Robert Boschgmbh

Helmut Keller

Hartmut Seiler

Gerhard Conzelmann

Karl Nagel

Adolf Kugelmann

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.

Cyclically operating transistorized power switching circuit system

A plurality of luminescent elements, such as light-emitting diodes, incandescent lamps or the like, are located adjacent each other, each connected to the output of a difference amplifier. The respective inputs of the difference amplifier are connected, on the one hand, to a voltage divider to have different reference voltages applied thereto and, on the other, in common to the input voltage to be sampled so that, as the voltage changes between the amplification ranges of the difference amplifiers, the output therefrom will change in accordance with input voltage so that the brightness of the respectively connected luminescent elements will also change, thus providing gradual increase in brightness of any individual element as the voltage changes. The difference amplifiers may be differentially connected operational amplifiers.

Luminescent voltage indicator circuit

Supplementary metallized connection parts short-circuiting or connecting incremental sub-components of one or more circuit elements of an integrated circuit are laid down on the semiconductor slice at the same time as the usual metallized connection pattern is made. The components associated with the incremental sub-components are measured to determine the program of adjustment and selective burnout of the supplementary connections. The selective burnout is carried out by applying a sequence of pulses to the segments to be burned out under monitoring by a measuring circuit, which blocks the delivery of further pulses, either immediately or after one or a few more pulses, when the measuring circuit detects the opening of the connection. The process is preferably carried out on integrated circuits before the semiconductor slice on which they are made is separated into individual circuit units. The pulses are applied in sequences in which individual pulses or series of pulses have increasing amplitude and/or pulse duration and/or pulse frequency.

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Reutlingen, Germany

Helmut Keller