JP2009171715A - Constant current regulator with current sensing circuit loop - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a constant current regulator with a current sensing circuit loop for especially supplying a constant current to a load device. <P>SOLUTION: The current sensing circuit loop 30 connected to a switch device SW of the constant current regulator is included in the constant current regulator 3 for detecting a current flowing through the switch device SW and generating a detection current Is proportional to current flowing through the switch device SW. To guide a detection voltage Vs, the detection current Is flows through a detection resistor Rs. To generate an error voltage Ve in a pulse width modulation controller 32, a differential amplifier 36 causes a gate driving circuit 31 to control a switching operation for supplying the constant current to the load device connected to the output voltage of the regulator of the switch device SW based on the prescribed voltage Vset and received detection voltage. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

The present invention relates to a constant current regulator, and more particularly to a constant current regulator having a current sensing circuit loop for supplying a constant current to a load device.

Light emitting diodes (LEDs) have been widely used in lighting and backlighting applications. Different applications of LEDs require different color illumination and different powers of LEDs. For all currently available LED types, the best performance is often shown with constant current drive. Thus, the power supply circuit designated to drive the LED-based circuit must be characterized by providing a constant current output. In many cases, constant current regulators are used to provide the desired constant current power source. In all kinds of circuits, the LEDs must be connected in series to ensure a constant and identical current flow through all the LEDs.

Various constant current regulators are available including a buck type constant current regulator and a boost type constant current regulator.

FIG. 1 of the accompanying drawings shows a control circuit of a conventional buck type constant current regulator, which is usually designated by reference numeral 1a. The back type constant current regulator 1a includes a first switch device SW1 and a second switch device SW. The first switch device SW1 is connected in series to a drain connected to the input voltage Vin and the inductor L, and There is a source connected to the output voltage Vo. The second switch device SW2 has a drain connected to a node between the inductor L and the source of the first switch device SW1, and a source connected to the ground potential. The input voltage Vin is connected in parallel with the input capacitor Cin.

Both the first and second switch devices SW1 and SW2 have a gate connected to the gate drive circuit 11. The pulse width modulation (PWN) controller 12 controls the switching operation of the first and second switch devices SW1 and SW2 via the gate drive circuit 11.

The load device 2 includes a large number of light emitting diodes (LEDs) connected in series, the positive terminal of the load device 2 is connected to the output voltage Vo, and the negative terminal of the load device 2 is connected in series to the detection resistor Rs. The output voltage Vo is connected so as to be further grounded. When the load current I _L flows through the load device 2, the feedback voltage Vfb is obtained at a node connected between the negative terminal of the load device 2 and the detection resistor Rs.

The reference voltage input terminal of the amplifier 13 receives the reference voltage Vref, whereas the feedback voltage Vfb is applied to the feedback voltage input terminal of the differential amplifier 13. The differential amplifier 13 has an error signal output terminal connected to an RC circuit which is composed of a resistor Rc and a capacitor Cc and is also connected to the PWN controller 12. Based on the error between the reference voltage Vref and the feedback voltage Vfb, the differential amplifier 13 generates an error voltage Ve applied to the RC circuit and the PWN controller 12 at the error signal output terminal.

In the circuit of the conventional arrangement of the detection resistor Rs is connected in series to the high-current circuit loop load current I _L flows. Therefore, when the load current I _L is increased, the sensing resistor Rs consumes more power.

FIG. 2 of the accompanying drawings shows another conventional buck type constant current regulator control circuit, which is designated by reference numeral 1b. This conventional buck type constant current regulator 1b includes a first switch device SW1, a second switch device SW2, an inductor L, a gate drive circuit 11, a PWM controller 12, a comparator 14, a detection resistor Rs, and a reference voltage device. 15 is provided. The detection resistor Rs is connected in series between the input voltage Vin and the drain of the first switch device SW1. The reference voltage device 15 supplies the reference voltage Vref to the reference voltage input terminal of the comparator 14. The load device 2 is composed of a number of LEDs connected in series, and has an end connected to the output voltage Vo and an end located at the opposite position connected to the ground potential. In the circuit, the sensing resistor Rs is also connected in series to the high-current circuit loop load current I _L travels through the load device 2 flows.

FIG. 3 of the accompanying drawings shows a control circuit of a conventional boost type constant current regulator, which is designated by reference numeral 1c. The conventional boost type constant current regulator 1c includes a first switch device SW1 and a second switch device SW2, where the first switch device SW1 is connected to an input voltage Vin and a ground potential via an inductor L. There is a drain connected to The second switch device SW2 has a drain connected to a node between the inductor L and the first switch device SW1 and a source connected to the output voltage Vo. The output voltage Vo is connected in parallel with the output capacitor Co.

Both the first and second switch devices SW 1 and SW 2 have a gate connected to the gate drive circuit 11. The PWN controller 12 controls the switching operation of the first and second switch devices SW1 and SW2 via the gate drive circuit 11.

In the load device 2 composed of a number of light emitting diodes (LEDs) connected in series, the positive terminal of the load device 2 is connected to the output voltage Vo, and the negative terminal of the load device 2 is connected in series to the detection resistor Rs. And connected to the output voltage Vo so as to be further grounded. When the load current I _L flows through the load device 2, the feedback voltage Vfb is obtained at a node connected between the negative terminal of the load device 2 and the detection resistor Rs.

While the reference voltage input terminal of the amplifier 13 receives the reference voltage Vref, the feedback voltage Vfb is applied to the feedback voltage input terminal of the differential amplifier 13. The differential amplifier 13 includes a resistor Rc and a capacitor Cc, and has an error signal output terminal connected to an RC circuit that is also connected to the PWN controller 12. Based on the error between the reference voltage Vref and the feedback voltage Vfb, the differential amplifier 13 generates an error voltage Ve applied to the RC circuit and the error signal input terminal of the PWN controller 12 at the error signal output terminal.

In the circuit of the conventional arrangement of Figure 3, the sensing resistor Rs is connected in series to the high-current circuit loop load current I _L flows. Therefore, when the load current I _L is increased, the sensing resistor Rs, even small though the resistance of the resistor Rs consumes more power.

