CN100468939C - DC/AC conversion driving circuit - Google Patents
DC/AC conversion driving circuit Download PDFInfo
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- CN100468939C CN100468939C CNB2005101317503A CN200510131750A CN100468939C CN 100468939 C CN100468939 C CN 100468939C CN B2005101317503 A CNB2005101317503 A CN B2005101317503A CN 200510131750 A CN200510131750 A CN 200510131750A CN 100468939 C CN100468939 C CN 100468939C
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Abstract
The invention is concerned with a DC/AC transition driving circuit to drive fluorescence lamp with at lest one switch, controller, resonant groove circuit and feedback loop. The at least one switch connects the first electrical source. The controller exports at least one driving signal to the at least one switch and controls the export or close states of the electric power of the first electrical source. The resonant groove circuit owns the first side and the second side, and the first side couples the at least switch, the second side couples the fluorescence lamp to afford the electric power of this fluorescence lamp. The feedback loop couples this fluorescence lamp and sends direction signal to controller when the fluorescence lamp is guiding. After starting the DC / AC transition driving circuit, the controller controls the at least one driving control signal as the first operation frequency, and after accepting the direction order, changes the first operation frequency as the second frequency and locks this second frequency.
Description
Technical field
The present invention provides a kind of DC/AC conversion driving circuit and controller thereof, refers to a kind of DC/AC conversion driving circuit and controller thereof with soft start especially.
Background technology
(Liquid Crystal Display LCD) has the advantage of thin typeization to LCD, and therefore more traditional CRT does not take up space, and the billboard in domestic TV that is applied to maximize or public place has had general gradually trend.But the operation of LCD principle be utilize its liquid crystal material revolve optical activity (Optical Rotary Power) and electrooptics characteristic, come a kind of flat-panel screens of display image and Word message, itself does not have emitting characteristics, therefore the backlight that need add is as auxiliary, and its backlight commonly used is generally the light source of fluorescent lamp and so on.
AC/DC conversion fluorescence lamp drive circuit on typical prior art generally abbreviates converter (inverter) as.When being used for LCD application backlight, mostly adopt fixing frequency operation, the invention provides a kind of control method, the design of converter is more prone to according to fluorescent lamp conduction status decision frequency of operation for reducing to disturb.
Summary of the invention
Main purpose of the present invention provides a kind of circuit design of AC/DC conversion fluorescence lamp drive circuit, can reach the easy purpose of design with the mode driving fluorescent lamp of suitable operating frequency control semiconductor switch.
Another object of the present invention provides a kind of circuit design with AC/DC conversion fluorescence lamp drive circuit of soft start, the abrupt voltage wave of circuit in the time of can suppressing to start.
A further object of the present invention provides a kind of circuit design with AC/DC conversion fluorescence lamp drive circuit of digital latch circuit, can be behind fluorescent tube point, change the frequency of operation and the locking of fluorescent tube, frequency of operation is dropped near the resonance frequency of resonance trough always.
Thereby, in order to reach above purpose, the invention provides a kind of controller that is used for power driving circuit, comprise frequency generator, pulse width modulator and drive circuit.This frequency generator comprises latch cicuit, and after this controller starts, provides the pulse signal with first frequency, and after this latch cicuit received index signal, this first frequency that changes this pulse signal was a second frequency, and is locked in this second frequency.This pulse width modulator is according to this pulse signal and indicate the feedback signal of this power driving circuit supply of electric power state that pulse-width signal is provided.This drive circuit is controlled a plurality of semiconductor switchs according to this pulse-width signal.
The present invention also provides a kind of DC/AC conversion driving circuit, is used for the driving fluorescent lamp pipe, comprises at least one switch, controller, resonance trough circuit and feedback loop.This at least one switch connects first power supply.This controller is exported at least one drive control signal to correspond to this at least one switch respectively, serves as output or closed condition with the electric power of controlling this first power supply.This resonance trough circuit has first side and second side, this at least one switch of this first side coupling, and this second side this fluorescent tube that is coupled is to provide this fluorescent tube electric power.This feedback loop, this fluorescent tube that is coupled, and when this fluorescent tube conducting, export index signal to this controller.Wherein, this controller is controlled this at least one drive control signal in first frequency of operation after this DC/AC conversion driving circuit starts, and after accepting this index signal, changing this first frequency of operation is a second frequency, and is locked in this second frequency.
The present invention also provides a kind of protective circuit, is used to protect the operation of power driving circuit, comprises: comparator, receive detection signal and reference voltage, and when the pass of this detection signal and this reference voltage is when conforming to a predetermined condition, the output comparison signal; And logic control circuit; receive this comparison signal and pulse wave signal; when receiving this comparison signal; promptly produce status signal; and the time span that produces each this status signal is that the time span of the duty ratio of this pulse wave signal is a prearranged multiple; when the duration length of the duration of this status signal length or non-this status signal surpasses the scheduled time during length, the output protection signal.
