A method and a circuit comprising an electrically controlled transistor element ( 303 ) configured for conveying a current from an input terminal ( 300 ) to an output terminal ( 320 ), wherein the current is of a magnitude belonging within a pre-determined current range; and a control circuit configured for controlling said transistor element is such a manner that the transistor element ( 303 ) is controlled to produce a pre-selected voltage drop across the transistor element independently of the traversing current. Hereby an extremely effective circuit is provided that has high efficiency for transporting large current values form a supply module to a power consuming module and hence the option is provided of substituting the circuit according to the invention in an active system; a so-called hot swap. The circuit can also easily be dimensioned to a desired application by adding a number of transistor elements in parallel.
1. A circuit configured for coupling a power-supplying module of a plurality of power supply modules to a common point, one such circuit associated with each power-supplying module of the plurality of power supplying modules to connect each power-supplying module to the common point, and wherein the circuit comprises an electronically controlled transistor element configured for conveying a current of a magnitude belonging within a predefined range, a device for detecting the direction of the current, and a control circuit configured for controlling said transistor element in such a manner that a current from the common point to one of said modules can be essentially prevented, further wherein said transistor element can be controlled in such a manner that a pre-selected voltage drop is produced across the transistor element independently of said current magnitude.
2. A circuit according to claim 1 , wherein said transistor element comprises a number of transistor elements interconnected in parallel.
3. A circuit according to claim 1 , wherein said transistor element comprises at least one MOSFET transistor.
4. A circuit according to claim 1 , wherein the circuit comprises a buffer circuit configured for driving said transistor element.
5. A circuit according to claim 1 , wherein the circuit comprises an active regulator loop configured for detecting changes in said current.
6. A circuit according to claim 1 , wherein the circuit partakes in a power supply system.
7. A method of coupling a number of power-supplying modules to a common point, wherein an electronically controlled transistor element conveys a current of a magnitude belonging within a pre-defined range from a respective one of the power-supplying modules, and wherein the direction of the current is detected, and wherein a current from the common point to said module is essentially prevented by controlling said transistor element off if a current flows from the common point to the module, further wherein said transistor element is controlled in such a manner that a preselected voltage drop is provided across the transistor element independently of said current magnitude.
8. A method according to claim 7 , wherein said transistor element comprises a number of transistor elements that are interconnected in parallel.
9. A method according to claim 7 , wherein the transistor element comprises at least one MOSFET transistor.
10. A method according to claim 7 , wherein the transistor element is driven by a buffer circuit.
11. A method according to claim 7 , wherein changes in said current are detected by an active regulator loop.
12. A circuit configured for coupling a power-supplying module of a plurality of power supplying modules to a common point, one such circuit associated with each power-supplying module of the plurality of power supplying modules to connect each power-supplying module to the common point, and wherein the circuit comprises an electronically controlled transistor element configured for conveying a current of a magnitude belonging within a predefined range, a device for detecting the direction of the current, and a control circuit configured for controlling said transistor element in such a manner that a current from the common point to one of said modules can be essentially prevented, further wherein said transistor element can be controlled in such a manner that a pre-selected voltage drop is produced across the transistor element independently of said current magnitude, said control circuit having an input coupled across the transistor element and having an output coupled to a control electrode of said transistor element to maintain said pre-selected voltage drop.
13. A method of coupling a number of power-supplying modules to a common point, wherein an electronically controlled transistor element conveys a current of a magnitude belonging within a pre-defined range from a respective one of the power-supplying modules, and wherein the direction of the current is detected, and wherein a current from the common point to said module is essentially prevented by controlling said transistor element off if a current flows from the common point to the module, further wherein said transistor element is controlled in such a manner that a pre-selected voltage drop is provided across the transistor element independently of said current magnitude by monitoring the voltage drop across the transistor element and providing a feedback voltage to a control electrode of the transistor element to maintain the pre-selected voltage drop.