EV5103 [GMT]

G5103 White LED Demo Board V1.0; G5103白光LED演示板V1.0


型号：	EV5103
厂家：	GLOBAL MIXED-MODE TECHNOLOGY INC
描述：	G5103 White LED Demo Board V1.0 G5103白光LED演示板V1.0
文件：	总4页 (文件大小：146K)
中文：	中文翻译
下载：	下载PDF数据表文档文件

Global Mixed-mode Technology Inc.

EV5103-10

G5103 White LED Demo Board V1.0

Introduction

G5103 is a step-up (boost) DC/DC converter, using constant peak inductor current and minimum OFF

time PFM topology. It could output up to 16V and drive 20mA from a 2.5V ~ 5.5V input power source,

such as a Li-Ion battery. G5103 is suitable for series 2~4 white LED driver application because its

maximum 16V output capability. This solution possess high efficiency about 84% when drive 4 white

LED at 20mA output LED current with a 3.6V Li-Ion battery power input.

This demo board could demonstration:

Drive 2 ~ 4 white LED @ 20mA.

200Hz PWM dimming control.

Only need 3.0V ~ 5.5V power source. A Li-Ion battery is a good power source.

200Hz PWM Dimming White LED Driver Demo Schematic

2 ~ 4 White LED

10uH/0.5A

MBR0530

JP1

+3VDC

VCC

VCC Jumper

VBAT

OUT

LED1

LED2

LED3

LED4

1uF

GND

4.7uF

0.1uF

VCC

SHDN BYP

G914C

0.1uF

VBAT

SHDN

BATT

G5103

+3VDC U3

SW1

VDD VSS

DIM Low

SW2

PWMDim

GP5

GP4

GP3

GP0

GP1

GP2

+3VDC

PIC12C508

DIM High

SW3

240K_1%

120K_1%

VISEN

18.5mA

27_1%

PWMDim

FREQ

620K_1%

PWM Dimming Control Introduction

SW1: Dimming dark ( minimum dimming duty = 0%)

SW2: Dimming light ( maximum dimming duty = 100%)

SW3: Change PWM dimming frequency ( 150Hz 250Hz)

Fig.1

Jan 21, 2003

TEL: 886-3-5788833

http://www.gmt.com.tw

Global Mixed-mode Technology Inc.

Components List

EV5103-10

Designation

Qty

Value& P/N

27Ω_1%

120KΩ_1%

240KΩ_1%

620KΩ_1%

4.7µF

0.1µF

1µF

0.1µF

Description

Current Sense Resistor

Feedback Resistor (recommend)

PWM Dimming Control Bias Resistor

PWM Dimming Control Mixer Resistor

Input Capacitor

Output Capacitor

Input Capacitor

Output Capacitor

Bypass Capacitor

Vendor

Std

TAIYO YUDEN

MURATA

10µH/0.5A IDC

(LQH32CN100K31)

10µH/0.5A IDC

(976AS-100M)

Inductor

TOKO

SW1~3

LED1~4

0.5A/30V(MBR0530) Schottky Diode

ON Semi

Global Mixed-Mode Technology

http://www.gmt.com.tw

Miocrochip

Std

NICHIA corporation

G5103

Micro Power Step-up DC/DC Converter

G914C

PIC12C509A

Mirco power LDO regulator. V_OUT=3.0V

8 bits micro-controller

Push button switch

NSCW100

White LED

Circuit Description

The demo board is configured as a constant current supply. Current regulation is accomplished by regulating

the voltage across a current sense resistor R1. For dimming the LEDs is to inject a pulse width modulated

(PWM) voltage for analog dimming. With this method, the PWM control voltage is converted to its equivalent

analog control voltage. The demo board is designed so that the negative duty cycle from 0% to 100% varies

the LED current from 0mA to 20mA. The output current increases as the duty cycle increases. Use the

equation below to calculate the correctly resistor values.

V_BAT

Li-Ion battery power input, bypass to ground with a 4.7µF MLCC capacitor.

+3.0VDC provide a PWM dimming DC bias voltage. It is generated by G914C from V_BAT

is LED current sense resistor. R1= 0.60V / I^LED,MAX= 0.60V / 20mA = 30Ω

is feedback resistor, 120KΩ is recommended.

V_BIAS

R1:

R2:

R4:

is PWM dimming control mixer resistor. The value is depended on PWM dimming control signal

amplitude. R4= (V_H- V_L) / (0.6V / 120KΩ). (maximum value, a little small value could be used)

For 3.0V PWM control signal: R4= 3V / (0.6V / 120KΩ) = 600KΩ.

For 3.3V PWM control signal: R4= 3.3V / (0.6V / 120KΩ) = 660KΩ.

