System to protect switch mode DC/DC converters against overload current
DCFirst Claim
1. A switch mode DC:
- DC converter having an input node coupleable to a source of potential Vin and having an output node providing an output potential Vo and an output current, comprising;
an inductor having a first inductor node and a second inductor node and an inherent resistance therebetween;
a switch, having a control node, coupled to said converter so as to switchingly control current flow from said input node to said inductor; and
means for sensing solely from DC signal components present at said first inductor node and at said second inductor node a measure of said output current and for outputting to said control node a signal proportional to said measure.
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Abstract
A method and circuit arrangement for sensing the output current in a switch mode power converter in order to provide protection arrangements which are responsive to overload or short circuit conditions. In a switch mode power converter including an inductor for providing output current to a load circuit, the inductor having an inherent resistance, a filter circuit is coupled to both the first terminal of the inductor and to the second terminal of the inductor. The filter circuit provides the DC component of the voltage across the inherent resistance of the inductor to an error amplifier. The error amplifier provides an output signal representing the output current, and the output signal is used to adjust an operating parameter of the switching circuit, e.g. duty cycle.
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Citations
27 Claims
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1. A switch mode DC:
- DC converter having an input node coupleable to a source of potential Vin and having an output node providing an output potential Vo and an output current, comprising;
an inductor having a first inductor node and a second inductor node and an inherent resistance therebetween; a switch, having a control node, coupled to said converter so as to switchingly control current flow from said input node to said inductor; and means for sensing solely from DC signal components present at said first inductor node and at said second inductor node a measure of said output current and for outputting to said control node a signal proportional to said measure. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
- DC converter having an input node coupleable to a source of potential Vin and having an output node providing an output potential Vo and an output current, comprising;
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14. A switch mode DC:
- DC converter having an input node coupleable to a source of potential Vin and having an output node providing an output potential Vo and an output current, comprising;
an inductor having a first inductor node and a second inductor node and an inherent resistance therebetween; a switch, having a control node, coupled to said converter so as to switchingly control current flow from said input node to said inductor; a low-pass filter system having a first filter input coupled to said first inductor node and having a second filter input coupled to said second inductor node, an output of said low-pass filter system representing a difference in DC signal components present at said first inductor node and at said second inductor node and providing a measure of said output current; and means, coupled to said output of said low-pass filter system for outputting to said control node a signal proportional to said measure of said output current. - View Dependent Claims (15, 16, 17, 18, 19, 20, 21, 22)
- DC converter having an input node coupleable to a source of potential Vin and having an output node providing an output potential Vo and an output current, comprising;
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23. A method of sensing output current to protect a DC:
- DC switch mode converter against overload, in which the switch mode DC;
DC converter includes an input node coupleable to a source of potential Vin, an output node providing an output potential Vo and an output current, an inductor having a first inductor node and a second inductor node and an inherent resistance therebetween, and further includes a switch, having a control node, coupled to said converter so as to switchingly control current flow from said input node to said inductor, the method comprising the following steps;(a) sensing DC signal components without sensing substantial AC signal components at said first inductor node and at said second inductor node; (b) differentially comparing signals sensed at step (a) to obtain a drive signal that provides a measure of at least one of (i) said output current and (ii) temperature within said converter; and (c) coupling said drive signal obtained at step (b) to said control node of said switch. - View Dependent Claims (24, 25, 26, 27)
- DC switch mode converter against overload, in which the switch mode DC;
Specification