TWI520657B - Converting control circuit - Google Patents

Description

Conversion control circuit

The present invention relates to a conversion control circuit, and more particularly to a conversion control circuit that can be adjusted according to load conditions.

Due to the rapid advancement of light-emitting diode (LED) technology, coupled with the maturity of related technologies and the awareness of energy saving and carbon saving, the application of light-emitting diodes has become increasingly popular and diversified. From the early low-power power indicator light and mobile phone button light source, the light-emitting diode backlight module and general lighting products with low power consumption, long life and high color rendering progress.

The light-emitting diode is a non-linear load, the threshold voltage changes with temperature, and the luminescence spectrum changes depending on the current. Therefore, how to drive the light-emitting diode to obtain a stable light source is more difficult than driving other light sources. Moreover, since the brightness that a single light-emitting diode can provide cannot generally satisfy most applications, there are multiple light-emitting diodes connected in series or in parallel or simultaneously in series and in parallel to provide sufficient brightness for the second light-emitting diode. Polar body light source. However, the variation of the driving characteristics between the light-emitting diodes is quite large, and when the light-emitting diodes are illuminated in parallel, the same driving voltage cannot ensure that the different light-emitting diodes have the same current and brightness. Therefore, for the parallel light-emitting diodes, the parallel light-emitting diodes must have the same current in a current-sharing circuit, so that the brightness is substantially the same. This will require a maximum voltage of the light-emitting diode to provide a driving voltage, so that each of the light-emitting diodes can smoothly emit light. In the case where the threshold voltage of the light-emitting diode is uncertain, the driving voltage is required to be higher to ensure that each of the light-emitting diodes can flow through a predetermined current. In such a case, the driving efficiency of the light-emitting diode is lowered. In addition, when the light-emitting diodes emit light in series, the open circuit does not emit light due to the damage of any of the light-emitting diodes, or the driving voltage rises, which may cause the light-emitting diode to fail to reach the predetermined time when the voltage is driven. Current, not even light.

These problems are the driving diodes that must be considered and overcome, especially It is a more difficult circuit design challenge in the environment of simultaneous parallel series driving.

Due to the driving characteristics of the light-emitting diode, there are quite a few difficulties in design, making the previous driving circuit unsuitable or unable to properly drive the light-emitting diode. The present invention provides a feedback signal according to the actual operation condition of the light-emitting diode through the new feedback circuit structure, so that the feedback controller used to control the conversion circuit can correctly drive the light-emitting diode. Alternatively, the feedback circuit architecture of the present invention can also be used to compensate for the feedback control in the conventional conversion circuit, so that the conventional conversion circuit can also properly drive the light-emitting diode.

To achieve the above object, the present invention provides a conversion control circuit for controlling a conversion circuit to convert an input voltage into an output voltage to drive a load. The conversion control circuit includes a current control circuit, a first detection circuit, a second detection circuit, a feedback controller, and a feedback circuit. The current control circuit has at least one control terminal coupled to the load to regulate the current of the load. The first detecting circuit is coupled to the current control circuit and generates a first detecting signal according to the voltage of the at least one control terminal. The second detecting circuit is coupled to the converting circuit and generates a second detecting signal according to the output voltage. The feedback controller receives the second detection signal to control the conversion circuit to convert the input voltage into an output voltage. The feedback circuit is coupled to the first detection circuit and the second detection circuit to generate a feedback signal according to the first detection signal to adjust the level of the second detection signal.

The present invention also provides another conversion control circuit for controlling a conversion circuit to convert the power of an input voltage to drive a load. The conversion control circuit includes a controller, a first detection circuit, and a feedback circuit. The controller controls the conversion circuit to perform power conversion of the input voltage according to a feedback detection signal. The first detecting circuit is coupled to the load to generate a first detecting signal. The feedback circuit is coupled to the first detection circuit and generates a feedback signal according to the first detection signal. The feedback circuit includes a capacitor and a charge and discharge unit. The above capacitor is used to generate a feedback signal, and The charging and discharging unit charges and discharges the capacitor according to the first detecting signal to generate the feedback signal.

The above summary and the following detailed description are exemplary in order to further illustrate the scope of the claims. Other objects and advantages of the present invention will be described in the following description and drawings.

Please refer to the first figure, which is a circuit block diagram of a conversion control circuit according to the present invention. The switching control circuit includes a feedback controller 130, a detecting circuit 105 and a feedback circuit 100 for controlling the converting circuit 140 to convert and output the power of an input voltage Vin to drive a load 160. The detection circuit 105 is coupled to the load 160 to generate a detection signal Sde1. The feedback circuit 100 is coupled to the detection circuit 105 and generates a feedback signal Sco according to the detection signal Sde1. The feedback controller 130 performs power conversion of the input voltage Vin according to the feedback signal Sco in accordance with the feedback signal Sco. Since the detecting circuit 105 generates the detecting signal Sde1 according to the driving state of the load 160, the converting circuit 140 can appropriately drive the load 160.

