9.4.5.1 Overload and Short Circuit Current Protection

TPA3220 has fast reacting current sensors on all high-side and low-side FETs. To prevent output current from increasing beyond the overcurrent threshold, TPA3220 uses current limiting of the output current for each switching cycle (Cycle By Cycle Current Control, CB3C) in case of excess output current. CB3C prevents premature shutdown due to high output current transients caused by high level music transients and a drop of real speaker’s load impedance, and allows the output current to be limited to a maximum programmed level. If the maximum output current persists, i.e. the power stage being overloaded with too low load impedance, the device will shut down the affected output channel and the affected output is put in a high-impedance (Hi- Z) state until a RESET cycle is initiated. CB3C works individually for each full-bridge output. If an over current event is triggered, CB3C performs a state flip of the full-bridged output that is cleared upon beginning of next PWM frame.

Figure 48. CB3C Timing Example