CN103874262A - Load driving device associated with light emitting diode - Google Patents
Load driving device associated with light emitting diode Download PDFInfo
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- CN103874262A CN103874262A CN201210526189.9A CN201210526189A CN103874262A CN 103874262 A CN103874262 A CN 103874262A CN 201210526189 A CN201210526189 A CN 201210526189A CN 103874262 A CN103874262 A CN 103874262A
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Abstract
The invention provides a load driving device associated with a light emitting diode. According to the invention, the compensation voltage on a compensation pin (CMP) of a control chip does not react to (change with) the change (namely, enabling and disabling) of a pulse width modulation signal required for dimming. In other words, no matter whether the pulse width modulation signal required for dimming is enabled or disabled, the compensation voltage on the compensation pin (CMP) of the control chip remains unchanged. Therefore, a light emitting diode string does not generate impulse current at the moment of current switching.
Description
Technical field
The invention relates to a kind of capacity load Driving technique, and relate to especially one and be associated with the load drive device of light-emitting diode (light-emitting-diodes, LEDs).
Background technology
Current-mode control chip (current mode controlchip) in tradition light emitting diode drive device can dispose dimming function (the pulse-width-modulation dimmingfunction of pulse-width modulation, PWM dimming function), so that the brightness of light-emitting diodes pipe string (LED string) is adjusted.On the other hand, in order to want the required direct voltage of stabilized illumination diode string operation, generally can be at the compensation pin position of control chip (compensation pin, CMP) upper external resistance capacitance serial connection network (RC series network), compensates with the bucking voltage on the compensation pin position to control chip.But, the variation that can react on the required pulse width modulation signal (PWM signal) of (or along with) light modulation due to the bucking voltage on the compensation pin position of control chip (, activation and forbidden energy) and change (, up lifting), to such an extent as to light-emitting diodes pipe string easily has the generation of overshoot current (over-shoot current) in the moment of current switching.
Summary of the invention
The object of the present invention is to provide a kind of load drive device that is associated with light-emitting diode, the problem of being addressed to solve known technology.
For achieving the above object, load drive device provided by the invention, comprising:
One power supply conversion line, it is configured to provide a VD to a light-emitting diodes pipe string;
One light modulation circuit, be connected in series, and it is configured to adjust the brightness of this light-emitting diodes pipe string with this light-emitting diodes pipe string;
One control chip, couple this power supply conversion line and this light modulation circuit, and it is configured to:
The running that reacts on the comparison of a bucking voltage and a triangular wave signal and produce a grid pulse width modulation signal and control this power supply conversion line;
The running that reacts on a light modulation input pulse width modulation signal and produce a light modulation output pulse width modulation signal and control this light modulation circuit; And
React on the activation of this light modulation input pulse width modulation signal and conduct the compensation pin position of this bucking voltage to this control chip; And
One compensated line, couples this compensation pin position, and it is configured to store this bucking voltage, and this bucking voltage is compensated so that this power supply conversion line stably provides this VD;
Wherein, this control chip reacts on the forbidden energy of this light modulation input pulse width modulation signal and stops conducting this bucking voltage to this compensation pin position, to cause this stored bucking voltage of this compensated line not change along with the variation of this light modulation output pulse width modulation signal.
Described load drive device, wherein, this power supply conversion line is configured to receive a DC input voitage, and reacts on this grid pulse width modulation signal and provide this VD to this light-emitting diodes pipe string.
Described load drive device, wherein, this power supply conversion line is at least a direct current booster circuit, and this DC boosting circuit comprises:
One inductance, its first end is in order to receive this DC input voitage;
One diode, its anode couples the second end of this inductance, and its negative electrode is coupled to the anode of this light-emitting diodes pipe string so that this VD to be provided;
One first electric capacity, its first end couples the negative electrode of this diode, and its second end is coupled to an earthing potential;
One power switch, its drain electrode couples the second end of this inductance and the anode of this diode, and its grid is in order to receive this grid pulse width modulation signal; And
One first resistance, is coupled between the source electrode and this earthing potential of this power switch.
Described load drive device, wherein, this light modulation circuit is configured to react on this light modulation output pulse width modulation signal and the brightness of adjusting this light-emitting diodes pipe string, and this light modulation circuit comprises:
One dimmer switch, its drain electrode is coupled to the negative electrode of this light-emitting diodes pipe string, and its grid is in order to receive this light modulation output pulse width modulation signal; And
One second resistance, is coupled between the source electrode and this earthing potential of this dimmer switch.
Described load drive device, wherein, this compensated line comprises:
One second electric capacity, its first end is coupled to this compensation pin position; And
One the 3rd resistance, is coupled between second end and this earthing potential of this second electric capacity.