FIG. 4 of the accompanying drawings shows another conventional boost type constant current regulator control circuit, designated by reference numeral 1d. This conventional boost type constant current regulator 1d includes a first switch device SW1, a second switch device SW2, an inductor L, a gate drive circuit 11, a PWM controller 12, a comparator 14, a reference voltage device 15, and a detection resistor. Has Rs. The detection resistor Rs is connected in series between the first switch device SW1 and the ground. The load device 2 is composed of a number of LEDs connected in series, and has an end connected to the output voltage Vo and an end at the opposite position to be grounded. The reference voltage device 15 supplies the reference voltage Vref to the reference voltage input terminal of the comparator 14. In this circuit, the detection resistor Rs is similarly connected in series to the high current circuit loop constituted by the first switch device SW1, so that when the current flowing through the first switch SW1 becomes large, the detection resistor Rs is detected. The resistor Rs consumes more power even if the resistance of the resistor Rs is small.

All of these four types of conventional constant current regulators employ a circuit design in which a sensing resistor is connected in series with a circuit loop through which a large current flows in the control circuit. Thus, due to the large current flow therethrough, even if the resistance of the detection circuit Rs is very small, a considerable voltage drop is generated across the resistor, which consumes a significant amount of power Means that.

In addition to the conventional constant current regulator described above, other circuits are also found in prior art references. For example, US Pat. No. 7,135,182 discloses an LED driver circuit that also connects a sense resistor in the LED load circuit loop to generate a feedback voltage. Thus, in the reference power supply, the sensing resistor is connected in series with the load device, so when the current flowing through the load circuit increases, even if the resistance of the resistor is small, the resistor is still a large amount Consume power. Another embodiment is disclosed in US Pat. No. 6,980,181 where a drive circuit is provided for the LED and connected in series to its switching circuit loop to generate a period voltage applied to the error amplifier. A sense resistor. The switching circuit loop is still considered a high current circuit loop, and again the reference circuit suffers from the same obstacle of significant power consumption.
US Patent No. 7,135,182 US Patent No. 6,980,181

In view of the above problems existing in known devices, the object of the present invention is to provide a current feedback type constant current regulator, which is without a sensing resistor connected in a high current circuit loop. In order to generate a feedback signal, adjust a constant current based on the feedback signal and supply it to the load device, a current flow through the load device is detected.

Another object of the present invention is to provide a constant current regulator that also has a current sensing circuit loop, where the current sensing circuit loop detects the current flowing through the switch device and the current flowing through the switch device. Is connected to a switching device of a constant current regulator that generates a detection current proportional to the control current, thereby controlling a switching operation of the switching device based on the detection current.

A further object of the present invention is to provide a constant current power supply that is particularly suitable for a series connected arrangement, in particular, a load circuit loop constituted by light emitting diodes connected in series is connected thereto. Does not require a sense resistor.

In order to solve the above problem, the invention of claim 1 is directed to a switch device having a first terminal connected to an input voltage and a second terminal connected to output power via an inductor, and a gate of the switch device. A gate drive circuit connected to the gate drive circuit, a pulse width modulation controller connected to the gate drive circuit and having an error signal input terminal, and a current flowing through the switch device is detected, and the switch device is detected at a constant ratio. A current sensing circuit loop connected to the switch device to generate a detection current that is proportional to the current flowing therethrough and that flows through a detection resistor that induces a detection voltage; and a predetermined voltage connected to a predetermined voltage A differential amplifier having an input terminal, a detection voltage input terminal connected to the detection resistor for receiving the detection voltage, and a differential signal output terminal; Is a switching control signal for controlling the switch device to the gate driving circuit based on the detection voltage for generating an error voltage applied to the pulse width modulation controller at the predetermined voltage and the differential signal output terminal thereof. And thereby supplying a constant current to a load device connected to the output voltage.

The invention according to claim 2 is the constant current regulator according to claim 1, wherein the load device includes a light emitting diode array including a plurality of light emitting diodes connected in series.

The invention of claim 3 wherein the current sensing circuit loop is used from an input voltage such that when the current from the adjustable current source flows through the resistor, the predetermined voltage is induced across the resistor. A current setting circuit that receives a voltage and includes an adjustable current source and a resistor connected in series; and a current detection circuit that receives the operating voltage from an input voltage and includes the detection resistor through which the detection current flows. The constant current regulator according to claim 1, wherein:

According to a fourth aspect of the present invention, in order to generate a half cycle compensation detection voltage, the detection voltage generated by the current detection circuit is applied to the half cycle compensation circuit, and is applied to the voltage input terminal of the differential amplifier. The constant current regulator according to claim 3, wherein the constant current regulator is added.

According to a fifth aspect of the present invention, the half-cycle compensation circuit includes a coupler, a half-cycle compensation switch device, and a capacitor, the coupler receives the detection voltage from the current detection circuit, and the half-cycle compensation switch device includes the 5. The gate connected to the gate drive circuit controlled by the switching control signal generated by a gate drive circuit, and the switch device has a power source connected to the capacitor. The constant current regulator described in 1.

According to a sixth aspect of the present invention, there is provided a switch device having a first terminal connected to an input voltage via an inductor, and further connected to a second terminal connected to the input voltage and ground via a diode, and connected to a gate of the switch device. A gate drive circuit, a pulse width modulation controller connected to the gate drive circuit and having an error signal input terminal;
To detect a current flow through the switch device and to generate the detected current that is proportionally proportional to the current flow through the switch device and that is passed through a sense resistor that induces a sense voltage. A current sensing circuit loop connected to the switch device; a predetermined voltage input terminal connected to a predetermined voltage; a detection voltage input terminal connected to the detection resistor for receiving the detection voltage; and a differential signal output terminal A differential amplifier, the differential amplifier based on the predetermined voltage and the detection voltage for generating an error voltage applied to the pulse width modulation controller at the differential signal output terminal thereof, and similarly the gate drive circuit Generating a switching control signal for controlling the switch device, thereby supplying a constant current to a load device connected to the output voltage. Characterized in that a constant current regulator.

