SE3505 [SEAWARD]

1.9A Fixed Frequency White LED Driver;


型号：	SE3505
厂家：	Seaward Electronics Inc.
描述：	1.9A Fixed Frequency White LED Driver
文件：	总9页 (文件大小：926K)
中文：	中文翻译
下载：	下载PDF数据表文档文件

SE3505

1.9A Fixed Frequency White LED Driver

General Description

Features

The SE3505 is a step-up converter designed  2.5V to 5.5V operating input voltage range

for driving up to 8 series white LEDs for  Drives up to 8 series White LEDs

backlighting application. The SE3505 uses  1.2MHz Fixed Switching Frequency

current mode, 1.2MH^Zfixed frequency  Wide range for PWM dimming (200Hz to

architecture to regulate the LED current, which

200KHz)

is set through an external current sense  Internal 1.9A switching current limit

resistor. Its low 300mV feedback voltage  Over Voltage Protection (OVP)

reduces power loss and improves efficiency.  Internal Soft-start Function

The OV pin monitors the output voltage and  Current limit and Thermal shutdown

turns off the converter if an over-voltage

protection

condition is present due to an open circuit  Under voltage Lockout

condition. The SE3505 includes under-voltage  Available in the 6-pin SOT-23 Package

lockout, current limiting and thermal shutdown

protection preventing damage in the event of

an output overload. The driver is available in

small 6-pin SOT-23 package.

Applications



Camera Flash White LED

Mobile Phone, Smart Phone LED Backlight

PDA LED Backlight

Digital Still Cameras

Camcorder

Typical Application

(1) 8 series LED application

Rev1.0

Preliminary and all contents are subject to change without prior notice.

9/4/2012

SE3505

1.9A Fixed Frequency White LED Driver

(2) LED Dimming application

Pin Configuration

SOT-23-6

Pin Description

NO.

Pin Name

Pin Function Description

Switch Output Pin

Ground Pin

GND

Feedback Pin; Put a Resistor to GND to Setting the Current

Enable with Dimming Pin; Internal Pull-Low; Logic High Active

OVP Sense Pin

VCC

Power Input Pin

Rev1.0

Preliminary and all contents are subject to change without prior notice.

9/4/2012

SE3505

1.9A Fixed Frequency White LED Driver

Functional Block Diagram

Ordering Information

Part Number Marking Information

Package

Remarks

SE3505

SE3505-LF

YYWW means Production batch

LF means Lead Free

SOT-23-6

YYWW--LF

Absolute Maximum Ratings

Symbol

Parameter

Maximum

GND - 0.3 to GND + 6

GND - 0.3 to VCC + 0.3

Units

VCC

VCC Pin Voltage

EN,FB, OV Pin Voltage

SW, OV Pin Voltage

Power Dissipation

VSW

(TJ-TA)/θJA

℃

TST

TOP

θJC

Storage Temperature Range

-65 to +150

-40 to +125

180

Operating Junction Temperature Range

Thermal Resistance from Junction to case

Thermal Resistance from Junction to ambient

℃

℃/W

θJA

250

Note: ΘJA is measured with the PCB copper area of approximately 1 in (Multi-layer).

Rev1.0

Preliminary and all contents are subject to change without prior notice.

9/4/2012

SE3505

1.9A Fixed Frequency White LED Driver

Electrical Characteristics

（Vcc =5V ;Iout=20mA ;Tj=25℃ unless otherwise specified）

Characteristics

Input Voltage Range

Step-Up Voltage Range

OV Sense Voltage

Under Voltage Lockout

UVLO Hysteresis

Symbol

VCC

Conditions

Min

2.5

Typ

Max Uints

5.5

VOUT

VOV

27.5

30.5

UVLOV

Rising

2.25 2.45

100

300

315

Feedback Voltage

VFB

V^IH

VIL

285

1.4

Logic-High Voltage

Logic-Low Voltage

EN Hysteresis

EN Threshold

0.4

200

170

Operating Quiescent Current

Shutdown Current

ICCQ

ISD

IOUT =0mA,VFB =0.5V

VEN=0V,tEN>20ms

N-Channel MOSFET Current Limit

MOSFET On-Resistance

ILIM

Duty=50%

1.9

V^CC=3V,ISW=1A

VCC=5V,ISW=1A

0.6

0.45

RDS(on)

