loading
Richtek

Asynchronous Boost Converter for 10 WLEDs

EVB_RT4533AGJ6

Share

The RT4533A is a highly integrated LED driver IC capable of driving 10 WLEDs in series. It is composed of a current mode Boost converter integrated with a 36.5V/1.2A power switch. The RT4533A supports a wide input voltage range from 2.5V to 5.5V and runs at a fixed frequency of 1.1MHz. The LED current is set via an external resistor and the feedback voltage is regulated to 300mV. For brightness dimming, the RT4533A supports PWM dimming which determines the feedback reference voltage.

Purpose

The RT4533A is a highly integrated LED driver IC capable of driving 10 WLEDs in series. It is composed of a current mode Boost converter integrated with a 36.5V/1.2A power switch. For brightness dimming, the RT4533A supports PWM dimming which determines the feedback reference voltage.


Introduction

General Product Information

The RT4533A is a highly integrated LED driver IC capable of driving 10 WLEDs in series. It is composed of a current mode Boost converter integrated with a 36.5V/1.2A power switch. The RT4533A supports a wide input voltage range from 2.5V to 5.5V and runs at a fixed frequency of 1.1MHz. The LED current is set via an external resistor and the feedback voltage is regulated to 300mV. For brightness dimming, the RT4533A supports PWM dimming which determines the feedback reference voltage.


Product Features

  • 2.5V to 5.5V Input Voltage Range
  • 36.5V Open LED Protection for 10 WLEDs
  • PWM Dimming Brightness Control
  • 300mV Reference Voltage with ±2% Accuracy
  • 1.1MHz Switching Frequency
  • Built-In Soft-Start
  • Over-Temperature Protection
  • Internal Compensation
  • Current Limit
  • RoHS Compliant and Halogen Free

 

Key Performance Summary Table

Key Features

Evaluation Board Number : PCB072_V1

Default Input Voltage

2.5V to 5.5V

Max Output Current

20mA

Default Output Voltage

36.5V

Default Marking & Package Type

RT4533AGJ6, TSOT-23-6

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

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

Signal Name

Description

LX

Switch Node

This is the switching node of the IC. Connect the switched side of the inductor to LX. This pin is also used to sense the output voltage for open LED protection.

GND

Ground

Ground.

FB

Feedback Voltage Input

Connect the sense resistor from FB to GND.

EN

Enable Control Input

Control pin of the boost converter. It is a multifunctional pin which can be used for enable control and PWM dimming.

VOUT

Output Voltage

The output supply pin for the IC.

VIN

Supply Voltage Input

The input supply pin for the IC. Support 2.5V to 5.5V Input Voltage.



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 JP5 is the PWM control pin.

5. The ILED setting supports PWM dimming as below.


Output ILED Setting

1. PWM Brightness Dimming

The EN pin is used for the control input for both PWM dimming mode and digital dimming mode. Shutdown delay when the EN voltage is logic low for more than specific time, the driver will be shut down.

2. OCP

The driver provides cycle-by-cycle current limit function to control the current on power switch. The boost switch turns off when the inductor current reaches this current threshold and it remains off until the beginning of the next switching cycle. This protects the RT4533A and external component under overload conditions.

3. OVP

The Over Voltage Protection is detected by a resistor divider circuit from VOUT. Once VOUT goes over the OVP voltage, LX pin stops switching and the power N-MOSFET will be turned off. Then, the VOUT will be discharged by external resistor. OVP will be released until EN goes from Lo to Hi again.

4. OTP

As the die temperature is higher than 160°C, the chip also will enter protection mode. The power MOSFET will be turned off during protection mode to prevent abnormal operation. The device is released from shutdown automatically when the junction temperature decreases by 15°C.



Schematic, Bill of Materials & Board Layout

EVB Schematic Diagram

Technical Document Image Preview



Bill of Materials

Reference

Qty

Part Number

Description

Package

Manufacturer

U1

1

RT4533AGJ6

DC-DC Converter

TSOT-23-6

RICHTEK

L1

1

NR4018T220M

22µH

L-SH4018

TAIYO YUDEN

C2

1

C0603X5R1E225DT

2.2µF/16V/X5R/0603

Capacitor Ceramic

C-0603

TDK

C5

1

GMK107BJ105KA

1µF/50V/X5R/0805

Capacitor Ceramic

C-0805

TAIYO YUDEN

D1

1

SR26

Schottky Diode

D-1206

PANJIT

R3

NC

R6

1

0603 10R0 1%

Resistor, 1%, 10Ω

R-0603

WALSIN

R8

1

Short

D9, D13

2

0603 JUMP

Resistor, 1%, 0Ω

D-0603

WALSIN

D2, D3, D4, D5, D6, D7, D8, D10, D11, D12

10

LNL-190UW-4H

WLED

D-0603

光楠



EVB Layout

Technical Document Image Preview

Top View

Technical Document Image Preview

Bottom View

Title Last Update Share Download
Evaluation Board User Guide 2016/08/02
Bill of Materials 2016/08/02
Gerber File 2016/08/02
Schematic 2016/08/02
TOP