Method and device for driving a power output stage
AssigneeSiemens Aktiengesellschaft
InventorsCyrille Brando, Mark Elliott, Johann Falter
Life of this patent
Estimating the term…
Abstract
In order to drive it with compatible electromagnetic interference, a circuit breaker is charged with a high charging current until the drain current exceeds a current threshold. The circuit breaker is then charged further with a smaller charging current associated with the desired rate of rise, until the drain voltage falls below a predefined voltage threshold. The circuit breaker is then charged further with the high charging current for a predefined period. In order to close the circuit breaker, a nearly reverse sequence is followed.
Claims3
A method for driving power output stages, which comprises the steps of:
- providing a power output stage for switching a load connected in series with a MOSFET circuit breaker disposed between terminals of a voltage source;
- charging the MOSFET circuit breaker with a predefined high charging current until a drain current of the MOSFET circuit breaker exceeds a predefined current threshold from a start of a control signal;
- charging the MOSFET circuit breaker with a predefined small charging current until a drain voltage of the MOSFET circuit breaker falls below a predefined voltage threshold, the predefined small charging current being smaller than the predefined high charging current;
- charging the MOSFET circuit breaker further, for a predefined charging period, with the predefined high charging current;
- discharging the MOSFET circuit breaker with a predefined high discharge current until the drain voltage exceeds the predefined voltage threshold after an end of the control signal;
- and
- discharging the MOSFET circuit breaker with a predefined small discharge current until the drain current falls below the predefined current threshold, and then, for a predefined discharge period, the MOSFET circuit breaker being discharged with the predefined high discharge current, the predefined small discharge current being smaller than the predefined high discharge current.
A device, comprising:
- a positive terminal for a supply voltage;
- a MOSFET circuit breaker having a gate terminal, a drain and a source;
- a first constant current source providing a high charging current disposed between said positive terminal and said gate terminal of said MOSFET circuit breaker;
- a second constant current source providing a small charging current disposed in parallel with said first constant current source;
- a negative terminal for the supply voltage;
- a third constant current source providing a high discharge current connected between said gate terminal of said MOSFET circuit breaker and said negative terminal for the supply voltage;
- a fourth constant current source providing a small discharge current disposed in parallel with said third constant current source;
- and
- a control circuit operated on the supply voltage and outputting switching signals-to switch said first, said second, said third and said fourth constant current source on and off in dependence on:
- control signals received by said control circuit;
- a ratio of a drain voltage of said drain and a predefined voltage threshold;
- a ratio of a drain current flowing through said MOSFET circuit breaker and a predefined current threshold;
- and
- at least one predefined time period.
Dependencies are inferred from the claim text.