TS19720
Taiwan Semiconductor
5 Version: B15
APPLICATION INFORMATION
Start-up Current
The typical start-up current is around 45μA. Very low start-up current allows the PWM controller to increase the
value of start-up resistor and then reduce the power dissipation.
Under Voltage Lockout (UVLO)
A hysteresis UVLO comparator is implemented in TS19720. The turn-on and turn-off thresholds level are fixed at
17.5V and 8V respectively. This hysteresis shown in Fig.3 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 should be matched with
the start-up capacitor.
Leading-Edge Blanking (LEB)
Each time the power MOSFET is switched on, a turn-on spike will inevitably occur at the sense resistor. To avoid
fault trigger, a 400ns 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 cannot switch off the gate driver.
Gate Clamp
Driver is clamped to 12.5V by an internal clamping circuit to avoid the Gate of MOSFET to get damaged.
Over Current Protection (OCP)
The TS19720 has built-in cycle by cycle over current protection function on CS pin. As the CS pin voltage is larger
than V
OCP
(1.4V), the gate output will be turned off immediately to avoid the driver board to be burned out.
Over Voltage Protection (OVP) on V
CC
To prevent the LED driver from being damaged, the TS19720 has an implemented OVP function on V
CC
. When the
V
CC
voltage is higher than the V
OVP
(31V), the output gate driver circuit will be shut down immediately to stop the
switching of power MOSFET. The V
CC
pin OVP function is an auto recovery type protection. If the OVP condition
happens, the pulses will be stopped until the V
CC
pin voltage is down to the UVLO off level. The TS19720 is
working in an auto-recovery mode as shown in Fig. 4.
Fig. 4
Fig.3
