is31lt3 515 preliminary integrate d silicon solution , inc. C www.issi.com r ev. a , 10 / 1 2 /201 2 1 high voltage led lighting driver for buck, boost or buck - boost topology september 2012 general description the IS31LT3515 is a current mode pwm controller designed to drive an external mosfet for high current led applications. with a current sense amplifi er threshold of 250mv, the led current is programmable with one external current sense resistor. the IS31LT3515 is ideal for buck, boost or buck - boost operation. with 250khz operating frequency (typical, and this frequency can be set up by external resisto r), the external inductor and capacitors can be small while maintaining high efficiency. dimming can be either analog or pwm digital. input dc voltage from ld pin for analog dimming. input pwm signal from pwm pin can get either analog dimming or pwm dimmin g. the sn3515 is available in sop - 16 package and qfn - 16 3*3 package. features ? wide voltage: vin up to 40v, vout up to higer ? buck, boost or buck - boost operation ? easy dimming: analog, pwm or pwm converting to analog with an external capacitor ? output over v oltage protection(ovp) ? internal soft start to avoid inrush current ? current mode pwm with an 250khz operating frequency(typical, rset=150kohms) ? output short circuit protection ? vin under voltage lock out and over temperature protection(otp) applications ? gen eral industrial high power led lighting ? desk lights and room lighting, street lighting ? display backlight typical application circuit copyright ? 2011 integrated silicon solution , inc. all rights reserved. issi reserves the right to make changes to thi s specification and its products at any time without notice. issi assumes no liability arising out of the application or use of any information , products or services described herein. customers are advised to obtain the latest version of this device specif ication before relying on any published information and before placing orders for products. integrated silicon solution , inc. does not recommend the use of any of its products in life support applications where the failure or malfunction of the product can reasonably be expected to cause failure of the life support system or to significantly affect its safety or effectiveness. pr oducts are not authorized for use in such applications unless integrated silicon solution , inc. receives written assurance to its satisfaction , that: a.) the risk of injury or damage has been minimized; b.) the user assume all such risks; and c.) potential liability of integrated silicon solution , inc is adequately protected under the circumstances buck boost configuration
is31lt3 515 preliminary integrate d silicon solution , inc. C www.issi.com r ev. a , 10 / 1 2 /201 2 2 pin configuration package pin conf igurations (top view) sop - 16 pin description pin no. pin name function 1 vcc the power supply pin 2 pwmd pwm dimming input. the pwm signal will convert to analog signal with an external capacitor. (low is enable, internal have pull down resistor) 3 en enable pin. floating(pull down internal), enable; pull to high, shutdown mode 4 ld analog dimming input. 5 ,12 gnd ground 6 opt structure selection. floating: boost. connect to ground: buck - boost 7 fset with an external resistor to set operation frequency. (250khz, r fset =150kohms) 8 cs sense current sense mirror pin, connect a res to cs pin(1:5000) 9 ovp over voltage protect, this pin voltage exceed 1.23v, gate will pull low. 10 isn the led current sense amplifier negative input 11 isp the led current sense amplifier positive input 12 gnd ground 13 cs mosfet current sense 14 fault this pin is the same as pwm signal and when isp - isn>0.5v, pulled to ground (short circuit is detected) 15 gate gate drive to the external mosfet(12v ) 16 vccout ldo 12v output , need an external cap(1uf) ordering information industrial range: - 40c to +85c order part no. package qty/ r eel is31lt3 515 - grls2 - tr sop - 16 , lead - free 2500
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