Light emitting diode multiphase driver circuit and method

• US 20060208669A1
• Filed: 05/22/2006
• Published: 09/21/2006
• Est. Priority Date: 02/04/2005
• Status: Active Grant

• Current Assignee: Sinotechnix LLC
• Original Assignee: Kimlong Huynh, Vinhrhu Quoc Tran
• Inventors: Tran, Vinhrhu Quoc, Huynh, Kimlong
• Granted Patent: US 7,439,944 B2
• Time in Patent Office: Days
• US Class Current: 315/312
• CPC Class Codes: H05B 45/48 having LEDs organised in strings and incorporating parallel shunting devices
• CPC Class Codes: H05B 45/50 responsive to malfunctions or undesirable behaviour of LEDs; responsive to LED life; Protective circuits
• CPC Class Codes: H05B 45/56 involving measures to prevent abnormal temperature of the LEDs
• CPC Class Codes: Y02B 20/30 Semiconductor lamps, e.g. solid state lamps [SSL] light emitting diodes [LED] or organic LED [OLED]
• CPC Class Codes: Y10S 362/80 Light emitting diode
• CPC Class Codes: Y10S 362/801 Bedroom lighting, e.g. modular combinations
• CPC Class Codes: Y10S 362/806 Ornamental or decorative

Abstract

A method and a circuit for driving light emitting diodes (LEDs) in multiphase are provided. A string of LEDs divided into groups connected to each other in series is provided. Each group is coupled to ground through separate conductive paths. A phase switch is provided in each conductive path. Increasing the input voltage turn on the string of LEDs, group by group in the sequence downstream the string. To reduce power dissipation, the phase switch of an upstream group is turned off when next downstream group is turned on.

Claims

1. A driver circuit for driving light emitting diodes (LEDs) in multiphase, comprising:

a string of LEDs divided into n groups, said n groups of LEDs being electrically connected to each other in series in a sequence from group 1 to group n, each group having an upstream end and a downstream end, and the downstream end of group m−

1 being electrically connected to the upstream end of group m, where m is a positive integer equal to or less than n;

a plurality of phase switches, each of the phase switches being coupled to the downstream end of a corresponding group at one end and coupled to a ground at the other end.

2. The driver circuit of claim 1, wherein the phase switch comprises a transistor.

3. The driver circuit of claim 2, wherein the phase switch comprises a NPN darlington transistor, or a PNP darlington transistor, or a combination of these transistors connected in a cascade or a cascode configuration.

4. The driver circuit of claim 1, further comprising an over-voltage protection circuit and a hysteresis circuit to alter a voltage threshold of the over-voltage protection circuit where the over-voltage protection circuit de-activates.

5. A driver circuit for driving light emitting diodes (LEDs) with over-voltage protection, comprising:

a group of LEDs;

a power source coupled to an upstream end of the group of LEDs to provide an input voltage;

a phase switch coupled to a downstream end of the group of LEDs at one end and coupled to a ground at another end.

6. The driver circuit of claim 5, wherein the phase switch comprises a transistor.

7. The driver circuit of claim 5, wherein the phase switch comprises a NPN darlington transistor, or a PNP darlington transistor, or a N-Channel MOSFET, or a P-Channel MOSFET, or a NPN bipolar transistor, or a PNP bipolar transistor, or an Insulated Gate Bipolar Transistor (IGBT), or an analog switch, or a relay, or a combination of these devices connected in a cascade or a cascode configuration.

8. The driver circuit of claim 5, further comprising an over-voltage protection circuit and a hysteresis circuit to alter a voltage threshold of the over-voltage protection circuit where the over-voltage protection circuit de-activates.