TS19702

High Power Factor Corrector LED Driver

4/9

Version: A12

Application Circuit

Application Information

Start-up Current

The typical start-up current is around 8uA. Very low start-up current allows the PWM controller to increase the

value of start-up resistor and then reduce the power dissipation on it.

UVLO (Under Voltage Lockout)

A hysteresis UVLO comparator is implemented in TS19702, then the turn-on and turn-off thresholds level are fixed

at 15V and 8V respectively. This hysteresis shown in Fig.11 ensures that the start-up capacitor will be adequate to

supply the chip during start-up. For quickly startup the LED driver, the start-up resistor should be matched with the

startup capacitor. Due to the low UVLO on level, so the turn-on delay time will also never greater than the general

PWM IC.

Oscillator

The maximum duty-cycle of internal oscillator is up to 90% for driving high LED voltage string. The frequency of the

oscillator is fixed to 45KHz by internal setting.

LEB (Leading-Edge Blanking)

Each time the power MOSFET is switched on, a turn-on spike will inevitably occur at the sense resistor. To avoid

fault trigger, a 410ns leading-edge blanking time is built in. Conventional RC filtering can therefore be omitted.

During this blanking period, the current-limit comparator is disabled and can not switch off the gate driver.