| 摘要 |
<p>The present invention relates to an overload protection device for a switching mode power supply (SMPS) having a power factor correction (PFC) function and, more specifically, to the overload protection device for a switching mode power supply which maximally suppresses interferences between an SMPS main body and the overload protection device, accelerates a response characteristic of a load voltage, and fundamentally prevents a reference voltage of an overload detecting unit from fluctuating due to an abrupt decrease in a secondary side voltage of a transformer when the load is short-circuited. The overload protection device further prevents a low voltage, which is generated when an initial external voltage is applied to the SMPS, from being erroneously identified as the overload and also prevents a malfunction due to a low operation voltage for a photocoupler, etc. due to the overload caused by a short-circuit by using minimal components and a very simple and organic control logic. Also, the overload protection device operates normally even when driving voltages supplied to the overload protection device vary, and prevents a shutdown of the SMPS due to an instantaneous overload or a predetermined inductive noise signal. Also, an operation of a PFC integrated circuit (IC) is simply shut down by using a feedback terminal without using a separate shutdown circuit which disconnects the driving voltage applied to the PFC IC. Consequently economic feasibility, efficiency, stability, and reliability of a system are superior to those of conventional overload protection devices.</p> |