Described load drive device, wherein, this control chip comprises:
One computing transduction amplifier, it is configured to receive cross-pressure and an acquiescence light modulation reference voltage of this second resistance, and produces according to this this bucking voltage;
One grid signal generation unit, couple this computing transduction amplifier, and it is configured to receive this bucking voltage and this triangular wave signal, and react on the activation of this light modulation input pulse width modulation signal and relatively this bucking voltage and this triangular wave signal, to produce this grid pulse width modulation signal;
One light modulation signal generation unit, it is configured to receive and this light modulation input pulse width modulation signal of Buffer output, to produce this light modulation output pulse width modulation signal; And
One switch unit, couples this computing transduction amplifier, and it is configured to receive this bucking voltage, and reacts on the activation of this light modulation input pulse width modulation signal and conduct this bucking voltage to this compensation pin position;
Wherein, this switch unit is configured to react on the forbidden energy of this light modulation input pulse width modulation signal and stops conducting this bucking voltage to this compensation pin position;
Wherein, this grid signal generation unit is configured to react on the forbidden energy of this light modulation input pulse width modulation signal and stops producing this grid pulse width modulation signal.
Described load drive device, wherein, this switch unit at least adopts the combination of a transmission lock and a reverser to implement.
Described load drive device, wherein, this switch unit at least adopts a transistor switch to implement.
Described load drive device, wherein: this control chip has a grid output pin position, and this grid signal generation unit is controlled the switching of this power switch to export this grid pulse width modulation signal by this grid output pin position;
This control chip has a light modulation input pin position, and this light modulation signal generation unit is inputted pulse width modulation signal by this light modulation input pin position to receive this light modulation;
This control chip has a light modulation output pin position, and this light modulation signal generation unit is controlled the switching of this dimmer switch to export this light modulation output pulse width modulation signal by this light modulation output pin position; And
This control chip has a light modulation detecting pin position, and this computing transduction amplifier is detected pin position to receive the cross-pressure of this second resistance by this light modulation.
Described load drive device, wherein, this grid signal generation unit is configured to react on cross-pressure and an acquiescence overcurrent protection reference voltage of this first resistance and determines whether to start an over current protection protection mechanism;
Wherein, this grid signal generation unit is configured to react on the startup of this over current protection protection mechanism and stops producing this grid pulse width modulation signal.
Described load drive device, wherein, this control chip has a current sense pin position, and this grid signal generation unit by this current sense pin position to receive the cross-pressure of this first resistance.
Described load drive device, comprising: an output feedback unit, be coupled between this VD and this earthing potential, and it is configured to provide a feedback voltage that is associated with this VD;
Wherein, this grid signal generation unit is configured to react on this feedback voltage and to be given tacit consent to overvoltage protection reference voltage and determines whether to start an overvoltage protection mechanism,
Wherein, this grid signal generation unit is configured to react on the startup of this overvoltage protection mechanism and stops producing this grid pulse width modulation signal.
Described load drive device, wherein, this output feedback unit comprises:
One the 4th resistance, its first end is in order to receive this VD, and its second end is in order to provide this feedback voltage; And
One the 5th resistance, is coupled between second end and this earthing potential of the 4th resistance.
Described load drive device, wherein, this control chip has a detecting voltage pin position, and this grid signal generation unit by this detecting voltage pin position to receive this feedback voltage.
Described load drive device, wherein:
This control chip has a power supply pin to receive this required DC input voitage of operation, and this control chip has a grounding leg position to be coupled to this earthing potential.
Based on above-mentioned, in the present invention, because the bucking voltage on the compensation pin position of control chip can't react on the variation (, activation and forbidden energy) of the required pulse width modulation signal (, light modulation output pulse width modulation signal) of (or along with) light modulation and change.In other words, no matter the required pulse width modulation signal (, light modulation output pulse width modulation signal) of light modulation in activation or forbidden energy, the bucking voltage on the compensation pin position of control chip all can remain unchanged.Therefore, light-emitting diodes pipe string does not have the generation of overshoot current (over-shoot current) in the moment of current switching, thereby is solved the problem that prior art is addressed.
Brief description of the drawings
Accompanying drawing is below a part for specification of the present invention, has illustrated example embodiment of the present invention, principle of the present invention is described together with the description of accompanying drawing and specification.
Fig. 1 illustrates the schematic diagram into the load drive device of the present invention's one example embodiment (load drivingapparatus) 10.
Fig. 2 illustrates the enforcement schematic diagram into the load drive device 10 of Fig. 1.
Fig. 3 A illustrates the enforcement schematic diagram into the switch unit 207 of Fig. 2.
Fig. 3 B illustrates another enforcement schematic diagram into the switch unit 207 of Fig. 2.
Fig. 4 illustrates the part operation oscillogram into the load drive device 10 of Fig. 1.
Primary clustering symbol description in accompanying drawing:
10: load drive device
20: light-emitting diodes pipe string
101: power supply conversion line
103: light modulation circuit
105: control chip
107: compensated line
109: output feedback unit
201: computing transduction amplifier
203: grid signal generation unit
205: light modulation signal generation unit
207: switch unit
L1: inductance
D1: diode
C1, C2: electric capacity
Q1: power switch
Q2: dimmer switch
MN: transistor switch
R1～R5: resistance
TG: transmission lock
INV: reverser
VDD: power supply pin
GND: grounding leg position
OVP: detecting voltage pin position
OCP: current sense pin position
GATE: grid output pin position
CMP: compensation pin position
INN: light modulation detecting pin position
DIM_I: light modulation input pin position
DIM_O: light modulation output pin position
V
dC_IN: DC input voitage
V
dC_OUT: VD
GPW: grid pulse width modulation signal
DPW_I: light modulation input pulse width modulation signal
DPW_O: light modulation output pulse width modulation signal
V
cOMP: bucking voltage
Ramp_S: triangular wave signal
V
r1, V
r2: cross-pressure
V
fB: feedback voltage
Vref: acquiescence light modulation reference voltage
Vocp: acquiescence overcurrent protection reference voltage
Vovp: acquiescence overvoltage protection reference voltage
Embodiment
One embodiment of the invention provide a kind of load drive device, and it comprises: power supply conversion line, light modulation circuit, control chip, and compensated line.Power supply conversion line is configured to provide a VD to light-emitting diodes pipe string.Light modulation circuit is connected in series with light-emitting diodes pipe string, and it is configured to adjust the brightness of light-emitting diodes pipe string.
