CN108924995A - LED flow equalizing circuit and electronic equipment - Google Patents
LED flow equalizing circuit and electronic equipment Download PDFInfo
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- CN108924995A CN108924995A CN201810691024.4A CN201810691024A CN108924995A CN 108924995 A CN108924995 A CN 108924995A CN 201810691024 A CN201810691024 A CN 201810691024A CN 108924995 A CN108924995 A CN 108924995A
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- 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
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Abstract
The invention discloses a kind of LED flow equalizing circuits, including constant flow module, control module, tree-shaped current-sharing module and several paths of LEDs lamp strings；The constant flow module is connect with the anode of first LED in every LED light string described all the way respectively, and the constant flow module is used to provide constant total current for all LED light strings；The tree-shaped current-sharing module includes several metal-oxide-semiconductors, and the tree-shaped current-sharing module is connect with the cathode of the last one LED in every LED light string described all the way respectively, and the tree-shaped current-sharing module is connect with the control module and the constant flow module respectively；The control module is for exporting PWM drive signal to each metal-oxide-semiconductor respectively, to control the switch state of each metal-oxide-semiconductor；The tree-shaped current-sharing module is used to make the electric current mean allocation per the LED light string described all the way by the change of each metal-oxide-semiconductor switch state.The present invention is able to solve the problem that stream precision is not high.The invention also discloses the electronic equipments using above-mentioned LED flow equalizing circuit.
Description
Technical field
The present invention relates to technical field of electronic equipment, more particularly to a kind of LED flow equalizing circuit and electronic equipment.
Background technique
LED (Light Emitting Diode, light emitting diode), is a kind of solid state semiconductor devices, it can be straight
Connect and convert electricity to light), with the development of LED technology and universal, more and more electronic products can all use and arrive LED, such as
Television set, air conditioner etc. have the application of LED.In order to promote aesthetic feeling, multi-string LED usually will use in electronic equipment, every a string
LED is made of multiple LED lamp beads being sequentially connected in series, and in order to guarantee bright aobvious stability, needs to carry out at stream multi-string LED
Reason.
Traditional settling mode controls the form of same specification triode ON electric current using same current, such as Fig. 6 institute
Show, the principle of triode current share scheme is, in a given constant pressure source, to utilize the current-limiting resistance and three after constant pressure source
Conducting resistance RBE between pole pipe base stage and collector, the base of triode can be continued to flow through by generating constant current an IBE, IBE
Between pole and collector.Under magnification due to triode operation, the electric current ICE between emitter and collector and IBE it
Between there are proportional relation, specific formula is ICE=(1+ β) × IBE.β be determined by triode bulk properties, be a fixation not
The value of change.When LED multichannel exports simultaneously, triode (the i.e. β and RBE phase of a same specification is respectively connected in the output of every road
Collector and emitter together), and the emitter of all triodes is linked together, by the source-series same current limliting of same constant pressure
Resistance is respectively connected to the base stage of triode.At this point, the IBE and ICE that flow through each triode are identical.And ICE is to flow through single channel
LED current.Therefore every paths of LEDs electric current is identical, realization is flowed.
Above-mentioned traditional solution, is on the one hand limited by production technology, same specification triode in actual production, β and
RBE still has certain numerical value difference, causes stream precision insufficient；On the other hand, triode operation under magnification,
Its β and RBE will receive the influence of device temperature and environment temperature, and numerical value is caused to change, so that the feelings of temperature drift occurs in stream precision
Condition further affects stream precision.
Summary of the invention
An object of the present invention is to provide a kind of LED flow equalizing circuit, solves the prior art and flow that precision is not high to ask
Topic.
A kind of LED flow equalizing circuit, including constant flow module, control module, tree-shaped current-sharing module and several paths of LEDs lamp strings；
The constant flow module is connect with the anode of first LED in every LED light string described all the way respectively, the constant current mould
Block is used to provide constant total current for all LED light strings；
The tree-shaped current-sharing module includes several metal-oxide-semiconductors, and the tree-shaped current-sharing module is respectively and per the LED light described all the way
The cathode of the last one LED in string connects, and the tree-shaped current-sharing module respectively with the control module and the constant current mould
Block connection；
The control module is for exporting PWM drive signal to each metal-oxide-semiconductor respectively, to control each MOS
The switch state of pipe；The tree-shaped current-sharing module is used to make by the change of each metal-oxide-semiconductor switch state per described all the way
The electric current mean allocation of LED light string.