The invention according to claim 7 is the constant current regulator according to claim 6, wherein the load device comprises a light emitting diode array including a plurality of light emitting diodes connected in series.

The invention of claim 8 wherein the current sensing circuit loop is used from an input voltage such that when the current from an adjustable current source flows through the resistor, the predetermined voltage is induced across the resistor. A current setting circuit that receives a voltage and includes an adjustable current source and a resistor connected in series; and a current detection circuit that receives the operating voltage from an input voltage and includes the detection resistor through which the detection current flows. The constant current regulator according to claim 6, wherein:

According to the ninth aspect of the invention, in order to generate a half cycle compensation detection voltage, the detection voltage generated by the current detection circuit is applied to the half cycle compensation circuit, and is applied to the voltage input terminal of the differential amplifier. The constant current regulator according to claim 8, wherein the constant current regulator is added.

According to a tenth aspect of the present invention, the half cycle compensation circuit includes a coupler, a half cycle compensation switch device, and a capacitor, and the coupler receives the detection voltage from the current detection circuit, and the half cycle compensation switch device includes: The gate device connected to the gate driving circuit controlled by the switching control signal generated by the gate driving circuit, and the switch device has a power source connected to the capacitor. 9. The constant current regulator according to 9.

The invention of claim 11 is a first switch device having a first terminal connected to an input voltage via an inductor and a grounded second terminal, and a first switch device connected to the first terminal of the first switch device. A second switching device having a terminal and a second terminal connected to the output voltage, and for controlling the first and second switching devices via first and second switching control signals, respectively, A gate drive circuit connected to the gate and the gate of the second switch device; a pulse width modulation controller connected to the gate drive circuit and having an error signal input terminal; and a current flow through the second switch device. Detecting and generating the detected current flowing through a detection resistor that induces a detection voltage proportional to the current flow through the second switch device by a constant ratio In order to receive the detection voltage generated by the detection resistor and generating a half-cycle compensated detection voltage, the current sensing circuit is connected to the first and second switch devices. A half cycle compensation circuit connected to the detection resistor of the loop, a predetermined voltage input terminal connected to a predetermined voltage, a detection voltage input terminal connected to the detection resistor for receiving the detection voltage, and a differential signal output terminal A differential amplifier having a predetermined voltage input terminal connected to a predetermined voltage, a detection voltage input terminal connected to the half cycle compensation circuit receiving the half cycle compensation detection voltage, and a differential signal output terminal The differential amplifier generates an error voltage applied to the pulse width modulation controller at the predetermined voltage and the differential signal output terminal thereof And generating the first and second switching control signals for controlling the first and second switching devices respectively in the gate driving circuit based on the received half-cycle compensated detection voltage for generating the output voltage. It is a constant current regulator characterized by supplying a constant current to the load apparatus connected to.

The invention of claim 12 is the constant current regulator according to claim 11, wherein the load device comprises a light emitting diode array including a plurality of light emitting diodes connected in series.

The invention of claim 13 wherein the current sensing circuit loop is used from an input voltage such that when the current from an adjustable current source flows through a resistor, the predetermined voltage is induced across the resistor. A current setting circuit that receives a voltage and includes an adjustable current source and a resistor connected in series; and a current detection circuit that receives the operating voltage from an input voltage and includes the detection resistor through which the detection current flows. The constant current regulator according to claim 11, wherein:

According to a fourteenth aspect of the present invention, the half cycle compensation circuit includes a coupler, a half cycle compensation switch device, and a capacitor. The coupler receives the detection voltage from the current detection circuit, and the half cycle compensation switch device includes: A gate connected to the gate drive circuit controlled by the second switching control signal generated by the gate drive circuit, and the switch device has a power supply connected to the capacitor; A constant current regulator according to claim 11.

According to a fifteenth aspect of the present invention, a first switch device having a first terminal connected to an input voltage via an inductor and a grounded second terminal, and a first terminal connected to the first terminal of the first switch device And a second switch device having a second terminal connected to the output voltage, and a gate of the first switch device for controlling the first and second switch devices via first and second switching control signals, respectively. And a gate drive circuit connected to the gate of the second switch device, a pulse width modulation controller connected to the gate drive circuit and having an error signal input terminal, and a current passing through the first and second switch devices Detecting the current, proportional to the current flow through the first and second switch devices by a fixed ratio, and flowing through a sensing resistor that induces a sense voltage. A current sensing circuit loop connected to the first and second switch devices, a predetermined voltage input terminal connected to a predetermined voltage, a detection voltage input terminal connected to the detection resistor, and A differential amplifier having a differential signal output terminal, the differential amplifier based on the predetermined voltage and the detected voltage for generating an error voltage applied to the pulse width modulation controller at the differential signal output terminal; Similarly, the gate driving circuit generates first and second switching control signals for controlling the first and second switching devices, respectively, thereby supplying a constant current to a load device connected to the output voltage. This is a constant current regulator.

The invention according to claim 16 is the constant current regulator according to claim 15, wherein the load device includes a light emitting diode array including a plurality of light emitting diodes connected in series.

The invention of claim 17 is characterized in that the current sensing circuit loop uses a voltage from an input voltage such that the predetermined voltage is induced across the resistor when current from an adjustable current source flows through the resistor. A current setting circuit including an adjustable current source and a resistor connected in series, and a current detection circuit including the detection resistor that receives a use voltage from an input voltage and flows the detection current. The constant current regulator according to claim 15, characterized in that it is a constant current regulator.

Compared to known techniques, the present invention provides a constant current adjustment to generate a sense current proportional to the load device for controlling the current flowing through the switch device or the current supplied to the load device. Use the technology of current sensing circuit loop combined with the detector. Since the sense resistor is not connected to the load circuit loop, a large amount of power is no longer consumed by the sense resistor provided by the sense resistor provided to the load circuit loop, as taught by known techniques. It is no longer consumed. Moreover, in accordance with the present invention, the sense resistor is connected to a current mirror circuit employed in the current sensing circuit loop, so that the resistance of the sense resistor is not subject to any restrictions. This is different from known techniques where only small resistance resistors can be used. Thus, the present invention provides more flexibility for circuit design.