Control chip couples power supply conversion line and light modulation circuit, and it is configured to: react on the comparison of a bucking voltage and a triangular wave signal and the running that produces a grid pulse width modulation signal and control power supply conversion line; The running that reacts on a light modulation input pulse width modulation signal and produce a light modulation output pulse width modulation signal and control light modulation circuit; And react on the activation of described light modulation input pulse width modulation signal and conduct the compensation pin position of described bucking voltage to control chip.
Compensated line couples described compensation pin position, and it is configured to store described bucking voltage, and described bucking voltage is compensated so that power supply conversion line stably provides described VD.Especially, control chip more can react on the forbidden energy of described light modulation input pulse width modulation signal and stop conducting described bucking voltage to described compensation pin position, use and cause the stored bucking voltage of compensated line can not change along with the variation of described light modulation output pulse width modulation signal (, activation and forbidden energy).
In an example embodiment of the present invention, power supply conversion line more can be configured to receive a DC input voitage, and reacts on described grid pulse width modulation signal and provide described VD to light-emitting diodes pipe string.With this understanding, power supply conversion line can be DC boosting circuit, and this booster circuit comprises: inductance, diode, the first electric capacity, power switch, and the first resistance.The first end of inductance is in order to receive described DC input voitage.The anode of diode couples the second end of inductance, and the negative electrode of diode is coupled to the anode of light-emitting diodes pipe string so that described VD to be provided.The first end of the first electric capacity couples the negative electrode of diode, and the second end of the first electric capacity is coupled to an earthing potential.The drain electrode of power switch couples the second end of inductance and the anode of diode, and the grid of power switch is in order to receive described grid pulse width modulation signal.The first resistance is coupled between the source electrode and described earthing potential of power switch.
In an example embodiment of the present invention, light modulation circuit can be configured to react on described light modulation output pulse width modulation signal and the brightness of adjusting light-emitting diodes pipe string, and this light modulation circuit comprises: dimmer switch and the second resistance.The drain electrode of dimmer switch is coupled to the negative electrode of light-emitting diodes pipe string, and the grid of dimmer switch is in order to receive described light modulation output pulse width modulation signal.The second resistance is coupled between the source electrode and described earthing potential of dimmer switch.
In an example embodiment of the present invention, compensated line comprises: the second electric capacity and the 3rd resistance.The first end of the second electric capacity is coupled to described compensation pin position.The 3rd resistance is coupled between second end and described earthing potential of the second electric capacity.
In an example embodiment of the present invention, control chip comprises: computing transduction amplifier (operational transconductance amplifier, OTA), grid signal generation unit, light modulation signal generation unit, and switch unit.Computing transduction amplifier is configured to receive cross-pressure and an acquiescence light modulation reference voltage of the second resistance, and produces according to this described bucking voltage.Grid signal generation unit couples computing transduction amplifier, and it is configured to receive described bucking voltage and described triangular wave signal, and react on the activation of described light modulation input pulse width modulation signal and more described bucking voltage and described triangular wave signal, to produce described grid pulse width modulation signal.
Light modulation signal generation unit be configured to receive and Buffer output described in light modulation input pulse width modulation signal, to produce described light modulation output pulse width modulation signal.Switch unit couples computing transduction amplifier, and it is configured to receive described bucking voltage, and reacts on the activation of described light modulation input pulse width modulation signal and conduct described bucking voltage to described compensation pin position.Especially, switch unit more can be configured to react on the forbidden energy of described light modulation input pulse width modulation signal and stop conducting described bucking voltage to described compensation pin position; In addition, grid signal generation unit more can be configured to react on the forbidden energy of described light modulation input pulse width modulation signal and stop producing described grid pulse width modulation signal.
In an example embodiment of the present invention, control chip more can have a grid output pin position, and grid signal generation unit can carry out by described grid output pin position the switching of power ratio control switch to export described grid pulse width modulation signal.
In an example embodiment of the present invention, control chip more can have a light modulation input pin position, and light modulation signal generation unit can be by described light modulation input pin position to receive described light modulation input pulse width modulation signal.
In an example embodiment of the present invention, control chip more can have a light modulation output pin position, and light modulation signal generation unit can be controlled by described light modulation output pin position the switching of dimmer switch to export described light modulation output pulse width modulation signal.
In an example embodiment of the present invention, control chip more can have a light modulation detecting pin position, and computing transduction amplifier can be by described light modulation detecting pin position to receive the cross-pressure of the second resistance.
