CN103249208A - Short-circuit protection control circuit and relevant control method - Google Patents

Short-circuit protection control circuit and relevant control method Download PDF

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Publication number
CN103249208A
CN103249208A CN2012100322449A CN201210032244A CN103249208A CN 103249208 A CN103249208 A CN 103249208A CN 2012100322449 A CN2012100322449 A CN 2012100322449A CN 201210032244 A CN201210032244 A CN 201210032244A CN 103249208 A CN103249208 A CN 103249208A
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China
Prior art keywords
short
circuit
circuit protection
emitting diode
protection mechanism
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CN2012100322449A
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Chinese (zh)
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林崇伟
李弘庆
黄威旗
洪宗良
刘百丰
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Leadtrend Technology Corp
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Leadtrend Technology Corp
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Priority to CN2012100322449A priority Critical patent/CN103249208A/en
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    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
    • Y02B20/00—Energy efficient lighting technologies, e.g. halogen lamps or gas discharge lamps
    • Y02B20/40—Control techniques providing energy savings, e.g. smart controller or presence detection

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Abstract

The invention discloses a control method and a short-circuit protection control circuit. The short-circuit protection control circuit comprises a detection circuit, a first logic circuit and a timer, wherein the detection circuit is coupled with a plurality of light-emitting diode chains and used for generating an indication signal when any terminal voltage of the plurality of light-emitting diode chains is smaller than a reference value of an over-low current; when the indication signal is generated, the first logic circuit starts to intercept a short-circuit protection mechanism; when the short-circuit protection mechanism is intercepted, the timer starts timing and produces a timing result; and when the timing result displays that after the short-circuit protection mechanism continues interruption until at least the preset time is exceeded, the first logic circuit restores the short-circuit protection mechanism. Therefore, the short-circuit protection control circuit can be intercepted after the over-low current incident; the pause time for the short-circuit protection mechanism to be intercepted at least is the preset time corresponding to the reference value; after each over-low current incident happens, a counter performs recalculation; and in the period of non-luminance, the counter can stop counting.

Description

Short-circuit protection control circuit and relevant control method
Technical field
The invention relates to the control method circuit at a plurality of light emitting diode string (LED chain), especially about the control method of short-circuit protection in the light emitting diode string.
Background technology
For these epoch of being particular about carbon reduction, (light-emitting diode LED) has been a kind of light source that widely uses to light-emitting diode, because it has quite good luminous efficiency and exquisite assembly volume.For instance, modern LCD screen (LCD panel) mostly replaces in the past CCFL with LED, is used as backlight.
Fig. 1 is a kind of LED power supply unit 18 of the backlight module for LCD screen, mainly is the luminous of control light emitting diode string L1-L4, and each light emitting diode string has the light-emitting diode of a plurality of serial connections.Power switch in the backlight controller 20 control booster circuits (booster) 19 makes Inductive component draw energy from input IN, and output OUT is released energy, and sets up suitable output voltage V at output OUT OUTDrive light emitting diode string.Backlight controller 20 is by overvoltage protection end OVP, divider resistance RD 1With RD 2, detect output voltage V OUT
The drive end LED of backlight controller 20 1-LED 4Be connected respectively to light emitting diode string L 1-L 4, in order to draw light emitting diode string L 1-L 4Drive current, and the electric current that control makes each light emitting diode string of flowing through is all about equally, to reach the purpose of uniformly light-emitting.
Backlight controller 20 also can be from drive end LED 1-LED 4Whether have light-emitting diode abnormal situation (fault condition) take place, trigger corresponding protection if differentiating.For instance, if drive end LED 1On LED detecting voltage V LED-1Be 0 volt always, that light emitting diode string L 1May be an open circuit light emitting diode string, wherein have at least one diode to open a way; Backlight controller 20 is just closed light emitting diode string L 1Driving.This protection generally is referred to as open-circuit-protection.For another example, if drive end LED 1On LED detecting voltage V LED-1Far above drive end LED 2On LED detecting voltage V LED-2, that can pick out light emitting diode string L haply 1In some light-emitting diodes are arranged is short circuits, therefore close light emitting diode string L 1Driving.This protection generally is referred to as short-circuit protection.