The present invention must pass through with following diagram and detailed description, in order to do getting more deep understanding.
Description of drawings
Fig. 1 a to 1d is the AC/DC conversion fluorescence lamp drive circuit schematic diagram of preferred embodiment of the present invention.
Fig. 2 a-1 to 2a-4,2b-1 to 2b-4 and 2c-1 to 2c-4 are the AC/DC conversion fluorescence lamp drive circuit protective circuit part signal waveform schematic diagram of preferred embodiment of the present invention.
Fig. 3 revises the schematic diagram that partial circuit becomes another embodiment for the AC/DC conversion fluorescence lamp drive circuit of this case preferred embodiment.
Fig. 4 revises the schematic diagram that partial circuit becomes another embodiment for the AC/DC conversion fluorescence lamp drive circuit of this case preferred embodiment.
[main element label declaration]
201,201 ', 201 " direct voltage source
201A indication control system voltage source
202,202 ', 202 " semiconductor power switch
202A PMOS semiconductor power switch
202B NMOS semiconductor power switch
P1, P2 PMOS semiconductor power switch
N1, N2 NMOS semiconductor power switch
203 resonance troughs, 204 fluorescent lamps
205 fluorescent lamp current detection circuits
206 fluorescent lamp terminal voltage testing circuits
207 pulse width modulators
208 fluorescent lamp frequency generators
209 drive circuits
209a, 209a ', 209a " signaling conversion circuit
210 protective circuits, 211 timers
221 step-up transformers
222,223,224 resonating capacitors
261 error amplifiers, 262 resistance
263 electric capacity, 264 comparators
265 controlled current sources, 266 switches
267 switches, 268 soft start current sources
269 soft start comparators
The 270AND gate
OUT1, OUT2 drive output signal
271 soft start capacitors
272 logic control circuits
274,275,276 comparators
281,282 comparators
283 current sources
284 time capacitors, 285 transistors
286 digital latch circuit
291,292 inverters
Embodiment
Seeing also Fig. 1 a to 1d is the AC/DC conversion fluorescence lamp drive circuit schematic diagram of this case preferred embodiment.Shown in Fig. 1 a to 1d, AC/DC conversion fluorescence lamp drive circuit comprises direct voltage source 201, one group of semiconductor switch 202, resonance trough 203, fluorescent lamp 204, fluorescent lamp current detection circuit 205, fluorescent lamp terminal voltage testing circuit 206, pulse width modulator 207, fluorescent lamp frequency generator 208, drive circuit 209, signaling conversion circuit 209a, protective circuit 210 and timer 2 11.
Its electrical connection is as described below: this direct voltage source 201 is coupled to this semiconductor switch 202.The output of this semiconductor switch 202 is coupled to the input of this resonance trough 203.The output of this resonance trough 203 is coupled to an end of this fluorescent lamp 204, and this resonance trough 203 includes a step-up transformer 221 and resonating capacitor 222,223,224.
The two ends of this fluorescent lamp 204 are coupled respectively to this fluorescent lamp current detection circuit 205 and this fluorescent lamp terminal voltage testing circuit 206.This fluorescent lamp current detection circuit 205 also is electrically connected to this pulse width modulator 207, and this pulse width modulator 207 is coupled to this fluorescent lamp frequency generator 208 and this drive circuit 209.This drive circuit 209 is coupled to this semiconductor switch 202 behind signaling conversion circuit 209a, form so-called control loop.
Wherein, this semiconductor switch 202 comprises two semiconductor switch 202A and 202B.This semiconductor switch 202A can be P-type mos (PMOS) switch and reaches, this switch 202B can be N type metal oxide semiconductor (NMOS) switch, but two semiconductor switch 202A and 202B are not limited to metal-oxide semiconductor (MOS) (MOS) switch, also can be all kinds of transistor switches, as BJT of NPN or positive-negative-positive etc.
This fluorescent lamp frequency generator 208 produces the triangular signal S2 and the pulse wave signal S1 of same frequency.Yet in the present invention, triangular signal S2 is not limited to the use of triangular signal, all any slopes (Rampsignal) or sawtooth signal all is applicable to the present invention.
This fluorescent lamp current detection circuit 205 is connected with this fluorescent lamp 204, and the conduction status that provides a signal S3 to be used to indicate this fluorescent lamp, and another signal S4 is used to indicate the current value that flows through this fluorescent lamp.This fluorescent lamp terminal voltage testing circuit 206 is by this resonance trough 203 in parallel with this fluorescent lamp 204, utilizes resonant capacitor 223,224 wherein and detects the terminal voltage that signal S5 is used to indicate this fluorescent lamp 204.