In an example embodiment of the present invention, grid signal generation unit more can be configured to react on cross-pressure and an acquiescence overcurrent protection reference voltage of the first resistance and determine whether to start an over current protection protection mechanism.With this understanding, grid signal generation unit more can be configured to react on the startup of described over current protection protection mechanism and stop producing described grid pulse width modulation signal.
In an example embodiment of the present invention, control chip more can have a current sense pin position, and grid signal generation unit can be by described current sense pin position to receive the cross-pressure of the first resistance.
In an example embodiment of the present invention, the load drive device of carrying more can comprise: output feedback unit.Output feedback unit is coupled between described VD and described earthing potential, and it is configured to provide a feedback voltage that is associated with described VD.With this understanding, grid signal generation unit more can be configured to react on described feedback voltage and an acquiescence overvoltage protection reference voltage and determine whether to start an overvoltage protection mechanism.And grid signal generation unit more can be configured to react on the startup of described overvoltage protection mechanism and stop producing described grid pulse width modulation signal.
In an example embodiment of the present invention, control chip more can have a detecting voltage pin position, and grid signal generation unit can be crossed described detecting voltage pin position to receive described feedback voltage.
In an example embodiment of the present invention, control chip more can have a power supply pin to receive the required DC input voitage of operation.
In an example embodiment of the present invention, control chip more can have a grounding leg position to be coupled to described earthing potential.
Will be appreciated that, above-mentioned general description and following embodiment are only exemplary and illustrative, and it can not limit the scope that institute of the present invention wish is advocated.
With detailed reference to example embodiment of the present invention, the example of described example embodiment is described in the accompanying drawings.In addition, all possibility parts are used the assembly/member of same numeral to represent identical or similar portions in drawings and the embodiments.
Fig. 1 illustrates the schematic diagram into the load drive device of the present invention's one example embodiment (load drivingapparatus) 10, and Fig. 2 illustrates the enforcement schematic diagram into the load drive device 10 of Fig. 1.Please refer to Fig. 1 and Fig. 2, load drive device 10 comprises: power supply conversion line (powerconversion circuit) 101, light modulation circuit (dimming circuit) 103, (current mode) control chip (current-mode control chip) 105, compensated line (compensation circuit) 107, and output feedback unit (output feedback unit) 109.
Power supply conversion line 101 is configured to receive DC input voitage (DC input voltage) V
dC_IN, and react on grid pulse width modulation signal (gatepulse-width-modulation signal, the gate PWM signal) GPW from control chip 105 and VD (DC output voltage) V is provided
dC_OUTgive light-emitting diodes pipe string (LED string) 20 (that is, many light-emitting diodes that are forward serially connected).
In this example embodiment, power supply conversion line 101 can be DC boosting circuit (DCboost circuit), and it can comprise: inductance (inductor) L1, diode (diode, for example Schottky (Schottky) diode, but be not restricted to this) D1, electric capacity (capacitor) C1, (N-type) power switch (power switch) Q1, and resistance (resistor) R1.
The first end of inductance L 1 is in order to receive DC input voitage V
dC_IN.The anode (anode) of diode D1 couples the second end of inductance L 1, and the negative electrode (cathode) of diode D1 is coupled to the anode of light-emitting diodes pipe string 20 so that VD V to be provided
dC_OUT.The first end of capacitor C 1 couples the negative electrode of diode D1, and the second end of capacitor C 1 is coupled to earthing potential (groundpotential).The drain electrode (drain) of (N-type) power switch Q1 couples the second end of inductance L 1 and the anode of diode D1, and the grid (gate) of (N-type) power switch Q1 is in order to receive the grid pulse width modulation signal GPW from control chip 105.Resistance R 1 is coupled between the source electrode (source) and earthing potential of (N-type) power switch Q1.
On the other hand, light modulation circuit 103 can be connected in series with light-emitting diodes pipe string 20, and it is configured to react on the brightness of adjusting light-emitting diodes pipe string 20 from light modulation output pulse width modulation signal (the dimming output PWMsignal) DPW_O of control chip 105.In this example embodiment, light modulation circuit can 103 to comprise: (N-type) dimmer switch (dimming switch) Q2 and resistance R 2.The drain electrode of (N-type) dimmer switch Q2 is coupled to the negative electrode of light-emitting diodes pipe string 20, and the grid of (N-type) dimmer switch Q2 is in order to receive the light modulation output pulse width modulation signal DPW_O from control chip 105.Resistance R 2 is coupled between the source electrode and earthing potential of (N-type) dimmer switch Q2.
1) react on bucking voltage (compensation voltage) V
cOMPproduce grid pulse width modulation signal GPW with the comparison of triangular wave signal (rampsignal) Ramp_S and control the running of power supply conversion line 101;
2) react on light modulation input pulse width modulation signal (dimming input PWM signal) DPW_I and produce light modulation output pulse width modulation signal DPW_O and control the running of the running 103 of light modulation circuit; And
3) react on the activation of light modulation input pulse width modulation signal DPW_I and conduct bucking voltage V
cOMPto compensation pin position (compensation pin) CMP of control chip 105.Even, control chip 105 also can be configured to: 4) react on light modulation and input the forbidden energy of pulse width modulation signal DPW_I and stop conducting bucking voltage V
cOMPto compensating pin position CMP.
