Trip-point detection circuit
First Claim
1. A method for providing a trip-point detection signal when a current that is delivered to a load decreases below a predetermined threshold, the method comprising:
- coupling a current (IOUT) to a common node through a pass circuit that is responsive to a first control signal such that the current (IOUT) is controlled;
coupling the current (IOUT) from the common node through a sense circuit to the load at an output node;
setting a trip-point level with a first resistor circuit and a first current source, wherein the first current source is series coupled to the common node through the first resistor circuit, and wherein the first current source is configured to provide an approximately constant current level;
monitoring a voltage associated with the load to provide a sensed output voltagecomparing the trip-point level with the sensed output voltage;
asserting the trip-point detection signal when the current (IOUT) decreases from a current limit level (IMAX) to a predetermined threshold level as indicated by the change in the sensed output voltage relative to the trip point level;
selecting a tap-point in the first resistor circuit in response to a selection signal; and
adjusting the trip-point level associated with trip-point detection signal in response to the selected tap-point in the first resistor circuit.
1 Assignment
0 Petitions
Accused Products
Abstract
A current is provided from a power source to a load through a pass circuit that is series coupled to a sense resistor. A current trip-point detection circuit is arranged to detect a change in the current that is provided to a load. The current trip-point detection circuit includes at least two resistors that are series coupled from the sense resistor to a current source. A comparator compares a sense voltage to a tap-point between the two resistors such that the comparator asserts a trip-point detection signal when the current to the load reaches a predetermined threshold. The sense voltage can correspond to the voltage across the load or some other voltage that is proportional to the voltage across the load. The circuit arrangement has a simplified design that sets the trip-point as a percentage of the maximum output current. The current level trip-point can be temperature compensated.
-
Citations
21 Claims
-
1. A method for providing a trip-point detection signal when a current that is delivered to a load decreases below a predetermined threshold, the method comprising:
-
coupling a current (IOUT) to a common node through a pass circuit that is responsive to a first control signal such that the current (IOUT) is controlled; coupling the current (IOUT) from the common node through a sense circuit to the load at an output node; setting a trip-point level with a first resistor circuit and a first current source, wherein the first current source is series coupled to the common node through the first resistor circuit, and wherein the first current source is configured to provide an approximately constant current level; monitoring a voltage associated with the load to provide a sensed output voltage comparing the trip-point level with the sensed output voltage; asserting the trip-point detection signal when the current (IOUT) decreases from a current limit level (IMAX) to a predetermined threshold level as indicated by the change in the sensed output voltage relative to the trip point level; selecting a tap-point in the first resistor circuit in response to a selection signal; and adjusting the trip-point level associated with trip-point detection signal in response to the selected tap-point in the first resistor circuit. - View Dependent Claims (2, 3)
-
-
4. A method for providing a trip-point detection signal when a current that is delivered to a load decreases below a predetermined threshold comprising:
-
coupling a current (IOUT) to a common node through a pass circuit that is responsive to a first control signal such that the current (IOUT) is controlled; coupling the current (IOUT) from the common node through a sense circuit to the load at an output node; setting a trip-point level with a first resistor circuit and a first current source, wherein the first current source is series coupled to the common node through the first resistor circuit, and wherein the first current source is configured to provide an approximately constant current level; monitoring a voltage associated with the load to provide a sensed output voltage comparing the trip-point level with the sensed output voltage; asserting the trip-point detection signal when the current (IOUT) decreases from a current limit level (IMAX) to a predetermined threshold level as indicated by the change in the sensed output voltage relative to the trip point level; coupling a first input of an amplifier to the output node; coupling a second input of the amplifier to the first resistor circuit and the first current source; providing the first control signal in response to an output of the amplifier coupling a first amplifier to the output node through a second resistor circuit; coupling a second current source to the output node through the second resistor circuit; and adjusting at least one of a current level associated with the second current source and a resistance level that is associated with the second resistor circuit in response to the sensed output voltage.
-
-
5. An apparatus for providing a trip-point detection signal when a current that is delivered to a load decreases below a predetermined threshold, the apparatus comprising:
-
a first current source that is arranged to provide a first current, wherein the first current has a first level that is approximately constant, and wherein the first current source is controlled; a first resistor circuit that is coupled between a common node and the first current source, wherein the first resistor circuit has an associated tap-point, wherein the first resistor circuit comprises at least a first resistor and a second resistor that are coupled together at the tap point; a pass circuit that is coupled between an input source node and the common node; a sense circuit that is coupled between the common node and an output node; a comparator circuit that includes a first input that is coupled to the tap-point in the first resistor circuit, a second input that is coupled to the output node, and an output node that indicates the trip-point detection signal when the current (IOUT) decreases from a current limit level (IMAX) to a predetermined threshold level. - View Dependent Claims (6, 7, 8, 9, 10, 11, 12, 13)
-
-
14. An apparatus for providing a trip-point detection signal when a current that is delivered to a load decreases below a predetermined threshold, the apparatus comprising:
-
a first voltage drop means that is coupled to a common node and arranged to provide a trip-point level at a tap-point, wherein the first voltage drop means comprises; a resistor means that comprises at least a first resistance means and a second resistance means that are coupled together at the tap point; and a current source means that is arranged to couple a sense current to the resistor means such that the trip point level is provided at the tap point in response to the sense current; a pass means that is coupled between an input source node and the common node; a sense means that is coupled between the common node and an output node; a comparator means that includes a first input that is coupled to the tap-point, a second input that is coupled to the output node, wherein the comparison means is arranged to assert the trip-point detection signal when the current (IOUT) decreases from a current limit level (IMAX) to a predetermined threshold level. - View Dependent Claims (15, 16, 17, 18, 19)
-
-
20. An apparatus for providing a trip-point detection signal when a current that is delivered to a load decreases below a predetermined threshold, the apparatus comprising:
-
a first current source that is arranged to provide a first current to a first sense node, wherein the first current has a first level that is approximately constant, and wherein the first current source is controlled; a first resistor circuit that is coupled between a common node and a tap-point; a second resistor circuit that is coupled between the tap-point and the first sense node; a pass circuit that is coupled between an input source node and the common node; a sense circuit that is coupled between the common node and an output node; a comparator circuit that includes a first input that is coupled to the tap-point, a second input that is coupled to the output node, and an output that indicates the trip-point detection signal when the current (IOUT) decreases from a current limit level (IMAX) to a predetermined threshold level; a third resistor circuit that is coupled between the output node and a second sense node; a second current source that is arranged to provide a second current to the second sense node, wherein the second current source is controlled in response to changes in a voltage associated with the output node; and an amplifier circuit that is arranged to provide a variable control signal for the pass circuit, wherein the amplifier circuit has a first input that is coupled to the first sense node, and a second input that is coupled to the second sense node. - View Dependent Claims (21)
-
Specification