Just, open-circuit-protection and short-circuit protection each other, interference that may be mutual.So the proper procedure deactivation need be arranged or close open circuit and short-circuit protection, so, just can reflect and really want the protection effect that obtains.
Summary of the invention
Embodiments of the invention disclose a kind of control method, are applicable to that control is used for the short-circuit protection mechanism of a plurality of light emitting diode string.A plurality of drive currents these light emitting diode string of flowing through respectively.This control method comprises: whether at least the low current event took place in detecting wherein any of these drive currents; When this crosses the generation of low current event, blocking short-circuit protection mechanism, wherein, this short-circuit protection mechanism can provide short-circuit protection to these light emitting diode string; And, in this short-circuit protection interdicted at least surpass Preset Time after, recover this short-circuit protection mechanism.
Embodiments of the invention disclose a kind of short-circuit protection control circuit, are applicable to control short-circuit protection mechanism.This short-circuit protection mechanism can provide short-circuit protection to a plurality of light emitting diode string.This short-circuit protection control circuit comprises circuit for detecting, first logical circuit and timer.This circuit for detecting is coupled to these light emitting diode string, and wherein any was lower than the low current reference value in order to the terminal voltage when these light emitting diode string, produced index signal.This first logical circuit when this index signal is enabled, begins to interdict this short-circuit protection mechanism.This timer, timing when this short-circuit protection mechanism is interdicted, and produce timing result.After this timing result showed that this short-circuit protection mechanism is interdicted at least and surpasses Preset Time, this first logical circuit recovered this short-circuit protection mechanism.
Description of drawings
Fig. 1 is a kind of LED power supply unit of the backlight module for LCD screen.
The backlight controller of Fig. 2 for implementing according to the present invention.
Show a kind of protective circuit among Fig. 3, can be used among Fig. 2.
Fig. 4 shows among Fig. 2 and Fig. 3, as light emitting diode string L 1Some signal waveforms when having become open circuit.
Fig. 5 shows another kind of protective circuit, can be used among Fig. 2.
Fig. 6 shows among Fig. 2 and Fig. 5, as light emitting diode string L 1Some signal waveforms when having become open circuit.
Fig. 7 shows another kind of circuit for detecting.
The timer of Fig. 8 display simulation.
Wherein, description of reference numerals is as follows:
18 LED power supply units
19 booster circuits
20 backlight controllers
22 1-22 4Decide current driver
24 1-24 4, 27 error amplifiers
26 feedback selectors
28,28 a, 28 bProtective circuit
30 pulse wave width modulation devices
50,50a circuit for detecting
52 or the door
54,54a and door
56 counters
57,57a timer
58 digital comparators
60 1-60 4, 80,90,94 comparators
62,82 SR flip-flops
64 protection decision circuitry
66 LED open loop protection circuits
68 LED short-circuit protection circuits
70 1-70 4, 92,98 pulse generators
96 electric capacity
The CLK frequency signal
The input of CLK-IN frequency
D 1-D 10Timing result
D S-1-D S-10Reference value
I LED-1Drive current
The IN input
L 1-L 4Light emitting diode string
LED 1-LED 4Drive end
N 1Nmos pass transistor
OVP overvoltage protection end
The OUT output
The R end of resetting
RD 1, RD 2Divider resistance
RS 1Current sense resistance
S DIMDim signal
S EN-1-S EN-4Select signal
S RESETReset signal
S SP-BLOCKShort circuit protection obstruction signal
t OP, t OVP, t RCVTime point
V C-SETSetting voltage
V DRVDrive signal
V LED-1-V LED-4LED detects voltage
V LED-MINMinimum detecting voltage
V OUTOutput voltage
V OVER-LOWThe low current reference value
V OVPDetecting voltage
V OVP-REFThe overvoltage reference value
V TARTarget voltage
V TIME-REFTime reference voltage
Embodiment
The backlight controller 20 of Fig. 2 for implementing according to the present invention can be for the LED power supply unit 18 of Fig. 1.In one embodiment, backlight controller 20 is the monocrystalline integrated circuit.In this manual, backlight controller 20 drives four light emitting diode string L is arranged 1-L 4In other embodiments, embodiments of the invention can drive the light emitting diode string of other number, are not limited to four.
