CN1968559A - Serial powering circuit and method of an LED string - Google Patents
Serial powering circuit and method of an LED string Download PDFInfo
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- CN1968559A CN1968559A CN 200610077811 CN200610077811A CN1968559A CN 1968559 A CN1968559 A CN 1968559A CN 200610077811 CN200610077811 CN 200610077811 CN 200610077811 A CN200610077811 A CN 200610077811A CN 1968559 A CN1968559 A CN 1968559A
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Abstract
A circuit is used for driving a plurality of LEDs by an external voltage source. The LEDs are coupled in series. The circuit comprises a plurality of switches coupled to the LEDs in parallel, respectively, for individually controlling the brightness of the LEDs. The circuit further includes a plurality of Pulse-Width Modulation (PWM) signals coupled to the switches, respectively, for individually controlling the switches.
Description
The application requires that sequence number is 60/676,448, " the serial power supply of LED string " by name, the applying date be the priority of U.S.'s pending trial temporary patent application on April 29th, 2005, at this, with its in full content be incorporated herein by reference.
Technical field
The present invention relates to a kind ofly be used to drive or power to the circuit of load, these loads are LED (light-emitting diode) for example, relates in particular to a kind of being used to drive or power to the circuit or the method for a plurality of LED coupled in series.
Background technology
With reference to figure 1, show a kind of being used to of the prior art to drive or power to the typical circuit 10 of a plurality of LED.For example, among Fig. 1, circuit 10 is used to drive four LED 22,24,26 and 28.Should find out that LED 22,24,26 and 28 is in parallel.An external voltage source is connected to driver 12, is used for providing voltage vcc to driver 12.Driver 12 has low (LDO) adjuster 14 that reverses, and the voltage Vreg that is used to provide adjusted is to LED 22,24,26 and 28.Adjusted voltage Vreg for example can be 3.3 volts.LED 22,24,26 and 28 is connected respectively to switch 32,34,36 and 38 and resistance 42,44,46 and 48.As shown in fig. 1, LED 22,24,26 and 28, switch 32,34,36 and 38 and resistance 42,44,46 and 48 be connected in series respectively.
For instance, suppose that each all needs the operating current of 10mA in LED 22,24,26 and 28.So, a kind of situation is, the voltage vcc of external voltage source is 30V, and LED 22,24,26 and 28 power requirement are Pw, and wherein the computing formula of Pw is as follows: Pw=30V*4*10mA=1.2W.
In actual use, circuit 10 can be installed in the mancarried device, for example cellular phone, digital camera, laptop computer, electric automobile or portable power tool etc.As illustrated in prior art fig. 1, use single high voltage integrated circuit (IC), and therefore only provide a single high voltage source.No matter load current still flows out from the higher pressure adjuster from low-pressure regulator, the electric current IC that all flows through, and must consume the power of remarkable quantity.This is significant from some angle, and for example, IC design, system power distribute and intrasystem power consumption.
Summary of the invention
One object of the present invention be to provide a kind of be used to use low current to drive or power supply to circuit or the method for a plurality of LED.
In order to obtain above-mentioned purpose, the invention provides a kind of circuit, it drives a plurality of LED by an external voltage source.These LED are connected in series.This circuit comprises a plurality of switches that are parallel to a plurality of LED respectively, are used for controlling separately the brightness of each LED.In another embodiment, this circuit also comprises a plurality of pulse-width modulations (PWM) signal that is connected respectively to above-mentioned a plurality of switch, is used for controlling separately each switch.
Description of drawings
Other purpose of the present invention, advantage and novel feature will become clearer owing to the following detailed description of being carried out in conjunction with the accompanying drawings.
Fig. 1 is for being used to drive the circuit structure diagram of a plurality of LED in the prior art.
Fig. 2 is for being used to drive the circuit structure diagram of a plurality of LED according to an embodiment of the invention.
Fig. 3 is the schematic flow sheet of the method for battery charge according to an embodiment of the invention.