Next, please refer to the second figure, which is a circuit block diagram of another conversion control circuit according to the present invention. The conversion control circuit includes a first detection circuit 105, a second detection circuit 115, a feedback controller 130, and a feedback circuit 100 for controlling a conversion circuit 140 to convert an input voltage Vin into an output voltage Vout. To drive a load 160. The first detecting circuit 105 is coupled to the load 160 to generate a detecting signal Sde1. The second detecting circuit 115 is coupled to the converting circuit 140 to generate a detecting signal Sde2 according to the output voltage Vout. The feedback circuit 100 is coupled to the first detection circuit 105 and the second detection circuit 115. The feedback signal Sde1 is used to generate the feedback signal Sco, and the feedback signal Sco is used to adjust the level of the detection signal Sde2. The feedback controller 130 receives the compensated detection signal Sde1 to thereby control the conversion circuit 140 to convert the input voltage Vin into the output voltage Vout. Compared with the conversion control circuit shown in the first figure, the feedback signal Sco generated by the feedback circuit 100 shown in the second figure is used to compensate the detection signal Sde2 of the second detection circuit 115. Since the second detecting circuit 115 detects the output of the converting circuit 140 and cannot determine whether the load is operating correctly, the detecting circuit 105 detects the load 160 to generate the detecting signal Sde1, and is appropriately compensated by the feedback circuit 100. The conversion circuit 140 can drive the load 160 appropriately.

Referring to the third figure, there is shown a circuit diagram of a feedback circuit in accordance with a first preferred embodiment of the present invention. The feedback circuit 100 includes a capacitor C and a charge and discharge unit. The charge and discharge unit includes a first current source I1, a second current source I2, a first switch S1, a second switch S2, and a charge and discharge control circuit 102. The charge and discharge control circuit 102 receives the detection signal Sde1, and accordingly controls the on or off of the first switch S1 and the second switch S2, so that the first current source I1 charges the capacitor C or the second current source I2 discharges the capacitor C. To generate the feedback signal Sco. The charge and discharge control circuit 102 can compare the level of the detection signal Sde1 with a predetermined level value, and discharge the capacitor C when the level of the detection signal Sde1 is higher than the predetermined level, and when the level of the detection signal Sde1 is detected Capacitor C is charged below a predetermined level. In addition, the feedback circuit 100 can additionally include an output control switch S3 coupled to the capacitor C to control whether to output the feedback signal Sco. For example, the dimming signal DIM can be used to control the on and off of the output control switch S3 to achieve the function of matching dimming.

Please refer to the fourth figure, which is a circuit diagram of a feedback circuit according to a second preferred embodiment of the present invention. Compared with the embodiment shown in the third figure, the feedback circuit shown in the fourth figure additionally adds a decoupling unit 104 and an output resistor R. In order to avoid coupling to the external circuit, the external circuit will transfer energy to the capacitor C to affect the capacitor C, thus providing a decoupling function to isolate the external circuit from affecting the feedback circuit 100 through the coupling action. In the present embodiment, the decoupling unit 104 is a double amplifier, and in addition to providing a decoupling function, the driving capability of the feedback circuit 100 can also be increased. The dimming signal DIM can be used to enable or disable the decoupling unit 104 to achieve the function of dimming.

Referring to FIG. 5, a circuit diagram of a feedback circuit according to a third preferred embodiment of the present invention. Compared with the embodiment shown in FIG. 4, the feedback circuit shown in FIG. 5 uses the current regulating circuit 101, the controlled current source Iadj and an impedance element Rco instead of the capacitor C and the charging and discharging unit. The current regulating circuit 101 adjusts the current of the controlled current source Iadj according to the first detecting signal Sde1 to flow through the impedance element Rco. The decoupling unit 104 outputs the feedback signal Sco according to the signal generated by the impedance element Rco via the output resistor R. Since the feedback circuit shown in the third and fourth figures includes the capacitor C, although the noise immunity is better, the transient response is slower, and the feedback circuit shown in the fifth figure is better. Transient response capability.

In addition, the feedback circuit 100 receives a driving voltage VCC and ground, so the level of the feedback signal Sco provided is also equal to the control between the driving voltage VCC and the ground. When the feedback signal Sco is used as the compensation detection signal Sde2, the compensation range has a certain range, that is, the control adjustment range can be achieved. In addition, by adjusting the resistance of the output resistor R, the effect of adjusting the compensation range can also be achieved.

