Supply voltage management

Patent metadata

Field	Value
Publication number	US-10122252-B2
Application number	US-201514707730-A
Country	US
Kind code	B2
Filing date	May 8, 2015
Priority date	Nov 15, 2012
Publication date	Nov 6, 2018
Grant date	Nov 6, 2018

Abstract

A method for the start-up and/or the maintenance of a supply voltage for a driver circuit for a solid state light source is described. The driver circuit comprises a switched-mode power converter with a switch and a transformer. The switched-mode power converter converts an input voltage into an output voltage. The driver circuit has a controller which generates a gate control signal for putting the power converter switch into an on-state or an off-state. The driver circuit comprises a supply voltage capacitor to provide a voltage to the controller. A primary coil of the transformer is arranged in series with the power converter switch. A secondary coil arrangement of the transformer provides the output voltage. and is coupled to the supply voltage capacitor via a supply voltage transistor which is controlled such that the supply voltage provided by the supply voltage capacitor lies within a pre-determined voltage interval.

First claim

What is claimed is:

1. A driver circuit for a solid state light source, wherein the driver circuit comprises
a switched-mode power converter comprising a power converter switch and a transformer; wherein the switched-mode power converter is configured to convert an input voltage at an input of the switched-mode power converter into an output voltage at an output of the switched-mode power converter;
a controller configured to generate a gate control signal for putting the power converter switch into an on-state and/or an off-state;
a supply voltage capacitor coupled to the controller and configured to provide a supply voltage to the controller; wherein
a primary coil of the transformer is arranged in series with the power converter switch;
a secondary coil arrangement of the transformer is configured to provide the output voltage;
the secondary coil arrangement is coupled to the supply voltage capacitor via a supply voltage transistor;
the controller is configured to control the supply voltage transistor in a switched mode to be open or closed such that the supply voltage provided by the supply voltage capacitor lies within a pre-determined voltage interval for operation of the controller;
the controller is further configured to control the supply voltage transistor in the switched mode to separate time intervals for measuring an auxiliary signal indicative of a current through the power converter switch, from time intervals for recharging the supply voltage capacitor; and
the controller is further configured to determining the auxiliary signal at a first time interval, when the supply voltage transistor is open.

2. The driver circuit of claim 1 , wherein the secondary coil arrangement comprises
a secondary coil of the transformer configured to provide the output voltage; and
an auxiliary coil of the transformer coupled to the supply voltage capacitor via the supply voltage transistor .

3. The driver circuit of claim 2 , wherein the secondary coil is arranged in series with a secondary switch, e.g. a secondary diode, such that the secondary coil is operated in a flyback mode with respect to the primary coil.

4. The driver circuit of claim 2 , wherein the auxiliary coil is arranged in series with an auxiliary switch, e.g. an auxiliary diode, such that the auxiliary coil is operated in a forward mode with respect to the primary coil.

5. The driver circuit of claim 2 , wherein the auxiliary coil is arranged in series with an auxiliary switch, e.g. an auxiliary diode, such that the auxiliary coil is operated in a flyback mode with respect to the primary coil.

6. The driver circuit of claim 2 , wherein
the controller is configured to generate the gate control signal for putting the power converter switch into the on-state and the off-state in an alternating manner;
the driver circuit comprises current sensing means configured to sense a current through the auxiliary coil, thereby yielding the auxiliary signal; and
the controller is configured to determine a duration of the on-state of the power converter switch based on the auxiliary signal.

7. The driver circuit of claim 6 , wherein the controller is configured to
determine a first duration of the on-state of the power converter switch based on the auxiliary signal at the first time interval;
maintain the power converter switch in on-state for the first duration at a succeeding second time interval, when the supply voltage transistor is closed.

8. The driver circuit of claim 1 , wherein the supply voltage transistor is an internal power transistor of the controller.

9. The driver circuit of claim 1 , wherein the controller is configured to
control the power converter switch to be in alternating on-periods, where the power converter switch is in on-state, and off-periods, where the power converter switch is in off-state; and
control the supply voltage transistor to be in off-state at least for every second on-period of the power converter switch.

10. The driver circuit of claim 1 , further comprising
a start-up resistor configured to couple the input of the switched-mode power converter to the supply voltage capacitor; and
a start-up switch and a measurement resistor arranged in parallel to the supply voltage capacitor such than when the start-up switch is closed, the start-up resistor and the measurement resistor form a voltage divider.

11. The driver circuit of claim 2 , wherein the controller
is configured to receive the auxiliary signal indicative of a voltage drop at the auxiliary coil; and/or
comprises a rectification unit configured to rectify the auxiliary signal; and/or
comprises a voltage divider arranged in parallel to the supply voltage transistor and the supply voltage capacitor, and configured to sense the auxiliary signal, when the supply voltage transistor is open.

12. The driver circuit of claim 11 , wherein the rectification unit comprises a plurality of rectification switches configured to switch an operational mode of the auxiliary coil with respect to the primary coil between a flyback mode and a forward mode.

13. The driver circuit of claim 2 , further comprising a discharging transistor arranged in parallel with the auxiliary coil and configured to discharge a parasitic capacitance at an input of the controller.

14. A light bulb assembly comprising:
a housing;
a solid state light source, located within the housing;
an electrical connection module, attached to the housing, and adapted for connection to a mains supply; and
a driver circuit located within the housing, connected to receive an electricity supply signal from the electrical connection module, and operable to supply an output voltage to the light source, wherein the driver circuit comprises
a switched-mode power converter comprising a power converter switch and a transformer; wherein the switched-mode power converter is configured to convert an input voltage at an input of the switched-mode power converter into an output voltage at an output of the switched-mode power converter;
a controller configured to generate a gate control signal for putting the power converter switch into an on-state and/or an off-state;
a supply voltage capacitor coupled to the controller and configured to provide a supply voltage to the controller; wherein
a primary coil of the transformer is arranged in series with the power converter switch;
a secondary coil arrangement of the transformer is configured to provide the output voltage;
the secondary coil arrangement is coupled to the supply voltage capacitor via a supply voltage transistor;
the controller is configured to control the supply voltage transistor in a switched mode to be open or closed such that the supply voltage provided by the supply voltage capacitor lies within a pre-determined voltage interval for operation of the controller;
the controller is further configured to control the supply voltage transistor in the switched mode to separate time intervals for measuring an auxiliary signal indicative of a current through the power converter switch, from time intervals for recharging the supply voltage capacitor; and

the controller is further configured to determining the auxiliary signal at a first time interval, when the supply voltage transistor is open.

15. A method for providing a supply voltage, the method comprising the steps of:
providing a switched-mode power converter comprising a power converter switch and a transformer; wherein the switched-mode power converter converts an input voltage at an input of the switched-mode power converter into an output voltage at an output of the switched-mode po

Assignees

• Dialog Semiconductor Gmbh

Inventors

• Knoedgen Horst

Classifications

• H02M3/33507

  with automatic control of the output voltage or current, e.g. flyback converters (H02M3/33561, H02M3/33569 take precedence) · CPC title

• F02P3/0884

  Closing the discharge circuit of the storage capacitor with semiconductor devices · CPC title

• H05B41/24

  in which the lamp is fed by high frequency AC {, or with separate oscillator frequency} (H05B41/26 takes precedence) · CPC title

• H05B45/10

  Controlling the intensity of the light · CPC title

• H05B33/0845

  Electricity · mapped topic