10.2.2.1 Power-Limited Start-Up

This design example assumes a 12-V system voltage with an operating tolerance of ±2 V. The rated load current is 10 A. If the current exceeds 11 A, then the device must shut down and then attempt to restart. Ambient temperatures may range from 20°C to 60°C. The load has a minimum input capacitance of 470 μF. The load is turned on only after the PG signal is asserted. Figure 41 shows a simplified system block diagram of the proposed application.

This design procedure seeks to control the junction temperature of device under both static and transient conditions by proper selection of current limit, fault timeout, and power limit. The design procedure assumes the worst case as a unit running at full load and maximum ambient temperature experiences a short circuit event. Adjust this procedure to fit the application and design criteria.

Figure 41. Simplified Block Diagram of the System Constructed in the Design Example