Please refer to the sixth figure, which is a circuit diagram of a conversion control circuit according to a first preferred embodiment of the present invention. The conversion control circuit includes a detection circuit 205, a controller and a feedback circuit 200 for controlling a conversion circuit to convert the power of an input voltage Vin to drive a load 260, wherein the controller and the conversion circuit constitute a control conversion The circuit 230 and the load 260 are a single string of LED modules. In the present embodiment, the control conversion circuit 230 is exemplified by a regulator TL431 manufactured by Texas Instruments. In practical applications, the conversion control circuit of the present invention can also use a common linear regulator (Linear Dropout Regulator). , LDO) to carry out power conversion.

The detecting circuit 205 is coupled to the load 260 to generate a detecting signal Sde1 according to the current flowing through the load. The feedback circuit 200 is coupled to the detection circuit 205 and generates a feedback signal Sco according to the detection signal Sde1. In this embodiment, the feedback circuit 200 can use any of the feedback circuits in accordance with the present invention, including the feedback circuit shown in the above embodiments. The input terminal 1 of the control conversion circuit 230 is coupled to the input voltage Vin through the input resistor Rin, and the ground terminal 2 is grounded to flow a shunt current. The signal terminal 3 of the control conversion circuit 230 receives the feedback signal Sco to adjust the magnitude of the shunt current according to the feedback signal Sco, so that the LED module of the load 260 can stably flow through a predetermined current to stably emit light.

Please refer to the seventh figure, which is a circuit diagram of a conversion control circuit according to a second preferred embodiment of the present invention. The switching control circuit includes a feedback controller 330, detection circuits 305 and 315, and a feedback circuit 300 for controlling a conversion circuit 340 to convert the power of an input voltage Vin to drive a load 360. The detection circuit 305 is coupled to the load 360 to generate a detection signal Sde1 according to the current flowing through the load, and the detection circuit 315 is coupled to the conversion circuit 340 and generates a detection signal Sde2 according to an output voltage Vout of the conversion circuit 340. The feedback circuit is coupled to the detection circuit 305 and generates a feedback signal Sco according to the detection signal Sde1 to adjust the level of the detection signal Sde2. The feedback controller 330 receives the compensated detection signal and outputs a control signal Sc accordingly to regulate the conversion of the input voltage Vin by the conversion circuit 340.

The feedback controller 330 includes an error amplifier 332, a pulse width modulation unit 334, and a drive circuit 336. The error amplifier 332 receives the compensated detection signal at the inverting input terminal, receives a reference voltage signal Vr at the non-inverting input terminal, and outputs an error amplification signal Sea according to the output terminal. The pulse width modulation unit 334 receives a ramp signal at the inverting input terminal, and receives the error amplification signal Sea at the non-inverting input terminal to output a pulse width modulation signal Spwm accordingly. The driving circuit 336 receives the pulse width modulation signal Spwm to adjust the duty cycle of the control signal Sc accordingly, so that the conversion circuit 340 outputs power to stably drive the load 360. In addition, the driving circuit 336 and the feedback circuit 300 can also receive a dimming signal DIM for dimming the load 360. In addition, the error amplifier 332 can also be replaced by a transducing unit (e.g., a transconductance amplifier), which is well known to those skilled in the art and will not be described herein.

In this embodiment, the conversion circuit 340 is a switching DC-to-DC boost conversion circuit, including an inductor L, a diode D, an output capacitor Co, and a switch SW, wherein the switch SW switches according to the control signal Sc. , the input voltage Vin is boosted to the output voltage Vout. Since the voltage of the output voltage Vout is high, the conventional switching control circuit causes the output voltage Vout to be directly applied to the feedback controller 330 when the load 360 is short-circuited. Through the feedback circuit 300 of the present invention, the output voltage Vout during the short circuit can be prevented from being directly applied to the feedback control. The device 330 protects the feedback controller 330 from burning.

