| 摘要 |
To provide for uniformity of power dissipation in the components of the switching system, regardless of the duty cycle upon repetitive, cyclical operation, the coupling resistors connected to the driver transistor and to the power transistor are so dimensioned relative to each other, and to the internal resistances of the driver transistor and the power transistor of the system that, in an initial approximation, the dissipation losses arising in the system are independent of the duty cycle of the switching transistor; this is obtained by selecting the sum of the resistance value of the collector resistor for the driver transistor and the base transistor of the power transistor such that (a) when the driver transistor is blocked, current flowing to the base of the power transistor holds the power transistor in full, saturated conduction and (b) the value of the collector resistor for the driver transistor is so selected that, when the driver transistor is conductive, the sum of the dissipated power in the collector-emitter path of the driver transistor, and in the collector-resistor of the driver transistor is approximately equal to the sum of the power which is dissipated in the collector resistor of the driver, the base resistor of the power transistor and the collector-emitter path of the power transistor, when the driver transistor is in blocked state. The entire system can be constructed on a monolithic chip and has a particular application as the switching circuit in automotive voltage regulators.
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