Substantially,, in order to allow control chip 105 normally be operated, control chip 105 can have a power supply pin (power pin) VDD to receive the required DC input voitage V of operation
dC_IN, and there is a grounding leg position (ground pin) GND to be coupled to earthing potential.Thus, control chip 105 can be to DC input voitage V
dC_INchange (for example: lifting/voltage reducing) to obtain the required operating voltage of its internal circuit.
In this example embodiment, control chip 105 can comprise: computing transduction amplifier (operational transconductance amplifier, 201 OTA), grid signal generation unit (gatesignal generation unit) 203, light modulation signal generation unit (dimming signal generationunit) 205, and switch unit (switching unit) 207.Wherein, computing transduction amplifier (OTA) 201 is configured to receive the cross-pressure V of resistance R 2
r2with acquiescence light modulation reference voltage Vref, and produce according to this bucking voltage V
cOMP.
In other words, the positive input terminal (+) of computing transduction amplifier (OTA) 201 is in order to receive acquiescence light modulation reference voltage Vref, and the negative input end (-) of computing transduction amplifier (OTA) 201 is in order to receive the cross-pressure V of resistance R 2
r2, the output of computing transduction amplifier (OTA) 201 is in order to produce and to export bucking voltage V
cOMP.In this example embodiment, control chip 105 more can have light modulation detecting pin position (dimming detection pin) INN, and computing transduction amplifier (OTA) 201 can be detected pin position INN to receive the cross-pressure V of resistance R 2 by light modulation
r2.Wherein, feed back to the voltage V of the light modulation detecting pin position INN of control chip 105
r2in fact can be close with acquiescence light modulation reference voltage Vref, but be not restricted to this.
Grid signal generation unit 203 couples computing transduction amplifier (OTA) 201, and it is configured to receive bucking voltage V
cOMPwith triangular wave signal Ramp_S, and react on the activation of light modulation input pulse width modulation signal DPW_I and comparison bucking voltage V
cOMPwith triangular wave signal Ramp_S, use and produce grid pulse width modulation signal GPW.In addition, grid signal generation unit more can 203 be configured to react on the forbidden energy of light modulation input pulse width modulation signal DPW_I and stop producing grid pulse width modulation signal GPW.In this example embodiment, control chip more can have grid output pin position (gate output pin) GATE, and grid signal generation unit 203 can be controlled by grid output pin position GATE the switching of (N-type) power switch Q1 with output grid pulse width modulation signal GPW.
Light modulation signal generation unit 205 is configured to receive and Buffer output light modulation input pulse width modulation signal DPW_I, uses and produces light modulation output pulse width modulation signal DPW_O.In this example embodiment, light modulation signal generation unit 205 can adopt at least two reversers that are serially connected (inverter) to implement, but is not restricted to this.Apparently, light modulation output pulse width modulation signal DPW_O in fact can to input pulse width modulation signal DPW_I identical with light modulation.And control chip 105 more can have light modulation input pin position (dimming input pin) DIM_I, and light modulation signal generation unit 205 can be by light modulation input pin position DIM_I to receive light modulation input pulse width modulation signal DPW_I; In addition, control chip 105 more can have light modulation output pin position (dimming output pin) DIM_O, and light modulation signal generation unit 205 can be controlled by light modulation output pin position DIM_O the switching of (N-type) dimmer switch Q2 with output light modulation output pulse width modulation signal DPW_O.
In this example embodiment, switch unit 207 can adopt the combination of transmission lock (transmissiongate) TG and reverser (inverter) INV to implement, and as shown in Figure 3A, but is not restricted to this.In other example embodiment of the present invention, switch unit 207 also can adopt single N-type transistor switch MN to implement, as shown in Figure 3 B.In other words, the visual actual design/application demand of enforcement aspect of switch unit 207 decides, as long as maintain the existing function of switch unit 207.
On the other hand, as shown in Figure 2, compensated line 107 can be coupled to the compensation pin position CMP of control chip 105, and it is configured to store bucking voltage V
cOMP, and to bucking voltage V
cOMPcompensate so that power supply conversion line 101 stably provides VD V
dC_OUT.In this example embodiment, compensated line 107 can be a resistance capacitance serial connection network (RC seriesnetwork), and it can comprise: capacitor C 2 and resistance R 3.The first end of capacitor C 2 is coupled to compensation pin position CMP, and resistance R 3 is coupled between second end and earthing potential of capacitor C 2.Certainly, in other example embodiment of the present invention, capacitor C 2 can be put upside down configuration with resistance R 3, that is: the first end of resistance R 3 changes into and is coupled to compensation pin position CMP, and capacitor C 2 changes between the second end and earthing potential that is coupled to resistance R 3.
It is worth mentioning that at this, store bucking voltage V because compensated line 107 can react on the activation of light modulation input pulse width modulation signal DPW_I by capacitor C 2
cOMP, and react on the forbidden energy of light modulation input pulse width modulation signal DPW_I and present the state of suspension joint (floating).Hence one can see that, the bucking voltage V that compensated line 107 is stored
cOMPcan't change along with the variation of light modulation output pulse width modulation signal DPW_O (, activation and forbidden energy).In other words, no matter light modulation output pulse width modulation signal DPW_O is in activation or forbidden energy, the bucking voltage V on the compensation pin position CMP of control chip 105
cOMPcapital remains unchanged.
