DRIVER CIRCUIT WITH EXTENDED OPERATION RANGE

• US 20170055322A1
• Filed: 02/13/2015
• Published: 02/23/2017
• Est. Priority Date: 02/24/2014
• Status: Active Grant

• Current Assignee: Signify Holding B.V. (Signify N.V.)
• Original Assignee: Philips Lighting Holding BV (Signify N.V.)
• Inventors: JIANG, Junmin, XU, Shu, FU, Jie, RADERMACHER, Harald Josef Gunther, DELOS AYLLON, Julia
• Granted Patent: US 10,034,334 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: H02M 3/07 using capacitors charged and discharged alternately by semiconductor devices with control electrode , e.g. charge pumps
• CPC Class Codes: H02M 3/158 including plural semiconductor devices as final control devices for a single load
• CPC Class Codes: H05B 45/3725 Switched mode power supply [SMPS]
• CPC Class Codes: H05B 45/375 using buck topology
• CPC Class Codes: H05B 45/38 using boost topology
• CPC Class Codes: Y02B 20/30 Semiconductor lamps, e.g. solid state lamps [SSL] light emitting diodes [LED] or organic LED [OLED]

Abstract

A system comprising a driver circuit wherein the driver circuit comprises a converter. The system further comprises a controller operable to control a ratio between an input voltage supplied to the driver circuit and a target output voltage to be output from the driver circuit by varying a pulse width modulated signal, and by switching between operating modes of said converter. The controller is configured to determine that the driver circuit is operating in an undesired state caused by a combination of the duty cycle and the operating mode of the converter. The system further comprises a resistance adjustment circuit configured to adjust an equivalent output resistance of the driver circuit in response to the controller determining that the driver circuit is operating in an undesired state.

Claims

1. A system comprising:

a driver circuit comprising switched capacitor a voltage converter having multiple operating modes;

a controller operable to control a ratio between an input voltage supplied to the driver circuit and a target output voltage to be output from the driver circuit by varying a duty cycle of a pulse width modulated signal, and by switching between operating modes of said voltage converter;

wherein the controller is configured to determine that the driver circuit is operating in an undesired state caused by a combination of the duty cycle and the operating mode of the converter said undesired state corresponding to an efficiency below a threshold efficiency level; and

a resistance adjustment circuit configured to adjust an equivalent output resistance of the driver circuit in response to said determination.

2. The system according to claim 1, wherein the driver circuit is operable to provide an output voltage at a varying efficiency dependent on said ratio, wherein the undesired state corresponds to a region of a relationship between the efficiency and said ratio.

3. The system according to claim 1, wherein the resistance adjustment circuit is configured to adjust the equivalent output resistance of the driver circuit by controlling a gate drive voltage output to switches of the voltage converter.

4. The system according to claim 1, wherein the resistance adjustment circuit is configured to adjust the equivalent output resistance of the driver circuit by controlling a switching frequency of switches of the voltage converter.

5. The system according to claim 1, wherein the resistance adjustment circuit is configured to adjust the equivalent output resistance of the driver circuit by controlling a dead time associated with switches of the voltage converter.

6. The system according to claim 1, wherein the resistance adjustment circuit is configured to adjust the equivalent output resistance of the driver circuit based on receiving an error signal, said error signal generated based on comparing a reference voltage and a sense voltage.

7. The system according to claim 1, wherein the controller is configured to determine that the driver circuit is operating in an undesired state based on said ratio.

8. The system according to claim 1, wherein the controller is configured to determine that the driver circuit is operating in an undesired state based on the duty cycle of the pulse width modulated signal.

9. The system according to claim 1, wherein the controller is configured to determine that the driver circuit is operating in an undesired state based on the input voltage supplied to the driver circuit.

10. The system according to claim 1, wherein the controller is configured to determine that the driver circuit is operating in an undesired state based on determining the efficiency of the driver circuit.

11. The system according to claim 1, wherein the controller is configured to constrain the duty cycle of the pulse width modulated signal to be limited within a limited duty cycle range.

12. The system according to claim 1, wherein the controller is configured to constrain the duty cycle of a pulse width modulated signal to be at a constant value within said limited duty cycle range in response to determining that the driver circuit is operating in an undesired state.

13. The system according to claim 1, wherein said voltage converter is formed by a switched capacitor converter based on a Dickson ladder topology comprising a first set of switches and a second set of switches.

14. A light module comprising at least one light source and the system according to claim 1, wherein the driver circuit provides an output voltage that drives said at least one light source.

15. A computer program product for controlling a driver circuit comprising a voltage converter, and a resistance adjustment circuit, the computer program product comprising code embodied on a computer-readable medium and being configured so as when executed on a processor to:

control a ratio between an input voltage supplied to the driver circuit and a target output voltage to be output from the driver circuit by varying a duty cycle of a pulse width modulated signal, and by switching between operating modes of said voltage converter;

determine that the driver circuit is operating in an undesired state caused by a combination of the duty cycle and the operating mode of the converter; and

supply the pulse width modulated signal to the resistance adjustment circuit to adjust an equivalent output resistance of the driver circuit in response to said determination.