Driver circuit for LED vehicle lamp
First Claim
1. A LED Driver comprising:
- means for driving a first LED string in response to a STOP signal;
means for driving a second LED string in response to said STOP signal;
means for detecting a predetermined drop in an input voltage (VIN) to said driver and generating a bypass signal;
means connected across at least one LED in said first LED string, for bypassing said at least one LED in response to said bypass signal from said detecting means;
means connected across at least one LED in said second LED string for bypassing said at least one LED in response to said bypass signal from said detecting means.
2 Assignments
0 Petitions
Accused Products
Abstract
A first vehicle lamp driver circuit for a light emitting diode (LED) array, the LED array having a first string of four LEDs in series and a second string of four LEDs in series. A first LED driver drives the first LED string and a second LED driver drives the second LED string. In a STOP mode of operation, the current to both LED strings is controlled by the LED driver in series with the LED string. In a TAIL mode of operation, the current is provided to only one LED string via a series connected diode and resistor. When there is reduced input voltage, operation of the LED strings is provided by switching circuits that short-out one LED in each LED string. A second vehicle lamp driver circuit comprises a first LED string and a second LED string in series with a control switch having a feedback circuit for maintaining constant current regulation to control the sum of the current in each LED string and reduce switching noise.
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Citations
13 Claims
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1. A LED Driver comprising:
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means for driving a first LED string in response to a STOP signal; means for driving a second LED string in response to said STOP signal; means for detecting a predetermined drop in an input voltage (VIN) to said driver and generating a bypass signal; means connected across at least one LED in said first LED string, for bypassing said at least one LED in response to said bypass signal from said detecting means; means connected across at least one LED in said second LED string for bypassing said at least one LED in response to said bypass signal from said detecting means. - View Dependent Claims (2, 3, 4, 5)
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6. A LED driver comprising:
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a first LED string having an anode of a first LED connected to an input voltage (VIN) and a cathode of a last LED connected to a first current sensing resistor; a second LED string having an anode of a first LED connected to said input voltage and a cathode of a last LED connected to a second current sensing resistor; a control switch connected to said first current sensing resistor and said second current sensing resistor for providing regulation of current passing through said first LED string and said second LED string in response to a STOP signal and a TAIL signal provided to said LED driver; a feedback circuit connected to said control switch for controlling said control switch and the current passing through said first LED string and said second LED string in accordance with the state of said STOP signal and said TAIL signal. - View Dependent Claims (7, 8, 9, 10, 11, 12, 13)
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Specification