CONFIGURABLE LIGHT SOURCE DRIVER DEVICE

• US 20160295649A1
• Filed: 03/31/2015
• Published: 10/06/2016
• Est. Priority Date: 03/31/2015
• Status: Active Grant

• Current Assignee: Avago Technologies International Sales Pte Limited (Broadcom, Inc.)
• Original Assignee: Avago Technologies General IP PTE Limited (Broadcom, Inc.)
• Inventors: Davidovic, Milos, Swoboda, Robert
• Granted Patent: US 10,667,342 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: H05B 45/3725 Switched mode power supply [SMPS]
• CPC Class Codes: H05B 45/397 Current mirror circuits
• CPC Class Codes: Y02B 20/30 Semiconductor lamps, e.g. solid state lamps [SSL] light emitting diodes [LED] or organic LED [OLED]

Abstract

A configurable light source driver device includes circuitry that detects the presence of a resistor when connected to a terminal of the device and automatically configures the device to operate as a differential driver circuit with low EMI emission and a level of circuit stability that is selected on the basis of parasitic impedance conditions of the differential driver circuit. When the terminal is left unconnected, the configurable light source driver device automatically configures itself to operate as a single ended driver circuit with low power consumption and a different level of circuit stability that is selected on the basis of parasitic impedance conditions of the single ended driver circuit. Furthermore, the configurable light source driver device can include a pulse width adjustment circuit for modifying certain operating characteristics of each of the differential driver circuit and the single ended driver circuit.

Claims

1. An integrated circuit comprising:

a first externally-accessible terminal;

a second externally-accessible terminal;

a resistor presence detector circuit;

a first switch operable to draw a first pulsed current through a light source coupled to the first externally-accessible terminal; and

a second switch operable to draw a second pulsed current through a resistor when the resistor presence detector circuit detects coupling of the resistor to the second externally-accessible terminal and places the integrated circuit in a differential driver circuit mode of operation.

2. The integrated circuit of claim 1, further comprising:

a pulse width adjusting (PWA) circuit configured to receive a first detector output signal from the resistor presence detector circuit when the resistor presence detector circuit detects coupling of the resistor to the second externally-accessible terminal, and in response to receiving the first detector output signal, modify at least one of;

a) a pulse width or a pulse shape of a first switch control signal that is provided to the first switch or b) a pulse width or a pulse shape of a second switch control signal that is provided to the second switch.

3. The integrated circuit of claim 2, wherein the PWA circuit is further configured to receive a second detector output signal from the resistor presence detector circuit when the resistor presence detector circuit detects the second externally-accessible terminal is in an unconnected state, and in response to receiving the second detector output signal, place the integrated circuit in a single ended driver circuit mode of operation.

4. The integrated circuit of claim 3, wherein placing the integrated circuit in the single ended driver circuit mode of operation comprises one of:

a) providing the first switch control signal to the first switch and inhibiting providing of the second switch control signal to the second switch or b) providing the first switch control signal to the first switch and providing the second switch control signal to the second switch.

5. The integrated circuit of claim 3, wherein the first detector output signal is provided by the resistor presence detector circuit as a first logic level and the second detector output signal is provided as an opposite logic level.

6. The integrated circuit of claim 1, further comprising:

a stabilization control circuit operable to select a first stabilization circuit that provides a first level of circuit stability when the resistor presence detector circuit detects coupling of the resistor to the second externally-accessible terminal and places the integrated circuit in the differential driver circuit mode of operation, and to select a second stabilization circuit that provides a second level of circuit stability when the resistor presence detector circuit detects a lack of coupling of the resistor to the second externally-accessible terminal and places the integrated circuit in a single-ended driver circuit mode of operation.

7. The integrated circuit of claim 6, wherein the first stabilization circuit comprises one or more components that are selected on the basis of a first set of parasitic components associated with the differential driver circuit mode of operation and wherein the second stabilization circuit comprises one or more components that are selected on the basis of a second set of parasitic components associated with the single ended driver circuit mode of operation.

8. The integrated circuit of claim 7, wherein the one or more components of the first stabilization circuit comprises a first resistor and a first capacitor, and the one or more other components of the second stabilization circuit comprises a second resistor and a second capacitor that are different than the first resistor and the first capacitor respectively.

