2 Root cause of False Fault Glitch

The following process occurs as V_IN ramps fast from 0 V to the recommended operation range:

• Before V_IN reach to UVLO threshold to start reset, the internal circuit status is unknown.
• If V_IN ramps pretty fast, the voltage on point B maybe coupled through C1.
• If the voltage on point B is larger than the threshold voltage V_th, T3 may pull down the FAULT pin.
• The whole circuit resumes to normal after the internal reset.

Figure 2-1 Simplified Internal Circuit Between IN Pin and Fault Pin

Due to the unknown status of the gate of T3, the Fault pin has the chance to be pulled down to 0 V.