YB1519 Schematic ( PDF Datasheet ) - YOBON TECHNOLOGIES

Teilenummer	YB1519
Beschreibung	High-Power White LED Driver
Hersteller	YOBON TECHNOLOGIES
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Gesamt 7 Seiten www.DataSheet4U.com YB1519 High-Power White LED Driver Description The YB1519 is a high-power boost converter. An adjustable current limit, wide range of input voltage, and up to 40V of switch voltage are designed to drive white LEDs back-lighting for large LCD panel. It can drive up to 10 LEDs in series or 18 LEDs in parallel/series configuration. The wide application VIN range makes YB1519 suitable for many types of battery applications such as Li-ions, Alkaline, or Sealed Lead Acid batteries. The adjustable inductor current optimizes the performance for different output drive capability by an external resistor. The LED current is set by a resistor connected to FB pin. The On/Of duty with clock frequency from 1K to 100KHz at EN pin can control the LED brightness Typical Application Circuit Features „ 2V to 16V Input Voltage „ 40V Maximum Output Voltage „ Drive up to 18 White LEDs „ Adjustable Inductor Current „ 1μs Constant Off-time PFM Control „ 1KHz to 100KHz PWM Dimming Control Applications „ High Power WLED Backlight Solution „ LCD Monitor „ LCD TV „ Car TV, Portable DVD „ GPS navigation system „ Handheld Game VIN = 6 to14V EN Bypass Iset 10uF 16V VIN YB 1519 22uH SL12 LX LX FB 43.75uVF BZV55-B 36 36V 2K 10nF 6.3V 10K AGND PGND Figure 1. Typical application circuit RFB 60OHM YB1519 MRev.1.2 www.yobon.com.tw 1 www.DataSheet4U.com YB1519 High-Power White LED Driver GND is able to set inductor current. An 8μA current source is coming out of the YB1519 and going through the ISET resistor to ground. The higher the ISET pin voltage, the larger the peak inductor current is built up. Application Information Enable/Shutdown The YB1519 comes with an active-high enable pin that allows the white LED driver to be enabled. Forcing the enable pin low disables the chip and puts it into the shutdown mode. This pin cannot be left floating; as it may cause an undetermined state. Input/Output Capacitor It is recommended to use a 10µF capacitor on the YB1519 input and a 4.7µF capacitor on the output. Higher capacitance is allowed to reduce the voltage and current ripple. Choose low ESR capacitors for the output to minimize output ripple. Multilayer ceramic capacitors are good choice for the input and output capacitor. Inductor The appropriate inductor for a given application is calculated using the following equation: L = ⎜⎜⎝⎛ VOUT − VIN,MIN ISET + VD ⎟⎟⎠⎞ TOFF Where VD is the schottky diode voltage, ISET is the setting for inductor current, and TOFF is the switch off time designed for 1μs. When using this equation be sure to use the minimum input voltage for the application, such as for battery-powered application. Choosing inductor with low ESR decrease power losses and increase efficiency. Diode selection To maintain high efficiency, the average current rating of the schottky diode should be large than the peak inductor current. Schottky diode with a low forward drop and fast switching speeds are ideal for increase efficiency in portable application. Choose a reverse breakdown of the schottky diode large than the output voltage. Thermal Consideration: When YB1519 is set to handle high switch current will result in internal power dissipation and thus generating heat. Always beware the amount of power dissipated during operation. To resolve the thermal built up issue, reduce resistance at ISET which lower the peak switch current. Layout consideration The input capacitor CIN must be placed close to the IC. This will reduce copper trace resistance which effect input voltage ripple of the IC. The output capacitor, COUT, should also be placed close to the IC. Any copper trace connections for the COUT capacitor can increase the series resistance, which directly effect output voltage ripple. The feedback resister should be kept close to the FB pin to YB1519 MRev.1.2 www.yobon.com.tw 6 6 Page
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