The Over Power Protection, OPP, limits the maximum average output power. When the output is overloaded, it is important to shutdown the module to prevent it from further damage, or propagating the fault into other portion of the entire system. Given the extremely high switching frequency, it is not practical to implement the traditional cycle-by-cycle current limit. Instead, the UCC14340-Q1 device relies on the Over Power Protection (OPP) working together with the output undervoltage protection.

As discussed in Power Handling Capability, with the input voltage feedforward, and the "baby" burst duty cycle adjustment, the maximum power delivery capability of the UCC14340-Q1 is well controlled. The impact of OPP on the relationship between Vin and maximum output power is shown in Figure 8-8.

Figure 8-8 Maximum Output Power Under Different Input Voltage Condition

When the load exceeds the maximum power delivery capability, the output voltage starts to droop. When the output voltage falls below the Under Voltage Protection threshold, the output undervoltage protection is triggered and the parts latches off into a safe state.