Datenblatt-Suchmaschine für elektronische Bauteile |
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SP6415 Datenblatt(PDF) 6 Page - Sipex Corporation |
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SP6415 Datenblatt(HTML) 6 Page - Sipex Corporation |
6 / 12 page 6 Feb27-07 Rev K Integrated White LED Driver With Organic LED Display Power Supply © 2007 Sipex Corporation The S P645 is designed for white LED & OLED back- lighting in mobile phone applications. It has a main display loop which can drive up to 4 white LEDS in series and a SUB display loop which is designed to drive OLED up to 20V/0mA or 3 white LEDs. The S P645 operates at a wide input voltage range suitable for Li-ion battery and has a constant off time for smaller inductor and capacitors. The block diagram refers the operation circuit. By SEL pin, it can choose the different channel to turn on CH or CH2. Current Limit Protection The S P645 has current limiting protection to prevent excessive stress on itself and external components dur- ing overload conditions. The internal current limit com- parator will disable the NMOS power device at a typical switch peak current limit of 300mA. The output capacitor needs to be a minimum of uF with 25V rating. For applications with 5V input, an output capacitor of 2.2uF or 4.7uF may be needed to lower output ripple and improve regulation. For better voltage filtering, ceramic capacitors with low ESR are recommended. X5R and X7R types are suitable be- cause of their wider voltage and temperature ranges. Output Over-Voltage Protection The S P645 contains dedicated circuitry for monitoring the output voltage. In the event that the primary LED network is disconnected the output will increase and be limited to 22V(typ.). There is a ~V hysteresis associated with this circuitry, which will turn the NMOS off when the output voltage is at 23V(max.) until the output voltage reach 2V(typ.) or lower. The 22V limit allows the use of 25V µF ceramic output capacitors creating an overall small solution for white LED applications. Under Voltage Protection The S P645 has a UVP comparator to turn the NMOS powerdeviceoffincasetheinputvoltageorbatteryvoltage is too low ,preventing an on state of the power device con- ductinglargeamountsofcurrent.Thereisa~Vhysteresis associated with this circuitry, which will turn the NMOS off when the output voltage is at 23V(max.) until the output voltage reaches 2V(typ.) or lower. The 22V limit allows the use of 25V mF ceramic output capacitors creating an overall small solution for white LED applications. Capacitor Selection A 4.7µF input capacitor can reduce input ripple. For better voltage stability, to increase the input capacitor value or using an LC filter is feasible, especially in Li- Ion battery applications. The input capacitor acts as a bypass to the IC and needs to be connected directly to the VIN pin and the GND pin for proper low ripple reg- ulation. Diode Selection A Schottky diode is a good choice for SP645 because of its lower forward voltage drop and faster reverse recovery. Using Schottky diodes can help ob- tain better efficiency. High speed rectification is also a good characteristic of Schottky diodes for high switch- ing frequency. Current rating of the diode must meet the root mean square of the peak current and output average current multiplication. Inductor Selection The recommended value of inductor for S P645ap- plications is 0uH. Small size and better efficiency are the major concerns for portable device, such as S P645 used for dual panel mobile phone. The inductor should have low DCR for better efficiency. To avoid inductor saturation, current rating should be at least 600mA. The input range is 2.7V to 5.5V. Detailed Description Application Information |
Ähnliche Teilenummer - SP6415 |
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Ähnliche Beschreibung - SP6415 |
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