SLIS178B October 2017 – January 2018 TPS92830-Q1
PWM Threshold Setting
DiagEN Setting (Enables LED-Open Detection When V(IN) > 9 V
DERATE Setting (Reduces Current Output When V(IN) > 18 V
To deliver 300 mA with a single MOSFET package, the designer must consider the maximum thermal-dissipation condition. The power dissipation of a MOSFET is usually at its peak when input voltage is at 16 V in a full-brightness condition. Assume the minimal LED forward voltage at 300 mA is 6 V.
MOSFET package and layout design must be considered to dissipate 2.702 W at maximum ambient temperature, usually 85°C.
The TPS92830 device can support a variety of N-channel MOSFETs in the markets. Adding a capacitor between the gate and source increases the loop phase margin. The recommended total capacitance at Gx is greater than 4 nF.