Outline
When the output terminal of a DC-DC converter short circuits for some reason, excessive current flows through the output, causing various kinds of troubles such as fuming, firing, and breakdown. Previously, a short-circuit protection circuit consisting of a transistor, Zener diode, and resistor, etc. was installed to prevent this. However, simply by inserting "POSISTOR" into the output side, abnormal current flow when a short circuit occurs can be limited and the DC-DC converter protected from damage. Murata's "POSISTOR" for overcurrent protection generates heat by itself due to abnormal current flow during short circuits, increases the resistance of the "POSISTOR" to limit the abnormal current flow, and prevents the DC-DC converter from fuming, firing, or being damaged. An appropriate shape of "POSISTOR" (discrete type or surface mount type) can be selected according to the circuit current and mounting method. Circuit example: Protecting DC-DC converters from short circuits
		When the output terminal of a DC-DC converter shorts out, the output current rapidly increases possibly causing various troubles such as overheating, fuming, or even firing. To prevent this from happening, short-circuit protection comprising a Zener diode, transistor, and resistor has been adopted in many cases. But a simpler and more cost-effective way is required. Chip "POSISTOR" (0603-size chip-type component) presents a solution because it can detect over-current by itself and suppress it to the safe level.
	Roles of "POSISTOR"
Increases the resistance of "POSISTOR" due to abnormal current flow when short circuits occur on the DC-DC converter, and limits the abnormal current flow to prevent the DC-DC converter from fuming, firing, or being damaged. Decreases the resistance of "POSISTOR" and unlike the fuse, recovers its original resistance when the short-circuiting stops.

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