Preferred embodiments of the present invention will be described below in detail with reference to the accompanying drawings.

Referring to the drawings and particularly FIG. 5, a control circuit according to a first preferred embodiment of the present invention is shown, which is applicable to a buck type half cycle sensing constant current regulator. For convenience, parts / components / devices that are identical or similar to corresponding parts illustrated in the prior art devices described above have been given the same reference numerals.

The constant current regulator shown in FIG. 5 according to the first embodiment of the present invention is shown extensively at 3, the output voltage via the drain (first terminal) connected to the input voltage Vin and the inductor L. A switch device SW having a source (second terminal) connected to Vo is provided. The source of the switch device SW is also connected to the negative terminal of the diode D. Diode D has a positive terminal that is grounded. The diode D may be a Schottky diode, for example.

The load device 2 composed of a number of light emitting diodes (LEDs) connected in series has an end connected to the output voltage Vo and an end at the opposite position grounded.

The switch device SW has a gate connected to the gate drive circuit 31. The pulse width modulation (PWM) controller 32 has an error signal input terminal 32a connected to an RC circuit constituted by a resistor Rc and a capacitor Cc. The error signal input terminal 32a of the PWM controller 32 has a switching control signal V for the PWN controller 32 to generate the pulse width modulation signal V _PWM in the gate drive circuit 31 and similarly to control the switching operation of the switch device SW. Based on generating the _SW , it functions to receive the error signal Ve.

The constant current regulator 3 of the present invention is also referred to as a current sensing circuit loop, and detects or senses a current flowing through the switch device SW, as well as a differential amplifier 36 that supplies an error signal Ve to the PWM controller 32. It further comprises a current feedback circuit loop 30 that functions to provide an input.

The current sensing circuit loop 30 includes a current setting circuit 33, which receives a use voltage from the input voltage Vin. The current setting circuit 33 comprises an adjustable current source Iset and a resistor Rref connected in series. When current from the adjustable current source Iset flows through the resistor Rref, the predetermined circuit Vset is obtained beyond the resistor Rref.

The current detection circuit 34 receives a use voltage from the input voltage Vin. The current detection circuit 34 includes a detection current Is and a resistor Rs connected in series. When the detection current Is flows through the resistor Rs, the detection voltage Vs is induced across the resistor Rs. Detection current Is and the load current I _L flows through the switch devices SW is, N is shown in the drawings: N as an imaginary line that indicates the first current ratio: 1 proportionality.

Since the fast-acting embodiment is applied to a back-type half-cycle sensing constant current regulator, the detection voltage Vs generated by the current detection circuit 34 is applied to the detection voltage input terminal 36a of the differential amplifier 36 at the half-cycle compensation detection voltage. In order to generate Vs ′, the processing of the half cycle compensation circuit 35 is required. The predetermined voltage Vset generated by the current setting circuit 33 is applied to the predetermined voltage input terminal 36 b of the differential amplifier 36. Based on the supply signal Vset and the half cycle compensation detection voltage Vs', the differential amplifier 36 generates an error voltage Ve applied to the error signal input terminal 32a of the PWM controller 32 at the differential signal output terminal 36c.

FIG. 6 shows a more detailed control circuit for the current setting circuit 33 of FIG. 5, comprising a feedback amplifier 331, switch devices T21, T22, T33 and resistors Rref, Rset together forming a current mirror circuit, The current Iset flowing through the switching device T21 is set exactly the same as the current Iset flowing through the switching device T22, which is illustrated in the drawing by an imaginary line indicating a current ratio of 1: 1. Since a current mirror circuit is employed, the resistance of the resistor Rset is not limited at all, which is contrary to the prior art where a resistor with a small resistance must be used.

FIG. 7 shows a more detailed control circuit of the current detection circuit 34 and the half cycle compensation circuit 35 of FIG. 5, and includes switch devices SW, T12, T13, T14, T15, T16, and T17 that together form a current mirror circuit. . When the switch device SW is conducted, the following relationship between the currents I1, I2, I _L , Is is satisfied.
That is, the detection current Is and the load current I _L N: meet 1 ratio.

The half cycle compensation circuit 35 includes a coupler 351, a half cycle compensation switch device 352, and a capacitor CH. The coupler 352 receives the detection voltage Vs from the current detection circuit 34. The half cycle compensation switch device 352 has a gate connected to the gate drive circuit 31 and is controlled by a switching control signal _VSW generated by the gate drive circuit 31. Half cycle compensation switch device 352 has a source connected to capacitor CH.

FIG. 8 shows the waveform of the signal taken at the node of the circuit of FIG. In the drawing, I _L (maximum) represents the maximum load current, I _L (minimum) represents the minimum load current, and I _L (average) represents the average of the load currents. When the load current I _L flows through the load device 2, the current detection circuit 34 detects the plus half cycle (within the period ton between time points T1 and T1 ′) of the load current I _L detection circuit Is, The detection voltage Vs is induced. The detection voltage Vs is transmitted through the half cycle compensation circuit 35 and then applied to the differential amplifier 36 to induce an error signal Ve at the differential signal output terminal 36c of the differential amplifier 36. The PWM controller 32 generates a high level gate drive voltage V _PWM when receiving the error signal Ve, which generates a switching control signal V _SW that controls the switching operation of the switch device SW. Processed by.

When the negative half cycle of the load current I _L (within the period toff between the time points T1 ′ and T2) passes through the load device 2, the current detection circuit 34 detects the no-load current I _L and detects the zero detection voltage Vs. To induce. Within the negative half cycle range of the load current I _L , the capacitor CH of the half cycle compensation circuit 35 is current sensing to ensure that the PWM controller 32 does not perform an incorrect operation when performing pulse width modulation. The detection voltage Vs generated by the circuit 34 is maintained.

FIG. 9 shows a control circuit according to a second embodiment of the present invention, which is applicable to a boost type half cycle sensing constant current regulator. The constant current regulator according to the second embodiment of the invention is shown extensively at 3a and is connected to the input voltage Vin via the inductor L and further connected to the output voltage Vo via the diode D. A switch device SW is provided. The switch device SW has a source that is grounded.