Please refer to the eighth figure, which is a circuit diagram of a conversion control circuit according to a third preferred embodiment of the present invention. The conversion control circuit includes a current control circuit 410, detection circuits 405, 415, a feedback controller 430, and a feedback circuit 400 for controlling a conversion circuit 440 to convert an input voltage Vin into an output voltage Vout to drive a Load 460. In this embodiment, the load 460 has a plurality of LED arrays of parallel LED strings, and the current control circuit 410 has a plurality of control terminals D1 D Dn respectively connected to the LED strings. Regulate the current of each LED string. The detecting circuit 405 includes a plurality of diodes. The positive terminals are connected to each other and connected to a driving voltage VCC through a resistor, and the negative terminals are coupled to the control terminals D1 D Dn to have a minimum voltage according to the control terminals D1 D Dn. The control terminal generates a detection signal Sde1. The detecting circuit 415 is coupled to the converting circuit 440 and generates a detecting signal Sde2 according to the output voltage Vout. The feedback circuit 400 is coupled to the detection circuits 405 and 415 to generate a feedback signal Sco according to the detection signal Sde1 to adjust the level of the detection signal Sde2. The feedback controller 430 receives the compensated detection signal to control the conversion circuit 440 to change the input voltage to Vin to the output voltage Vout. The feedback controller 430 includes a comparison unit 432, a flip-flop unit 434, and a drive circuit 436. The comparing unit 432 receives the compensated detection signal and a reference voltage signal Vr to generate a comparison signal Scom. The flip-flop unit 434 receives the comparison signal Scom and a pulse signal to output a pulse width modulation signal Spwm. In this embodiment, the flip-flop unit 434 is an SR flip-flop, receives the pulse signal at the set terminal S, the reset terminal R receives the comparison signal Scom, and outputs the pulse width modulation signal Spwm at the output terminal Q. The driving circuit 436 receives the pulse width modulation signal Spwm to adjust the duty cycle of the control signal Sc accordingly, so that the conversion circuit 440 outputs power to stably drive the load 460. In addition, the driving circuit 436 and the feedback circuit 400 can also receive a dimming signal DIM for dimming the load 460. In this embodiment, the conversion circuit 440 is a forward conversion circuit including a transformer T, a switch SW, a current sense resistor Rse, a rectifier diode D1, D2, an inductor L, and an output capacitor Co. The current sensing resistor Rse generates a current sensing signal Ise to the driving circuit according to the current flowing through the switch SW. 436. The driving circuit 436 determines whether the switch SW is overcurrent according to the current sensing signal Ise, and if so, temporarily stops the switch SW to avoid damage due to overcurrent.

As described above, the present invention fully complies with the three requirements of the patent: novelty, advancement, and industrial applicability. The invention has been described above in terms of the preferred embodiments, and it should be understood by those skilled in the art that the present invention is not intended to limit the scope of the invention. It should be noted that variations and permutations equivalent to those of the embodiments are intended to be included within the scope of the present invention. Therefore, the scope of the invention is defined by the scope of the following claims.

1‧‧‧ input

2‧‧‧ Grounding

3‧‧‧ Signal end

100, 200, 300, 400‧‧‧ feedback circuits

101‧‧‧current control circuit

102‧‧‧Charge and discharge control circuit

104‧‧‧Decoupling unit

105, 115, 205, 305, 315, 405, 415‧‧ ‧ detection circuit

130, 230, 330, 430‧‧‧ feedback controller

140, 340, 440‧‧‧ conversion circuit

160, 260, 360, 460‧‧‧ load

332‧‧‧Error amplifier

334‧‧‧ pulse width modulation unit

336‧‧‧Drive circuit

410‧‧‧ Current Control Circuit

432‧‧‧Comparative unit

434‧‧‧Factor unit

436‧‧‧ drive circuit

Vin‧‧‧Input voltage

Vout‧‧‧ output voltage

Sde1, Sde2‧‧‧ detection signals

Sco‧‧‧Reward signal

C‧‧‧ capacitor

I1‧‧‧ first current source

I2‧‧‧second current source

S1‧‧‧ first switch

S2‧‧‧ second switch

S3‧‧‧Output control switch

DIM‧‧‧ dimming signal

R‧‧‧ output resistance

Iadj‧‧‧controlled current source

Rco‧‧‧impedance component

VCC‧‧‧ drive voltage

Rin‧‧‧ input resistance

Vr‧‧‧ reference voltage signal

Sea‧‧‧Error amplification signal

Spwm‧‧‧ pulse width modulation signal

Sc‧‧‧ control signal

L‧‧‧Inductance

D‧‧‧ diode

Co‧‧‧ output capacitor

SW‧‧ switch

D1~Dn‧‧‧ control terminal

Scom‧‧‧ comparison signal

S‧‧‧Setting end

R‧‧‧Reset

Q‧‧‧output

T‧‧‧Transformer

Rse‧‧‧ current sense resistor

D1, D2‧‧‧ Rectifier

Ise‧‧‧ current sensing signal

The first figure is a circuit block diagram of a conversion control circuit in accordance with the present invention.