In the backlight controller 20, decide current driver 22 1-22 4Be connected respectively to drive end LED 1-LED 4, the phase makes the light emitting diode string L that flows through 1-L 4Drive current I LED-1-I LED-4Approximately all equate, make light emitting diode string L 1-L 4Uniformly light-emitting.For instance, decide current driver 22 1 Error amplifier 24 is arranged 1, nmos pass transistor N 1, and current sense resistance R S 1From deciding current driver 22 1Circuit diagram can know by inference, when normal running, drive current I LED-1Can approximate setting voltage V greatly C-SETDivided by R RS1, wherein, R RS1Be current sense resistance R S 1Resistance value.Decide current driver 22 2-22 4Can infer current driver 22 by class 1Learn.
In one embodiment, feedback selector 26 is detected voltage V with LED LED-1-V LED-4In minimum one, as minimum detecting voltage V LED-MIN, give the backward end of error amplifier 27.The non-return termination of error amplifier 27 is received default target voltage V TARPulse wave width modulation device 30 produces and drives signal V according to the output of error amplifier 27 DRV, the power switch in the control booster circuit 19.When stable state, minimum detecting voltage V LED-MINBig appointment equals target voltage V TAR, can approximately make the LED power supply unit 18 of Fig. 1 operate in more efficient state like this.
Protective circuit 28 is according to the detecting voltage V on the overvoltage protection end OVP OVP, and drive end LED 1-LED 4On LED detecting voltage V LED-1-V LED-4, differentiate whether light emitting diode string L is arranged 1-L 4Abnormal situation takes place, and selects signal S to produce EN-1-S EN-4For instance, abnormal situation comprise LED open circuit event (having a string open circuit that presents in the light emitting diode string at least), LED short circuit event (having a string short circuit that presents in the light emitting diode string at least), etc.Protective circuit in other embodiment can be extraly or individually according to error amplifier 24 1-24 4Output or input, differentiate whether light emitting diode string L is arranged 1-L 4Abnormal situation takes place.For instance, if light emitting diode string L 1Assert the undesired situation that taken place, protective circuit 28 just forbidden energy is selected signal S EN-1The selection signal S of forbidden energy EN-1Make and decide current driver 22 1No longer drive light emitting diode string L 1, drive current I just LED-1Become 0 ampere.The selection signal S of forbidden energy EN-1Also can make minimum detecting voltage V LED-MINBe independent of LED detecting voltage V LED-1, just make feedback selector 26 can not choose LED detecting voltage V LED-1As minimum detecting voltage V LED-MIN
LED open circuit event may the false triggering short-circuit protection.For instance, if light emitting diode string L 1At time point, because certain reason has become open circuit; And light emitting diode string L 2-L 4Still normal.LED detecting voltage V LED-1Can approximate 0V greatly, cause minimum detecting voltage V LED-MINAlso be approximately 0V, be lower than target voltage V TARAt this moment, the output voltage of error amplifier 27 can be drawn high always, and pulse wave width modulation device 30 then makes booster circuit 19 improve the output electric energy, draws high output voltage V OUTAnd LED detecting voltage V LED-2-V LED-4Just in case circuit design is careful inadequately, this moment light emitting diode string L 2-L 4Be easy to be mistaken as the LED short circuit event taken place, and false triggering short-circuit protection because this moment, LED detecting voltage V LED-2-V LED-4To detect voltage V far above LED LED-1Or target voltage V TAR
Show a kind of protective circuit 28 among Fig. 3 a, when being used among Fig. 2, can prevent LED open circuit event false triggering short-circuit protection.Protective circuit 28 aIn have circuit for detecting 50, timer 57, protection decision circuitry 64, with door 54 and SR flip-flop 62.
In the circuit for detecting 50, comparator 60 1-60 4Be couple to light emitting diode string L respectively 1-L 4Comparator 60 1-60 4Output be coupled with the pulse generator 70 that rising edge triggers 1-70 4Pulse generator 70 1-70 4Output all be connected to or the door 52.Haply, whenever any one LED detecting voltage V LED-n(wherein n is an integer among the 1-4) was lower than low current reference value V OVER-LOWThe time, comparator 60 nBecome transition in logic " 1 ", thereby triggering pulse generator 70 nSend pulse, as index signal.This pulse will by or the door 52, come across reset signal S RESETIn.With light emitting diode string L 1Be example, as LED detecting voltage V LED-1Be lower than low current reference value V OVER-LOWThe time, just mean drive current I LED-1Also cross low, so assert light emitting diode string L 1The low current event has taken place to cross.As long as low current event, the reset signal S that circuit for detecting 50 is exported have taken place to cross in any a string light emitting diode string RESETOn pulse just appears.