The load device 2 composed of a number of LEDs connected in series has an end connected to the output voltage Vo and an end in the opposite position that is grounded.

The switch device SW has a gate connected to the gate drive circuit 31. The PWM controller 32 has an error signal input terminal 32a connected to an RC circuit constituted by a resistor Rc and a capacitor Cc. The error signal input terminal 32a of the PWM controller 32 has a switching control signal V for the PWN controller 32 to generate the pulse width modulation signal V _PWM in the gate drive circuit 31 and similarly to control the switching operation of the switch device SW. Based on generating the _SW , it functions to receive the error signal Ve.

The constant current regulator 3a of the present invention functions to detect or sense the current flowing through the switching device SW and provides an input to a differential amplifier 36 that supplies an error signal Ve to the PWM controller 32. A feedback circuit loop 30a is further provided.

The current sensing circuit loop 30a includes a current setting circuit 33a, which receives a use voltage from the input voltage Vin. The current setting circuit 33a includes an adjustable current source Iset and a resistor Rref connected in series. When current from the adjustable current source Iset flows through the resistor Rref, the predetermined circuit Vset is obtained beyond the resistor Rref.

The current detection circuit 34a receives a use voltage from the input voltage Vin. The current detection circuit 34a includes a detection current Is and a resistor Rs connected in series. When the detection current Is flows through the resistor Rs, the detection voltage Vs is induced across the resistor Rs. The detection current Is and the load current I _L flowing through the switch device SW are in a proportional relationship of N: 1, as indicated by an imaginary line indicating a current ratio of N: 1 shown in the drawing.

Since the fast-acting embodiment is applied to a boost type half cycle sensing constant current regulator, the detection voltage Vs generated by the current detection circuit 34a is applied to the detection voltage input terminal 36a of the differential amplifier 36 at the half cycle compensation detection voltage. In order to generate Vs', the processing of the half cycle compensation circuit 35a is required. The predetermined voltage Vset generated by the current setting circuit 33 a is applied to the predetermined voltage input terminal 36 b of the differential amplifier 36. Based on the predetermined voltage (feedback signal) Vset and the half cycle compensation detection voltage Vs ′, the differential amplifier 36 generates an error voltage Ve applied to the error signal input terminal 32a of the PWM controller 32 at the difference signal output terminal 36c. .

The current setting circuit 33a is composed of a control circuit which is a current mirror circuit, which is exactly the same as the current setting circuit 33 (FIG. 6) of the previous embodiment.

FIG. 10 shows a more detailed control circuit of the current detection circuit 34a and the half cycle compensation circuit 35a of FIG. 9, and includes a switch device SW and other switch devices that together form a current mirror circuit. When the switch device SW is conducted, the following relationship between the currents I1, I2, I _L , Is is satisfied.
That is, the detection current Is and the load current I _L, N: meet 1 ratio.

The half cycle compensation circuit 35a includes a coupler 351, a half cycle compensation switch device 352, and a capacitor CH. The coupler 351 receives the detection voltage Vs from the current detection circuit 34a. The half cycle compensation switch device 352 has a gate connected to the gate drive circuit 31 and is controlled by a switching control signal _VSW generated by the gate drive circuit 31. Half cycle compensation switch device 352 has a source connected to capacitor CH.

FIG. 11 shows the waveform of the signal taken at the node of the circuit of FIG. When the load current I _L flows through the load device 2, the current detection circuit 34a detects the detection circuit Is caused by the plus half cycle of the load current I _L (within the period ton between the time points T1 and T1 ′). Detect and induce a detection voltage Vs. The detection voltage Vs is transmitted through the half cycle compensation circuit 35a and then applied to the differential amplifier 36 to induce an error signal Ve at the differential signal output terminal 36c of the differential amplifier 36. When the PWM controller 32 receives the error signal Ve, the PWM controller 32 generates a high level gate drive voltage V _PWM, which generates a gate control signal V _SW for controlling the switching operation of the switch device SW. Processed by the circuit 31.

When the negative half cycle of the load current I _L (within the period toff between the time points T1 ′ and T2) passes through the load device 2, the current detection circuit 34a detects the no-load current I _L and detects the zero detection voltage Vs. To induce. Within the negative half cycle range of the load current I _L , the capacitor CH of the half cycle compensation circuit 35a has a current to ensure that the PWM controller 32 does not perform an incorrect operation when performing pulse width modulation. The detection voltage Vs generated by the detection circuit 34a is maintained.

FIG. 12 shows a control circuit according to a third embodiment of the present invention, which is also applicable to a boost type half cycle sensing constant current regulator. The constant current regulator according to the third embodiment of the invention is shown extensively at 3b and comprises a first switch device SW1 and a second switch device SW2, where the first switch device SW1 includes: There is a drain connected via an inductor L to the input voltage Vin and the source to be grounded. The second switch device SW2 has a drain connected to the drain of the first switch SW1 and a source connected to the output voltage Vo. Both the first switching device SW1 and the second switch device SW2, is connected to the gate drive circuit 31 to receive the first switching control signal V _SW1 and the second switching control signal V _SW2 which is controlled thereby, respectively There is a gate.

The PWM controller 32 has an error signal input terminal 32a connected to an RC circuit constituted by a resistor Rc and a capacitor Cc. The error signal input terminal 32a of the PWM controller 32 causes the PWN controller 32 to generate the pulse width modulation signal V _PWM in the gate drive circuit 31, and similarly controls the switching operations of the first and second switch devices SW1 and SW2, respectively. In order to do so, it functions to receive the error signal Ve based on generating the first and second switching control signals V _SW1 and V _SW2 .

The constant current regulator 3b of the present invention functions to detect or sense the current flowing through the switch device and provides an input to a differential amplifier 36 that supplies an error signal Ve to the PWM controller 32. A circuit loop 30b is further provided.

The current sensing circuit loop 30b includes a current setting circuit 33b, which receives a use voltage from the input voltage Vin. The current setting circuit 33b includes an adjustable current source Iset and a resistor Rref connected in series. When current from the adjustable current source Iset flows through the resistor Rref, the predetermined circuit Vset is obtained beyond the resistor Rref.

