US 4,054,828 AGranted

Cyclically operating transistorized power switching circuit system

AssigneeRobert Bosch GmbH

InventorsGerhard Conzelmann, Karl Nagel, Helmut Keller

Life of this patent

Estimating the term…

Loading patent…

Abstract

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.

Transistor power cyclical switching circuit system, particularly for variable duty cycles, having a power switching transistor component (2), a load (R,L) connected to the power switching transistor component (2), driver transistor component (1) connected to selectively control repetitive, cyclical conduction of the power transistor, and at least two coupling resistor components (R.sub.1, R.sub.2) connected to the driver transistor (1) and to the power transistor (2);

wherein the collector of the driver transistor (1) is connected over a first resistor component (R.sub.1) with one terminal of a source of operating potential;
the emitter of the driver transistor (1) and of the power transistor (2) being, each, connected to the other terminal of the source of operating voltage;
a second one of said resistance components (R.sub.2) connecting the base of the power transistor (2) to the collector of the driver transistor (1);
and wherein the values of said components meet the conditions:
a. the resistance value of the first resistor component (R.sub.1) is so dimensioned that, when the driver transistor is conductive, or ON, the sum of the power dissipated in said first resistor (R.sub.1) and in the collector-emitter path of the driver transistor (1) is at least approximately equal to the sum of the power being dissipated in the two resistor components (R.sub.1, R.sub.2) and in the power transistor (2) when the driver transistor (1) is blocked, or OFF;
and
b. the resistance value of the second resistor component (R.sub.2) is so dimensioned that, when the driver resistor (1) is blocked, or OFF, the sum of the resistance values of the two resistance components (R.sub.1, R.sub.2) provide a base current to the base of the power transistor (2) at a level to hold the power transistor under all possible operating conditions of the system in saturated conduction,
to provide for power dissipation losses in the system which are, in an initial approximation, independent of the duty cycle of the power switching transistor (2).

5 more elements

Facts

Application

05/539,441Filed 8 Jan 1975

Priority

DT 240170115 Jan 1974

Granted

18 Oct 1977

Term ends

Not estimatedThe source records don’t support an estimate.

Classification8 codes

H03K 17/64
The devices being bipolar transistors: having inductive loads
H02J 7/70
Circuit arrangements for charging or discharging batteries or for supplying loads from batteries: characterised by the mechanical construction
H03K 17/60
By the use, as active elements, of semiconductor devices: the devices being bipolar transistors
H10D 84/642
Combinations of only vertical BJTs: combinations of non-inverted vertical BJTs of the same conductivity type having different characteristics,…

Abstract

Claims42