In addition, in order to avoid the intraware of light-emitting diodes pipe string 20 and/or load drive device 10 to be subject to overcurrent (over current, OC) impact and damaging, therefore in this example embodiment, grid signal generation unit 203 more can be configured to react on the cross-pressure V of resistance R 1
r1determine whether start over current protection protection mechanism (OC protectionmechanism) with acquiescence overcurrent protection reference voltage Vocp.Once grid signal generation unit 203 determines to start over current protection protection mechanism, grid signal generation unit 203 can react on the startup of over current protection protection mechanism and stop producing grid pulse width modulation signal GPW, until occur without overcurrent.With this understanding, control chip 105 more can have current sense pin position (current sense pin) OCP, and grid signal generation unit 203 can be by current sense pin position OCP to receive the cross-pressure V of resistance R 1
r1thereby, judge whether the generation of overcurrent.
Even, in order to avoid the intraware of light-emitting diodes pipe string 20 and/or load drive device 10 to be subject to overvoltage (over voltage, OV) impact and damaging, therefore in this example embodiment, control chip 105 can be by the feedback voltage V with reference to from output feedback unit 109
fBand whether decision starts overvoltage protection mechanism (OV protection mechanism).In this example embodiment, output feedback unit 109 is coupled to VD V
dC_OUTand between earthing potential, and it is configured to provide and is associated with VD V
dC_OUTfeedback voltage V
fB.
Clearer, output feedback unit 109 can comprise: resistance R 4 and R5.The first end of resistance R 4 is in order to receive VD V
dC_OUT, the second end of resistance R 4 is in order to provide feedback voltage V
fB, resistance R 5 is coupled between second end and earthing potential of resistance R 4.Apparently, feedback voltage V
fBfor VD V
dC_OUTdividing potential drop signal, that is: V
fB=V
dC_OUT* (R5/ (R4+R5)).
The feedback voltage V providing based on output feedback unit 109
fB, grid signal generation unit 203 more can be configured to react on feedback voltage V
fBdetermine whether start overvoltage protection mechanism with acquiescence overvoltage protection reference voltage Vovp.Once grid signal generation unit 203 determines to start overvoltage protection mechanism, grid signal generation unit 203 can react on the startup of overvoltage protection mechanism and stop producing grid pulse width modulation signal GPW, until occur without overvoltage.With this understanding, control chip 105 more can have detecting voltage pin position (voltage sense pin) OVP, and grid signal generation unit 203 can be by detecting voltage pin position OVP to receive feedback voltage V
fBthereby, judged whether superpotential generation.Certainly,, in other example embodiment of the present invention, grid signal generation unit 203 also can react on the feedback voltage V that output feedback unit 109 provides
fBand adjust the grid pulse width modulation signal GPW producing, all are looked closely actual design/application demand and discuss.
Based on above-mentioned, as shown in Figure 4, it illustrates the part operation oscillogram into the load drive device 10 of Fig. 1.Please refer to Fig. 1～Fig. 4, can clearly be seen that from Fig. 4, light modulation output pulse width modulation signal DPW_O is identical with light modulation input pulse width modulation signal DPW_I in fact.And, it is worth mentioning that " the V that Fig. 4 indicates
cOMP" be the stored bucking voltage V of compensated line 107
cOMP, that is: the bucking voltage V on the compensation pin position CMP of control chip 105
cOMP.
Base this, grid signal generation unit 203 can react on the activation of light modulation input pulse width modulation signal DPW_I and comparison bucking voltage V
cOMPwith triangular wave signal Ramp_S, use the switching that produces the grid pulse width modulation signal GPW with default responsibility cycle (predetermined duty cycle) and control (N-type) power switch Q1.In addition, grid signal generation unit 203 also can react on the forbidden energy of light modulation input pulse width modulation signal DPW_I and stop producing grid pulse width modulation signal GPW.Apparently, by applying the light modulation input pin position DIM_I of light modulation input pulse width modulation signal DPW_I to control chip 105, can realize the object that the brightness of light-emitting diodes pipe string 20 is adjusted.
On the other hand, switch unit 207 can react on the activation of light modulation input pulse width modulation signal DPW_I and conduct bucking voltage V
cOMPmake compensated line 107 to bucking voltage V to compensating pin position CMP, using
cOMPstore and compensation, thereby allow power supply conversion line 101 that VD V is stably provided
dC_OUT.In addition, switch unit 207 can react on the forbidden energy of light modulation input pulse width modulation signal DPW_I and stop conducting bucking voltage V
cOMPto compensating pin position CMP.Thus, due to the state of compensated line 107 in suspension joint, so the stored bucking voltage V of compensated line 107
cOMPcan't change along with the variation of light modulation output pulse width modulation signal DPW_O (, activation and forbidden energy).In other words, no matter light modulation output pulse width modulation signal DPW_O is in activation or forbidden energy, the bucking voltage V on the compensation pin position CMP of control chip 105
cOMPcapital remains unchanged.
