Circuit arrangement for an LED light source

Patent metadata

Field	Value
Publication number	US-9516711-B2
Application number	US-201013509475-A
Country	US
Kind code	B2
Filing date	Nov 15, 2010
Priority date	Nov 13, 2009
Publication date	Dec 6, 2016
Grant date	Dec 6, 2016

Abstract

A light-emitting diode module is provided that includes a housing and a printed circuit board, which is connected to a light-emitting diode and which has an LED driver, a control module, and a circuit arrangement. The circuit arrangement has a DC/DC converter and a bypass connected in parallel to the DC/DC converter. The bypass is activatable by a comparator circuit. The comparator circuit is arranged between an input of the circuit arrangement and the DC/DC converter and detects the level of an input voltage of the circuit arrangement and compares it with a first and second threshold value. The comparator circuit activates the bypass when the input voltage is below the first threshold value and deactivates the bypass when the second threshold value is exceeded.

First claim

The invention claimed is:

1. A light-emitting diode module, comprising:
a housing;
at least one light-emitting diode; and
at least one printed circuit board including an LED driver, a control module, and a circuit arrangement, the at least one printed circuit board being connected with the at least one light-emitting diode,
wherein the LED driver provides an operating point for operation of the at least one light-emitting diode controlled by the control module,
wherein the circuit arrangement comprises a DC/DC converter,
wherein the DC/DC converter is an integrated down-converter and the circuit arrangement further comprises a bypass circuit connected in parallel to the integrated down-converter, the bypass circuit being controlled by a comparator circuit, and
wherein the comparator circuit enables the bypass circuit when an input voltage applied to the circuit arrangement falls below a first threshold value and disables the bypass circuit when the input voltage exceeds a second threshold value.

2. The light-emitting diode module as claimed in claim 1 , wherein the comparator circuit comprises at least a first transistor, a first resistor, a second resistor, and a zener diode, and wherein the first resistor is connected in parallel with a base-emitter diode of the first transistor and provides a division ratio with the second resistor such that, if the level of the input voltage is above the second threshold value, a base-emitter voltage drop at the first resistor is sufficient to switch the first transistor on, and such that, if the level of the input voltage is below the first threshold value, the first transistor is blocked and enables the bypass circuit.

3. The light-emitting diode module as claimed in claim 2 , wherein the comparator circuit comprises a third resistor connected to the first resistor and the bypass circuit so that, when the bypass circuit is enabled, the third resistor forms a parallel circuit with the first resistor, so that the division ratio changes and the threshold voltage for disabling the bypass circuit increases.

4. The light-emitting diode module as claimed in claim 3 , wherein the comparator circuit comprises circuit having a second transistor, a voltage divider, and a capacitor, wherein the capacitor is adapted, in case of high frequency signals superimposed on the input DC voltage, to de-tune the voltage divider so that a supply voltage for the first transistor is blocked.

5. The light-emitting diode module as claimed in claim 1 , wherein the bypass circuit comprises a field effect transistor with a gate that is controlled by the comparator circuit.

6. The light-emitting diode module as claimed in claim 1 , wherein the control module is a PWM module or a semiconductor switch, the control module being actuatable by a separate switch or a pushbutton or an external switching input.

7. The light-emitting diode module as claimed in claim 1 , wherein the control module is a mechanical switch.

8. The light-emitting diode module as claimed in claim 1 , wherein the circuit arrangement includes an overvoltage protection circuit having a field effect transistor that limits supply voltage in case of an overvoltage.

9. The light-emitting diode module as claimed in claim 1 , wherein the circuit arrangement includes a reverse polarity protection circuit having a field effect transistor, a diode, and a resistor, wherein the field effect transistor is arranged between an input of the circuit arrangement and the comparator circuit.

10. The light-emitting diode module as claimed in claim 9 , wherein the circuit arrangement comprises a first filter circuit arranged between the input and the comparator circuit.

11. The light-emitting diode module as claimed in claim 10 , wherein the circuit arrangement comprises a second filter circuit arranged between the DC/DC converter and the comparator circuit.

12. The light-emitting diode module as claimed in claim 10 , further comprising at least one suppressor diode and/or at least one varistor arranged between the input and the first filter circuit.

13. The light-emitting diode module as claimed in claim 10 , further comprising a plurality of suppressor diodes and/or varistors arranged at the output side and/or input side of the at least one light-emitting diode and of other components of the LED printed circuit board, between the input and the first filter circuit, and/or between the input and the LED driver.

14. The light-emitting diode module as claimed in claim 5 , further comprising a first diode is arranged between an output of the circuit arrangement and the transistor, and a second diode arranged between the output and the converter module.

15. The light-emitting diode module as claimed in claim 1 , wherein the circuit board is a multi-part rigid circuit board, the circuit board parts being connected by flexible sections of conductive traces and being enclosed in the housing in folded relationship.

16. The light-emitting diode module as claimed in claim 1 , wherein the light-emitting diode module is used for aviation purposes.

17. The light-emitting diode module as claimed in claim 1 , wherein the light-emitting diode module is used in reading lights or light source arrangements for coupling light into light-guiding media.

18. The light-emitting diode module as claimed in claim 1 , wherein the light-emitting diode module is used in or for medical-technology equipment.

19. The light-emitting diode module as claimed in claim 1 , wherein the LED driver provides a constant operating point with a voltage range between 4.5 V and 32.5 V.

20. The light-emitting diode module as claimed in claim 1 , wherein the circuit arrangement provides a hysteresis for enabling and/or disabling the bypass circuit.

21. The light-emitting diode module as claimed in claim 20 , wherein the hysteresis is 0.5 V.

22. The light-emitting diode module as claimed in claim 1 , wherein the second threshold value is greater than the first threshold value.

23. A light-emitting diode module, comprising:
a housing;
at least one light-emitting diode; and
at least one printed circuit board including an LED driver, a control module, and a circuit arrangement, the at least one printed circuit board being connected with the at least one light-emitting diode,
wherein the LED driver provides an operating point for operation of the at least one light-emitting diode controlled by the control module,
wherein the circuit arrangement comprises a DC/DC converter,
wherein the DC/DC converter is an integrated down-converter and the circuit arrangement further comprises a bypass connected in parallel to the integrated down-converter, the bypass being activatable by a comparator circuit,
wherein the comparator circuit can detect a level of an input voltage applied to the circuit arrangement, to activate the bypass when the level is below a threshold value, and to deactivate the bypass when the level exceeds the threshold value, and
wherein the comparator circuit comprises at least a first transistor, a first resistor, a second resistor, and a zener diode, and wherein the first resistor is connected in parallel with a base-emitter diode of the first transistor and provides a division ratio with the second resistor such that, if the level of the input voltage is above the threshold value, a base-emitter voltage drop at the first resistor is sufficient to switch the first transistor on, and such that, if the level of the input voltage is below the th

Assignees

• Weil Achim
• Bleisinger Bjoern
• Siebenrock Stefan
• Schmitt Ulrich
• Schott Ag

Inventors

• Weil Achim
• Bleisinger Bjoern
• Siebenrock Stefan
• Schmitt Ulrich

Classifications

• H05B33/0818 Primary

  Electricity · mapped topic

• H05B45/3725 Primary

  Switched mode power supply [SMPS] · CPC title