Feedback circuit for power switching circuit
AssigneeKoninklijke Philips Electronics N.V.
InventorsNicolas Wheeler, Philip Rutter
Life of this patent
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Abstract
A power switching circuit has high and low side switches (6, 8). The load-side FET (8) has a main body part (30) and a sense FET part (32). The current sensing circuit (32) measured the low side current. A capacitance (56) couples the switch node (10) to a current signal node (52) to provide a combined signal on current output (58), the combined signal including the low side current and timing information.
Claims10
A power switching circuit, comprising:
- a high side switch (6) and a low side switch (8) arranged in series with a switch node (10) therebetween;
- a current sensing circuit (32) for sensing the current passing through the low side switch and providing a signal on a current signal node (52) representing the current through the low side switch;
- and
- a capacitance (56) coupling the switch node (10) to the current signal node (52) for coupling switching pulses on the switch node (10) onto the signal provided on the current signal node (52).
A power switching circuit according to any preceding claim wherein the current signal node (52) is connected to switch node (10) through a capacitor (56) and a resistor (54) in series.
A power conversion circuit comprising
- a power switching circuit according to any preceding claim;
- a current regeneration circuit (60) having an input connected to the current signal node for regenerating a current signal from the information output by the current signal node of the power switching circuit;
- and
- a drive circuit (62) having an input connected to the current regeneration circuit and outputs connected to the high side switch (6) and the low side switch (8) for switching the high and low side switches on alternately in accordance with the regenerated current signal.
A current feedback signal (76) for signalling from a switching circuit having high and low side FETs to a drive circuit driving the switching circuit, the current feedback signal including a current signal (70) corresponding to the instantaneous current through the low side FET when the low side FET is on and pulses (72) superimposed on the current signal indicating the switching times of the FETs.
A method of operation of a power switching circuit having high (6) and low (8) side switches connected in series at a switch node (10), including:
- switching the high and low side switches (6, 8) on alternately;
- sensing the current through the low side switch (8) and providing a current feedback signal corresponding to the sensed current;
- and
- capacitively coupling (56, 54) the switch node to the current feedback signal to provide switching pulses (72) on the current feedback signal corresponding to the switching times of the switches (6, 8).
Dependencies are inferred from the claim text.