This pulse width modulator 207 comprises inverting integrator and the comparator 264 that error amplifier 261, resistance 262 and electric capacity 263 are formed.In addition, this pulse width modulator 207 also comprises current source 265, switch 267, and this current source 265 is connected to the end of oppisite phase input of this error amplifier 261 via switch 267, and this switch 267 is indicated the terminal voltage feedback signal S17 of this fluorescent lamp 204 to control.
The current source 268 that in this pulse width modulator 207, also comprises soft start (Soft-Start) comparator 269 and control soft start in addition, and the capacitor 271 of control soft start.
The output S8 of this pulse width modulator 207 is that both produce after 270 computings of AND gate by comparator 264 output S8a and soft start comparator 269 output S8b.
This protective circuit 210 comprises logic control circuit 272, and this protective circuit 210 receives this signal S3 of being used for indicating the fluorescent lamp conduction status, be used to indicate the output signal S6 of the error amplifier 261 of this signal S5 of fluorescent lamp terminal voltage and this pulse width modulator 207.
This timer 2 11 is made up of two groups of comparators 281,282 and current source 283.
This drive circuit 209 receives pulse width modulator 207 output S8; and cooperate the pulse wave signal S1 of fluorescent lamp frequency generator 208 outputs and the output signal S18 of protective circuit 210 to produce two drive output signal OUT1 and OUT2; wherein inverter 292 rear drives of OUT1 in signaling conversion circuit 209a are in order to control semiconductor switch 202A, and OUT2 then directly controls semiconductor switch 202B.
In the present embodiment, the timing mode of this timing circuit 211 is to utilize 283 pairs of time capacitors of this current source 284 charging, the voltage S12 that makes this time capacitor 284 in time increase and rise.Before the voltage S12 of this capacitor 284 surpasses reference level Vref 1, send and reset signal S11, and the time of sending when the voltage S12 of this time capacitor 284 rises to above reference level Vref 2 is to (TimeOut) signal S10.The signal of reseting that signal S11 can be used as analog or digital circuit (for example: pulse width modulator 207, logic control circuit 272, drive circuit 209 and fluorescent lamp frequency generator 208) in the circuit is reseted in utilization, can reset circuit when making opportune moment.This current source 283 and the signal S13 control that is subjected to indicating control system voltage source 201A, when the direct voltage source 201A of this control system voltage is lower than reference level Vref 3, this current source 283 is closed (off), and with the voltage S12 of this time capacitor 284 by transistor 285 ground connection by control signal S13 control.Can make system when control system begins to start this direct voltage source 201A by no-voltage each time by such design, this time capacitor 284 on this timer 2 11 all is to begin charging by no-voltage.
Direct voltage source in the present embodiment has two, one direct voltage sources 201 that provide driving fluorescent lamp 204, and another then provides the required control system direct voltage source 201A of The whole control system operation.In the present embodiment, both voltage and inequality.And in the application of many reality, also can be identical voltage source.And present embodiment is the interference that other control circuit is caused can reduce semiconductor switch 202 and switch the time with the benefit of different voltage sources.
Fluorescent lamp frequency generator 208 in the present embodiment also is subjected to signal S14 control, and whether this signal S14 is the conducting of indication fluorescent lamp.Also have a digital latch (Digital Latch) circuit 281 to cooperate the whether signal S14 control fluorescent lamp frequency generator 208 of conducting of indication fluorescent lamp in the present embodiment.When control system just is activated, is reseted signal S11 and the output S14a of this digital latch circuit 286 can be set in fluorescent lamp 204 state of conducting not as yet by what timing circuit 211 sent.In case the fluorescent lamp conducting, the output S14a of this digital latch circuit 286 then can be set (and locking) state at fluorescent tube conducting.This fluorescent lamp frequency generator 208 is at the output S14a of this digital latch circuit 286 indication fluorescent lamp 204 as yet not under the situation of conducting, send the fluorescent lamp starting frequency, and under the situation of the output S14a of this digital latch circuit 286 indication fluorescent lamp 204 conducting, send another fluorescent lamp frequency of operation to drive circuit 209.At present embodiment, the preferred configuration of this circuit is that from then on the frequency of operation that outputs to fluorescent lamp 204 is fixed on this frequency and changed by other control signal.Whether the advantage of the conducting decision fluorescent lamp frequency of operation resonance frequency that is this resonance trough 203 is in fluorescent lamp its situation of conducting and inequality whether with fluorescent lamp 204 in the present embodiment, and such design can utilize different fluorescent lamp frequencies to carry out the operation of different conducting situations.The system of operate as normal can operated near the resonance frequency of resonance trough 203 under the situation of fluorescent lamp 204 different conductings, make the more efficient running of system.This signal S14 is that the comparator 274 in this signal S3 of being provided by this fluorescent lamp current detection circuit 205 and this protective circuit 210 determine, and as this indication fluorescent lamp Continuity signal S3 during above reference level Vref 4, this fluorescent lamp 204 is regarded as conducting.