Embodiment
Power with reference to the serial of the LED of embodiments of the invention string and to be described in detail.When describing in conjunction with the embodiments when of the present invention, be appreciated that it can not attempt to limit the invention among these embodiment.On the contrary, the present invention is intended to cover all selections, distortion and the equivalent that is included in the spirit and scope of the present invention that are defined by the following claims.
In addition, in following detailed description of the present invention, a large amount of details have been stated, so that complete understanding of the present invention to be provided.Yet one it will be recognized by those of ordinary skills, and the present invention need not these details and just can implement.In addition, in some cases, cover flesh and blood of the present invention, known method, processing procedure, element and circuit are not described in detail in order to be unlikely.
Please refer to Fig. 2, its show according to the embodiment of the invention be used for drive and the circuit 100 of a plurality of loads (for example LED) is given in power supply.Circuit 100 shown in Figure 2 is used for driving four LED 122,124,126 and 128, and certainly, in other embodiments, the number of load should not be restricted, and circuit 100 can be supported the load of any number, for example n LED (n=2,3,4 ...).For a person skilled in the art, obviously also support in other embodiments of the invention to use the load of other type to replace LED 122,124,126 and 128.
As shown in Figure 2, LED 122,124,126 and 128 is one another in series and is connected, and forms a LED string 150.One external voltage source is connected in driver 112, provides voltage vcc in order to give driver 112.Driver 112 has linear regulator, and for example voltage follower, shunt regulator or low (LDO) adjuster 114 that reverses are used for providing adjusted voltage Vreg to LED 122,124,126 and 128.For the person of ordinary skill of the art, obviously voltage vcc is usually above adjusted voltage Vreg, and external voltage source is without overregulating.
LED 122,124,126 after the series connection and 128 connects with resistance 140 and switch 130 jointly.Other has a plurality of switches 132,134,136 and 138 to be parallel to respectively on each LED 122,124,126 and 128, and for example, switch 132 is connected in parallel with LED 122.In one embodiment, the modulated voltage Vreg that regulates via the ldo regulator 114 of driver 112 is output to resistance 140 and LED 122,124,126 and 128, thereby all LED 122,124,126 and 128 are lighted.
Switch 132,134,136 and 138 in parallel with LED 122,124,126 and 128 respectively can be controlled LED 122,124,126 and 128 brightness separately separately.Switch 132,134,136 and 138 is used separately as the bypass of the current path of LED 122,124,126 and 128.For example, switch 132 is as the bypass of the current path of LED 122, and switch 134 is as the bypass of the current path of LED 124, and switch 136 serves as the bypass of the current path of LED 126, and switch 138 is as the bypass of the current path of LED 128.As can be seen, when switch 132 by short circuit or when being under an embargo, LED 122 will be closed.
On the contrary, when switch 132 is unlocked or enables, LED 122 will be switched on.Similarly, LED 124,126 and 128 realizes opening and closing respectively under the control of switch 134,136 and 138.
In conjunction with a specific embodiment, the present invention also can further introduce pulse-width modulation circuit (PWM) control method.In other words, pwm signal can be applied on switch 132,134,136 and 138, with the brightness of independent control LED 122,124,126 and 128.With LED 122 is example, can use a controller (not shown) to produce pwm signal and enable or disable switch 132, so that control the brightness of LED 122 or make the brightness deepening of LED 122.Particularly, when in LED 122,124,126 and 128 any by short circuit or when turn-offing, the brightness of all the other LED also will change.Can use pwm signal to control the switch of all the other LED, change so that suppress its brightness.In addition, when LED 122,124,126 when 128 have different colors, also can use switch 132,134,136 and 138 to eliminate luminance difference between LED 122,124,126 and 128.
According to one embodiment of present invention, the flow through electric current of each LED 122,124,126 and 128 can be turned to by switch 132,134,136 and 138.The scope of diverted current of switch of flowing through from 0 to lowest high-current value Id_max, as shown in formula 1:
Id_max＝Vled/Ronsw (1)
In formula 1, Vled is the rated voltage of each LED 122,124,126 and 128; And Ronsw be electric current at the resistance 140 of flowing through less than the condition of [Vreg-NxVled]/R1 under each switch 132,134,136 and 138 impedance, will describe in detail hereinafter.