The LED flow equalizing circuit proposed according to the present invention carries out segmentation PWM light modulation using metal-oxide-semiconductor, using accurate PWM timing,
Realizing digital current-sharing replaces traditional simulation to flow, and keeps stream precision higher, can be avoided because the error generation of device is flowed
Uneven problem, improves the reliability of system.In the on-state due to metal-oxide-semiconductor work, amplify without using metal-oxide-semiconductor inside
Characteristic, further ensures the precision flowed at the case where avoiding constant current accuracy temperature drift caused by under operating temperature difference.This
Outside, driving signal is issued by control module, reliable and stable, will not be by PCB trace and external environment (such as temperature, humidity) to electricity
It is influenced caused by stream precision, the stability that the system that improves flows.
In addition, the LED flow equalizing circuit provided according to the present invention, can also have following additional technical characteristic：
Further, the tree-shaped current-sharing module includes several N-channel MOS pipes and several P-channel metal-oxide-semiconductors, the P
The quantity of channel MOS tube and the N-channel MOS pipe is equal.
Further, the number of the LED light string is 2n, n is the integer more than or equal to 1, then the tree-shaped current-sharing module
The sum of middle metal-oxide-semiconductor is 2n+1- 2, wherein the quantity of the N-channel MOS pipe and the P-channel metal-oxide-semiconductor is 2n- 1, the control
The quantity of the PWM drive signal of molding block output is n.
Further, the duty ratio of each PWM drive signal of the control module output is 50%.
Further, the tree-shaped current-sharing module includes the tree-shaped MOS circuit of n string, is set in every a string of tree-shaped MOS circuits
There are the N-channel MOS pipe and P-channel metal-oxide-semiconductor that quantity is equal, in the first tree-shaped MOS circuit of string directly connecting with the LED light string
Metal-oxide-semiconductor total quantity be 2n, and when n is greater than 1, the quantity of the metal-oxide-semiconductor in preceding a string of tree-shaped MOS circuits is tree-shaped latter a string
Twice of the quantity of MOS circuit.
Further, in the drain electrode and the LED light string of each metal-oxide-semiconductor in the tree-shaped MOS circuit of first string most
The cathode of the latter LED connects；When n is equal to 1, the source electrode of each metal-oxide-semiconductor in the tree-shaped MOS circuit of first string with it is described
Constant flow module connection；When n is greater than 1, in the source electrode and latter a string tree-shaped MOS circuits of the metal-oxide-semiconductor in preceding a string of tree-shaped MOS circuits
Metal-oxide-semiconductor drain electrode connection, the source electrode of each metal-oxide-semiconductor in last a string of tree-shaped MOS circuits connect with the constant flow module.
Further, the frequency of n-th of PWM drive signal of the control module output is f, then the control module is defeated
The frequency of the 1st PWM drive signal out is 2n-1*f。
Further, the grid of each metal-oxide-semiconductor is connect with the control module respectively, the control module be used for
The 1st PWM drive signal of each metal-oxide-semiconductor output in the tree-shaped MOS circuit of first string, and so on, the control
N-th of PWM drive signal that each metal-oxide-semiconductor that molding block is used for into the tree-shaped MOS circuit of n-th string exports.
Further, sampling resistor is connected between the constant flow module and the tree-shaped current-sharing module.
It is another object of the present invention to propose a kind of electronic equipment, it is equal which includes at least above-mentioned LED
Current circuit.Since the electronic equipment has above-mentioned LED flow equalizing circuit, LED flows that precision is higher, and the display of LED is more steady
It is fixed reliable.
Additional aspect and advantage of the invention will be set forth in part in the description, and will partially become from the following description
Obviously, or practice through the invention is recognized.
Detailed description of the invention
Above-mentioned and/or additional aspect of the invention and advantage will become from the description of the embodiment in conjunction with the following figures
Obviously and it is readily appreciated that, wherein：
Fig. 1 is the structural schematic diagram of the LED flow equalizing circuit of one embodiment of the invention；
The structural schematic diagram of LED flow equalizing circuit when Fig. 2 is n=1；
The structural schematic diagram of LED flow equalizing circuit when Fig. 3 is n=2；
Driving signal schematic diagram in LED flow equalizing circuit when Fig. 4 is n=2；
When Fig. 5 is n=5 in LED flow equalizing circuit tree-shaped current-sharing module MOS distribution map；
Fig. 6 is traditional LED flow equalizing circuit schematic illustration.