Reset signal S RESETOn pulse SR flip-flop 62 can be set, the short circuit protection obstruction signal S of activation SR flip-flop 62 output SP-BLOCKReset signal S RESETOn the pulse timer 57 of also having reset, make timer 57 get back to its starting point, prepare to pick up counting.
In the protection decision circuitry 64 LED open loop protection circuit 66 and LED short-circuit protection circuit 68 are arranged, opened circuit protection mechanism and short-circuit protection mechanism are provided respectively.In one embodiment, assert when light emitting diode string the low current event had been taken place to cross, and detecting voltage V OVPSurpass overvoltage reference value V OVP-REFThe time, the opened circuit protection mechanism that LED open loop protection circuit 66 provides can assert that LED open circuit event has taken place that light emitting diode string, and the corresponding selection signal of forbidden energy, it is for selecting signal S EN-1-S EN-4One of them.In one embodiment, as LED detecting voltage V LED-nBe higher than short circuit reference value V SP-REFThe time, the short-circuit protection mechanism in the LED short-circuit protection circuit 68 can be assert light emitting diode string L nLED open circuit event has taken place, and forbidden energy is selected signal S EN-nAs short circuit protection obstruction signal S SP-BLOCKDuring for forbidden energy, LED short-circuit protection circuit 68 operate as normal provide short-circuit protection mechanism.As short circuit protection obstruction signal S SP-BLOCKDuring for activation, the short-circuit protection mechanism that LED short-circuit protection circuit 68 provides is interdicted, and just selects signal S instantly EN-1-S EN-4Can not be subjected to the detecting result of LED short-circuit protection circuit 68 and influence, or LED short-circuit protection circuit 68 is not comprehended LED detecting voltage V LED-1-V LED-4
Counter 56 and digital comparator 58 are arranged in the timer 57.Counter 56 is counted according to the signal of frequency input.Timing result D when counter 56 1-D 10When arriving certain condition, for example with reference value D S-1-D S-10The same, digital comparator 58 just produces pulse, replacement SR flip-flop 62, forbidden energy short circuit protection obstruction signal S SP-BLOCK, recover the short-circuit protection mechanism that LED short-circuit protection circuit 68 provides.
Frequency input with door 54 control counters 56.Only at dim signal S DIMWith short circuit protection obstruction signal S SP-BLOCKWhen all being activation, frequency signal CLK can be delivered to the frequency input of counter 56 with door 54.As dim signal S DIMDuring for activation, represent that normal light emitting diode string (also not being found to take place the light emitting diode string of undesired situation) needs are luminous.Otherwise, as dim signal S DIMBe forbidden energy, all light emitting diode string are not luminous.
In simple terms, as long as the low current event has taken place to cross in any a string light emitting diode string, will activation short circuit protection obstruction signal S SP-BLOCK, blocking short-circuit protection mechanism, and counter reset 56.56 calculating of counter are when normal light emitting diode string is luminous, and short circuit protection obstruction signal S SP-BLOCKBe the time out of going through under the activation.In a single day this time out arrives reference value D S-1-D S-10Behind the corresponding Preset Time, short circuit protection obstruction signal S SP-BLOCKWill be disabled, recover short-circuit protection mechanism.
In the embodiments of figure 3, when short-circuit protection mechanism was interdicted, if the low current event has taken place again once to cross, counter 56 can be reset again, prepares reclocking.In other embodiments, when short-circuit protection mechanism was interdicted, if the low current event has taken place again once to cross, counter can reclocking.
