preliminary datasheet LP3308 LP3308C 00 version1.0 datasheet feb.-2010 www.lowpowersemi.com page 1 of 9 1.4mhz,30v/1.3a high perf ormance, boost converter general description the LP3308 is a 1.4mhz pwm boost switching regulator designed for constant-voltage boost applications. the LP3308 can drive a string of up to 30v. the LP3308 implements a constant frequency 1.4mhz pwm control scheme. the high frequency pwm operation also saves board space by reducing external component sizes. to improve efficiency, the feedback voltage is set to 1230 mv, which reduces the power dissipation in the voltage setting resistor. highly integration and internal compensation network minimizes as 5 external component counts. optimized operation frequency can meet the requirement of small lc filters value and low operation current with high efficiency. ordering information LP3308 f: pb-free package: b5: sot23-5 b6: tsot23-6 pin configurations (tsot23-6) (sot23-5) features high efficiency: 90% ? 1.4mhzfixed-frequency pwm operation maximum output voltage up to 30v guaranteed 13v/200ma output with 5v input operating range : 2.7v to 5.5v shutdown supply current:<1ua ? programmable soft-star available in tsot23-6/sot23-5 package ? minimize the external component rohs compliant and 100% lead (pb)-free applications panel bais voltage supply oled backlight driver notebook computers portable applications mid/ptv typical application circuit c1 4.7uf vin r1 860k r2 100k c2 4.7uf c3/nc 100pf LP3308 2 4 3 6 1 5 gnd shdn fb vin lx ss c4 33nf 10uh d1 ss0520 marking information please view website .
preliminary datasheet LP3308 LP3308C 00 version1.0 datasheet feb.-2010 www.lowpowersemi.com page 2 of 9 functional pin description sot-23-5 sot-23-6 pin name pin function 1 1 lx switch pin. connect this pin to inductor and catch diode. minimize the track area to reduce emi. 2 2 gnd ground pin 3 3 fb feedback reference voltage pin. series connect a resistor between vout and ground as a voltage sense. the feedback voltage is 1230mv. 4 4 /shdn chip enable (active high). voltage sensing input to trigger the function of over voltage protection. note that this pin is high impedance. there should be a pull low 100k resistor connected to gnd when the control signal is floating. 5 ss softstar pin. leave ss open to disable the soft-star function. 5 6 vin supply input voltage pin. bypass 1uf capacitor to gnd to reduce the input noise. function block diagram
preliminary datasheet LP3308 LP3308C 00 version1.0 datasheet feb.-2010 www.lowpowersemi.com page 3 of 9 absolute maximum ratings supply input voltage--------------------------------------------------------------------------------------------------- ? 0.3v to 6.0v lx input voltage -------------------------------------------------------------------------------------------------------- ? 0.3v to 33v the other pins ---------------------------------------------------------------------------------------------------------- ? 0.3v to 5.5v power dissipation, p d @ t a = 25c tsot-23-5/6-----------------------------------------------------------------------0.455w lead temperature (soldering, 10 sec.) -------------------------------------------------------------------------------- 260c operation temperature range --------------------------------------------------------------------------------- ? 40c to 80c storage temperature range ---------------------------------------------------------------------------------------- ? 65c to 150c electrical characteristics parameter s y mbol test condition min typ. max units system supply input operation voltage range v dd 2.7 6 v under voltage lock out v dd 2.2 2.4 2.6 v supply current i dd fb=0.2v, switch 430 550 ua shut down current i dd v en < 0.4v 0.1 1 ua line regulation v in : 3.0~4.3v 2 % oscillator operation frequency f osc 1.4 mhz maximum duty cycle 93 % feedback voltage LP3308 1.21 1.23 1.255 v mosfet on resistance of mosfet r ds(on) 0.7 sw current limit ilm 1.4 a protection shut down voltage v en 0.3 v enable on voltage v en 1.0 v
preliminary datasheet LP3308 LP3308C 00 version1.0 datasheet feb.-2010 www.lowpowersemi.com page 4 of 9 typical operating characteristics
preliminary datasheet LP3308 LP3308C 00 version1.0 datasheet feb.-2010 www.lowpowersemi.com page 5 of 9
preliminary datasheet LP3308 LP3308C 00 version1.0 datasheet feb.-2010 www.lowpowersemi.com page 6 of 9
preliminary datasheet LP3308 LP3308C 00 version1.0 datasheet feb.-2010 www.lowpowersemi.com page 7 of 9 applications information inductor selection the recommended value of inductor for 30v applications are 4.7 to 22h. small size and better efficiency are the major concerns for portable device, such as LP3308 used for mobile phone. the inductor should have low core loss at 1.4mhz and low dcr for better effi ciency. to avoid inductor saturation current rating should be considered.
preliminary datasheet LP3308 LP3308C 00 version1.0 datasheet feb.-2010 www.lowpowersemi.com page 8 of 9 packing information
preliminary datasheet LP3308 LP3308C 00 version1.0 datasheet feb.-2010 www.lowpowersemi.com page 9 of 9
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