Specific embodiment
To keep objects, features and advantages of the present invention more obvious and easy to understand, with reference to the accompanying drawing to tool of the invention
Body embodiment is described in detail.Several embodiments of the invention are given in attached drawing.But the present invention can be with many not
With form realize, however it is not limited to embodiment described herein.On the contrary, purpose of providing these embodiments is makes to this
The disclosure of invention is more thorough and comprehensive.
It should be noted that it can directly on the other element when element is referred to as " being fixedly arranged on " another element
Or there may also be elements placed in the middle.When an element is considered as " connection " another element, it, which can be, is directly connected to
To another element or it may be simultaneously present centering elements.Term as used herein " vertical ", " horizontal ", " left side ",
" right side ", "upper", "lower" and similar statement for illustrative purposes only, rather than the device or member of indication or suggestion meaning
Part must have a particular orientation, be constructed and operated in a specific orientation, therefore be not considered as limiting the invention.
In the present invention unless specifically defined or limited otherwise, term " installation ", " connected ", " connection ", " fixation " etc.
Term shall be understood in a broad sense, for example, it may be being fixedly connected, may be a detachable connection, or be integrally connected；It can be machine
Tool connection, is also possible to be electrically connected；It can be directly connected, two members can also be can be indirectly connected through an intermediary
Connection inside part.For the ordinary skill in the art, above-mentioned term can be understood in this hair as the case may be
Concrete meaning in bright.Term " and or " used herein include the arbitrary of one or more relevant listed items and
All combinations.
Referring to Fig. 1, the LED flow equalizing circuit that one embodiment of the invention proposes, including constant flow module 10, control module
20, tree-shaped current-sharing module 30 and several paths of LEDs lamp strings 40.
The constant flow module 10 respectively in several paths of LEDs lamp strings 40 per the LED light string described all the way in first LED
Anode connection, the constant flow module 10 is used to for all LED light strings provide constant total current, and constant flow module 10 can
To be not limited thereto using conventional constant-current circuit.
The tree-shaped current-sharing module 30 includes several metal-oxide-semiconductors, and the tree-shaped current-sharing module 30 is respectively and per described all the way
The cathode of the last one LED in LED light string connects, and the tree-shaped current-sharing module 30 respectively with the control module 20 and institute
State the connection of constant flow module 10.
The control module 20 is each described to control for exporting PWM drive signal to each metal-oxide-semiconductor respectively
The switch state of metal-oxide-semiconductor.
The tree-shaped current-sharing module 30 is used to make several paths of LEDs lamp strings by the change of each metal-oxide-semiconductor switch state
Electric current mean allocation in 40 per the LED light string described all the way.
Wherein, the tree-shaped current-sharing module 30 includes several N-channel MOS pipes and several P-channel metal-oxide-semiconductors, the P ditch
The quantity of road metal-oxide-semiconductor and the N-channel MOS pipe is equal.
The number of the LED light string 40 is 2n, n is the integer more than or equal to 1, then MOS in the tree-shaped current-sharing module 30
The sum of pipe is 2n+1- 2, wherein the quantity of the N-channel MOS pipe and the P-channel metal-oxide-semiconductor is 2n- 1, the control mould
The quantity for the PWM drive signal that block 20 exports is n.
The duty ratio for each PWM drive signal that the control module 20 exports is 50%.
The tree-shaped current-sharing module 30 includes the tree-shaped MOS circuit of n string, wherein is equipped in every a string of tree-shaped MOS circuits
Quantity equal N-channel MOS pipe and P-channel metal-oxide-semiconductor, first directly connect with the LED light string are gone here and there in tree-shaped MOS circuit
The total quantity of metal-oxide-semiconductor is 2n, and when n is greater than 1, the quantity of the metal-oxide-semiconductor in preceding a string of tree-shaped MOS circuits is tree-shaped latter a string
Twice of the quantity of MOS circuit.