Under normal condition, present embodiment is operated as described below in more detail:
After system begins the power supply starting, this timer 2 11 begins 284 chargings of this time capacitor, when these time capacitor 284 voltages are uncharged reach this reference level Vref 1 before, this that sent by this timer 2 11 reseted signal S11 with transistor 266 conductings (turn on) ground connection and make soft start current source 268 stop output current, the output S8b that forces comparator 269 is zero duty ratio, so that the duty ratio of the output S8 of pulse width modulator 207 becomes 0%.
And drive circuit 209 also makes OUT1 and OUT2 also all become 0% duty ratio by inverter 291 to stop semiconductor switch 202 conductings reseting signal S11.
When this time capacitor 284 continues to be charged to greater than after this reference level Vref 1, reset signal S11 cancellation and reset transistor switch 266 that state makes this ground connection by (turn off), 268 of soft start current sources produce the voltage signal S20 that slowly rises to soft start capacitor 271 chargings and at this electric capacity 271.
Another comparator 269 of pulse width modulator 207 then is the voltage signal S20 that slowly rises on soft start capacitor 271 of comparison and triangular signal S2 and produce duty ratio by the 0% pulse-width signal S8b that slowly increases.
These two groups of pulse-width signals: the S8a of 100% duty ratio and after 0% S8b that slowly increases duty ratio is through 270 computings of AND logic generation from the 0% pulse-width signal S8 that slowly increases duty ratio.That is, this this direct voltage source 201 of semiconductor switch 202 conductings to the increase of resonance trough 203 duty ratios is no more than set rate.
This drive circuit 209 receives this this pulse-width signal S8 and pulse wave signal S1, produce two groups of signal OUT1 and OUT2 behind signaling conversion circuit 209a, drive respectively semiconductor switch 202A and 202B by or conducting output to the electric power of fluorescent lamp 204 with adjustment.
Before the conducting, fluorescent lamp terminal voltage S16's this fluorescent lamp 204 can not raise because of the increase gradually of this pulse-width signal S8 duty ratio.This protective circuit 210 is sent the fluorescent lamp terminal voltage and is surpassed signal S17 the inverting input of 267 conductings of the switch on the current source 265 (Turn On) to this error amplifier 261 detecting when this indication fluorescent lamp terminal voltage signal S5 surpasses default reference level Vref 6; 261 output S6 diminish this error amplifier, reduce its corresponding pulse-width signal S8a duty ratio then.
In case the pulse-width signal S8b that the duty ratio of pulse-width signal S8a slowly rises less than soft start.Then the pulse-width signal S8 of this pulse width modulator 207 promptly reduces duty ratio is transported to this fluorescent lamp 204 with minimizing electric power.
If causing, this result who reduces the electric power conveying detecting indication fluorescent lamp terminal voltage signal S5 less than this default reference potential Vref6, then this current supply switch 267 is by (OFF), and then this error amplifier 261 output S6 become big and make the pulse-width signal S8 of this pulse width modulator 207 increase.So this fluorescent lamp terminal voltage S16 just obtains stable regulation under such negative feedback control.
And be stabilized in the process of adjusting at fluorescent lamp terminal voltage S16, the voltage S20 of soft start capacitor 271 still continues to rise to make the pulse-width signal S8b of comparator 269 output become and keeps 100%.Because pulse-width signal S8b keeps 100%, so the duty ratio of pulse-width signal S8 after this of pulse width modulator 207 determined by the pulse-width signal S8a that comparator 264 is produced.
In case fluorescent lamp is lighted conducting down by enough voltage S16 and time, according to fluorescent lamp characteristics, the fluorescent lamp terminal voltage S16 of this conducting can rapid drawdown to half less than and approximate fixing operating voltage, make this fluorescent lamp voltage detecting circuit 206 because do not produce an indication fluorescent lamp terminal voltage signal S5 above Vref6, and ineffective.This fluorescent lamp current detection circuit 205 is sent indication fluorescent lamp Continuity signal S3 to this protective circuit 210 simultaneously; produce the output frequency that this indicating lamp tube Continuity signal S14 changes this fluorescent lamp frequency generator 208; also send the error amplifier 261 of this indication fluorescent lamp current signal S4, the electric current of the fluorescent lamp of flowing through is stabilized on the default value by negative feedback control to this pulse width modulator 207.
