PURPOSE: To contrive to simplify the circuit constitution and to miniaturize the device by connecting a power MOSFET in series with a rush current generating circuit and utilizing the inter-drain-source on-resistance change with respect to the change in the inter-gate-source voltage. CONSTITUTION: In closing a power switch 2 in a rush current preventing circuit, a voltage from a DC power supply 1 is fed to a resistor 9, a smoothing capacitor 7 and one terminal of a load circuit 8. Since a power MOSFET 11 connected to the other terminal of the capacitor 7 and the circuit 8 is turned off at this point of time, no current (i) flows. On the other hand, the capacitor 10 is charged via a resistor 9 having a sufficiently large resistance, the voltage across the capacitor 10 is increased and it is fed between the gate and source of the FET 11. The inter-gate-source voltage VGS of the FET 11 and a current IDS flowing through the drain and source have a characteristic shown in figure. Thus, the inter-drain-source on-resistance of the FET 11 starts decreasing gradually after application of current, the current (i) starts flowing slowly and reaches the steady-state current gradually. COPYRIGHT: (C)1988,JPO&Japio

Rush current preventing circuit

PROBLEM TO BE SOLVED: To improve the operability of tack welding and the quality of a welded part by a method wherein a recessed part is formed in an intermediate part on the lateral side of a connector so that the fore end of a jig for airtightness inspection can be engaged therewith. SOLUTION: Each of connectors 16 and 17 is surrounded on four peripheries by a butting face 10, a joining face 11 and a pair of lateral faces 12, while recessed parts 19 are formed in the intermediate parts of the lateral faces 12 respectively. Moreover, thin-wall parts 20 are formed by the recessed parts 19 at the opposite end edge parts in a part of each of the connectors 16 and 17 positioned to the butting face 10. Besides, the outer end edge parts of the recessed parts 19, that is, the end edge parts thereof on the sides opposite to the thin-wall parts 20, are so formed that the fore ends of engagement pieces 22 provided for a jig 21 for airtightness inspection can be engaged therewith. On the occasion of tacking each of the connectors 16 and 17 to each header temporarily, the end edges of the thin-wall parts 20 and the outer peripheral surface of the header are subjected to spot welding. The heat capacity of the thin-wall parts 20 is small and the temperature of the end edges of the thin-wall parts 20 rises in almost the same way as the outer peripheral surface part of the header at the time of welding. Accordingly, the operability of the tack welding and the quality of the welded part are improved.

Connector device for heat exchanger

PURPOSE: To provide a P-channel FET drive circuit whose power loss is smaller. CONSTITUTION: A switch means 11 is used to bias a P-channel FET 5 to the conductive state to reduce components required for a P-channel FET drive circuit 7, which biases a passive component to the non-conductive state, and the power loss. The energy stored in an inductor 15 in the period when the P-channel FET 5 is in conductive is used to give a current through a capacitor 13 connected in series to capacitance of the gate and the source of the P-channel FET 5. Thus, this stored electric charge is reduced to turn off the P-channel FET 5.

Manfureeto Beete

Papers

Drive circuit for power field effect switching transistor