DMAX

Maximum Duty Cycle

Line Regulation

VCC=3V to 5V

Switching Frequency

Dimming Clock Rate

FB Input Leakage Current

SW Leakage Current

FOSC

FDIM

0.9

1.2

1.5

200

100

MHz

KHz

0.2

IFB-LKG

ISWL

VFB = 0.5V

Vsw=27V,VFB =0.5V

VEN = VCC

0.01

I^{EN -LKG1}

IEN -LKG2

TSHDN

TSD

1.5

0.01

EN Input Leakage Current

VEN = GND

0.1

Shutdown Delay

Thermal Shutdown

150

℃

Thermal Shutdown Hysteresis

TSH

Rev1.0

Preliminary and all contents are subject to change without prior notice.

9/4/2012

SE3505

1.9A Fixed Frequency White LED Driver

Typical Performance Characteristics

Efficiency vs. Output Current

Efficiency vs. Input Voltage

Output Voltage vs. Output Current

Quiescent Current vs. Input Voltage

Frequency vs. Input Voltage

Frequency vs. Temperature

Rev1.0

Preliminary and all contents are subject to change without prior notice.

9/4/2012

SE3505

1.9A Fixed Frequency White LED Driver

Typical Performance Characteristics (Continuous)

Reference Voltage vs. Input Voltage Reference Voltage vs. Temperature

LED Current vs. Duty

Enable Threshold vs. Input Voltage

Rev1.0

Preliminary and all contents are subject to change without prior notice.

9/4/2012

SE3505

1.9A Fixed Frequency White LED Driver

Typical Performance Characteristics (Continuous)

Power ON from VIN

Power ON from EN

Steady State Operation

Normal Operation into OVP

PWM Dimming from EN (200Hz)

PWM Dimming from EN (20KHz)

Rev1.0

Preliminary and all contents are subject to change without prior notice.

9/4/2012

SE3505

1.9A Fixed Frequency White LED Driver

Applications Information

Setting the ILED Current

Input Capacitor Selection

Application circuit item shows the basic The input capacitor reduces the surge current

application circuit with SE3505 adjustable drawn from the input and switching noise from

output version. The external resistor sets the the device. The input capacitor impedance at

LED output current according to the following the switching frequency shall be less than

equation:

input source impedance to prevent high

frequency switching current passing to the

input. A low ESR input capacitor sized for

maximum RMS current must be used. Ceramic

capacitors with X5R or X7R dielectrics are

highly recommended because of their low ESR

and small temperature coefficients. A 4.7µF

ceramic capacitor for most applications is

ILED

15Ω

20mA

350mA

6mW

0.857Ω

105mW

sufficient. For

lower output power

Over Voltage Protection

requirement application, this value can be

decreased.

OV measure the output voltage for open circuit

protection. Connect OV pin to the output at the

top of the LED string. If V^OUTabove 29V, the

OVP protection is happened that stops the

internal driver until V^OUTbelow 29V.

Output Capacitor Selection

The output capacitor is required to keep the

output voltage ripple small and to ensure

regulation loop stability. The output capacitor

must have low impedance at the switching

frequency. Ceramic capacitors with X5R or

X7R dielectrics are recommended due to their

low ESR and high ripple current. A 1uF

ceramic capacitors works for most of the

applications. Higher capacitor values can be

used to improve the load transient response.

Under Voltage Lockout (UVLO)

To avoid mis-operation of the device at low

input voltages an under voltage lockout is

included that disables the device, if the input

voltage falls below (2.25V-100mV).

Rev1.0

Preliminary and all contents are subject to change without prior notice.

9/4/2012

SE3505

1.9A Fixed Frequency White LED Driver

Outline Drawing For SE3505

联系方式：

北京思旺电子技术有限公司–中国总部

地址：中国北京市海淀区信息路 22 号上地科技综合楼 B 座二层

邮编：100085

电话:010-82895700/1/5

传真:010-82895706

Seaward Electronics Corporation – 台湾办事处

2F, #181, Sec. 3, Minquan East Rd,

Taipei, Taiwan R.O.C

电话: 886-2-2712-0307

传真: 886-2-2712-0191

Seaward Electronics Incorporated – 北美办事处

1512 Centre Pointe Dr.

Milpitas, CA95035, USA

电话: 1-408-821-6600

Rev1.0

Preliminary and all contents are subject to change without prior notice.

9/4/2012

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