And then, in the time that light modulation input pulse width modulation signal DPW_I enters to enabled status from disabled state, due to the transmission lock TG meeting conducting in switch unit 207, add the relatively large output impedance (output impedance) of computing transduction amplifier (OTA) 201, the voltage to such an extent as to computing is transduceed on the output of amplifier (OTA) 201 can present the stored bucking voltage V of compensated line 107 at once
cOMP.Therefore, grid signal generation unit 203 will react on the activation of light modulation input pulse width modulation signal DPW_I and comparison bucking voltage V again
cOMPwith triangular wave signal Ramp_S, the grid pulse width modulation signal GPW to produce with identical default responsibility cycle controls the switching of (N-type) power switch Q1.Apparently, light-emitting diodes pipe string 20 does not have the generation of overshoot current (over-shoot current) in the moment of current switching, and it is because of the bucking voltage V on the compensation pin position CMP of control chip 105
cOMPgrid signal generation unit 203 remains unchanged, so can't produce in the moment of the current switching of light-emitting diodes pipe string 20 the grid pulse width modulation signal GPW of standard-sized sheet (, responsibility cycle is 100%).
In addition,, in the operation of load drive device 10, the grid signal generation unit 203 in control chip 105 can continue to monitor the cross-pressure (V of resistance R 1 and R5
r1, V
r5), to have judged whether overcurrent and/or superpotential generation.Once grid signal generation unit 203 is judged overcurrent and/or overvoltage occurs, grid signal generation unit 203 can stop producing grid pulse width modulation signal GPW immediately, until occur without overcurrent and/or overvoltage.
In sum, in the present invention, due to the bucking voltage V on the compensation pin position CMP of control chip 105
cOMPcan't react on the variation (, activation and forbidden energy) of the required pulse width modulation signal (, light modulation output pulse width modulation signal DPW_O) of (or along with) light modulation and change.In other words, no matter the required pulse width modulation signal (, light modulation output pulse width modulation signal DPW_O) of light modulation is in activation or forbidden energy, the bucking voltage V on the compensation pin position CMP of control chip 105
cOMPcapital remains unchanged.Therefore, light-emitting diodes pipe string 20 does not have the generation of overshoot current (over-shoot current) in the moment of current switching, thereby is solved the problem that prior art is addressed.
Although the present invention illustrates as above with embodiment; so it is not in order to limit the present invention; those skilled in the art without departing from the spirit and scope of the present invention, when doing a little change and retouching, are as the criterion therefore protection scope of the present invention is worked as the content defining depending on the claim scope of application.
In addition, arbitrary embodiment of the present invention or claim must not reached the disclosed whole objects of the present invention or advantage or feature.In addition, summary part and title are only the use of searching for auxiliary patent document, are not used for limiting interest field of the present invention.
Claims (15)
1. a load drive device, comprising:
One power supply conversion line, it is configured to provide a VD to a light-emitting diodes pipe string;
One light modulation circuit, be connected in series, and it is configured to adjust the brightness of this light-emitting diodes pipe string with this light-emitting diodes pipe string;
One control chip, couple this power supply conversion line and this light modulation circuit, and it is configured to:
The running that reacts on the comparison of a bucking voltage and a triangular wave signal and produce a grid pulse width modulation signal and control this power supply conversion line;
The running that reacts on a light modulation input pulse width modulation signal and produce a light modulation output pulse width modulation signal and control this light modulation circuit; And
React on the activation of this light modulation input pulse width modulation signal and conduct the compensation pin position of this bucking voltage to this control chip; And
One compensated line, couples this compensation pin position, and it is configured to store this bucking voltage, and this bucking voltage is compensated so that this power supply conversion line stably provides this VD;
Wherein, this control chip reacts on the forbidden energy of this light modulation input pulse width modulation signal and stops conducting this bucking voltage to this compensation pin position, to cause this stored bucking voltage of this compensated line not change along with the variation of this light modulation output pulse width modulation signal.
2. load drive device according to claim 1, wherein, this power supply conversion line is configured to receive a DC input voitage, and reacts on this grid pulse width modulation signal and provide this VD to this light-emitting diodes pipe string.
3. load drive device according to claim 2, wherein, this power supply conversion line is at least a direct current booster circuit, and this DC boosting circuit comprises:
One inductance, its first end is in order to receive this DC input voitage;
One diode, its anode couples the second end of this inductance, and its negative electrode is coupled to the anode of this light-emitting diodes pipe string so that this VD to be provided;
One first electric capacity, its first end couples the negative electrode of this diode, and its second end is coupled to an earthing potential;
One power switch, its drain electrode couples the second end of this inductance and the anode of this diode, and its grid is in order to receive this grid pulse width modulation signal; And
One first resistance, is coupled between the source electrode and this earthing potential of this power switch.
4. load drive device according to claim 3, wherein, this light modulation circuit is configured to react on this light modulation output pulse width modulation signal and the brightness of adjusting this light-emitting diodes pipe string, and this light modulation circuit comprises:
One dimmer switch, its drain electrode is coupled to the negative electrode of this light-emitting diodes pipe string, and its grid is in order to receive this light modulation output pulse width modulation signal; And
One second resistance, is coupled between the source electrode and this earthing potential of this dimmer switch.