The drain electrode of each metal-oxide-semiconductor in the tree-shaped MOS circuit of first string and the last one LED in the LED light string
Cathode connection；When n is equal to 1, the source electrode and the constant flow module of each metal-oxide-semiconductor in the tree-shaped MOS circuit of first string
Connection；When n is greater than 1, source electrode and the metal-oxide-semiconductor in latter a string tree-shaped MOS circuits of the metal-oxide-semiconductor in preceding a string of tree-shaped MOS circuits
Drain electrode connection, the source electrode of each metal-oxide-semiconductor in last a string of tree-shaped MOS circuits connect with the constant flow module.
The frequency for n-th of PWM drive signal that the control module 20 exports is f, then the control module 20 exports
The frequency of 1st PWM drive signal is 2n-1*f。
The grid of each metal-oxide-semiconductor is connect with the control module 20 respectively, and the control module 20 is used for described
The 1st PWM drive signal of each metal-oxide-semiconductor output in the first tree-shaped MOS circuit of string, and so on, the control mould
N-th of PWM drive signal that each metal-oxide-semiconductor that block is used for into the tree-shaped MOS circuit of n-th string exports.
Specifically, can connect sampling resistor R between the constant flow module 10 and the tree-shaped current-sharing module 30, it is used for
Electric current is acquired, current monitoring is carried out.
In order to which the working principle of above-mentioned LED flow equalizing circuit is described in detail, below to be said for n=1 and n=2
It is bright.
When n=1, referring to Fig. 2, there is two paths of LED lamp string, respectively LED light string 1, LED light string 2, it should be pointed out that
LED light string 1 only depicts two LED in Fig. 2, but is not the limitation to the quantity of LED in LED light string, in LED light string
The quantity of LED can be multiple.Then the sum of metal-oxide-semiconductor is 2 in the tree-shaped current-sharing module 30, wherein N-channel MOS pipe and P ditch
The quantity of road metal-oxide-semiconductor is 1, respectively N-channel MOS pipe Q11 and P-channel metal-oxide-semiconductor Q12, the PWM that the control module 20 exports
The quantity of driving signal is 1.The duty ratio of this PWM drive signal of output is 50%.Tree-shaped current-sharing module 30 only includes 1
It goes here and there tree-shaped MOS circuit, there is 1 N-channel MOS pipe Q11 and 1 P-channel metal-oxide-semiconductor Q12 in this tree-shaped MOS circuit of 1 string, this two
It the drain electrode of a metal-oxide-semiconductor and is connect respectively with the cathode of the last one LED in two LED light strings, the source electrode of two metal-oxide-semiconductors and institute
State constant flow module connection.The grid of two metal-oxide-semiconductors is connect with the control module 20 respectively, and the control module 20 is for distinguishing
The PWM drive signal for being f to N-channel MOS pipe Q11 and P-channel metal-oxide-semiconductor Q12 output frequency.
When normal work, if the electric current that constant flow module 10 provides is Io.Control module 20 can give Q11 and Q12 simultaneously at this time
One frequency fix (specially f), duty ratio be 50% square-wave signal, due to Q11 be N-channel MOS pipe, Q12 is P-channel
Metal-oxide-semiconductor, thus when square-wave signal is high level, Q11 conducting, Q12 cut-off, at this point, LED light string 1 forms access, LED
The electric current that lamp string 1 flows through is Io；When square-wave signal is low level, Q11 cut-off, Q12 conducting, LED light string 2 forms logical
Road, the electric current that LED light string 2 flows through are Io.Therefore in terms of a cycle, the average current that LED light string 1 flows through is Io/2, LED light
The average current that string 2 flows through also is Io/2.Thereby realize the stream of LED light string 1 and LED light string 2.
When n=2, referring to Fig. 3, there is two paths of LED lamp string, respectively LED light string 1, LED light string 2, LED light string 3, LED light
String 4, then the sum of metal-oxide-semiconductor is 6 in the tree-shaped current-sharing module 30, wherein the quantity of N-channel MOS pipe and P-channel metal-oxide-semiconductor is equal
It is 3, respectively N-channel MOS pipe Q11, N-channel MOS pipe Q13, N-channel MOS pipe Q21, P-channel metal-oxide-semiconductor Q12, P-channel MOS
Pipe Q14, P-channel metal-oxide-semiconductor Q22.
The quantity for the PWM drive signal that the control module 20 exports is 2, respectively driving signal 1 and driving signal 2,
The duty ratio of two PWM drive signals is 50%.The frequency of driving signal 1 is 2f, and the frequency of driving signal 2 is f.
