DESCRIPTION
Moreover, PT6903 controls the internal MOS at a modulated switch frequency up to 1MHz. Output current to an LED string can be programmed to any value between its minimum value to its maximum value at the linear dimming control input of PT6903. PT6903 provides a low-frequency PWM dimming input that can accept an external control signal with a duty cycle of 0~100% and a frequency between 100Hz and a few KHz. PT6903 integrates more protection functions. The reliability of LEDs and device can be promoted by these protection functions. PT6903 provides over current protection when output short-circuit or LEDs current rises up about two times setting current. PT6903 must be power-up again if over current protection happens. PT6903 also provides over temperature protection. There are two ways to protect LEDs and device when temperature rises up to limited level. One is internal thermalshutdown function. If internal temperature rises up about 135 , PT6903 will turn off switch. It will turn-on again when internal temperature falls down about 115 .
PTC
