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Richtek

Boost Converter with 6-CH LED Driver Evaluation Board

EVB_RT4539AGQW

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The Evaluation Board demonstrates the RT4539A device provides a highly integrated white LED driver solution for Notebook and Tablet LCD backlight. The device is a white-LED driver featuring a 36V high efficiency asynchronous boost converter and six 35mA high precision current sinks with a maximum of ±2% current mismatching for excellent brightness uniformity in each string of LEDs. The RT4539A has five dimming modes including DC mode, direct PWM mode, PWM-26k mode, mix mode and mix-26k mode that can be controlled by PWM signal or an I2C master, or both. In addition, the RT4539A has a wide input voltage operating range from 2.7V to 24V and contains I2C interface for controlling the dimming mode, operating frequency, LED current slope time and the LED current. It is suitable for single/two cell battery input to drive LED light bars which contain six strings in parallel.

General Description

The Evaluation Board demonstrates the RT4539A device provides a highly integrated white LED driver solution for Notebook and Tablet LCD backlight. The device is a white-LED driver featuring a 36V high efficiency asynchronous boost converter and six 35mA high precision current sinks with a maximum of ±2% current mismatching for excellent brightness uniformity in each string of LEDs. The RT4539A has five dimming modes including DC mode, direct PWM mode, PWM-26k mode, mix mode and mix-26k mode that can be controlled by PWM signal or an I2C master, or both. In addition, the RT4539A has a wide input voltage operating range from 2.7V to 24V and contains I2C interface for controlling the dimming mode, operating frequency, LED current slope time and the LED current. It is suitable for single/two cell battery input to drive LED light bars which contain six strings in parallel.



Performance Specification Summary

Summary of the RT4539AGQW Evaluation Board performance specification is provided in Table 1. The ambient temperature is 25°C.


Table 1. RT4539AGQW Evaluation Board Performance Specification Summary

Specification

Test Conditions

Min

Typ

Max

Unit

Input Voltage Range

2.7

3.8

24

V

Operation Frequency

Boost operates at PWM mode default = 600kHz @ 0x07h

300

600

1600

kHz

Switching Frequency Accuracy

Boost operates at PWM mode, fSW = 600kHz

-10

--

10

%

Switching Current Limitation

2

2.5

3

A

Maximum LED Current Setting

LED 100% setting, register address = ”02h”,

Step = 0.12mA

10.04

--

35

mA

LED Current Accuracy

PWM duty = 100%, IFBx = 20mA,

PWM frequency = 1kHz

-3

--

3

%

PWM duty = 5%, IFBx = 20mA,

PWM frequency = 1kHz

-5

--

5

PWM duty = 1%, IFBx = 20mA,

PWM frequency = 1kHz

-15

--

15

LED Current Matching

PWM duty = 100%, IFBx = 20mA,

PWM frequency = 1kHz

-2

--

2

%

PWM duty = 5%, IFBx = 20mA,

PWM frequency = 1kHz

-5

--

5

PWM duty = 1%, IFBx = 20mA,

PWM frequency = 1kHz

-10

--

10



Power-up Procedure

Suggestion Required Equipments

  • RT4539AGQW Evaluation Board
  • DC power supply capable of at least 30V and 4A
  • DC power supply capable of at least 6V and 1A
  • Function Generator
  • Oscilloscope
  • LED Light Bar

Quick Start Procedures

The Evaluation Board is fully assembled and tested. Follow the steps below to verify board operation. Do not turn on supplies until all connections are made.


Proper measurement equipment setup and follow the procedure below.

1) With power off, connect the input power supply to VIN and GND pins.

2) With power off, connect the input power supply to EN and GND pins.

3) With power off, connect the function generator to PWM and GND pins.

4) With power off, connect LED light bar to Vout and FB1 to FB6 pins.

5) Turn on the power supply at the input.

6) Once the proper output voltage is established, adjust the brightness within the operating ranges and observe the FB1 to FB6 current, switching frequency and other performance.



Detailed Description of Hardware

Headers Description and Placement

一張含有 電路, 文字, 電子工程, 螢幕擷取畫面 的圖片

自動產生的描述

Carefully inspect all the components used in the EVB according to the following Bill of Materials table, and then make sure all the components are undamaged and correctly installed. If there is any missing or damaged component, which may occur during transportation, please contact our distributors or e-mail us at evb_service@richtek.com.


Test Points

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

Test Point/

Pin Name

Function

LX

Switch node of boost converter.

PGND

Power ground.

SDA

Data signal input of I2C interface.

SCL

Clock signal input of I2C interface.

PWM

PWM dimming control input.

EN

Enable control input (active high).