Tree-shaped current-sharing module 30 includes the 2 tree-shaped MOS circuits of string, the first string respectively directly connecting with the LED light string
Tree-shaped MOS circuit 301 and the second tree-shaped MOS circuit 302 of string being connect with the first tree-shaped MOS circuit 301 of string, wherein first
Tree-shaped MOS circuit 301 go here and there due to directly connecting with LED light string, the first tree-shaped MOS circuit 301 of string is that the second string is tree-shaped
The tree-shaped MOS circuit of first a string of MOS circuit 302, and correspondingly, the second tree-shaped MOS circuit 302 of string is the tree-shaped MOS electricity of the first string
The quantity of the tree-shaped MOS circuit of latter a string of road 301, the metal-oxide-semiconductor in the first tree-shaped MOS circuit 301 of string is 4, is that the second string is tree-shaped
Twice of the quantity of metal-oxide-semiconductor in MOS circuit 302.
There is N-channel MOS pipe Q11, N-channel MOS pipe Q13, P-channel metal-oxide-semiconductor Q12, P in the first tree-shaped MOS circuit 301 of string
Channel MOS tube Q14.This four metal-oxide-semiconductors draining and connecting respectively with the cathode of the last one LED in four LED light strings.
There is N-channel MOS pipe Q21, P-channel metal-oxide-semiconductor Q22 in the second tree-shaped MOS circuit 302 of string.
MOS in the source electrode of four metal-oxide-semiconductors in the first tree-shaped MOS circuit 301 of string and the second tree-shaped MOS circuit 302 of string
The drain electrode of pipe connects, the tree-shaped MOS circuit 301 of the first string of drain electrode connection of a metal-oxide-semiconductor in the second tree-shaped MOS circuit 302 of string
In the source electrode of N-channel MOS pipe and the source electrode of a P-channel metal-oxide-semiconductor, specifically, the source electrode connection Q21 of Q11 and Q12
The drain electrode of the source electrode connection Q22 of drain electrode, Q13 and Q14, Q21 connect the constant flow module 10 with the source electrode of Q22.
The grid of Q11, Q12, Q13, Q14, Q21, Q22 are connect with the control module 20 respectively, the control module 20
For the driving signal 1 that Q11, Q12, Q13, Q14 into the tree-shaped MOS circuit of first string are exported, the control mould
The driving signal 2 that Q21, Q22 that block 20 is used for into the tree-shaped MOS circuit of the 2nd string are exported.
Driving signal schematic diagram is as shown in Figure 4.Wherein the period of driving signal 1 is T, and the period of driving signal 2 is 2T.?
That is the frequency of driving signal 1 is 2 times of driving signal.In terms of duty ratio, the duty ratio of driving signal 1 and driving signal 2
It is 50%.
Equally set electric current that constant flow module provides as Io, as can see from Figure 4：
First stage：Driving signal 1 is in high level, and driving signal 2 is also at high level, at this time the NMOS of Q11, Q13
Pipe conducting, the PMOS tube cut-off of Q12, Q14.The NMOS transistor conduction of Q21, the PMOS tube cut-off of Q22.Therefore only LED light string 1 can
With forming circuit, then the electric current for then flowing through LED light string 1 is Io.
Second stage：Driving signal 1 is in low level, and driving signal 2 is still high level, at this time the NMOS tube of Q11, Q13
Cut-off, the PMOS tube conducting of Q12, Q14.The NMOS transistor conduction of Q21, the PMOS tube cut-off of Q22.As long as therefore LED light string 2 can be with
Forming circuit, the electric current for then flowing through LED light string 2 is Io.
Phase III：Driving signal 1 becomes high level again, and driving signal 2 becomes low level, at this time the NMOS tube of Q11, Q13
Conducting, the PMOS tube cut-off of Q12, Q14.The NMOS tube of Q21 is ended, the PMOS tube conducting of Q22.As long as therefore LED light string 3 can be with
Forming circuit, the electric current for then flowing through LED light string 3 is Io.
Fourth stage：Driving signal 1 is in low level, and driving signal 2 is still low level, at this time the NMOS tube of Q11, Q13
Cut-off, the PMOS tube conducting of Q12, Q14.The NMOS tube of Q21 is ended, the PMOS tube conducting of Q22.As long as therefore LED light string 4 can be with
Forming circuit, the electric current for then flowing through LED light string 4 is Io.