The defencive function that the protective circuit 210 of present embodiment can reach includes: fluorescent tube does not connect, fluorescent tube damages, transformer electric leakage etc., and its detailed operating conditions is as described below:
When fluorescent lamp 204 did not ad initio just connect, indication fluorescent lamp terminal voltage signal S5 can continue to send the fluorescent lamp terminal voltage and surpass the message of this signal Vref6 to this digital control logic 272.This digital control logic 272 can be reset signal S11 and reset when control system is just started, all protection actions of reseting back digital control logic 272 all can be cancelled.And when this signal S10 sends into, be not failure to actuate.In case this signal S10 sends to this digital control logic 272, then this digital control logic 272 can be indicated under the too high situation of this fluorescent lamp terminal voltage above this signal Vref6 in this fluorescent lamp terminal voltage, this pulse wave signal S1 timing that the digital timing unit of utilization in digital control logic 272 produces with this fluorescent lamp frequency generator 208, in case the default time of digital timing unit that this fluorescent lamp terminal voltage surpasses in digital control logic 272 still is too high, then this digital control logic 272 is sent the signal S18 that stops to export to this drive circuit 209, stops the conducting of 202A and 202B in this semiconductor switch.
When fluorescent lamp damages open circuit in operation; this fluorescent lamp current detection circuit 205 can transmit signal S3 and indicate this not conducting of fluorescent lamp, sends indication fluorescent lamp Continuity signal S14 (message of not conducting of indication fluorescent lamp) to this digital control logic 272 behind this comparator 274 of this protective circuit 210.With above-mentioned, this digital control logic 272 is not failure to actuate when this signal S10 sends into.In case the time arrives, then this digital control logic 272 can be under the situation of not conducting of indication fluorescent lamp Continuity signal S14 indication fluorescent lamp, utilize digital timing unit with pulse wave signal S1 timing, in case fluorescent lamp surpasses default still not conducting of time, then this digital control logic 272 is sent the signal S18 that stops to export and is arrived this drive circuit 209, stops this semiconductor switch 202A, 202B conducting.
In addition, when badly damaged, because the extra load effect that electric leakage causes, the system that will make produces the overload phenomenon if run into that this transformer 221 has electric leakage under the situation of general operation.Under this situation, this error amplifier 261 will continue to increase its output S6 and stablize the fluorescent lamp electric current so that enough electric power to loads to be provided.In case electric leakage surpassed system can provide during maximum power, this error amplifier 261 output S6 certainly will be above the peak value of this triangular wave S2.This protective circuit 210 is compared this error amplifier 261 output S6 with the reference potential Vref7 slightly higher than triangular wave S2 peak value can obtain whether overload signal S19 of indication mechanism.Equally; start under the situation of this protective circuit 210 with S10 at this timer 2 11; if indication mechanism whether transship by overload signal S19 indication mechanism; when this pulse wave signal S1 timing that produces with fluorescent lamp frequency generator 208 through this digital control logic 272 also surpasses Preset Time again; then this digital control logic 272 is sent the signal S18 that stops to export and is arrived this drive circuit 209, stops the conducting of this semiconductor switch 202A and 202B.
Fig. 2 a-1 to 2a-4,2b-1 to 2b-4 and 2c-1 to 2c-4 are used for illustrating that present embodiment implements the sequential chart of a kind of implementation method of defencive function.At Fig. 2 a-1 to 2a-4 is a kind of embodiment of open-circuit-protection. what show in Fig. 2 a-1 is the voltage waveform that indication fluorescent lamp Continuity signal S3 delivers to protective circuit 210.S3 can be a voltage greater than Vref4 or less than the pulse wave of Vref4 for example is Pulse (1) or Pulse (2) or Pulse (n) among the figure.
Present embodiment relatively produces output signal S14 in the back as indication fluorescent lamp Continuity signal S3 and Vref4 in Fig. 2 a-2 figure; the time to signal S10 under digital control logic 272 situations in the start protection circuit 210; the falling edge of S14; as Fig. 2 a-3; triggered digital control logic 272 with the rising edge of several (present embodiment are three) pulse wave signal S1 as postponing td, and produce internal signal S3 ".
In Fig. 2 a-1, S3 is single Pulse (1) when indication fluorescent lamp Continuity signal, then the internal signal S3 that produces of digital control logic 272 " be the pulse wave signal Pulse to t3 (1 ") from t1.If but indication fluorescent lamp Continuity signal S3 is the pulse wave signal that produces continuously as Pulse (1), Pulse (2), the internal signal S3 that produces of digital control logic 272 then " be the pulse wave signal Pulse to t4 (2 ") from t1.In the present embodiment, the time of digital control logic 272 error detections is just as time T _ ERR_OPEN of calculating t4～t5 of Fig. 2 a-4.If T_ERR_OPEN is no more than preset time, digital control logic 272 is just removed the New count of laying equal stress on this error result, in case T_ERR_OPEN surpasses preset time, digital control logic 272 just this error result is pinned with the latch cicuit of inside and output S18 signal to stop the semiconductor switch conducting in the semiconductor switch 202.
