PT6908 high power led driver tel: 886-66296288 ? fax: 886-29174598 ? http://www.princeton.com.tw ? 2f, 233-1, baociao road, si ndian, taipei 23145, taiwan description PT6908 is a constant-current led driver ic utilized constant frequency, controls buck, boost or buck-boost switch converter. in each control mode, PT6908 adopts the inductance current continuous conduction, peak current control mode and the feedback of the output curren t. it?s controlled by the internal transconductance operational amplifier and external adjustable slope com pensation, it is able to gain the high precision output current in closed loop. the typical functions of PT6908 such as uvlo (under voltage lockout), input current limit, open led protection, output short ci rcuit protection, output current precision control, linear dimming, pwm dimming, etc. in addition, mu ltiple the sync pin of PT6908s or input the same clock signal, these ics will operate on the same frequency. input voltage of PT6908 is 9v to 36v, the oscillator frequency is 25khz~350khz that setting by the external resistors, and t he output pwm signal drive external power nmos. pwm dimming input can accept an external control signal with a duty cycle 0~100% and a frequency between 100hz to a few khz. applications ? led backlight ? automotive led lighting ? other dc/dc led drivers features ? >90% efficiency ? operating voltage: 9v~36v ? constant-current driver ? switch control mode: buck, boost, buck-boost ? stable operation frequency ? slope compensation ? output current closed loop control ? input current limit, output over voltage protection, output short-circuit protection ? linear dimming & pwm dimming ? synchronization ? soft start block diagram
PT6908 v1.3 2 february 2010 typical application
PT6908 v1.3 3 february 2010 order information valid part number package type top code PT6908-s (l) 16 pins, sop, 150mil PT6908-s pin configuration 16 pins, sop pin description pin name description pin no. vin input voltage 9v~36v dc. 1 vdd internal regulated voltage. 2 gate drives the gate of external n-channel mosfet. 3 gnd ground. 4 cs senses the external mosfet current. 5 sc slope compensation for current sense. 6 rt oscillator frequency control. 7 sync synchronization control. 8 clim input current limit & soft start. 9 ref reference voltage. 10 fault drives the gate of external n-channel mosf et. it will be locked at low level when ic works in error condition. 11 ovp over voltage protection. 12 pwmd low frequency pwm dimming pin, also enable pin. 13 comp output of ota, stable closed loop control. 14 iref sets the led string current level. 15 fb led string current feedback & out put short circuit protection. 16
PT6908 v1.3 4 february 2010 important notice princeton technology corporation (ptc ) reserves the right to make co rrections, modifications, enhancements, improvements, and other changes to its products and to discontinue any product without notice at any time. ptc cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a ptc product. no circuit patent licenses are implied. princeton technology corp. 2f, 233-1, baociao road, sindian, taipei 23145, taiwan tel: 886-2-66296288 fax: 886-2-29174598 http://www.princeton.com.tw
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