Turn-on procedure for a load control device
A load control device may be configured to turn on lighting loads to obtain a fast turn-on time that may be substantially consistent across lighting loads that have different load voltages. The load control device may comprise a power converter circuit configured to produce a voltage across a capacitor, and a control circuit configured to control the power converter circuit to generate the voltage across the capacitor. The control circuit may determine a learned voltage from the magnitude of the voltage across the capacitor. For example, the control circuit may measure the magnitude of the voltage and store the measured voltage as the learned voltage. The control circuit may determine an operating parameter for the power converter circuit as a function of the learned voltage, and control the power converter circuit according to the operating parameter to charge the capacitor until the magnitude of the voltage exceeds a threshold.
1 . A light-emitting diode (LED) lighting controller, comprising:
power converter circuitry;
LED driver circuitry; and
LED driver control circuitry coupled to the power converter circuitry and the LED driver circuitry, the LED driver control circuitry to:
determine threshold voltage for one or more LED emitters having a defined load voltage coupled to LED drive circuitry;
cause the power converter circuitry to charge a bus capacitor conductively coupled across an output of the power converter circuitry to the threshold voltage over a pre-load charge time using open loop control;
cause power supply circuitry to charge the bus capacitor to the defined load voltage over a delay time using closed-loop control; and
cause LED driver circuitry to illuminate the one or more LED emitters at the defined load voltage after the expiration of the delay time.
2 . The LED lighting controller of claim 1 , further comprising:
memory circuitry coupled to the LED driver control circuitry;
wherein to determine the threshold voltage for the one or more LED emitters, the control circuitry to further:
retrieve a learned voltage associated with the one or more LED emitters from the memory circuitry; and
determine the threshold voltage based on the retrieved learned voltage.
3 . The LED lighting controller of claim 2 , wherein the LED driver control circuitry to further:
cause the LED drive circuitry to operate the one or more LED emitters at a high-end intensity;
receive, from the LED drive circuitry an input that includes data indicative of a high-end voltage measured across the one or more LED emitters at the high-end intensity; and
store, as the learned voltage, the high-end voltage received from the LED drive circuitry.
4 . The LED lighting controller of claim 3 wherein to determine the threshold voltage based on the retrieved learned voltage, the LED driver control circuitry to further:
multiply the high-end voltage by a defined scale factor.
5 . The LED lighting controller of claim 3 wherein the LED driver control circuitry to further:
determine the pre-load on-time based on the learned voltage using a linear relationship between the pre-load on-time and the learned voltage.
6 . A light-emitting diode (LED) lighting control method, comprising:
determining, by LED driver control circuitry, a threshold voltage for one or more LED emitters having a defined load voltage coupled to LED drive circuitry;
controlling, by the LED driver control circuitry using open-loop control, operatively coupled power converter circuitry to charge a bus capacitor to the determined threshold voltage over a pre-load charge time;
controlling, by the LED driver control circuitry using closed-loop control, the power supply circuitry to charge the bus capacitor to the defined load voltage over a delay time; and
causing, by the LED driver control circuitry, the LED drive circuitry to illuminate the one or more LED emitters at the defined load voltage after the expiration of the delay time.
7 . The LED lighting control method of claim 6 wherein determining the threshold voltage for the one or more LED emitters, further comprises:
retrieving, by the LED driver control circuitry, a learned voltage associated with the one or more LED emitters from operatively coupled memory circuitry; and
determining, by the LED driver control circuitry, the threshold voltage based on the retrieved learned voltage.
8 . The LED lighting control method of claim 7 , further comprising:
causing, by the LED driver control circuitry, the LED drive circuitry to operate the one or more LED emitters at a high-end intensity;
receiving, by the LED driver control circuitry, an input from the LED drive circuitry, the input including data indicative of a high-end voltage measured across the one or more LED emitters at the high-end intensity; and
causing, by the LED driver control circuitry, a storage, as the learned voltage, the received data indicative of the high-end voltage received from the LED drive circuitry.
9 . The LED lighting control method of claim 8 wherein determining the threshold voltage based on the retrieved learned voltage, the control circuitry to further:
multiplying, by the LED driver control circuitry, the high-end voltage by a defined scale factor.
10 . The LED lighting control method of claim 8 , further comprising:
determining, by the LED driver control circuitry, the pre-load on-time based on the learned voltage using a linear relationship between the pre-load on-time and the learned voltage.
11 . A non-transitory, machine-readable, storage device that includes instructions that, when executed by light-emitting diode (LED) driver control circuitry, cause the LED driver control circuitry to:
determine a threshold voltage for one or more LED emitters;
wherein the one or more LED emitters are driven using LED driver circuitry operatively coupled to the LED driver control circuitry; and
wherein the one or more LED emitters have associated therewith a defined operating load voltage;
cause operatively coupled power converter circuitry operatively coupled to the LED driver control circuitry to charge a bus capacitor to the determined threshold voltage over a pre-load charge time using open-loop control;
wherein the bus capacitor is conductively coupled across an output of the power converter circuitry;
cause power supply circuitry to charge the bus capacitor to the defined operating load voltage of the one or more LED emitters over a delay time using closed-loop control; and
cause the LED drive circuitry to illuminate the one or more LED emitters at the defined operating load voltage after the expiration of the delay time.
12 . The non-transitory, machine-readable, storage device of claim 11 wherein the instructions that cause the LED driver control circuitry to determine the threshold voltage for the one or more LED emitters, further cause the LED driver control circuitry to:
retrieve a learned voltage associated with the one or more LED emitters from operatively coupled memory circuitry; and
determine the threshold voltage using the retrieved learned voltage.
13 . The non-transitory, machine-readable, storage device of claim 12 wherein the instructions, when executed by the LED driver control circuitry, further cause the LED driver control circuitry to:
cause the LED driver circuitry to illuminate the one or more LED emitters at a high-end intensity;
receive an input from the LED driver circuitry, the input including data indicative of a high-end voltage measured across the one or more LED emitters when illuminated at the high-end intensity; and
cause a storage of the received data indicative of the high-end voltage received from the LED driver circuitry as the learned voltage.
14 . The non-transitory, machine-readable, storage device of claim 13 wherein the instructions that cause the LED driver control circuitry to determine the threshold voltage based on the retrieved learned voltage, further cause the LED driver control circuitry to:
multiply the high-end voltage by a defined scale factor to determine the threshold voltage.
15 . The non-transitory, machine-readable, storage device of claim 13 , wherein the instructions, when executed by the LED driver control circuitry, further cause the LED driver control circuitry to:
determine the pre-load on-time based on the learned voltage using a linear relationship between the pre-load on-time and the learned voltage.