The device provides an N-channel MOSFET driver that can source or sink a peak current of 1.5 A. The peak sourcing current is larger when supplying an external VCC that is higher than 6.75-V VCC regulation target. During start-up especially when the input voltage range is below the VCC regulation target , the VCC voltage must be sufficient to completely enhance the MOSFET. If the MOSFET drive voltage is lower than the MOSFET gate plateau voltage during start-up, the boost converter may not start up properly and it can stick at the maximum duty cycle in a high power dissipation state. This condition can be avoided by selecting a lower threshold N-channel MOSFET switch and setting the V_SUPPLY(ON) greater than 6 to 7 V. Because the internal VCC regulator has a limited sourcing capability, the MOSFET gate charge should satisfy the following inequality.

Equation 18.

An internal 1-MΩ resistor is connected between GATE and PGND to prevent a false turnon during shutdown. In boost topology, switch node dV/dT must be limited during the 65-µs internal start-up delay to avoid a false turnon, which is caused by the coupling through C_DG parasitic capacitance of the MOSFET.