7.3.3 Power Limit

An important feature of the LM5069 is the MOSFET power limiting. The Power Limit function can be used to maintain the maximum power dissipation of MOSFET Q1 within the device SOA rating. The LM5069 determines the power dissipation in Q1 by monitoring its drain-source voltage (SENSE to OUT), and the drain current through the sense resistor (VIN to SENSE). The product of the current and voltage is compared to the power limit threshold programmed by the resistor at the PWR pin. If the power dissipation reaches the limiting threshold, the GATE voltage is modulated to reduce the current in Q1. While the power limiting circuit is active, the fault timer is active as described in Fault Timer and Restart.