It can be seen from the results above that within the time in period 2T, each LED within the period of each forming circuit
The electric current that lamp string flows through is Io, and the duration is T/2.Therefore available within the 2T time, flow through every paths of LEDs lamp string
Average current is Io/4.Thereby realize the stream of 4 paths of LEDs lamp strings.
Above-mentioned that the working principle of the LED flow equalizing circuit is only illustrated by taking n=1 and n=2 as an example, at least n is other positive integers
The case where, its working principle is that consistent, for example, referring to Fig. 5, thering are 32 string LED light strings to need to flow, needing when n=5
Metal-oxide-semiconductor sum is 62, wherein PMOS tube 31, and NMOS tube 31, needing driving signal number is 5, the frequency of driving signal 1
Rate is 16f, and the frequency of driving signal 2 is 8f, and the frequency of driving signal 3 is 4f, and the frequency of driving signal 4 is 2f, driving signal 5
Frequency be f, so as to realize that 32 paths of LEDs lamp strings flow, wherein each lamp string flow through electric current be Io/32.
In conclusion carrying out segmentation PWM light modulation according to the LED flow equalizing circuit that the present embodiment proposes using metal-oxide-semiconductor, utilizing
Accurate PWM timing, realizes digital current-sharing and traditional simulation is replaced to flow, and keeps stream precision higher, can be avoided because of device
Error, which is led to the problem of, flows unevenness, improves the reliability of system.Due to metal-oxide-semiconductor work in the on-state, without using
Amplification characteristic inside metal-oxide-semiconductor, further ensures the case where avoiding constant current accuracy temperature drift caused by under operating temperature difference
The precision flowed.It is reliable and stable in addition, driving signal is issued by control module, will not by PCB trace and external environment (such as
Temperature, humidity) it is influenced caused by current precision, the stability that the system that improves flows.
Another embodiment of the present invention also proposes a kind of electronic equipment, which includes at least above-mentioned LED and flow
Circuit, using the electronic equipment of the LED flow equalizing circuit, LED flows that precision is higher, and the display of LED is more reliable and more stable.The electronics
Equipment is, for example, television set, refrigerator, air-conditioning or other equipment needed using LED.
The embodiments described above only express several embodiments of the present invention, and the description thereof is more specific and detailed, but simultaneously
Limitations on the scope of the patent of the present invention therefore cannot be interpreted as.It should be pointed out that for those of ordinary skill in the art
For, without departing from the inventive concept of the premise, various modifications and improvements can be made, these belong to guarantor of the invention
Protect range.Therefore, the scope of protection of the patent of the invention shall be subject to the appended claims.
In the description of this specification, reference term " one embodiment ", " some embodiments ", " example ", " specifically show
The description of example " or " some examples " etc. means specific features, structure, material or spy described in conjunction with this embodiment or example
Point is included at least one embodiment or example of the invention.In the present specification, schematic expression of the above terms are not
Centainly refer to identical embodiment or example.Moreover, particular features, structures, materials, or characteristics described can be any
One or more embodiment or examples in can be combined in any suitable manner.
The embodiments described above only express several embodiments of the present invention, and the description thereof is more specific and detailed, but simultaneously
Limitations on the scope of the patent of the present invention therefore cannot be interpreted as.It should be pointed out that for those of ordinary skill in the art
For, without departing from the inventive concept of the premise, various modifications and improvements can be made, these belong to guarantor of the invention
Protect range.Therefore, the scope of protection of the patent of the invention shall be subject to the appended claims.
Claims (10)
1. a kind of LED flow equalizing circuit, which is characterized in that if including constant flow module, control module, tree-shaped current-sharing module and main line
LED light string；
The constant flow module is connect with the anode of first LED in every LED light string described all the way respectively, and the constant flow module is used
In providing constant total current for all LED light strings；
The tree-shaped current-sharing module includes several metal-oxide-semiconductors, and the tree-shaped current-sharing module is respectively and in every LED light string described all the way
The last one LED cathode connection, and the tree-shaped current-sharing module connects with the control module and the constant flow module respectively
It connects；
The control module is for exporting PWM drive signal to each metal-oxide-semiconductor respectively, to control each metal-oxide-semiconductor
Switch state；The tree-shaped current-sharing module is used to make by the change of each metal-oxide-semiconductor switch state per the LED light described all the way
The electric current mean allocation of string.
