TS19721A

Taiwan Semiconductor

Document Number: DS_P0000195

5

Version: A15

APPLICATION INFORMATION

Start-up Current

a high value start-up resistor and reduce overall power dissipation.

UVLO(Under Voltage Lockout)

A hysteretic UVLO comparator is implemented in TS19721A. The turn-on and turn-off thresholds level are fixed at

17.5V and 8V respectively. This hysteresis shown in Fig.1 ensures that the start-up capacitor will be adequate to

supply the chip during start-up. For quick start-up of the LED driver, the start-up resistor & capacitor needs to

optimize for application.

LEB(Leading-Edge Blanking)

Each time the power MOSFET is switched on, a turn-on spike will inevitably occur at the sense resistor. A 400ns

leading-edge blanking time is built in to avoid a false trigger.. Conventional RC filtering can therefore be omitted.

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

OCP(Over Current Protection)

The TS19721A has built-in cycle-by-cycle over-current protection functions available at the CS pin. When the CS

damage.

returns to the UVLO off level when the TS19721A will automatically recover as shown in Fig. 2.

Fig. 1

Fig. 2