PT6908 High Power LED Driver 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 current. It’s controlled by the internal transconductance operational amplifier and external adjustable slope compensation, 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 circuit protection, output current precision control, linear dimming, PWM dimming, etc. In addition, multiple the sync pin of PT6908s or input the same clock signal, these ICs will operate on the same frequency. 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 Input voltage of PT6908 is 9V to 36V, the oscillator frequency is 25KHz~350KHz that setting by the external resistors, and the 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 BLOCK DIAGRAM Tel: 886-66296288‧Fax: 886-29174598‧ http://www.princeton.com.tw‧2F, 233-1, Baociao Road, Sindian, Taipei 23145, Taiwan PT6908 TYPICAL APPLICATION V1.3 2 February 2010 PT6908 ORDER INFORMATION Valid Part Number PT6908-S (L) Package Type 16 Pins, SOP, 150mil Top Code PT6908-S PIN CONFIGURATION 16 PINS, SOP PIN DESCRIPTION Pin Name VIN VDD GATE GND CS SC RT SYNC CLIM REF FAULT OVP PWMD COMP IREF FB V1.3 Description Input voltage 9V~36V DC. Internal regulated voltage. Drives the gate of external N-channel MOSFET. Ground. Senses the external MOSFET current. Slope compensation for current sense. Oscillator frequency control. Synchronization control. Input current limit & Soft start. Reference voltage. Drives the gate of external N-channel MOSFET. It will be locked at low level when IC works in error condition. Over voltage protection. Low frequency PWM dimming pin, also enable pin. Output of OTA, stable closed loop control. Sets the LED string current level. LED string current feedback & output short circuit protection. 3 Pin No. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 February 2010 PT6908 IMPORTANT NOTICE Princeton Technology Corporation (PTC) reserves the right to make corrections, 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 V1.3 4 February 2010