Fig. 4 shows among Fig. 2 and Fig. 3, as light emitting diode string L 1Some signal waveforms when having become open circuit, from top to bottom, voltage V is detected in representative respectively OVP, drive signal V DRV, LED detecting voltage V LED-2, LED detecting voltage V LED-1, select signal S EN-1, minimum detecting voltage V LED-MIN, reset signal S RESET, dim signal S DIM, timing result D 1-D 10, and short circuit protection obstruction signal S SP-BLOCK
Please be simultaneously with reference to Fig. 2, Fig. 3 and Fig. 4.Among Fig. 4, at time point t OPBefore, light emitting diode string L 1-L 4Almost all the same, also normal all, LED detecting voltage V LED-1-V LED-4With minimum detecting voltage V LED-MINAll approximate target voltage V greatly TAR
Suppose light emitting diode string L 1At time point t OPThe time become open circuit suddenly, and light emitting diode string L 2-L 4Still normal.Therefore, at time point t OP, LED detecting voltage V LED-1With minimum detecting voltage V LED-MINTwo all become 0V suddenly.Because LED detecting voltage V LED-1Less than low current reference value V OVER-LOWSo, time point t OPThe time, reset signal S RESETA pulse has appearred, short circuit protection obstruction signal S SP-BLOCKBe enabled.From time point t OPBeginning, the short-circuit protection mechanism that LED short-circuit protection circuit 68 provides is interdicted, and short-circuit protection no longer is provided.
In order to make minimum detecting voltage V LED-MINToward target voltage V TARError amplifier 27 approaches, so can cause output voltage V with pulse wave width modulation device 30 OUTWith detecting voltage V OVPTogether raise.The cross-pressure of a string normal light emitting diode string is roughly fixed, so LED detecting voltage V LED-2Along with output voltage V OUTRise and rise, still, because light emitting diode string L 1Be open circuit, so LED detecting voltage V LED-1, together with minimum detecting voltage V LED-MIN, still rest on 0V, not with output voltage V OUTChange and change.
Time point t OVPThe time, detecting voltage V OVPSurpass overvoltage reference value V OVP-REF, so LED open loop protection circuit 66 is assert LED detecting voltage V on the low side LED-1(being 0V now) corresponding light emitting diode string L 1The LED of generation open circuit event is arranged, so forbidden energy is selected signal S EN-1The selection signal S that is disabled EN-1Make minimum detecting voltage V LED-MINBreak away from LED detecting voltage V LED-1Administration, so minimum detecting voltage V LED-MINSuddenly high jump begins to follow the minimum in other normal LED detecting voltage, as shown in the figure.
Time point t OVPAfterwards, also in order to make minimum detecting voltage V LED-MINToward target voltage V TARApproach, so output voltage V OUTWith detecting voltage V OVPAlong with the loss of electric energy, slowly descend.
Counter 56 is at time point t OPIn time, be reset.Then, at luminous period (dimming ON), just dim signal S DIMDuring for activation, counter 56 is counted with frequency signal CLK.At not luminous period (dimming OFF), just dim signal S DIMDuring for forbidden energy, counter 56 does not receive frequency signal CLK, so counting suspends.At time point t RCVThe time, the timing result D of counter 56 1-D 10Equal reference value D S-1-D S-10, short circuit protection obstruction signal S SP-BLOCKBe disabled, recover the short-circuit protection mechanism that LED short-circuit protection circuit 68 provides.
Can find from Fig. 4, at time point t OPWith time point t RCVBetween, short circuit protection obstruction signal S SP-BLOCKBe enabled, so all light emitting diode string L 1-L NShort-circuit protection all interdicted and do not acted on.Also can learn time point t from Fig. 4 OPWith time point t RCVBetween, just the time out that interdicted of short-circuit protection mechanism approximates reference value D greatly S-1-D S-10Corresponding preset time and the summation of luminous period not.Therefore, if the enough length of Preset Time design, although LED detecting voltage V LED-2May be because light emitting diode string L 1Open circuit and higher, light emitting diode string L 2Can do not taken place by the short circuit event that is judged to be of mistake yet.
Fig. 5 shows another kind of protective circuit 28 b, when being used among Fig. 2, can prevent LED open circuit event false triggering short-circuit protection.The protective circuit 28 of Fig. 5 b Protective circuit 28 with Fig. 3 aIdentical or similar place can be learnt according to previous introduction for Fig. 3, is not repeated.