In this case, according to one embodiment of present invention, electric current is shunted according to the proportional factor of the duty ratio with the pwm signal that is applied to switch.In order to illustrate, adopting LED 122 is example, and when the electric current on resistance 140 was Iex, the voltage of LED 122 was V122, and the impedance of switch 132 is R132.The electric current of switch 132 of flowing through changes to Id max=V122/R132 from 0, and the electric current of the LED 122 that flows through changes to Iex-(V122/R132) from Iex.If (V122/R132) be greater than or equal to Iex, the electric current of the LED122 that then flows through changes to 0 from Iex.
Similarly, the flow through electric current of LED 124,126 and 128 can be modulated to 0 by switch 134,136 and 138 from Iex respectively.Therefore, no matter there are what LED to be switched in the given time, the electric current of the LED that flows through can be regulated individually.
When all LED 122,124,126 and 128 need to be switched on, need to introduce an initial current Icc_max, as shown in formula 2:
Icc_max＝[Vreg-NxVled]/R1 (2)
In formula 2, NxVled is the voltage sum of LED 122,124,126 and 128; R1 is the resistance value of resistance 140.
According to one embodiment of present invention, initial current Icc_max must be less than maximum continuous current, and this maximum continuous current is the maximum demand electric current of LED 122,124,126 and 128 of flowing through.
According to another embodiment of the present invention, switch 130 can be used for turn-offing all LED 122,124,126 and 128.Equally, also can use switch 130 to control or lower the brightness of the whole LED string 150 of LED 122,124,126 and 128.
Obviously, circuit 100 according to an embodiment of the invention can power to or drive a plurality of LED (for example, LED 122,124,126 and 128), and the electric current of the LED of any number of the series connection that can reduce to flow through.Therefore, circuit 100 of the present invention can reduce power consumption significantly.
Please refer to Fig. 3, it shows the method 200 that is used for the driven for emitting lights diode according to an embodiment of the invention.According to step 210, a plurality of light-emitting diodes (LED) are connected in series.According to step 212, a plurality of first switches are parallel-connected to a plurality of LED respectively, that is, each of a plurality of LED all is parallel-connected in a plurality of first switches one to inductive switch.According to step 214, second switch is connected in series to LED.This switch is controlled the power of a plurality of LED.According to step 216, a power supply is connected to the end of a plurality of LED, with to a plurality of LED transmission powers.According to step 218, regulate power supply to produce a modulated voltage.Modulated voltage is connected to the end of a plurality of LED, is used for powering to LED.According to step 220, a plurality of pulse-width modulations (PWM) signal is connected respectively to a plurality of first switches, is used for controlling individually each the brightness of a plurality of LED.According to step 222, control whole brightness of a plurality of LED by the control second switch.That is, when second switch is closed, power supply will be powered to a plurality of LED; When second switch disconnected, power supply will be to a plurality of LED power supplies.
Above description and accompanying drawing have been represented the preferred embodiments of the present invention.Be appreciated that various increases, distortion and replacement all should be comprised within protection scope of the present invention under the condition that does not deviate from by the spirit and scope of the defined principle of the present invention of claims.Those skilled in the art are in actual use the of the present invention, can use the present invention in the mode of various forms, structure, layout, ratio, material, element and parts or the like distortion, these are only in order to adapt to the needs of specific environment and operation, and do not deviate from principle of the present invention.For example, can replace LED described in the foregoing description with the load of other types.And for example, pwm signal can be simulation or digital.Therefore current disclosed embodiment is considered to is illustrative in all fields, and nonrestrictive, and scope of the present invention is specified by claims and its legal equivalents, and is not limited to above-mentioned description.
Claims (20)
1. a circuit that is used for the driven for emitting lights diode is characterized in that, comprising:
One voltage source;
A plurality of light-emitting diodes that are connected in series, wherein said voltage source are connected to an end of described a plurality of light-emitting diodes; And
A plurality of switches, wherein each switch all with described a plurality of light-emitting diodes in a corresponding light-emitting diode be connected in parallel, in order to control the brightness of this corresponding light-emitting diode individually.
