Murata Manufacturing Co., Ltd.

Yumin Saigo

Hayato Katsu

Yasuhiro Nabika

Wataru Aoto

An LED drive circuit includes a power supply terminal, an LED, a first switch, and a first resistor are connected in series. The power supply terminal, a third resistor, and a second switch are connected in series. A connection point between the third resistor and the second switch, and a control terminal of the first switch are connected. A second resistor is connected between a connection point between the first switch and the first resistor, and a control terminal of the second switch. A first PTC thermistor is connected to a connection point between the control terminal of the second switch and the second resistor.

LED drive circuit

A laminated PTC thermistor element that includes a ceramic substrate including a plurality of ceramic layers, a plurality of internal electrodes within the ceramic substrate, and external electrodes on the surface of the ceramic substrate that provide electrical conduction to the internal electrodes. The ceramic substrate is 0.3 [&#x3bc;m] or more and 1.2 [&#x3bc;m] or less in average porcelain grain size. Furthermore, the relative density of the ceramic substrate has a lower limit of 70 [%], and an upper limit of &#x2212;6.43d+97.83 [%] when the average porcelain grain size is denoted by d.

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Nagaokakyo, Japan

Yumin Saigo