The current detection circuit 34b receives the use voltage from the input voltage Vin. The current detection circuit 34b includes a detection current Is and a resistor Rs connected in series. When the detection current Is flows through the resistor Rs, the detection voltage Vs is induced across the resistor Rs. Detection current Is and the load current I _L flows through the switch devices SW is, N is shown in the drawings: As imaginary lines indicate a first current ratio, N: 1 proportionality.

Since the fast-generating embodiment is applied to a boost type half-cycle sensing constant current regulator, the detection voltage Vs generated by the current detection circuit 34b is applied to the detection voltage input terminal 36a of the differential amplifier 36 at the half-cycle compensation detection voltage. In order to generate Vs', the processing of the half cycle compensation circuit 35b is required. The predetermined voltage Vset generated by the current setting circuit 33 b is applied to the predetermined voltage input terminal 36 b of the differential amplifier 36. Based on the predetermined voltage (feedback signal) Vset and the half cycle compensation detection voltage Vs ′, the differential amplifier 36 generates an error voltage Ve applied to the error signal input terminal 32a of the PWM controller 32 at its differential signal output terminal 36c. Let

The current setting circuit 33b is composed of a control circuit which is a current mirror circuit, which is exactly the same as the current setting circuit 33 (FIG. 6) of the first embodiment.

FIG. 13 shows a more detailed control circuit of the current detection circuit 34b and the half cycle compensation circuit 35b of FIG. 12, and shows the first switch device SW1, the second switch device SW2 and other switch devices that together form a current mirror circuit. Prepare. When the first switch device SW1 is turned off and the second switch device SW2 is conducted, the following relationship between the currents I1, I2, I _L , Is is satisfied.
That is, the detection current Is and the load current I _L, N: meet 1 ratio.

The half cycle compensation circuit 35b includes a coupler 351, a half cycle compensation switch device 352, and a capacitor CH. The coupler 351 receives the detection voltage Vs from the current detection circuit 34b. The half cycle compensation switch device 352 has a gate connected to the gate drive circuit 31 and is controlled by a second switching control signal V _SW2 generated by the gate drive circuit 31. Half cycle compensation switch device 352 has a source connected to capacitor CH.

FIG. 14 shows the waveform of the signal taken at the node of the circuit of FIG. When the load current I _L flows through the load device 2, the current detection circuit 34b detects the detection circuit Is caused by the plus half cycle of the load current I _L (within the period between time points T1 ′ and T2). Then, the detection voltage Vs is induced. The detection voltage Vs is transmitted through the half cycle compensation circuit 35b and then applied to the differential amplifier 36 to induce an error signal Ve at the differential signal output terminal 36c of the differential amplifier 36. By receiving the error signal Ve by the PWM controller 32, the gate drive circuit 31 generates a second switching control signal _VSW2 for controlling the switching operation of the second switch device SW2.

FIG. 15 shows a control circuit according to a fourth embodiment of the present invention, which is also applicable to a boost type half cycle sensing constant current regulator. The constant current regulator according to the third embodiment of the present invention is shown extensively at 3c and comprises a first switch device SW1 and a second switch device SW2, where the first switch device SW1 has an induction There is a drain connected to the input voltage Vin and the grounded source via a child L. The second switch device SW2 has a drain connected to the drain of the first switch SW1 and a source connected to the output voltage Vo. Both the first switching device SW1 and the second switch device SW2, is connected to the gate drive circuit 31 to receive the first switching control signal V _SW1 and the second switching control signal V _SW2 which is controlled thereby, respectively There is a gate.

The PWM controller 32 has an error signal input terminal 32a connected to an RC circuit constituted by a resistor Rc and a capacitor Cc. The error signal input terminal 32a of the PWM controller 32 causes the PWN controller 32 to generate the pulse width modulation signal V _PWM in the gate drive circuit 31, and similarly controls the switching operations of the first and second switch devices SW1 and SW2, respectively. In order to do so, it functions to receive the error signal Ve based on generating the first and second switching control signals V _SW1 and V _SW2 .

The constant current regulator 3c of the present invention functions to detect or sense the current flowing through the switch device and provides an input to a differential amplifier 36 that supplies an error signal Ve to the PWM controller 32. A circuit loop 30c is further provided.

The current sensing circuit loop 30c includes a current setting circuit 33c, which receives a working voltage from the input voltage Vin. The current setting circuit 33c includes an adjustable current source Iset and a resistor Rref connected in series. When current from the adjustable current source Iset flows through the resistor Rref, the predetermined circuit Vset is obtained beyond the resistor Rref.

The current detection circuit 34c receives a use voltage from the input voltage Vin. The current detection circuit 34c includes a detection current Is and a resistor Rs connected in series. When the detection current Is flows through the resistor Rs, the detection voltage Vs is induced across the resistor Rs. The detection current Is and the load current I _L flowing through the switch device SW are in a proportional relationship of N: 1, as indicated by an imaginary line indicating a current ratio of N: 1 shown in the drawing.

Since the fast implementation is applied to a boost type half cycle sensing constant current regulator, there is no need for a half cycle compensation circuit as employed in previous embodiments.

The current setting circuit 33c is composed of a control circuit which is a current mirror circuit, which is exactly the same as the current setting circuit 33 (FIG. 6) of the first embodiment.

FIG. 16 shows a more detailed control circuit of the current detection circuit 34c of FIG. 15, and includes a first switch device SW1, a second switch device SW2, and other switch devices that together form a current mirror circuit.

When the first switch device SW1 is conducted and the second switch device SW2 is turned off, the following relationship between the currents I1, I2, I3, I4, I _L , Is1, Is2 is satisfied.
And the first switching device SW1 is turned off conduction, when the second switching device SW2 is conducted, the following relationship between the currents I1, I2, I3, I4, I L, Is1, Is2 is satisfied.