VIN

Device power supply input.

VOUT

Output of boost converter.

VCP

Internal LDO output pin. Connect a capacitor (Ccp) between this pin and the ground reference.

FB1

Current sink for LED1.

FB2

Current sink for LED2.

FB3

Current sink for LED3.

FB4

Current sink for LED4.

FB5

Current sink for LED5.

FB6

Current sink for LED6.



Bill of Materials

VIN = 3.8V, EN = 3.3V, fSW = 600kHz, ILEDmax = 20mA/Ch

Reference

Count

Part Number

Value

Description

Package

Manufacturer

U1

1

RT4539AGQW

RT4539AGQW

LED Driver

WQFN-24L 4x4

RICHTEK

C1, C10

2

GRM31CR71H475KA12L

4.7µF

Capacitor, Ceramic, 50V, X7R

1206

MURATA

C4, C5

2

UMK316BJ225KD-T

2.2µF

Capacitor, Ceramic, 50V, X5R

1206

TAIYO YUDEN

C23

1

0603X105K250CT

1µF

Capacitor, Ceramic, 16V, X7R

0603

WALSIN

C24, C27

2

GRM21BR71H105KA12L

1µF

Capacitor, Ceramic, 50V, X7R

0805

MURATA

D2

1

SR26

SR26

SR26

SMA/DO-214AC

PANJIT

L2

1

LSXNH8080YKL100MJG

10µH

10µH

L-8x8

TAIYO YUDEN

R3

1

WR06X10R0FTL

10

10

0603

WALSIN

R5, R6

2

RTT034701FTP

4.7k

4.7k

0603

RALEC

R7, R8

2

RTT031001FTP

1k

1k

0603

RALEC



Typical Applications

EVB Schematic Diagram

Technical Document Image Preview


Measure Result

Efficiency Measurement

LED Current Measurement

Technical Document Image Preview

Technical Document Image Preview

OVP Threshold Voltage vs. Input Voltage

VDC Voltage vs. Temperature

Technical Document Image Preview

Technical Document Image Preview

Switching Frequency vs. I2C Code

Boost Switching Frequency vs. Input Voltage

Technical Document Image Preview

Technical Document Image Preview

IOUT Current vs. PWM Duty

Question Current vs. Input Voltage

Technical Document Image Preview

Technical Document Image Preview

Shutdown Current vs. Input Voltage

Power-On from EN

Technical Document Image Preview

Technical Document Image Preview

Power-Off from EN

Current Accuracy

Technical Document Image Preview

Technical Document Image Preview

Current Matching

Technical Document Image Preview



Evaluation Board Layout

Figure 1 to Figure 4 are RT453AGQW Evaluation Board layout. This board size is 75mm x 70mm and is constructed on four-layer PCB, outer layers with 1 oz. Cu and inner layers with 1 oz. Cu.

一張含有 文字, 地圖, 圖表, 螢幕擷取畫面 的圖片

自動產生的描述

Figure 1. Top View (1st layer)


Technical Document Image Preview

Figure 2. PCB Layout—Inner Side (2nd Layer)


一張含有 螢幕擷取畫面, 圓形, Rectangle, 樣式 的圖片

自動產生的描述

Figure 3. PCB Layout—Inner Side (3rd Layer)


一張含有 螢幕擷取畫面, 圓形, Rectangle, 圖表 的圖片

自動產生的描述

Figure 4. Bottom View (4th Layer)

Title Last Update Share Download
Evaluation Board User Guide 2024/03/05
Bill of Materials 2024/03/05
Schematic 2024/03/05
Gerber File 2024/03/05
RT4539A
RT4539A

RT4539A 是高效率的 LED 驱动器,适用于 1-2 节锂离子电池供电驱动 6 串 LED 并行连接的应用,其采用的内部电流吸入电路可达到最大 ±2% 电流一致性误差,使各串 LED 之间的亮度保持最大程度的一致性。为了给电流吸入电路留出足够的活动空间,Boost 转换器对各个反馈引脚进行电压监测并确保其最低值的稳定,因而可以获得最佳的转换效率。
RT4539A 有宽达 2.7V-24V 的可用输入电压范围,通过其自带的 I2C 接口可对其调光模式、工作频率和 LED 电流进行调节。它所使用的导通阻抗为 250mΩ、耐压 36V 的功率开关和电流模式控制架构具有过流保护功能,工作频率可在 300kHz-1.6MHz 间进行调节,容许在转换效率和元件尺寸间进行折中处理。
RT4539A 使用 WL-CSP-20B 1.71x2.371 (BSC) 和 WQFN-24L 4x4 封装供货。

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