9. An integrated circuit comprising:

circuitry configured to place the integrated circuit in one of a low electro-magnetic interference (EMI) mode of operation or a low power mode of operation, the low EMI mode of operation characterized by placing a light source in a pulsed mode of operation when the light source is coupled to a first externally-accessible terminal of the integrated circuit and a resistor is coupled to a second externally-accessible terminal of the integrated circuit, the low power mode of operation characterized by placing the light source in the pulsed mode of operation when the light source is coupled to the first externally-accessible terminal of the integrated circuit and the second externally-accessible terminal of the integrated circuit is left unconnected.

10. The integrated circuit of claim 9, wherein the circuitry comprises:

a current source; and

a first switch operable to place the light source in the pulsed mode of operation, the pulsed mode of operation of the light source characterized by a first pulsed current draw from a power supply; and

a second switch operable to effectuate a second pulsed current draw from the power supply and through the resistor when the integrated circuit is placed in the low EMI mode of operation, the second pulsed current draw having an opposite polarity to the first pulsed current draw.

11. The integrated circuit of claim 10, further comprising:

a control circuit configured to provide a first switch control signal for actuating the first switch to place the light source in the pulsed mode of operation, and a second switch control signal for actuating the second switch to produce the second pulsed current, the second switch control signal having an opposite polarity to the first switch control signal; and

a resistor presence detector circuit configured to detect a presence of the resistor when coupled to the second externally-accessible terminal and to generate a first detector output signal that is provided to the control circuit for placing the integrated circuit in the low EMI mode of operation.

12. The integrated circuit of claim 11, wherein the resistor presence detector circuit is further configured to detect an absence of the resistor and generate a second detector output signal that is provided to the control circuit for placing the integrated circuit in the low power mode of operation, the low power mode of operation characterized by the control circuit disabling the second switch control signal.

13. The integrated circuit of claim 11, wherein the control circuit is configured to receive a pulse input and use the pulse input to generate the first switch control signal and the second control signal.

14. The integrated circuit of claim 11, wherein the control circuit is configured to adjust a pulse width of at least one of the first switch control signal or the second switch control signal based on a detector output signal provided to the PWA circuit by the resistor presence detector circuit.

15. The integrated circuit of claim 11, wherein the control circuit is configured to select a first stabilization circuit that provides a first level of circuit stability when the resistor presence detector circuit detects coupling of the resistor to the second externally-accessible terminal, and to select a second stabilization circuit that provides a second level of circuit stability when the resistor presence detector circuit detects a lack of coupling of the resistor to the second externally-accessible terminal.

16. A method of using an integrated circuit, comprising:

making a determination to operate the integrated circuit in one of a low electro-magnetic interference (EMI) mode of operation or a low power mode of operation;

when determined to operate the integrated circuit in the low EMI mode of operation, coupling a light source to a light source driver terminal of the integrated circuit and coupling a resistor to a resistor sensing terminal of the integrated circuit; and

when determined to operate the integrated circuit in the low power mode of operation, coupling the light source to the light source driver terminal of the integrated circuit and leaving the resistor sensing terminal of the integrated circuit unconnected.

17. The method of claim 16, further comprising:

using a resistor presence detector circuit to detect the coupling of the resistor to the resistor sensing terminal and providing a detector output signal from the resistor presence detector circuit to a control circuit; and

using the control circuit to place the integrated circuit in one of the low EMI mode of operation or the low power mode of operation based on the detector output signal.

18. The method of claim 16, wherein coupling the resistor to the resistor sensing terminal of the integrated circuit comprises selecting a resistance value of the resistor to set a first pulsed current draw through the resistor to be substantially equal to a second pulsed current draw through the light source.

19. The method of claim 16, wherein coupling the resistor to the resistor sensing terminal of the integrated circuit comprises selecting a resistance value of the resistor to obtain a first voltage swing across the resistor that substantially matches a second voltage swing across the light source.

20. The method of claim 16, wherein coupling the resistor to the resistor sensing terminal of the integrated circuit comprises selecting a resistance value of the resistor on the basis of an EMI threshold level.