SDB9HB

SDB9HB SHOUDING | Alldatasheet

Document overview

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Technical content

APPLICATIONS

1.20MHz Constant Frequency Operation 1.20MHz, The SDB9HB Lithium Ion battery. The SDB9HB SDB9HB The SDB9HB SDB9HB Rev1.0 3V-24V Input High Efficiency Boost White LED Driver High Efficiency: Up to 90% Integrated internal Power MOSFET Drives up to 7 Series WLEDs Low 200mV Feedback Voltage Soft-start/Dimming with wide Frequency Range UVLO, Thermal Shutdown Internal Current limit Over Voltage Protection Small LC Filter Minimize the External Component <1µA Shutdown Current SOT23-6 Package Camera Flash White LED Mobile Phone, Smart Phone LED Backlight PDA LED Backlight Digital Still Cameras Camcorder is a step -up converter designed for driving up to 7 series white LEDs from a single cell uses current mode, fixed frequency architecture to regulate an LED current, which is measured through an external current sense resistor. Its low 200mV feedback voltage reduces power loss and improves efficiency. includes under -voltage lockout , current limiting and thermal overload protection preventing damage in the event of an output overload. Optimized operation frequency can meet the requirement of small LC filters value and low operation current with high efficiency. Internal soft start function can reduce the inrush current. Tiny package type provide the best solution for PCB space saving and total BOM cost. Figure 1. Basic Application Circuit

7 WLEDs

FEATURES

(Note 1) Input Supply Voltage………………-0.3V to 25V Thermal Resistance θ JC Thermal Resistance θ JA Operating Temperature Range…….-40°C to 85°C Lead Temperature(Soldering,10s)………...300°C Storage Temperature Range……..-65°C to 150°C ESD HBM(Human Body Mode)……………...2kV SW GND FB EN OV VIN TOP VIEW 6-LEAD PLASTIC SOT-23 T JMAX = 160°C, θ JA = 250°C/ W, θ JC = 130°C/W Order Part Number Package SOT23-6 Pin Name Pin Number Description SW 1 Inductor Connection. Connect to the switched side of the external inductor as well as the anode of the external diode. SW is high impedance during shutdown. GND 2 Ground Pin. FB 3 Current-Sense Feedback Input. Connect a resistor from FB to GND to set the LED current: I LED =0.2V/R CS EN 4 Enable and LED Brightness Control Input. Pull high to turn on IC.Drive EN with a 20kHz to 1MHz unfiltered PWM dimming signal for DC LED current that is proportional to the signal’s duty cycle. OV 5 Over Voltage Input. turn off the N-channel MOSFET when V OUT exceeds 28V .Connect OV to the output at the top of the LED string. VIN 6 Power Supply Input. Must be closely decoupled to GND with a 1µF or greater ceramic capacitor. SDB9HB ShoudingShoudingShoudingShoudingShoudingShoudingShouding SDB9HB Rev1.0 www.shouding.net

ELECTRICAL CHARACTERISTICS

(Note 3) IN EN =3.7V,T A = 25°C, unless otherwise noted.) PARAMETER CONDITIONS MIN TYP MAX UNIT Operating Input Voltage V Under Voltage Lockout 2.6 V Under Voltage Lockout Hysteresis 100 mV Current (Shutdown) V EN <0.4V µA Quiescent Current V FB =0.15V，No switching 200 µA Supply Current V FB =0V，switching 0.6 mA Regulated Feedback Voltage 194 200 206 mV Switching Frequency 1.2 MHz ON Resistance of NMOS 0.1 Ω Peak Current Limit V IN = 4.2V,Duty cycle=50% A EN Shutdown Voltage 0.4 V EN Enable Voltage 1.5 V EN Leakage Current ±0.01 ±1.0 µA OVP Threshold Open LED,V OUT Rising V Note 1: Absolute Maximum Ratings are those values beyond which the life of a device may be impaired. Note 2: T J is calculated from the ambient temperature T A and power dissipation P D according to the following formula: T J = T A + (P D ) x (250°C/W). Note 100% production test at 25°C. Specifications over the temperature range are guaranteed by design and characterization. SDB9HB ShoudingShoudingShoudingShoudingShoudingShoudingShouding SDB9HB Rev1.0 www.shouding.net

TYPICAL PERFORMANCE CHARACTERISTICS 0 20 40 60 80 100 I LED (mA) PWM Duty Cycle(%) LED Current vs. PWM Dimming @ 7S WLEDs F=100kHz 7S1P WLEDs SDB9HB ShoudingShoudingShoudingShoudingShoudingShoudingShouding SDB9HB Rev1.0 www.shouding.net

Normal Operation @ V IN =3.0V Normal Operation @ V IN =3.7V Normal Operation @ V IN =4.3V Normal Operation @ V IN =5.5V SDB9HB ShoudingShoudingShoudingShoudingShoudingShoudingShouding SDB9HB Rev1.0 www.shouding.net

Figure 2. SDB9HB the error amplifier the power FET is turned off. power delivered to the output.

