| 摘要 |
PURPOSE:To prevent other circuit elements from being destroyed even if a constant current element is destroyed by connecting a current limit element and the constant current element in series with the circuits elements to be destroyed if a forward current becomes a prescribed value or over. CONSTITUTION:n-Set of light emitting diodes 20-1-20-n, a resistor 22 and an MOSFET24 are connected in series. A current flowing to the light emitting diodes is a saturated drain current IDSS of the MOSFET. The value of a resistor R is set so that the current flowing to the light emitting diodes is smaller than the forward maximum current of each light emitting diode if the source and drain terminals of the MOSFET24 are short-circuited. Since the current flowing to the light emitting diodes is limited even if the MOSFET is destroyed, the destruction of the light emitting diodes is prevented. |