FIG. 17 shows the waveform of the signal taken at the node of the circuit of FIG. When the load current I _L flows through the load device 2, the current detection circuit 34c detects the detection circuit Is1 caused by the plus half cycle of the load current I _L (within the period between the time points T1 and T1 ′). Then, a detection voltage Vs is induced, which is applied to the differential amplifier 36 to generate an error signal Ve. When the negative half cycle of the load current I _L (within the range between the time points T1 ′ and T2) passes through the load device 2, the current detection circuit 34c has a negative half cycle (the time period between the time points T1 ′ and T2). ) To detect a detection current Is2 and induce a detection voltage Vs, which is applied to the differential amplifier 36 to generate an error signal Ve. Upon receipt of the error signal Ve by the PWM controller 32, the gate drive circuit 31 generates first and second switching control signals V _SW1 and V _SW2 for controlling the switching operation of the first switch device SW1 and the second switch device SW2. Let

Although the invention has been described with reference to preferred embodiments thereof, various modifications and changes may be made without departing from the scope of the invention, which is intended to be defined by the appended claims. This will be apparent to those skilled in the art.

Circuit diagram of conventional buck type constant current regulator Circuit diagram of another conventional buck type constant current regulator Circuit diagram of conventional boost type constant current regulator Circuit diagram of conventional boost type constant current regulator 1 is a circuit diagram of a constant current regulator configured in accordance with a first embodiment of the present invention. More detailed circuit diagram of the current setting circuit of the constant current regulator of FIG. More detailed circuit diagram of the current detection circuit and the half cycle compensation circuit of the constant current regulator of FIG. 6 shows waveforms taken at the nodes of the constant current regulator of FIG. Circuit diagram of a constant current regulator configured according to the second embodiment of the present invention More detailed circuit diagram of the current detection circuit and the half cycle compensation circuit of the constant current regulator of FIG. 10 shows waveforms taken at the node of the constant current regulator of FIG. Circuit diagram of a constant current regulator configured according to the third embodiment of the present invention 12 is a more detailed circuit diagram of the current detection circuit and the half cycle compensation circuit of the constant current regulator of FIG. FIG. 13 shows waveforms taken at the nodes of the constant current regulator of FIG. Circuit diagram of a constant current regulator configured according to the fourth embodiment of the present invention A more detailed circuit diagram of the current detection circuit of the constant current regulator of FIG. 16 shows waveforms taken at the node of the constant current regulator of FIG.

Explanation of symbols

SW1 first switch device SW2 second switch device Vin input voltage L inductors Vo output voltage Cin input capacitor LED light emitting diode Rs sensing resistor _{I L} the load current _{I L} (max) load current (maximum)
I _L (min) Load current (minimum)
I _L (avg) Load current (average)
Vfb feedback voltage Vref reference voltage Cc capacitor Ve error voltage Co output capacitor SW switch device D diode V _PWM pulse width modulation signal / gate drive voltage V _SW switching control signal Ve error signal / error voltage Iset adjustable current source Rset resistor Rref resistor Vset predetermined circuit / supply signal Is detection current Vs ′ half cycle compensation detection voltage Vs detection voltage I1 current I2 current CH capacitor V _SW1 first switching control signal V _SW2 second switching control signal Is1 detection circuit 1a back type constant current regulator 1b Buck type constant current regulator 1c Buck type constant current regulator 1d Boost type constant current regulator 11 Gate drive circuit 12 Pulse width modulation (PWN) controller 13 Differential amplifier 14 Comparator 15 Reference Pressure device 2 Load device 3 Constant current regulator 3a Constant current regulator 3b Constant current regulator 3c Constant current regulator 30 Current sensing circuit loop 30a Current sensing circuit loop 30b Current sensing circuit loop 30c Current sensing circuit loop 31 Gate drive circuit 32 Pulse width modulation (PWN) controller 32a Error signal input terminal 33 Current setting circuit 33a Current setting circuit 33b Current setting circuit 33c Current setting circuit 331 Feedback amplifier 34 Current detection circuit 34a Current detection circuit 34b Current detection circuit 34c Current detection circuit 35 Half Cycle compensation circuit 35a Half cycle compensation circuit 35b Half cycle compensation circuit 351 Coupler 352 Half cycle compensation switch device 36 (Error) Differential amplifier 36a Detection voltage input terminal 36b Default voltage input terminal 36c Detection voltage input terminal T21 Switch device T22 Switch device T3 Switch device T12 switch device T13 switch device T14 switch device T15 switch device T16 switch device T17 switch device

Claims (17)

