WO2005104623A1 - Dispositif d'alimentation en courant pour del - Google Patents

Dispositif d'alimentation en courant pour del Download PDF

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Publication number
WO2005104623A1
WO2005104623A1 PCT/DE2005/000771 DE2005000771W WO2005104623A1 WO 2005104623 A1 WO2005104623 A1 WO 2005104623A1 DE 2005000771 W DE2005000771 W DE 2005000771W WO 2005104623 A1 WO2005104623 A1 WO 2005104623A1
Authority
WO
WIPO (PCT)
Prior art keywords
current sink
transistor
led
resistor
power supply
Prior art date
Application number
PCT/DE2005/000771
Other languages
German (de)
English (en)
Inventor
Hans-Jürgen Neuhaus
Original Assignee
Siemens Aktiengesellschaft
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Siemens Aktiengesellschaft filed Critical Siemens Aktiengesellschaft
Publication of WO2005104623A1 publication Critical patent/WO2005104623A1/fr

Links

Classifications

    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B45/00—Circuit arrangements for operating light-emitting diodes [LED]
    • H05B45/10—Controlling the intensity of the light
    • H05B45/18—Controlling the intensity of the light using temperature feedback

Definitions

  • the invention relates to an LED power supply device, in particular for white light LEDs, according to the preamble of claim 1.
  • the lighting technology is traditionally dominated by filament lamps (including low-voltage or, more recently, high-voltage halogen lamps for years) and the various types of cold-light lamps.
  • the latter have a significantly improved efficiency and thus contribute to the tendency to reduce the energy requirement for lighting purposes.
  • light sources based on semiconductors had their main application in display technology until a few years ago. This is also due to the fact that they were initially only available as single-color light sources and that largely "white” light is to be preferred for lighting purposes. With the development of white light LEDs and the rapidly advancing development of manufacturing technology and the associated cost reduction, these have recently become established for lighting purposes.
  • White LEDs require an operating voltage of approx. 3.4 V.
  • the maximum continuous current at the current state of development is approx. 30 mA.
  • DC / DC converters are generally used for the supply.
  • Integrated control modules are also available on the market, especially for LEDs.
  • these solutions are complex and expensive and, at least according to the current state of the art, are not suitable for the inexpensive power supply of lamps.
  • Voltage sources for frequent LED applications that provide voltages with a value greater than 3.4 V are for example:
  • NiMh (NiCd) battery cells connected in series with 3.6 V in DECT devices.
  • the current sink according to FIG. 1 with LED as reference has the advantage of temperature stability, since the temperature coefficients of LED and transistor are the same (-2 mV / K) and cancel each other out. However, this current sink has a large voltage drop (approx. IV).
  • the two other circuit arrangements according to FIGS. 2 and 3 have a lower, but still relatively high voltage drop at approximately 0.7 V. Furthermore, these circuit arrangements have no temperature compensation, so that the voltage across the emitter resistor R E changes by -2 mV / K. This leads to corresponding temperature-dependent changes in current.
  • the invention is therefore based on the object of providing a simple, inexpensive power supply which is as temperature-stable as possible, in particular for the supply of white LEDs.
  • This object is achieved by a power supply device with the features of claim 1.
  • Appropriate developments of the inventive concept are the subject of the dependent claims.
  • An essential idea of the invention consists in a special combination of the elements of a current sink constructed with discrete components.
  • the invention includes the idea of providing a voltage regulator in an LED power supply device with a discrete structure, which is between ground and one Node is connected between the current sink transistor and its base resistor.
  • a simple ohmic resistor is provided instead of this voltage regulator.
  • the voltage regulator has a voltage regulator transistor.
  • the base of the voltage regulator transistor is assigned a voltage divider which lies between ground and a node between the current sink transistor and the base resistor assigned to it.
  • both a variant with only one current sink transistor — in this associated parallel connection of the LEDs — and a variant with a number of current sink transistors corresponding to the number of LEDs are possible.
  • a single voltage regulator or ohmic resistor which replaces it is used to connect the node between the current sink transistor and its base resistor to ground.
  • the power supply according to the invention with a discretely designed low-drop current sink, in particular for controlling white LEDs has the following advantages in particular: high automatic adaptability of the LED control circuit to different types of rechargeable batteries and batteries;
  • the invention proposes in particular to use a parallel voltage regulator as a reference - preferably implemented by a transistor with two resistors. This provides a simple reference voltage source that can be set with 2 resistors. As a result, the voltage drop across the emitter resistance of the transistor can be limited
  • the voltage drop can be at least halved compared to the standard solutions described above.
  • FIG. 5 shows a circuit for using the power supply device according to FIG. 4 for supplying a plurality of white light LEDs
  • FIG. 6 shows a circuit arrangement for the power supply of a plurality of white light LEDs according to a further embodiment of the invention.
  • FIG. 7 shows a power supply device according to a further embodiment of the invention which is simplified compared to the circuit arrangement according to FIG. 6.
  • Fig. 4 shows a discretely constructed, for the supply of
  • White light LED suitable current sink in which a current sink transistor Ti with a base resistor R B and a grounded emitter resistor R E , for which a parallel voltage regulator is connected in parallel between the base and the ground.
  • This comprises a parallel voltage regulator transistor T 2 , the emitter of which is connected to ground, the base of which is connected to a node in the connecting line between the base of the current sink transistor Ti and the base resistor R B associated therewith, and the base of which is connected to a node ver - Is bound between a first regulator resistor Ri, which is also connected to the connecting line between the base of the current sink transistor Ti and its associated base resistor R B , and a second regulator resistor R 2 connected in series with this to ground.
  • the temperature drift of the current sink transistor Ti is -2 mV / K.
  • the temperature drift of the parallel voltage regulator is -2 mV / K, multiplied by the amplification factor (Rl + R2) / R2 of the base-emitter voltage of the parallel voltage regulator transistor T 2 . Since the gain factor in the application described is slightly greater than one, the temperature influences largely cancel each other out.
  • the series resistor Rv must be connected in series with each LED in order to compensate for the scattering of the diodes. An approximately uniform current distribution and thus approximately the same brightness of the LEDs is achieved.
  • the current sink should be dimensioned so that a voltage of approx. 200 mV drops across the emitter resistor R E.
  • the total current of the current sink must be dimensioned so that the maximum continuous direct current of the LEDs is not exceeded.
  • the function of the current sink is fully effective when the operating voltage is high (battery full). If the voltage drops below approx. 3.7 V, the current sink transistor Ti saturates. In this operating case, Ti works as a (switching on) transistor.
  • the current is now limited by the diode resistors R v and the emitter resistor R E. So they stay LEDs switched on even at voltages below 3.4 V; only the brightness now decreases proportionally with the voltage reduction.
  • circuit arrangement shown in FIG. 6 avoids this effect - with somewhat higher circuit complexity.
  • a parallel voltage regulator according to FIG. 4 forms the basis for all current sinks. This can be
  • the resistor R B is connected directly to the anodes of the light emitting diodes and a simple ON / OFF switch is connected in series with the voltage source U BATT or R B.