To indicate fluorescent lamp Continuity signal S3 to change into internal signal S3 through digital control logic 272 " do timing action again and judge whether that the benefit of misoperation has two: one, can control the susceptibility of Error Detection Unit and avoid frequent false alarm; The 2nd, can directly use pulse wave as detection signal.Usually, be used for adding capacitor filtering on the path of the indication fluorescent lamp Continuity signal S3 that judges; Utilize the method error detection of present embodiment then need not use filter capacitor.
That show in Fig. 2 b-1 to 2b-4 is a kind of embodiment of over-voltage protection method.Indication fluorescent lamp terminal voltage signal S5 delivers to the voltage waveform of protective circuit 210.S5 can be a voltage greater than Vref6 or less than the pulse wave of Vref6 for example the Pulse shown in Fig. 2 b-1 (11), Pulse (12) ... Pulse (1n).The time to signal S10 under digital control logic 272 situations in the start protection circuit 210; the signal S5 voltage signal of indication fluorescent lamp terminal voltage is relatively producing pulse wave signal S17 in the back through comparator 276, the Pulse (11 ') shown in Fig. 2 b-2, Pulse (12 ') ..., Pulse (1n ').These pulse wave signals S17 is received by digital control logic 272, and cooperation pulse wave signal S1, digital control logic 272 is triggered by the rising edge of pulse wave signal S17, and three rising edges that utilize pulse wave signal S1 are as td ' time of delay, and produces another inner pulse wave signal S5 ".
In the embodiment of Fig. 2 b-1 to 2b-4, when the signal S5 of indication fluorescent lamp terminal voltage is single pulse wave signal Pulse (11), then will produce a corresponding pulse bandwidth at digital control logic 272 is the inside pulse wave signal Pulse to t3 (11 ") from t1.If the signal S5 of indication fluorescent lamp terminal voltage be the pulse wave signal Pulse (11), the Pulse (12) that occur continuously ... it is the inside pulse wave signal Pulse to t6 (1n ") from t1 that Pulse (1n) then will produce a corresponding pulse bandwidth at digital control logic 272.The Error Detection Unit of digital control logic 272 is with time T _ ERR_OVER of calculating the inner pulse wave signal Pulse of this section appearance (1n ") from t1 object as timing.When T_ERR_OVER less than Preset Time, digital control logic 272 is just removed the New count of laying equal stress on this error result.In case T_ERR_OPEN surpasses preset time, digital control logic 272 just this error result is pinned with the latch cicuit of inside and output S18 signal to stop the semiconductor switch conducting in the semiconductor switch 202.
Is to avoid frequent false alarm by the susceptibility that the mode that postpones can be controlled Error Detection Unit with present embodiment as the benefit of protected mode.
That show in Fig. 2 c-1 to 2c-4 is a kind of embodiment of overload protection method.Pulse among Fig. 2 c-1 (21), Pulse (22) ... Pulse (2n) is the voltage waveform S6 that protective circuit 210 is delivered in error amplifier 261 outputs.S6 can be a voltage greater than Vref7 or less than the pulse wave of Vref7.S6 produces output signal S19 through comparator 275 and Vref7 after relatively, as the Pulse (21 ') among Fig. 2 c-2, Pulse (22 ') ... Pulse (2n ').
The time to signal S10 under digital control logic 272 situations in the start protection circuit 210; the rising edge that S6 produces output signal S19 after relatively through comparator 275 and Vref7 can triggered digital control logic 272 utilizes pulse wave signal, as three rising edges as postponing td " produce inner pulse wave signal S6 ".
In the embodiment of Fig. 2 c-1 to 2c-4, S6 are single pulse wave signal Pulse (21) when error amplifier 261 output, and then will produce a corresponding pulse bandwidth at digital control logic 272 is the inside pulse wave signal Pulse to t3 (21 ") from t1.If error amplifier 261 output S6 be the pulse wave signal Pulse (21), the Pulse (22) that occur continuously ... Pulse (2n) then digital control logic 272 will produce a corresponding pulse bandwidth for from t1 to t6 inside pulse wave signal Pulse (2n ").The Error Detection Unit of digital control logic 272 is with time T _ ERR_LEAK of calculating the inner pulse wave signal Pulse of this section appearance (1n ") from t1 object as timing.When T_ERR_LEAK less than Preset Time, digital control logic 272 is just removed the New count of laying equal stress on this error result.In case T_ERR_LEAK surpasses preset time, digital control logic 272 just this error result is pinned with the latch cicuit of inside and output S18 signal to stop the semiconductor switch conducting in the semiconductor switch 202.
