TRANSIENT SUPPRESSION FOR BOOST REGULATOR
First Claim
1. An LED driver controller, comprising:
- a voltage regulator for controlling an output voltage to a top of a plurality of LED strings responsive to at least a reference voltage;
a plurality of first circuitries each associated with a node at a bottom of each of the plurality of LED strings for comparing a voltage at the bottom of each of the plurality of LED strings with a high reference voltage and a low reference voltage;
control logic for generating a first control signal when the voltage of at least one of node of the plurality of LED strings falls below the low reference voltage and for generating a second control signal when the voltage at the bottom of each node of the plurality of LED strings exceeds the high reference voltage;
second circuitry responsive to the first control signal and the second control signal for generating the reference voltage; and
wherein the second circuitry controls the reference voltage to cause the voltage at the bottom of a lowest voltage node of the plurality of LED strings to remain between the high reference voltage and the low reference voltage.
3 Assignments
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Accused Products
Abstract
A circuit for generating an output voltage to a top node of a plurality of LED strings. The circuit includes an inductor having a load current flowing therethrough and a switching transistor responsive to a switching control signal. An integrator generates a compensation voltage responsive to a voltage at a bottom node of the LED string and a reference voltage. Circuitry for combining an offset with the compensation voltage is responsive to the compensation voltage and the load current through the inductor. The offset is generated only during a step load change of the load current and substantially reduces voltage transients from the compensation voltage and the output voltage. A summation circuit sums the compensation voltage including the offset with at least the voltage at the bottom node of the LED string to generate a first control signal. A latch generates the switching control signal responsive to the first control signal and a leading edge blanking signal.
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Citations
20 Claims
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1. An LED driver controller, comprising:
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a voltage regulator for controlling an output voltage to a top of a plurality of LED strings responsive to at least a reference voltage; a plurality of first circuitries each associated with a node at a bottom of each of the plurality of LED strings for comparing a voltage at the bottom of each of the plurality of LED strings with a high reference voltage and a low reference voltage; control logic for generating a first control signal when the voltage of at least one of node of the plurality of LED strings falls below the low reference voltage and for generating a second control signal when the voltage at the bottom of each node of the plurality of LED strings exceeds the high reference voltage; second circuitry responsive to the first control signal and the second control signal for generating the reference voltage; and wherein the second circuitry controls the reference voltage to cause the voltage at the bottom of a lowest voltage node of the plurality of LED strings to remain between the high reference voltage and the low reference voltage. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. An LED driver controller, comprising:
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a voltage regulator for controlling an output voltage to a top of a plurality of LED strings responsive to at least a reference voltage; a plurality of first circuitries each associated with a node at a bottom of each of the plurality of LED strings, the plurality of first circuitries each comprising; a first comparator for comparing the voltage at the node at the bottom of the LED string with the high reference voltage; a second comparator for comparing the voltage at the node at the bottom of the LED string with the low reference voltage; an AND function for generating a first control signal responsive to the voltage at the bottom of all nodes of the plurality of LED strings exceeding a high reference voltage; and an OR function for generating a second control signal responsive to the voltage at the bottom of at least one LED string falling below a low reference voltage; counter/stepping logic responsive to the first control signal and the second control signal for generating a digital control signal associated with a desired reference voltage; a digital to analog converter for generating the reference voltage in analog format responsive to the digital control signal; and wherein the second circuitry controls the reference voltage to cause the voltage at the bottom of a lowest voltage node of the plurality of LED strings to remain between the high reference voltage and the low reference voltage. - View Dependent Claims (10, 11, 12, 13)
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14. A method for controlling an output voltage to a top of a plurality of LED strings, comprising the steps of:
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generating an output voltage to the top of the plurality of LED strings responsive to at least a reference voltage; comparing a voltage at the bottom of each of the plurality of LED strings with a high reference voltage and a low reference voltage; generating a first control signal when the voltage at the bottom of each node of the plurality of LED strings exceeds the high reference voltage; generating a second control signal when the voltage of at least one of node of the plurality of LED strings falls below the low reference voltage; generating the reference voltage responsive to the first control signal and the second control signal, wherein the reference voltage is controlled to cause the voltage at the bottom of a lowest voltage node of the plurality of LED strings to remain between the high reference voltage and the low reference voltage. - View Dependent Claims (15, 16, 17, 18, 19, 20)
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Specification