2. the circuit that is used for the driven for emitting lights diode as claimed in claim 1 is characterized in that, also comprises:
A plurality of pwm signals that are connected respectively to described a plurality of switches are in order to control each in a plurality of described switches individually.
3. the circuit that is used for the driven for emitting lights diode as claimed in claim 2 is characterized in that, one in described a plurality of pwm signals has a duty ratio, with the electric current of modulated stream through the light-emitting diode of described correspondence.
4. the circuit that is used for the driven for emitting lights diode as claimed in claim 3 is characterized in that, described electric current of flowing through corresponding light-emitting diode is modulated to a predetermined value from 0.
5. the circuit that is used for the driven for emitting lights diode as claimed in claim 1 is characterized in that, also comprises:
With the second switch that described a plurality of light-emitting diodes are connected, it is in order to control the brightness of described a plurality of light-emitting diodes.
6. the circuit that is used for the driven for emitting lights diode as claimed in claim 1 is characterized in that, also comprises:
A low adjuster that reverses that is connected with described voltage source, it gives described a plurality of light-emitting diodes in order to produce modulated voltage with power supply.
7. the circuit that is used for the driven for emitting lights diode as claimed in claim 1 is characterized in that, also comprises:
A resistance that is connected in series to described a plurality of light-emitting diodes.
8. a method that is used for the driven for emitting lights diode is characterized in that, comprising:
A plurality of light-emitting diodes are connected in series;
One power supply is connected to an end of described a plurality of light-emitting diodes; And
With in a plurality of switches each respectively with described a plurality of light-emitting diodes in a corresponding light-emitting diode be connected in parallel, in order to the brightness of the light-emitting diode of controlling described correspondence individually.
9. the method that is used for the driven for emitting lights diode as claimed in claim 8 is characterized in that, also comprises:
Open switch to turn-off the light-emitting diode of described correspondence; And
Closed described switch is to connect the light-emitting diode of described correspondence.
10. the method that is used for the driven for emitting lights diode as claimed in claim 8 is characterized in that, also comprises:
Come control switch by a pwm signal, control flows to the power of the light-emitting diode of described correspondence thus.
11. the method that is used for the driven for emitting lights diode as claimed in claim 10 is characterized in that, described pwm signal has a duty ratio, with the electric current of modulated stream through the light-emitting diode of described correspondence.
12. the method that is used for the driven for emitting lights diode as claimed in claim 10 is characterized in that, the electric current of described each light-emitting diode of flowing through all can be modulated to a predetermined value from 0.
13. the method that is used for the driven for emitting lights diode as claimed in claim 10 is characterized in that, also comprises:
Regulate described power supply to produce a modulated voltage, give described a plurality of light-emitting diodes in order to power supply.
14. the method that is used for the driven for emitting lights diode as claimed in claim 10 is characterized in that, also comprises:
Connect a second switch to described a plurality of light-emitting diodes, and this second switch is in order to control the brightness of described a plurality of light-emitting diodes.
15. a circuit that is used for the driven for emitting lights diode is characterized in that, comprising:
One voltage source;
First light-emitting diode, wherein said voltage source are connected to an end of described first light-emitting diode; And
First switch that is connected in parallel with described first light-emitting diode is in order to control the brightness of described first light-emitting diode.
16. the circuit that is used for the driven for emitting lights diode as claimed in claim 15 is characterized in that, also comprises:
Second light-emitting diode that is connected with described first light-emitting diode series connection; And
The second switch that is connected in parallel with described second light-emitting diode is in order to control the brightness of described second light-emitting diode.
17. the circuit that is used for the driven for emitting lights diode as claimed in claim 16 is characterized in that, also comprises:
The 3rd switch that is connected with described first light-emitting diode series connection is in order to control the brightness of described first and second light-emitting diodes.
18. the circuit that is used for the driven for emitting lights diode as claimed in claim 16 is characterized in that, also comprises:
The low adjuster that reverses that is connected to described voltage source in order to produce modulated voltage, is given described first and second light-emitting diodes with power supply.