5. load drive device according to claim 4, wherein, this compensated line comprises:
One second electric capacity, its first end is coupled to this compensation pin position; And
One the 3rd resistance, is coupled between second end and this earthing potential of this second electric capacity.
6. load drive device according to claim 5, wherein, this control chip comprises:
One computing transduction amplifier, it is configured to receive cross-pressure and an acquiescence light modulation reference voltage of this second resistance, and produces according to this this bucking voltage;
One grid signal generation unit, couple this computing transduction amplifier, and it is configured to receive this bucking voltage and this triangular wave signal, and react on the activation of this light modulation input pulse width modulation signal and relatively this bucking voltage and this triangular wave signal, to produce this grid pulse width modulation signal;
One light modulation signal generation unit, it is configured to receive and this light modulation input pulse width modulation signal of Buffer output, to produce this light modulation output pulse width modulation signal; And
One switch unit, couples this computing transduction amplifier, and it is configured to receive this bucking voltage, and reacts on the activation of this light modulation input pulse width modulation signal and conduct this bucking voltage to this compensation pin position;
Wherein, this switch unit is configured to react on the forbidden energy of this light modulation input pulse width modulation signal and stops conducting this bucking voltage to this compensation pin position;
Wherein, this grid signal generation unit is configured to react on the forbidden energy of this light modulation input pulse width modulation signal and stops producing this grid pulse width modulation signal.
7. load drive device according to claim 6, wherein, this switch unit at least adopts the combination of a transmission lock and a reverser to implement.
8. load drive device according to claim 6, wherein, this switch unit at least adopts a transistor switch to implement.
9. load drive device according to claim 6, wherein:
This control chip has a grid output pin position, and this grid signal generation unit is controlled the switching of this power switch to export this grid pulse width modulation signal by this grid output pin position;
This control chip has a light modulation input pin position, and this light modulation signal generation unit is inputted pulse width modulation signal by this light modulation input pin position to receive this light modulation;
This control chip has a light modulation output pin position, and this light modulation signal generation unit is controlled the switching of this dimmer switch to export this light modulation output pulse width modulation signal by this light modulation output pin position; And
This control chip has a light modulation detecting pin position, and this computing transduction amplifier is detected pin position to receive the cross-pressure of this second resistance by this light modulation.
10. load drive device according to claim 6, wherein, this grid signal generation unit is configured to react on cross-pressure and an acquiescence overcurrent protection reference voltage of this first resistance and determines whether to start an over current protection protection mechanism;
Wherein, this grid signal generation unit is configured to react on the startup of this over current protection protection mechanism and stops producing this grid pulse width modulation signal.
11. load drive devices according to claim 10, wherein, this control chip has a current sense pin position, and this grid signal generation unit by this current sense pin position to receive the cross-pressure of this first resistance.
12. load drive devices according to claim 6, comprising:
One output feedback unit, be coupled between this VD and this earthing potential, and it is configured to provide a feedback voltage that is associated with this VD;
Wherein, this grid signal generation unit is configured to react on this feedback voltage and to be given tacit consent to overvoltage protection reference voltage and determines whether to start an overvoltage protection mechanism,
Wherein, this grid signal generation unit is configured to react on the startup of this overvoltage protection mechanism and stops producing this grid pulse width modulation signal.
13. load drive devices according to claim 12, wherein, this output feedback unit comprises:
One the 4th resistance, its first end is in order to receive this VD, and its second end is in order to provide this feedback voltage; And
One the 5th resistance, is coupled between second end and this earthing potential of the 4th resistance.
14. load drive devices according to claim 12, wherein, this control chip has a detecting voltage pin position, and this grid signal generation unit by this detecting voltage pin position to receive this feedback voltage.
15. load drive devices according to claim 3, wherein:
This control chip has a power supply pin to receive this required DC input voitage of operation, and this control chip has a grounding leg position to be coupled to this earthing potential.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201210526189.9A CN103874262A (en) | 2012-12-07 | 2012-12-07 | Load driving device associated with light emitting diode |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201210526189.9A CN103874262A (en) | 2012-12-07 | 2012-12-07 | Load driving device associated with light emitting diode |
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| Publication Number | Publication Date |
|---|---|
| CN103874262A true CN103874262A (en) | 2014-06-18 |
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ID=50912293
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201210526189.9A Pending CN103874262A (en) | 2012-12-07 | 2012-12-07 | Load driving device associated with light emitting diode |
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| CN106683353A (en) * | 2017-02-22 | 2017-05-17 | 厦门益光照明科技股份有限公司 | Alarming module for abnormal input power of LED (Light Emitting Diode) lamp |
| CN113163540A (en) * | 2020-01-22 | 2021-07-23 | 立锜科技股份有限公司 | Dimmer interface circuit and buffer circuit therein |
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| TW201228462A (en) * | 2010-12-09 | 2012-07-01 | Rohm Co Ltd | Driving circuit of light emitting element, light emitting device using the same, and electronic device |
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| CN113163540B (en) * | 2020-01-22 | 2023-08-29 | 立锜科技股份有限公司 | Dimmer interface circuit and buffer stage circuit therein |
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Application publication date: 20140618 |