie EN test pin and ground GND for disabling the device.

4. The JP4 is the I2C control pin that incloud SDA, SCL, GND pin, and it need to connect to Richtek WrenBoard when use the RT4532 I2C dimming.

5. The ILED setting supports I2C dimming and PWM dimming as below.


Output ILED Setting

1. Linear Brightness Dimming

The chip is built-in an I2C 8-bit resolution brightness control with maximum 20mA/40mA selection. Reg0x02 <3> corresponds to full-scale LED current control. Reg0x04 <7:0> sets 8bits resolution brightness dimming control.

Technical Document Image Preview

Where

ILED, Full : the full-scale LED current set by Reg0x02 <3>.

Code : the 8bit brightness code Reg0x04 <7:0> programmed by I2C interface.

2. PWM Brightness Dimming

Besides programmable built-in I2C backlight LED current 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 (7 bit at >15kHz application), recommending dimming frequency have to be operated at range of 400Hz to 20kHz.

3. LED Short Protection

LED short protection prevents abnormal connection to cause IC damage avoiding FB1/FB2 connecting power supply. And, If unbalanced LEDs series (cause FB1 or FB2 > 9.6V) is different between channel1 and channel2, IC will also occur LED short event. As LED short event occur more than deglitch time 2ms, IC will shut-down latch until IC is reset by EN pin.


Schematic, Bill of Materials & Board Layout


EVB Schematic Diagram

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Bill of Materials

Reference

Qty

Part Number

Description

Package

Manufacture

U2

1

RT4532

DC-DC Converter

CSP-10B 0.87x2.07

RICHTEK

L1

1

NR4018T100M

10µH/1.2A/±20%,
DCR = 0.18Ω, Inductor

4mm x 4mm x 1.8mm

TAIYO YUDEN

C1

1

0603X106M6R3

10µF/±20%/ 6.3V/X5R

Ceramic Capacitor

0603

Walsin

C3

1

C2012X7R1H105KT

1µF/±10%/50V/X7R

Ceramic Capacitor

0805

TDK

R7

1

Short

R11

1

Short

R13

1

Short

D32, D34, D36,

D33, D35, D37,

D38, D40, D62,

D39, D41, D63,

D46, D48, D50,

D47, D49, D51,

D42, D44, D64,

D43, D45, D65

24

LED

TP

6

3V3, SCL, SDA,

1V8, FB1, FB2

Test Pin

GP

4

VIN, GND, GND, VOUT

Golden Pin

JP

3

JP1, JP2, JP4


EVB Layout

Technical Document Image Preview

PCB Layout—Top View

Technical Document Image Preview

PCB Layout—Bottom Side

Title Last Update Share Download
Evaluation Board User Guide 2015/08/17
Bill of Materials 2015/08/17
Gerber File 2015/09/18
Schematic 2015/09/18
Part NumberFree SampleBuy From Authorized Distributor
EVB_RT4532WSC Not available Buy from Distributor
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