Is to avoid frequent false alarm by the susceptibility that the mode that postpones can be controlled Error Detection Unit with present embodiment as the benefit of protected mode.
The present invention can also be according to the actual needs on using with other different modes driving fluorescent lamp 204, for example the signaling conversion circuit 209a among the embodiment in Fig. 1 b can be the design shown in 209a ' among Fig. 3, and semiconductor switch 202 can be the form that design (also can the be PMOS) transformer 221 of two NMOS of usefulness shown among Fig. 3 202 ' has then become among Fig. 3 221 ' center tap.(direct voltage source 201 ' then is to correspond to direct voltage source 201).The circuit that primary side connected of transformer 221 ' then can be that the circuit that connected with transformer 221 primary side is the same.
The present invention also can be with full-bridge type semiconductor switch driving fluorescent lamp 204 after adding some peripheral components.Fig. 4 is one of preferred embodiment.In this embodiment, signaling conversion circuit 209a " (with respect to signaling conversion circuit 209a) produce OUT1P, OUT1N and OUT2P, OUT2N respectively after the OUT1 of self-driven circuit 209 outputs and OUT2 conversion, to control semiconductor switch 202 respectively " P1, N1 and P2, N2 in (with respect to semiconductor switch 202).With with direct voltage source 201 " electric power of (with respect to direct voltage source 201) is sent to resonant capacitance 222 in the mode of pulse wave " (with respect to resonant capacitance 222) and transformer 221 " (with respect to transformer 221).In the present embodiment, transformer 221 " the circuit that primary side connected, then can be that the circuit that connected with transformer 221 primary side is the same.
Timer among the present invention, protective circuit also can be applied to various power supply circuits, and are not limited to AC/DC converter.Moreover the present invention is to be that preferred embodiment of the present invention describes with fluorescent lamp, is not applied to fluorescent lamp yet do not limit to, and the discharge lamp of any kind of or load all are applicable to the disclosed technology of the present invention.
The present invention must be appointed by those skilled in the art and executes that the craftsman thinks and be to modify right neither taking off as claims Protector that scope is desired as all.
Claims (21)
1. controller that is used for power driving circuit comprises:
Frequency generator, comprise latch cicuit, this frequency generator is after this controller starts, pulse signal with first frequency is provided, after this latch cicuit receives the index signal of the load conducting that is used to indicate this power driving circuit, this first frequency that changes this pulse signal is a second frequency, and is locked in this second frequency;
Pulse width modulator, this pulse width modulator is according to this pulse signal and indicate the feedback signal of this power driving circuit supply of electric power state that pulse-width signal is provided; And
Drive circuit is controlled a plurality of semiconductor switchs according to this pulse-width signal.
2. controller according to claim 1, wherein this pulse width modulator comprises the soft start unit, and this soft start unit begins to export soft-start signal after this controller starts, make this pulse width modulator provide this pulse-width signal according to this soft-start signal.
3. controller according to claim 2, wherein this soft start unit comprises soft start comparator, soft start current source and soft start capacitor device, this soft start electric current comes from this controller and starts the back this soft start capacitor is charged, this soft start comparator according to the voltage signal of this soft start capacitor and this pulse signal to export this soft-start signal.
4. controller according to claim 1; also comprise protective circuit; this protective circuit is judged the supply of electric power state of this power driving circuit to load according to the signal of the feedback loop of this power driving circuit, when the supply of electric power state of this load is conducting, exports this index signal.
5. controller according to claim 4, wherein this protective circuit is judged when the supply of electric power state of this load exceeds preset range, the output stop signal makes these these a plurality of semiconductor switchs of drive circuit control stop power output to this load.
6. controller according to claim 4, wherein this protective circuit is used to protect the operation of power driving circuit, and this protective circuit comprises:
Comparator receives detection signal and reference voltage, when the pass of this detection signal and this reference voltage is when conforming to a predetermined condition, and the output comparison signal; And
Logic control circuit; receive this comparison signal and pulse wave signal; when receiving this comparison signal; promptly produce status signal; and the time span that produces each this status signal is that the time span of the duty ratio of this pulse wave signal is a prearranged multiple; when the duration length of the duration of this status signal length or non-this status signal surpasses the scheduled time during length, the output protection signal.
7. controller according to claim 6, wherein this logic control circuit is when rising edge that detects this comparison signal or falling edge, exports this status signal.
8. controller according to claim 7 when wherein this power driving circuit receives this guard signal, stops electric power output.
9. controller according to claim 1, wherein this power driving circuit connects first voltage source, and so that load electric to be provided, and this controller connects second voltage source, for the electric power of this controller running.