The protective circuit 28 of Fig. 3 aDifferent, the protective circuit 28 of Fig. 5 bAdditionally show SR flip-flop 82, comparator 80, with door 54a.In simple terms, as detecting voltage V OVPSurpass overvoltage reference value V OVP-REFAfterwards, comparator 80 can be set SR flip-flop 82, and frequency signal CLK can arrive the frequency input of counter 56, and counter 56 just can begin counting.At digital comparator 58 forbidden energy short circuits protection obstruction signal S SP-BLOCKThe time, SR flip-flop 82 also is reset, and is output as in logic " 0 ".
Fig. 6 shows among Fig. 2 and Fig. 5, as light emitting diode string L 1Some signal waveforms when having become open circuit, from top to bottom, voltage V is detected in representative respectively OVP, drive signal V DRV, LED detecting voltage V LED-2, LED detecting voltage V LED-1, select signal S EN-1, minimum detecting voltage V LED-MIN, reset signal S RESET, dim signal S DIM, timing result D 1-D 10, and short circuit protection obstruction signal S SP-BLOCK
Please refer to Fig. 5 and Fig. 6.Although at time point t OP, counter 56 is reset, timing result D 1-D 10Become 0, but SR flip-flop 82 be output as in logic 0, counter 56 does not receive frequency signal CLK, thus counter 56 do not begin the counting.Frequency signal CLK will wait until time point t OVPThe time, detecting voltage V OVPSurpass overvoltage reference value V OVP-REFAfterwards, can arrive the frequency input of counter 56, counter 56 begins counting.Therefore, from Fig. 6, can find time point t OPWith time point t RCVBetween, just the time out that interdicted of short-circuit protection mechanism approximates time point t greatly OPTo time point t OVPTime, reference value D S-1-D S-10Corresponding preset time and not luminous time period, the summation of three times.If reference value D S-1-D S-10All the same, the time out in Fig. 4, the time out of Fig. 6 is long, has had more time point t OPTo time point t OVPTime.
Fig. 7 shows another kind of circuit for detecting 50a, in other embodiments, replaces the circuit for detecting 50 among Fig. 3 and Fig. 5.Minimum detecting voltage V LED-MINApproximately correspond to LED detecting voltage minimum in the normal light emitting diode string.So, if minimum detecting voltage V LED-MINDrop to and be lower than low current reference value V OVER-LOWThe time, represent certain and also taken place to cross the low current event in luminous light emitting diode string, so the pulse generator 92 that comparator 90 triggers rising edge sends pulse.
The timer 57a of Fig. 8 display simulation in other embodiments, replaces the timer 57 of numerical digit among Fig. 3 and Fig. 5.Pulse on the frequency input CLK-IN can make the cross-pressure stepping (stepwise) on the electric capacity 96 rise.Cross-pressure reference voltage time of advent V when electric capacity 96 TIME-REFThe time, the pulse generator 98 that comparator 94 triggers rising edge sends pulse.Enable signal on the replacement end R can cause the cross-pressure of electric capacity 96 to become 0V, and timer 57a is counted with the pulse on the frequency input CLK-IN again.
In above embodiment, protective circuit provided by the present invention and control method have following characteristic: after the first, short-circuit protection mechanism takes place from mistake low current event, just begin to be interdicted; The second, the time out that interdicted of short-circuit protection mechanism is reference value D at least S-1-D S-10The corresponding preset time; Three, after the generation of each low current event excessively, counter recomputates; Four, in the not luminous period, counter can suspend counting.
The above is the preferred embodiments of the present invention only, is not limited to the present invention, and for a person skilled in the art, the present invention can have various changes and variation.Within the spirit and principles in the present invention all, any modification of doing, be equal to replacement, improvement etc., all should be included within protection scope of the present invention.

Claims (14)

1. control method is applicable to that control is used for the short-circuit protection mechanism of a plurality of light emitting diode string, wherein, a plurality of drive currents these light emitting diode string of flowing through respectively, this control method is characterised in that and comprises:
Whether at least the low current event took place in detecting wherein any of these drive currents;
When this crosses the generation of low current event, blocking short-circuit protection mechanism, wherein, this short-circuit protection mechanism can provide short-circuit protection to these light emitting diode string; And
In this short-circuit protection interdicted at least surpass Preset Time after, recover this short-circuit protection mechanism.
