Circuits for sensing current levels within lighting apparatus
First Claim
1. A circuit comprising:
- at least one light emitting diode (LED) coupled between a supply voltage and a node;
a current sense circuit coupled between the node and a reference ground, the current sense circuit comprising a resistor coupled in parallel with at least one transistor, the at least one transistor being activated during a first state and being deactivated during a second state;
wherein the node is coupled to a current determination apparatus operable to determine a current flowing through the at least one LED during the second state using a voltage sensed at the node.
1 Assignment
0 Petitions
Accused Products
Abstract
Circuits for sensing current levels within an apparatus are disclosed. In specific cases, a constant voltage power supply is used to power an LED lighting apparatus in which there are uncertainties within the forward voltages of the LEDs, which in turn creates uncertainty with respect to the current level flowing through the LEDs. To manage these uncertainties, the current flowing through the LEDs is measured by determining a voltage level across a known resistor and calculating the current level. To prevent the known resistor from causing a significant reduction in the efficiency of the overall light engine, the circuit includes one or more transistors in parallel with the known resistor to reduce the effective resistance in the LED circuit during times that the current is not being sensed.
82 Citations
18 Claims
-
1. A circuit comprising:
-
at least one light emitting diode (LED) coupled between a supply voltage and a node; a current sense circuit coupled between the node and a reference ground, the current sense circuit comprising a resistor coupled in parallel with at least one transistor, the at least one transistor being activated during a first state and being deactivated during a second state; wherein the node is coupled to a current determination apparatus operable to determine a current flowing through the at least one LED during the second state using a voltage sensed at the node. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
-
-
11. A circuit comprising:
-
at least one light emitting diode (LED) coupled between a node and a reference ground; a current sense circuit coupled between a supply voltage and the node, the current sense circuit comprising a resistor coupled in parallel with at least one transistor, the at least one transistor being activated during a first state and being deactivated during a second state; wherein a voltage at the node is coupled to a current determination apparatus operable to determine a current flowing through the at least one LED during the second state. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18)
-
Specification