LED, testing method and article
AssigneeNucon GBR
InventorJörg Niggemeyer
Life of this patent
Estimating the term…
Abstract
A Light Emitting Diode (LED) driving circuit includes a reference-voltage terminal, an input terminal to receive a pulse-width modulated (PWM) power signal, and a PWM output terminal. An LED is coupled across the PWM output terminal and the reference-voltage terminal. A measurement capacitor circuit and a voltage-divider network are coupled in parallel with the LED. During an interruption of the PWM power signal, a sense node of the voltage-divider provides a voltage indicative of a temperature of the LED prior to the interruption. The voltage indicative of the temperature is used to control driving of the LED.
Claims20
A Light Emitting Diode (LED) driving circuit, comprising:
- a reference-voltage terminal;
- an input terminal configured to receive a pulse-width modulated (PWM) power signal;
- a PWM output terminal, wherein the PWM output terminal and the reference-voltage terminal are configured, in operation, to provide the PWM power signal to one or more LEDs;
- a measurement capacitor circuit coupled between the PWM output terminal and the reference-voltage terminal;
- a voltage-divider network coupled between the PWM output terminal and the reference-voltage terminal;
- and
- a sensed-voltage output terminal coupled to an intermediate node of the voltage divider network, and configured, in operation, to provide a voltage signal during an interruption of the PWM power signal which is indicative of a junction temperature of the one or more LEDs prior to the interruption of the PWM power signal.
A system, comprising:
- a reference-voltage terminal;
- an input terminal configured to receive a pulse-width modulated (PWM) power signal;
- a PWM output terminal, wherein the PWM output terminal and the reference-voltage terminal are configured, in operation, to provide the PWM power signal to one or more LEDs;
- a measurement capacitor circuit coupled between the PWM output terminal and the reference-voltage terminal;
- a voltage-divider network coupled between the PWM output terminal and the reference-voltage terminal;
- a sensed-voltage output terminal coupled to an intermediate node of the voltage divider network;
- and
- a controller coupled to the sensed-voltage output terminal and configured, in operation, to:
- interrupt the PWM power signal;
- and
- generate control signals to control the PWM power signal based on a voltage sensed on the sensed-voltage output terminal after the interruption of the PWM power signal, wherein the voltage sensed on the sensed-voltage output terminal is indicative of a junction temperature of the one or more LEDs prior to the interruption of the PWM power signal.
A method of controlling Light Emitting Diodes (LEDs), comprising:
- generating one or more pulse-width modulated (PWM) power signals to supply one or more LEDs;
- periodically interrupting the one or more PWM power signals;
- measuring, during a periodic interruption of the one or more PWM power signals, a voltage indicative of a junction temperature of the one or more LEDs just prior to the periodic interruption;
- and
- generating one or more control signals based on the measured voltage indicative of the junction temperature of the one or more LEDs just prior to the periodic interruption.
Dependencies are inferred from the claim text.