2. LED flow equalizing circuit according to claim 1, which is characterized in that the tree-shaped current-sharing module includes several N ditches
The quantity of road metal-oxide-semiconductor and several P-channel metal-oxide-semiconductors, the P-channel metal-oxide-semiconductor and the N-channel MOS pipe is equal.
3. LED flow equalizing circuit according to claim 1, which is characterized in that the number of the LED light string is 2n, n be greater than
Integer equal to 1, then the sum of metal-oxide-semiconductor is 2 in the tree-shaped current-sharing modulen+1- 2, wherein the N-channel MOS pipe and the P
The quantity of channel MOS tube is 2n- 1, the quantity of the PWM drive signal of the control module output is n.
4. LED flow equalizing circuit according to claim 3, which is characterized in that each PWM driving of the control module output
The duty ratio of signal is 50%.
5. LED flow equalizing circuit according to claim 3, which is characterized in that the tree-shaped current-sharing module includes that n string is tree-shaped
MOS circuit is equipped with quantity equal N-channel MOS pipe and P-channel metal-oxide-semiconductor in every a string of tree-shaped MOS circuits, directly and institute
The total quantity for stating the metal-oxide-semiconductor in the first tree-shaped MOS circuit of string of LED light string connection is 2n, and when n is greater than 1, first a string are tree-shaped
The quantity of metal-oxide-semiconductor in MOS circuit is twice of the quantity of latter a string tree-shaped MOS circuits.
6. LED flow equalizing circuit according to claim 5, which is characterized in that each of tree-shaped MOS circuit of first string
The drain electrode of metal-oxide-semiconductor is connect with the cathode of the last one LED in the LED light string；When n is equal to 1, first string is tree-shaped
The source electrode of each metal-oxide-semiconductor in MOS circuit is connect with the constant flow module；When n is greater than 1, in preceding a string of tree-shaped MOS circuits
The source electrode of metal-oxide-semiconductor is connect with the drain electrode of the metal-oxide-semiconductor in latter a string tree-shaped MOS circuits, each of last a string of tree-shaped MOS circuits
The source electrode of metal-oxide-semiconductor is connect with the constant flow module.
7. LED flow equalizing circuit according to claim 6, which is characterized in that n-th of PWM of the control module output drives
The frequency of dynamic signal is f, then the frequency of the 1st PWM drive signal of the control module output is 2n-1*f。
8. LED flow equalizing circuit according to claim 7, which is characterized in that the grid of each metal-oxide-semiconductor respectively with it is described
Control module connection, each metal-oxide-semiconductor that the control module is used for into the tree-shaped MOS circuit of first string export described the
1 PWM drive signal, and so on, each metal-oxide-semiconductor that the control module is used for into the tree-shaped MOS circuit of n-th string is defeated
N-th of PWM drive signal out.
9. LED flow equalizing circuit according to claim 1, which is characterized in that the constant flow module and the tree-shaped stream mould
Sampling resistor is connected between block.
10. a kind of electronic equipment, which is characterized in that including LED flow equalizing circuit described in claim 1 to 9 any one.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201810691024.4A CN108924995A (en) | 2018-06-28 | 2018-06-28 | LED flow equalizing circuit and electronic equipment |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201810691024.4A CN108924995A (en) | 2018-06-28 | 2018-06-28 | LED flow equalizing circuit and electronic equipment |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112562574A (en) * | 2020-12-01 | 2021-03-26 | Tcl华星光电技术有限公司 | Switch module and display device |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20100141180A1 (en) * | 2008-12-10 | 2010-06-10 | Han-Yu Chao | Light Source System |
| CN102629458A (en) * | 2011-10-21 | 2012-08-08 | 北京京东方光电科技有限公司 | Backlight circuit, backlight panel and light emitting diode driver |
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2018
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Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20100141180A1 (en) * | 2008-12-10 | 2010-06-10 | Han-Yu Chao | Light Source System |
| CN102629458A (en) * | 2011-10-21 | 2012-08-08 | 北京京东方光电科技有限公司 | Backlight circuit, backlight panel and light emitting diode driver |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112562574A (en) * | 2020-12-01 | 2021-03-26 | Tcl华星光电技术有限公司 | Switch module and display device |
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Application publication date: 20181130 |