The second figure is a circuit block diagram of another conversion control circuit in accordance with the present invention.

The third figure is a circuit diagram of a feedback circuit in accordance with a first preferred embodiment of the present invention.

The fourth figure is a circuit diagram of a feedback circuit in accordance with a second preferred embodiment of the present invention.

Figure 5 is a circuit diagram of a feedback circuit in accordance with a third preferred embodiment of the present invention.

Figure 6 is a circuit diagram of a conversion control circuit in accordance with a first preferred embodiment of the present invention.

Figure 7 is a circuit diagram of a switching control circuit in accordance with a second preferred embodiment of the present invention.

Figure 8 is a circuit diagram of a conversion control circuit in accordance with a third preferred embodiment of the present invention.

100‧‧‧Return circuit

105‧‧‧Detection circuit

130‧‧‧Return controller

140‧‧‧Transition circuit

160‧‧‧load

Vin‧‧‧Input voltage

Sde1‧‧‧ detection signal

Sco‧‧‧Reward signal

Claims (12)

A conversion control circuit for controlling a conversion circuit to convert an input voltage into an output voltage to drive a load, the conversion control circuit comprising: a current control circuit having at least one control end coupled to the load to regulate the current of the load a first detecting circuit coupled to the current control circuit and generating a first detecting signal according to the voltage of the at least one control terminal; a second detecting circuit coupled to the converting circuit and generating a signal according to the output voltage a second detection signal; a feedback controller that receives the second detection signal to control the conversion circuit to convert the input voltage into the output voltage; and a feedback circuit coupled to the first detection circuit and the The second detecting circuit generates a feedback signal according to the first detection signal, and determines whether to output the feedback signal according to a dimming signal to compensate the level of the second detection signal. The switching control circuit of claim 1, wherein the feedback circuit comprises: a capacitor for generating the feedback signal; and a charging and discharging unit that charges the capacitor according to the first detecting signal Discharge. The conversion control circuit of claim 2, wherein the load is a light emitting diode module having a plurality of parallel LED strings. The conversion control circuit of claim 3, wherein the current control circuit has a plurality of control terminals respectively coupled to the plurality of LED strings, the first detection circuit coupled to the plurality of control terminals The first detection signal is generated according to a control terminal having the lowest voltage among the plurality of control terminals. The conversion control circuit of claim 2 or 4, wherein the feedback circuit includes a decoupling unit to prevent the second detection circuit from being subjected to the feedback The circuit transfers energy. The conversion control circuit of any one of the first, second, and fourth aspects of the patent application, wherein the feedback controller comprises: an error amplifying unit that receives the compensated second detection signal to generate An error amplification signal; and a pulse width modulation unit for generating a pulse width modulation signal according to the error amplification signal. The conversion control circuit of any one of the first, second, and fourth aspects of the patent application, wherein the feedback controller comprises: a transduction unit that receives the compensated second detection signal to generate a transducing output signal; and a pulse width modulation unit for generating a pulse width modulation signal according to the transduction output signal. The conversion control circuit of claim 1, wherein the feedback controller comprises: an impedance component; and a controlled current source, according to the first detection signal outputting a current flowing through the impedance component to generate The feedback signal. The conversion control circuit of claim 2, wherein the feedback controller comprises: a comparison unit, receiving the compensated second detection signal to generate a comparison signal; and a positive and negative The unit generates a duty cycle adjustment signal according to the comparison signal. A conversion control circuit for controlling a conversion circuit to convert power of an input voltage to drive a load, the conversion control circuit comprising: a controller that controls the conversion circuit to perform power conversion of the input voltage according to a feedback detection signal; a detection circuit coupled to the load to generate a detection signal; and a feedback circuit coupled to the detection The circuit is configured to generate a feedback signal according to the detection signal, the feedback circuit includes: a capacitor for generating the feedback signal; and a charging and discharging unit that charges and discharges the capacitor according to the detection signal Generating the feedback signal, wherein the charging and discharging unit includes a first current source, a second current source, a first switch, a second switch, and a charge and discharge control circuit, and the charge and discharge control circuit receives the detection signal To control the first switch and the second switch to be turned on or off, the first current source charges the capacitor or the second current source discharges the capacitor. The switching control circuit of claim 10, wherein the load is a light emitting diode module having a plurality of parallel LED strings, the current control circuit having a plurality of control terminals respectively connected to the plurality of control terminals The light emitting diode string and the detecting circuit are coupled to the plurality of control terminals to generate the detecting signal according to the control terminal having the lowest voltage among the plurality of control terminals. The conversion control circuit of claim 10, wherein the conversion control circuit is a linear regulator.