LED driver circuit
AssigneeInfineon Technologies Austria AG
InventorBernd Pflaum
Life of this patent
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Abstract
A semiconductor chip includes an LED driver circuit operably coupled to at least one LED and configured to supply a load current to the at least one LED such that an average load current matches a desired current level defined by a drive signal. A temperature measurement circuit is thermally coupled to the LED driver circuit or the LED(s) or both, and is configured to generate, as drive signal, a temperature dependent signal in such a manner that the drive signal is approximately at a higher constant level for temperatures below a first temperature, is approximately at a lower constant level for temperatures above a second temperature but below a maximum temperature, and continuously drops from the higher constant level to the lower constant level for temperatures rising from the first temperature to the second temperature.
Claims20
A semiconductor chip including integrated circuitry, the semiconductor chip comprising:
- an LED driver circuit configured to be coupled to an LED to supply a load current to the LED such that an average load current matches a desired current level defined by a drive signal;
- and
- a temperature measurement circuit configured to be thermally coupled to the LED driver circuit or the LED or both to generate, as a drive signal, a temperature dependent signal in such a manner that the drive signal
- is approximately at a higher constant level for temperatures below a first temperature,
- is approximately at a lower constant level for temperatures above a second temperature but below a maximum temperature, and
- continuously drops from the higher constant level to the lower constant level for temperatures rising from the first temperature to the second temperature.
An apparatus comprising:
- an LED;
- semiconductor chip including integrated circuitry, the semiconductor chip comprising:
- an LED driver circuit coupled to an LED to supply a load current to the LED such that an average load current matches a desired current level defined by a drive signal;
- and
- a temperature measurement circuit thermally coupled to the LED driver circuit or the LED or both to generate, as a drive signal, a temperature dependent signal in such a manner that the drive signal
- is approximately at a higher constant level for temperatures below a first temperature,
- is approximately at a lower constant level for temperatures above a second temperature but below a maximum temperature, and
- continuously drops from the higher constant level to the lower constant level for temperatures rising from the first temperature to the second temperature.
Dependencies are inferred from the claim text.