A switching device having a first terminal connected to the input voltage and a second terminal connected to the output power via an inductor;
A gate drive circuit connected to the gate of the switch device;
A pulse width modulation controller connected to the gate drive circuit and having an error signal input terminal;
Detecting the current flowing through the switch device and generating a detection current flowing through a detection resistor that induces a detection voltage proportional to the current flowing through the switch device by a fixed ratio. A current sensing circuit loop connected to the switch device;
A differential amplifier having a predetermined voltage input terminal connected to a predetermined voltage, a detection voltage input terminal connected to the detection resistor receiving the detection voltage, and a differential signal output terminal;
The differential amplifier similarly controls the switch device to the gate drive circuit based on the predetermined voltage and the detection voltage for generating an error voltage applied to the pulse width modulation controller at the differential signal output terminal. A constant current regulator for generating a switching control signal for supplying a constant current to a load device connected to the output voltage. The constant current regulator according to claim 1, wherein the load device comprises a light emitting diode array including a plurality of light emitting diodes connected in series. The current sensing circuit loop receives and adjusts the working voltage from the input voltage so that when the current from the adjustable current source flows through the resistor, the predetermined voltage is induced across the resistor A current setting circuit including a current source and a resistor connected in series;
The constant current regulator according to claim 1, further comprising a current detection circuit including the detection resistor that receives a use voltage from an input voltage and through which the detection current flows. In order to generate a half cycle compensation detection voltage, the detection voltage generated by the current detection circuit is applied to the half cycle compensation circuit and to the voltage input terminal of the differential amplifier. The constant current regulator according to claim 3. The half-cycle compensation circuit includes a coupler, a half-cycle compensation switch device, and a capacitor. The coupler receives the detection voltage from the current detection circuit, and the half-cycle compensation switch device is generated by the gate drive circuit. 5. The constant current adjustment according to claim 4, wherein there is a gate connected to the gate driving circuit controlled by the switching control signal, and the switch device has a power source connected to the capacitor. vessel. A switch device having a first terminal connected to the input voltage via an inductor, and further connected to a second terminal connected to the input voltage and ground via a diode;
A gate drive circuit connected to the gate of the switch device;
A pulse width modulation controller connected to the gate drive circuit and having an error signal input terminal;
To detect a current flow through the switch device and to generate the detected current that is proportionally proportional to the current flow through the switch device and that is passed through a sense resistor that induces a sense voltage. A current sensing circuit loop connected to the switch device;
A differential amplifier having a predetermined voltage input terminal connected to a predetermined voltage, a detection voltage input terminal connected to the detection resistor receiving the detection voltage, and a differential signal output terminal;
The differential amplifier similarly controls the switch device to the gate drive circuit based on the predetermined voltage and the detection voltage for generating an error voltage applied to the pulse width modulation controller at the differential signal output terminal. A constant current regulator for generating a switching control signal for supplying a constant current to a load device connected to the output voltage. The constant current regulator according to claim 6, wherein the load device includes a light emitting diode array including a plurality of light emitting diodes connected in series. The current sensing circuit loop receives and adjusts the working voltage from the input voltage so that when the current from the adjustable current source flows through the resistor, the predetermined voltage is induced across the resistor A current setting circuit including a current source and a resistor connected in series;
The constant current regulator according to claim 6, further comprising: a current detection circuit that receives the use voltage from the input voltage and includes the detection resistor through which the detection current flows. In order to generate a half cycle compensation detection voltage, the detection voltage generated by the current detection circuit is applied to the half cycle compensation circuit and to the voltage input terminal of the differential amplifier. The constant current regulator according to claim 8. The half-cycle compensation circuit includes a coupler, a half-cycle compensation switch device, and a capacitor. The coupler receives the detection voltage from the current detection circuit, and the half-cycle compensation switch device is generated by the gate drive circuit. 10. The constant current adjustment according to claim 9, wherein there is a gate connected to the gate driving circuit controlled by the switching control signal, and the switch device has a power source connected to the capacitor. vessel. A first switching device having a first terminal connected to an input voltage via an inductor and a grounded second terminal;
A second switch device having a first terminal connected to the first terminal of the first switch device and a second terminal connected to an output voltage;
A gate drive circuit connected to the gate of the first switch device and the gate of the second switch device to control the first and second switch devices via first and second switching control signals, respectively;
A pulse width modulation controller connected to the gate drive circuit and having an error signal input terminal;
Detecting a current flow through the second switch device and proportionally proportional to the current flow through the second switch device by a fixed ratio, the detected current flowing through a detection resistor that induces a detection voltage; A current sensing circuit loop connected to the first and second switch devices for generating,
A half cycle compensation circuit connected to the sense resistor of the current sensing circuit loop to receive the sense voltage generated by the sense resistor and generating a half cycle compensated sense voltage;
A differential amplifier having a predetermined voltage input terminal connected to a predetermined voltage, a detection voltage input terminal connected to the detection resistor receiving the detection voltage, and a differential signal output terminal;
A differential amplifier having a predetermined voltage input terminal connected to a predetermined voltage, a detection voltage input terminal connected to the half cycle compensation circuit receiving the half cycle compensation detection voltage, and a differential signal output terminal;
The differential amplifier is based on the reception half-cycle compensation detection voltage for generating an error voltage applied to the pulse width modulation controller at the predetermined voltage and the differential signal output terminal thereof, and similarly to the gate driving circuit. Constant current regulation characterized in that the first and second switching control signals for controlling the first and second switching devices respectively are generated, thereby supplying a constant current to a load device connected to the output voltage vessel. The constant current regulator according to claim 11, wherein the load device includes a light emitting diode array including a plurality of light emitting diodes connected in series. The current sensing circuit loop receives and adjusts the working voltage from the input voltage so that when the current from the adjustable current source flows through the resistor, the predetermined voltage is induced across the resistor A current setting circuit including a current source and a resistor connected in series;
The constant current regulator according to claim 11, further comprising: a current detection circuit that receives the use voltage from the input voltage and includes the detection resistor through which the detection current flows. The half-cycle compensation circuit includes a coupler, a half-cycle compensation switch device, and a capacitor. The coupler receives the detection voltage from the current detection circuit, and the half-cycle compensation switch device is generated by the gate drive circuit. The constant current according to claim 11, further comprising: a gate connected to the gate driving circuit controlled by the second switching control signal, wherein the switch device includes a power source connected to the capacitor. Adjuster. A first switch device having a first terminal connected to an input voltage via an inductor and a grounded second terminal;
A second switch device having a first terminal connected to the first terminal of the first switch device and a second terminal connected to an output voltage;
A gate drive circuit connected to the gate of the first switch device and the gate of the second switch device to control the first and second switch devices via first and second switching control signals, respectively;
A pulse width modulation controller connected to the gate drive circuit and having an error signal input terminal;
Through a sense resistor that senses the current flow through the first and second switch devices and is proportional to the current flow through the first and second switch devices by a fixed ratio and induces a sense voltage A current sensing circuit loop connected to the first and second switch devices to generate the sensed current to be passed;
A differential amplifier having a predetermined voltage input terminal connected to a predetermined voltage, a detection voltage input terminal connected to the detection resistor, and a differential signal output terminal;
The differential amplifier is based on the detection voltage for generating an error voltage applied to the pulse width modulation controller at the predetermined voltage and the differential signal output terminal thereof, and similarly, the first and A constant current regulator, characterized by generating first and second switching control signals for controlling the second switch device, thereby supplying a constant current to a load device connected to the output voltage. The constant current regulator according to claim 15, wherein the load device includes a light emitting diode array including a plurality of light emitting diodes connected in series. The current sensing circuit loop receives and adjusts the working voltage from the input voltage so that when the current from the adjustable current source flows through the resistor, the predetermined voltage is induced across the resistor A current setting circuit including a current source and a resistor connected in series;
The constant current regulator according to claim 15, further comprising a current detection circuit that receives the use voltage from the input voltage and includes the detection resistor through which the detection current flows.