2. control method as claimed in claim 1 is characterized in that, comprising:
When this crosses the generation of low current event, the replacement timer.
3. control method as claimed in claim 2 is characterized in that, comprising:
When this crosses the generation of low current event, all reset this timer at every turn.
4. control method as claimed in claim 2 is characterized in that, other comprises:
When dim signal is forbidden energy, suspend this timer.
5. control method as claimed in claim 2 is characterized in that, this timer is to be counter, and when this short-circuit protection mechanism was interdicted, this counter was counted according to frequency signal.
6. control method as claimed in claim 1 is characterized in that, other comprises:
When this crosses the generation of low current event, counter reset; And
When the count results of this counter surpasses defaultly as a result the time, recover this short-circuit protection mechanism.
7. control method as claimed in claim 2 is characterized in that, other comprises:
Detect these light emitting diode string, come the voltage stabilizing out-put supply, wherein, this out-put supply is in order to drive
These light emitting diode string;
Detect this out-put supply; And
After this out-put supply surpasses overvoltage value, begin to make this timer timing.
8. control method as claimed in claim 2 is characterized in that, other comprises:
Detect these light emitting diode string, come the voltage stabilizing out-put supply, wherein, this out-put supply is in order to drive these light emitting diode string;
Relatively this out-put supply and overvoltage value; And
When this out-put supply surpasses this overvoltage value, and be somebody's turn to do after the low current event takes place, began to make this timer timing.
9. a short-circuit protection control circuit is applicable to control short-circuit protection mechanism, and wherein, this short-circuit protection mechanism can provide short-circuit protection to a plurality of light emitting diode string, and this short-circuit protection control circuit is characterised in that and comprises:
Circuit for detecting is coupled to these light emitting diode string, and wherein any was lower than the low current reference value in order to the terminal voltage when these light emitting diode string, produced index signal;
First logical circuit when this index signal is enabled, begins to interdict this short-circuit protection mechanism; And
Timer, timing when this short-circuit protection mechanism is interdicted, and produce timing result;
Wherein, after this timing result shows that this short-circuit protection mechanism is interdicted at least and surpasses Preset Time,
This first logical circuit recovers this short-circuit protection mechanism.
10. short-circuit protection control circuit as claimed in claim 9 is characterized in that, this circuit for detecting comprises:
At least one pulse generator when wherein any is lower than this and crosses the low current reference value, sends pulse, to begin to interdict this short-circuit protection mechanism in these terminal voltages.
11. short-circuit protection control circuit as claimed in claim 10 is characterized in that, this pulse this timer of resetting.
12. short-circuit protection control circuit as claimed in claim 9 is characterized in that this timer has the frequency input, this short-circuit protection control circuit comprises in addition:
Second logical circuit is when dim signal is activation, in order to transmit frequency signal to this frequency input.
13. short-circuit protection control circuit as claimed in claim 9 is characterized in that this timer has the frequency input, this short-circuit protection control circuit comprises in addition:
Second logical circuit is coupled to this frequency input and this first logical circuit, when this short-circuit protection mechanism is resumed, in order to stop this frequency signal, makes it can't be to this frequency input.
14. short-circuit protection control circuit as claimed in claim 9 is characterized in that this timer has the frequency input, this short-circuit protection control circuit comprises in addition:
Whether the overvoltage circuit for detecting surpasses overvoltage value in order to detect out-put supply; And
Second logical circuit is coupled to this frequency input, this first logical circuit and this overvoltage
Circuit for detecting, after this short-circuit protection mechanism is by blocking, and this out-put supply does not surpass this mistake
During magnitude of voltage, in order to stop this frequency signal, make it can't be to this frequency input.
CN2012100322449A 2012-02-14 2012-02-14 Short-circuit protection control circuit and relevant control method Pending CN103249208A (en)

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN109362146A (en) * 2018-10-09 2019-02-19 成都芯源系统有限公司 Short circuit/open circuit protection circuit and method
WO2021031753A1 (en) * 2019-08-16 2021-02-25 上海禾赛光电科技有限公司 Safe charging circuit for light-emitting module, protection method and laser radar emission system

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Application publication date: 20130814