10. a DC/AC conversion driving circuit is used for the driving fluorescent lamp pipe, comprises:
At least one switch connects first power supply;
Controller is exported at least one drive control signal to correspond to this at least one switch respectively, serves as output or closed condition with the electric power of controlling this first power supply;
The resonance trough circuit has first side and second side, this at least one switch of this first side coupling, and this second side this fluorescent tube that is coupled is to provide this fluorescent tube electric power; And
Feedback loop, this fluorescent tube that is coupled, and output is used to indicate the index signal of this fluorescent tube conducting to this controller when this fluorescent tube conducting;
Wherein, this controller is controlled this at least one drive control signal in first frequency of operation after this DC/AC conversion driving circuit starts, and after accepting this index signal, changing this first frequency of operation is second frequency, and is locked in this second frequency.
11. DC/AC conversion driving circuit according to claim 10, wherein this at least one drive control signal is before accepting this index signal, and the increase that the supply of electric power of controlling this first power supply is in the duty ratio of output state is no more than set rate.
12. DC/AC conversion driving circuit according to claim 10, wherein this controller is in first scheduled time after this DC/AC conversion driving circuit starts, and the supply of electric power of this first power supply is maintained at closed condition.
13. according to claim 11 or 12 described DC/AC conversion driving circuits, wherein this controller connects second source.
14. DC/AC conversion driving circuit according to claim 12, wherein this controller is during this first scheduled time to second scheduled time, and the supply of electric power of this first power supply is in the time scale of output state greater than zero.
15. DC/AC conversion driving circuit according to claim 10, wherein this controller comprises protective circuit and testing circuit, and this protective circuit contains:
Comparator receives the detection signal and the reference voltage of this testing circuit, when the relation of this detection signal and this reference voltage conforms to a predetermined condition, and the output comparison signal; And
Logic control circuit; receive this comparison signal and pulse wave signal; when receiving this comparison signal; promptly produce status signal; and the time span that produces each this status signal is that the time span of the duty ratio of this pulse wave signal is a prearranged multiple; when the duration length of the duration of this status signal length or non-this status signal surpasses the scheduled time during length, the output protection signal.
16. DC/AC conversion driving circuit according to claim 15, wherein this logic control circuit is when rising edge that detects this comparison signal or falling edge, exports this status signal.
17. DC/AC conversion driving circuit according to claim 16 when wherein this DC/AC conversion driving circuit receives this guard signal, stops electric power output.
18. DC/AC conversion driving circuit according to claim 15, also comprise signaling conversion circuit, and this at least one switch comprises PMOS switch and nmos switch, and this at least one drive control signal that this signaling conversion circuit is changed the output of this controller is with the conducting of controlling this PMOS switch and this nmos switch and close.
19. DC/AC conversion driving circuit according to claim 18, wherein this resonance trough circuit is the coil type transformer, and this at least one switch is transformer coupled with form and this coil type of center tap.
20. DC/AC conversion driving circuit according to claim 10, also comprise signaling conversion circuit, with each this at least one drive control signal of changing the output of this controller is a pair of conversion driving control signal, and this is to the conducting of two switches of conversion driving control signal control and close.
21. DC/AC conversion driving circuit according to claim 20, wherein this has fixing phase difference to the conversion driving control signal.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNB2005101317503A CN100468939C (en) | 2005-12-16 | 2005-12-16 | DC/AC conversion driving circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNB2005101317503A CN100468939C (en) | 2005-12-16 | 2005-12-16 | DC/AC conversion driving circuit |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN1983787A CN1983787A (en) | 2007-06-20 |
| CN100468939C true CN100468939C (en) | 2009-03-11 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CNB2005101317503A Expired - Fee Related CN100468939C (en) | 2005-12-16 | 2005-12-16 | DC/AC conversion driving circuit |
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| Country | Link |
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| CN (1) | CN100468939C (en) |
Families Citing this family (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102065603B (en) * | 2009-11-18 | 2014-03-05 | 登丰微电子股份有限公司 | Load drive circuit and multi-load feedback circuit |
| CN103036215A (en) * | 2011-09-28 | 2013-04-10 | 登丰微电子股份有限公司 | Drive circuit with output protection and drive protection circuit thereof |
| CN102654989B (en) * | 2012-05-04 | 2014-06-11 | 深圳市华星光电技术有限公司 | Backlight module drive method and system of liquid crystal display |
| JP2015012414A (en) * | 2013-06-28 | 2015-01-19 | ソニー株式会社 | Circuit |
| CN107070288B (en) * | 2016-11-24 | 2019-03-29 | 广州视源电子科技股份有限公司 | Pulse power supply circuit |
-
2005
- 2005-12-16 CN CNB2005101317503A patent/CN100468939C/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| CN1983787A (en) | 2007-06-20 |
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