Landscapes

  • Led Devices (AREA)
  • Circuit Arrangement For Electric Light Sources In General (AREA)

Abstract

L'invention concerne un dispositif d'alimentation en courant pour diode électroluminescente qui sert à alimenter en courant au moins une DEL à lumière blanche (DEL) et qui comprend une source de tension faible (UBATT) et un puits de courant formé par des composants discrets. Ce puits de courant comprend un transistor à absorption de courant (T1) ayant une résistance de base (RB) reliant le transistor à absorption de courant à une ligne de commutation (EF/HF), ainsi qu'une résistance d'émetteur (RE) montée entre le transistor à absorption de courant et la masse (RE). Le dispositif selon l'invention est caractérisé en ce qu'un régulateur de tension (T2, R1, R2) est monté entre la masse et un noeud situé entre le transistor à absorption de courant et la résistance de base de ce dernier.
PCT/DE2005/000771 2004-04-23 2005-04-22 Dispositif d'alimentation en courant pour del WO2005104623A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE102004020658A DE102004020658A1 (de) 2004-04-23 2004-04-23 LED-Stromversorgungseinrichtung
DE102004020658.9 2004-04-23

Publications (1)

Publication Number Publication Date
WO2005104623A1 true WO2005104623A1 (fr) 2005-11-03

Family

ID=34968183

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/DE2005/000771 WO2005104623A1 (fr) 2004-04-23 2005-04-22 Dispositif d'alimentation en courant pour del

Country Status (2)

Country Link
DE (1) DE102004020658A1 (fr)
WO (1) WO2005104623A1 (fr)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102010028795A1 (de) * 2010-05-10 2011-11-10 Osram Gesellschaft mit beschränkter Haftung Schaltung zum Betrieb einer Leuchteinheit sowie Leuchte mit einer solchen Schaltung

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS63136676A (ja) * 1986-11-28 1988-06-08 Canon Inc 発光ダイオ−ド駆動回路
WO1999039319A2 (fr) * 1998-01-29 1999-08-05 Ledi-Lite Ltd. Enseigne lumineuse
US20020014576A1 (en) * 1997-01-10 2002-02-07 Fujitsu Limited Light emitting element protecting device and method thereof
US6600274B1 (en) * 2001-12-14 2003-07-29 Dme Corporation LED current regulation circuit for aircraft lighting system

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3784844A (en) * 1972-12-27 1974-01-08 Rca Corp Constant current circuit
US6107985A (en) * 1997-10-30 2000-08-22 Ericsson Inc. Backlighting circuits including brownout detection circuits responsive to a current through at least one light emitting diode and related methods
DE29911372U1 (de) * 1999-07-01 1999-11-25 Wofi Leuchten Wortmann & Filz Gmbh, 59872 Meschede Stromversorgungseinrichtung zum Betrieb von Leuchtdioden
JP4240691B2 (ja) * 1999-11-01 2009-03-18 株式会社デンソー 定電流回路

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS63136676A (ja) * 1986-11-28 1988-06-08 Canon Inc 発光ダイオ−ド駆動回路
US20020014576A1 (en) * 1997-01-10 2002-02-07 Fujitsu Limited Light emitting element protecting device and method thereof
WO1999039319A2 (fr) * 1998-01-29 1999-08-05 Ledi-Lite Ltd. Enseigne lumineuse
US6600274B1 (en) * 2001-12-14 2003-07-29 Dme Corporation LED current regulation circuit for aircraft lighting system

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
PATENT ABSTRACTS OF JAPAN vol. 012, no. 395 (E - 671) 20 October 1988 (1988-10-20) *

Also Published As

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DE102004020658A1 (de) 2005-11-10

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