For 5.0V PWM control signal: R4= 5V / (0.6V / 120KΩ) = 1MΩ.

R3:

is PWM dimming control bias resistor. The value is depended on V^BIASvoltage.

R3=( V^BIAS– V_FB) /[(0.6V/120 KΩ)+(V^FB/ R4)].

For 3VDC V^BIAS:= (3.0V – 1.2V) / [(0.6V/120 KΩ)+(1.2V / 600 KΩ)] = 257 KΩ.

For 3.3VDC V^BIAS:= (3.3V – 1.2V) / [(0.6V/120 KΩ)+(1.2V / 660 KΩ)] = 308 KΩ

For 5VDC V^BIAS:= (5.0V – 1.2V) / [(0.6V/120 KΩ)+(1.2V / 1000 KΩ)] = 612 KΩ

After choose suitable resistors, designer should check I_LEDagain.

Jan 21, 2003

TEL: 886-3-5788833

http://www.gmt.com.tw

Global Mixed-mode Technology Inc.

EV5103-10

When PWM dimming signal is low (almost equal to 0V):

_LED= V_R1/ R1

_R1= V_FB– V_R2

_R2= I_R2x R2

_R2= I_R3– I_R4- I_FB= (V_R3/ R3) – (V_R4/ R4) - I_FB= ((V_BIAS– V_FB)/R3) – (V_FB/R4) - I_FB

I_LED= (V_FB– R2 x (((V_BIAS– V_FB)/R3) – (V_FB/R4) - I_FB)) / R1

_LEDshould be the design full current.

When PWM dimming signal is high (almost equal to V_{PWM_H}):

_LED= V_R1/ R1

_R1= V_FB– V_R2

_R2= I_R2x R2

_R2= I_R3– I_R4- I_FB= (V_R3/ R3) – (V_R4/ R4) - I_FB= ((V_BIAS– V_FB)/R3) – ((V_FB- V_{PWM_H})/R4) - I_FB

I_LED= (V_FB– R2 x (((V_BIAS– V_FB)/R3) – ((V_FB- V_{PWM_H})/R4) - I_FB)) / R1

_LEDshould be a little negative current to make sure that LED is full dark.

In this demo board, GMT choose R1 = 27Ω, R2=120 KΩ, R3=240KΩ, R4=620KΩ.

When PWM signal is low:

_LED= (1.2V – 120KΩ x (((3V – 1.2V)/240KΩ) – (1.2V/620KΩ) – 30nA)) / 27Ω = 19.7mA

When PWM signal is high:

I_LED= (1.2V – 120KΩ x (((3V – 1.2V)/240KΩ) – ((1.2V-3V)/620KΩ) – 30nA)) / 27Ω = -1.79mA

U2:

U3:

G914C is a micro power LDO regulator that make by GMT. It could regulate a +3VDC from a +3V

~ +5.5V power source. The +3VDC provide as V_BIASfor PWM dimming bias voltage, and provide

as the power of U3.

PIC12C509A is a 8bit micro controller that make by Microship. It is programmed as a PWM

dimming signal generator, and monitor 3 push button to change PWM duty and frequency for

dimming control.

Note: You need download the hex code to program a blank new PIC12C509A before solder it on demo board. You could

download this hex code from GMT web site http://www.gmt.com.tw

Jan 21, 2003

TEL: 886-3-5788833

http://www.gmt.com.tw

Global Mixed-mode Technology Inc.

How to Use This Demo Board

EV5103-10

LED driver circuit only

in red rectangle

Other circuit is for

PWM dimming control

demonstration.

Fig.2

J1:

is an input power connector. +BAT means positive side. The valid voltage range is from +3.0 to

+5.5V. one cell Li-Ion battery or 3 cell NiCd or NiMH battery or adjustable power supply are good

power source.

SW1:

SW2:

SW3:

is a push button switch, every click makes LEDs a little darker until 100% light.

is a push button switch, every click makes LEDs a little lighten until full dark.

is a push button switch, every click change dimming PWM frequency from 200Hz Æ 210Hz Æ

220Hz Æ 230Hz Æ 240Hz Æ 250Hz Æ 150Hz Æ 160Hz Æ 170Hz Æ 180Hz Æ 190Hz Æ 200Hz.

But the change could not be observed be human eyes. Only a oscilloscope could shows the

difference.

JP1:

is a jumper, which must be close for normal operating. You should open this jumper to measure

input current if you want to measure the efficiency of this demo board.

LED1 ~ LED4 has solder with white LED.

LEDs:

Jan 21, 2003

TEL: 886-3-5788833

http://www.gmt.com.tw

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