For controlling the LED brightness, the SDB9HB Adjusting LED Current Set the maximum LED current using a resistor from FB to GND. Calculate the resistance as follows:. LED CS I mV200R = where I LED is the desired maximum current through the LEDs. I LED (mA) R CS (mΩ ) 1 200 5 40 10 20 15 13.3 20 10 LED Dimming Control  Using a PWM Signal to EN Pin can perform the dimming control by applying a PWM signal to EN pin. The internal soft start and the wide range dimming frequency can eliminate inrush curren t and audio noise when dimming. The average LED current is proportional to the PWM signal duty cycle. The magnitude of the PWM signal should be higher than the maximum enable voltage of EN pin, in order to let the dimming control perform correctly for prev enting the flicker issue, the suggested PWM frequency is ≥20kHz and ≤1MHz. Figure 3  Using a DC Voltage Using a variable DC voltage to adjust the brightness is a popular method in some applications. According to the Superposition Theorem, as the DC voltage increases, the voltage contributed to V FB increases and the voltage drop on R 1 decreases, i.e. the LED current decreases. For example, if the V DC range is from 0V to 2.8V, the selection of resistors sets dimming co ntrol of LED current from 20mA to 0mA.The LED current can be calculated by the following equation: CS FBDC FB LED R )VV(1RV I −×− Figure4  Using a Filtered PWM signal Another common application is using a filtered PWM signal as an adjustable DC voltage for LED dimming control. A filtered PWM signal acts as the DC voltage to regulate the output current. The recommended application circuit is shown in the Figure 5. In th is circuit, the output ripple depends on the frequency of PWM signal. For smaller output voltage ripple (<100mV), the recommended frequency of 2.8V PWM signal should be above 2 0kHz. To fix the frequency of PWM signal and change the duty cycle of PWM signal can get different output current. Figure 5. EN R CS FB V OUT V DC SDB9HB ShoudingShoudingShoudingShoudingShoudingShoudingShouding SDB9HB SDB9HB SDB9HB Rev1.0 www.shouding.net

SDB9HB\` For best performance of the SDB9HB recommended for SDB9HB Schottky diode is a good choice for SDB9HB shows the relationship between LED current and PWM duty cycle.The LED current can be calculated by the following equation: CS FBPWM FB LED R 2R3R )VDutyV(1RV I + −××− Figure5 Inductor Selection The recommended value of inductor are 4.7 to 22µH. Small size and better efficiency are the major concerns for portable device, such as used for mobile phone. The inductor should have low core loss at 1.2MHz and low DCR for better efficiency. To avoid inductor saturation current rating should be considered. Capacitor Selection Input and output ceramic capacitors of 4.7µF are applications. For better voltage filtering, ceramic capacitors with low ESR are recom mended. X5R and X7R types are suitable because of their wider voltage and temperature ranges. Diode Selection because of its low forward voltage drop and fast reverse recovery. Using Schottky diode can get better efficiency. The high speed rectification is also a good characteristic of Schottky diode for high switching frequency. Current rating of the diode must meet the root mean square of the peak current and output average current multiplication as following : PEAKOUTD II)RMS(I ×= The diode’s reverse breakdown voltage should be larger than the output voltage. Layout Consideration , the following guidelines must be strictly followed.  Input and Output capacitors should be placed close to the IC and connected to ground plane to reduce noise coupling.  The GND should be connected to a strong ground plane for heat sinking and noise protection.  Keep the main current traces as possible as short and wide.  SW node of DC -DC converter is with high frequency voltage swing. It should be kept at a small area.  Place the feedback components as close as possible to the IC and keep away from the noisy device R CS FB V OUT 1μF SDB9HB ShoudingShoudingShoudingShoudingShoudingShoudingShouding SDB9HB SDB9HB Rev1.0 www.shouding.net

TOP VIEW RECOMMENDED SOLDER PAD LAYOUT FRONT VIEW SIDE VIEW 2.80 3.00 1.50 1.70 2.60 3.00 PIN 1 1.20 TYP 0.60 TYP 0.95 BSC 2.60 TYP 0.90 1.30 0.30 0.50

0.95 BSC

1.45 MAX

0.00 0.15 SEATING PLANE 0.09 0.20 SOT23-6 GAUGE PLANE

0.25 BSC

0.30 0.55 0°~8° SDB9HB ShoudingShoudingShoudingShoudingShoudingShoudingShouding SDB9HB Rev1.0 www.shouding.net