EV5103

EV5103 GMT | Alldatasheet

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Jan 21, 2003 TEL: 886-3-5788833 http://www.gmt.com.tw EV5103-10 Global Mixed-mode Technology Inc. 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: 1. Drive 2 ~ 4 white LED @ 20mA. 2. 200Hz PWM dimming control. 200Hz PWM Dimming White LED Driver Demo Schematic 10uH/0.5A 27_1% 120K_1% SW MBR0530 VCC 5 SW 1 FB 3SHDN4 VSS2 G5103 LED1 LED2 LED3 LED4 240K_1% 620K_1% VCC Jumper JP1 BATT VCC PWM Dim +3VDC FB VISEN VDD1 GP52 GP43 GP34 GP2 5GP1 6GP0 7VSS 8 PIC12C508 IN1 OUT 5 SHDN3 BYP 4 GND2 G914C 1uF VBAT 1uF 0.1uF +3VDC VBAT VCC 4.7uF 0.1uF +3VDC DIM Low SW1 PWM Dim DIM High SW2 FREQ SW3 18.5mA 2 ~ 4 White LED 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 EV5103-10 Global Mixed-mode Technology Inc. Components List Designation Qty Value& P/N Description Vendor R1 1 27Ω_1% Current Sense Resistor R2 1 120KΩ_1% Feedback Resistor (recommend) R3 1 240KΩ_1% PWM Dimming Control Bias Resistor R4 1 620KΩ_1% PWM Dimming Control Mixer Resistor Std C1 1 4.7µF Input Capacitor C2 1 0.1µF Output Capacitor C3 1 1µF Input Capacitor C4 1 1µF Output Capacitor C5 1 0.1µF Bypass Capacitor TAIYO YUDEN 10µH/0.5A IDC (LQH32CN100K31) Inductor MURATA L1 1 10µH/0.5A IDC (976AS-100M) Inductor TOKO D1 1 0.5A/30V(MBR0530) Schottky Diode ON Semi U1 1 G5103 Micro Power Step-up DC/DC Converter U2 1 G914C Mirco power LDO regulator. V OUT=3.0V Global Mixed-Mode Technology http://www.gmt.com.tw U3 1 PIC12C509A 8 bits micro-controller Miocrochip SW1~3 3 Push button switch Std LED1~4 4 NSCW100 White LED NICHIA corporation 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. VBIAS: +3.0VDC provide a PWM dimming DC bias voltage. It is generated by G914C from V BAT. R1: is LED current sense resistor. R1= 0.60V / I LED,MAX = 0.60V / 20mA = 30Ω R2: is feedback resistor, 120K Ω is recommended. R4: is PWM dimming control mixer resistor. The value is depended on PWM dimming control signal amplitude. R4= (VH - VL) / (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 BIAS voltage. R3=( VBIAS– VFB) /[(0.6V/120 KΩ)+(VFB / R4)]. For 5VDC VBIAS:= (5.0V – 1.2V) / [(0.6V/120 KΩ)+(1.2V / 1000 KΩ)] = 612 KΩ After choose suitable resistors, designer should check ILED again.

Jan 21, 2003 TEL: 886-3-5788833 http://www.gmt.com.tw EV5103-10 Global Mixed-mode Technology Inc. When PWM dimming signal is low (almost equal to 0V): ILED = VR1 / R1 VR1 = VFB – VR2 VR2 = IR2 x R2 IR2 = IR3 – IR4 - IFB = (VR3 / R3) – (VR4 / R4) - IFB = ((VBIAS – VFB)/R3) – (VFB/R4) - IFB ILED = (VFB – R2 x (((VBIAS – VFB)/R3) – (VFB/R4) - IFB)) / R1 ILED should be the design full current. When PWM dimming signal is high (almost equal to VPWM_H): ILED = VR1 / R1 VR1 = VFB – VR2 VR2 = IR2 x R2 IR2 = IR3 – IR4 - IFB = (VR3 / R3) – (VR4 / R4) - IFB = ((VBIAS – VFB)/R3) – ((VFB - VPWM_H)/R4) - IFB ILED = (VFB – R2 x (((VBIAS – VFB)/R3) – ((VFB - VPWM_H)/R4) - IFB)) / R1 ILED should 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: When PWM signal is high: U2: 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 BIAS for PWM dimming bias voltage, and provide as the power of U3. 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 EV5103-10 Global Mixed-mode Technology Inc. How to Use This Demo Board 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: is a push button switch, every click makes LEDs a little darker until 100% light. SW2: is a push button switch, every click makes LEDs a little lighten until full dark. SW3: 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. LEDs: LED1 ~ LED4 has solder with white LED. LED driver circuit only in red rectangle Other circuit is for PWM dimming control demonstration.