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Low-Line Overstress of Constant-Power Loads(2 of 4)
Relevance
Any switching-mode power supply or other constant-power device operating at low line without inherent or designed-in protection. If the device or circuit naturally inhibits operation at low input voltage, the problem may be masked, but the inherent starting voltage may not be satisfactory under worse case conditions. PWM controllers often inhibit voltage at low line, but this operation should be checked under worse case conditions.
Solvability
Inhibit operation at low input voltages. The normal solution is to add a circuit that prevents operation until an input voltage is reached that meets the circuit specification. This circuit usually requires hysteresis to prevent on/off oscillation near the sense point for slowly varying or non-monotonic input voltage. Soft start circuits are often added to further reduce the input current stress.
Do not use this information for design without independent verification of the information.