19. the circuit that is used for the driven for emitting lights diode as claimed in claim 15 is characterized in that, also comprises:
A pwm signal that is connected to described first switch is in order to control described first switch.
20. the circuit that is used for the driven for emitting lights diode as claimed in claim 15 is characterized in that, also comprises:
Be connected in series to the resistance of described first light-emitting diode.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US60/676,448 | 2005-04-29 | ||
| US11/282,097 | 2005-11-16 | ||
| US11/282,097 US7339323B2 (en) | 2005-04-29 | 2005-11-16 | Serial powering of an LED string |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN1968559A true CN1968559A (en) | 2007-05-23 |
Family
ID=38077026
Family Applications (2)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN 200620114828 Expired - Lifetime CN200976692Y (en) | 2005-04-29 | 2006-04-28 | Serial power supply circuit for LED string |
| CN 200610077811 Pending CN1968559A (en) | 2005-04-29 | 2006-04-28 | Serial powering circuit and method of an LED string |
Family Applications Before (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN 200620114828 Expired - Lifetime CN200976692Y (en) | 2005-04-29 | 2006-04-28 | Serial power supply circuit for LED string |
Country Status (1)
| Country | Link |
|---|---|
| CN (2) | CN200976692Y (en) |
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102239742A (en) * | 2008-09-05 | 2011-11-09 | 埃尔多实验室控股有限公司 | Led based lighting application |
| CN102404898A (en) * | 2010-09-13 | 2012-04-04 | 凯杰照明股份有限公司 | Driving circuit of light-emitting diode (LED) lamp |
| CN102960062A (en) * | 2010-06-30 | 2013-03-06 | 皇家飞利浦电子股份有限公司 | Dimmable lighting device |
| CN104717803A (en) * | 2009-08-14 | 2015-06-17 | 万斯创新股份有限公司 | Reduction of harmonic distortion for LED loads |
| CN104883789A (en) * | 2015-06-05 | 2015-09-02 | 罗成 | Constant-current control circuit for LED display device and display device |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2599461B (en) * | 2020-04-23 | 2022-09-21 | Cirrus Logic Int Semiconductor Ltd | Voltage regulator circuitry |
| US11500405B2 (en) | 2020-04-23 | 2022-11-15 | Cirrus Logic, Inc. | Voltage regulator circuitry |
-
2006
- 2006-04-28 CN CN 200620114828 patent/CN200976692Y/en not_active Expired - Lifetime
- 2006-04-28 CN CN 200610077811 patent/CN1968559A/en active Pending
Cited By (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102239742A (en) * | 2008-09-05 | 2011-11-09 | 埃尔多实验室控股有限公司 | Led based lighting application |
| CN102239742B (en) * | 2008-09-05 | 2015-07-22 | 埃尔多实验室控股有限公司 | LED based lighting application |
| CN104717803A (en) * | 2009-08-14 | 2015-06-17 | 万斯创新股份有限公司 | Reduction of harmonic distortion for LED loads |
| CN104717803B (en) * | 2009-08-14 | 2017-09-05 | 万斯创新股份有限公司 | Reduce the method and device of the harmonic distortion of LED load |
| CN102960062A (en) * | 2010-06-30 | 2013-03-06 | 皇家飞利浦电子股份有限公司 | Dimmable lighting device |
| CN102960062B (en) * | 2010-06-30 | 2016-08-10 | 皇家飞利浦电子股份有限公司 | Dimmable lighting equipment |
| CN102404898A (en) * | 2010-09-13 | 2012-04-04 | 凯杰照明股份有限公司 | Driving circuit of light-emitting diode (LED) lamp |
| CN104883789A (en) * | 2015-06-05 | 2015-09-02 | 罗成 | Constant-current control circuit for LED display device and display device |
Also Published As
| Publication number | Publication date |
|---|---|
| CN200976692Y (en) | 2007-11-14 |
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| PB01 | Publication | ||
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Open date: 20070523 |