TW201220655A - both the loading sampling resistance and sampling output current of insulation feedback circuit can be solved by the output current calculator located at the origin side, thus the circuit structure is simplified - Google Patents

Abstract

The present invention provides an electronic circuit and method that can be used in the illumination elements. Both the loading sampling resistance and sampling output current of insulation feedback circuit needed in the present technique can be solved by the electronic circuit via the output current calculator located at the origin side. Thus the circuit structure is simplified.

Description

201220655 VI. Description of the Invention: [Technical Field of the Invention] The present invention relates to an electronic circuit, and more particularly, the present invention relates to an electronic circuit for a light-emitting element. [Prior Art] Light Emitting Diode (LED) has attracted much attention in the field of lighting due to its advantages of no pollution, long life, and vibration resistance, and has been applied to certain applications. The brightness of an LED is usually determined by the average current flowing through it, so it is especially important to accurately control the average current flowing through the LED. In the existing LED electronic circuit, a sampling resistor connected in series with the LED is usually used to sample the current flowing through the LED, and the average current flowing through the LED is accurately controlled by the control of the subsequent controller of the circuit. The isolation conversion circuit 100 shown in FIG. 1 is an LED electronic circuit that is typically used in a reversing topology. The isolation conversion circuit 100 obtains an AC input voltage from a wall socket (grid), and converts the AC voltage into a voltage through a rectifier bridge. The DC voltage is converted to the required DC supply voltage by a flyback circuit. Specifically, the isolation conversion circuit 1 includes a rectifier bridge 101, an input capacitor C1N, a transformer T, a main switch Μ, a first sampling resistor Rs, a diode D, an output capacitor C 〇, a load sampling resistor R, and a controller 1 02, zero crossing detector 103 and isolation feedback circuit 110. The transformer T is an energy storage component, and includes a primary winding T!, a secondary winding T2, and a third winding T3. The rectifier bridge 1 0 1 receives the AC input voltage VIN and converts it into an uncontrolled DC voltage. -5- 201220655 The input capacitor cIN is connected in parallel to the two ends of the rectifier bridge 101, that is, the end of the input capacitor CIN is coupled to one end of the transformer T primary winding T, and the other end is connected to the primary side for reference grounding. The primary winding T of the transformer τ, the main switch Μ, the diode D, the secondary winding Τ2 of the transformer Τ2, and the output capacitor C〇 form a typical reversing topology. The manner of coupling is well known to those skilled in the art and will not be described in detail herein. The first sampling resistor Rs is coupled in series with the main switch 、, and the load sampling resistor R is coupled in series with the LED. The input terminal of the isolation feedback circuit 1 1 is coupled to the series coupling point of the load sampling resistor R and the LED, and the output end thereof is coupled to an input terminal of the controller 102. The input of the zero-crossing detector 1〇3 is coupled to one end of the third winding T3, and the output end thereof is coupled to the other input of the controller 1〇2. The other end of the third winding turns 3 is coupled to the ground. The third input end of the controller 102 is coupled to the series coupling point of the first sampling resistor Rs and the main switch, and the output end of the controller 102 is coupled to the control end of the main switch 。. Since the load sampling resistor R and the LED are coupled in series, the voltage across the load sampling resistor R reflects the current flowing through the LED. The first sampling resistor Rs is coupled in series with the main switch ,. Therefore, the voltage across the first sampling resistor Rs reflects the current flowing through the main switch ,, that is, the voltage across the first sampling resistor Rs is the current sampling signal Isense. When the isolation conversion circuit 1 is operated, the current flowing through the LED is sent to the controller 102 through the load sampling resistor R and the isolation feedback circuit 110, and the current flowing through the main switch is delivered through the first sampling resistor Rs. To controller 1〇2. Through the interaction of the zero crossing detector 103, the average current flowing through the LED can be controlled. Because the control method is well known to those skilled in the art -6- 201220655, for the sake of brevity, it will not be described in detail here. However, this type of control requires a current flow through the L E D , which increases the loss, the development of the technology and the improvement of environmental requirements, and is an important design factor. And this control circuit feeds back the state of the load, so that it is necessary to propose a circuit and method for controlling the average current of an LED such as an LED without a circuit. SUMMARY OF THE INVENTION Therefore, the object of the present invention is to solve the problem of circuit junction by sampling the output current of the load sampling resistor and the required output current. Based on the above object, the present invention provides a transformer including a primary winding, the primary winding for receiving the isolated secondary winding for providing a driving signal to the primary winding, and calculating according to a switching drive current And calculating an equivalent enthalpy of the flow according to the main switch conductive flow and the switch drive signal; a zero-crossing detector, a root pressure, providing a zero-cross detection signal; and controlling the external load sampling resistor to sample to reduce efficiency. As the electronic efficiency has become a power converter to the system, the isolation feedback structure needs to be complicated. The load sampling resistor and the current sampling of the isolated feedback optical component, thereby necessitating a circuit in which the traditional isolation conversion circuit needs to isolate the feedback circuit feedback structure complexity and the circuit low efficiency, including: the transformer secondary winding and the third winding, Input signal of the replaced circuit, the driving element; the main switch, the coupling signal is turned on and off; and the output of the main switch flowing through the driven element through the third winding rain The end of the appliance 'provides the switch drive signal according to the equivalent 値, zero 201220655 cross detection signal, the current flowing through the main switch during the main switch conduction period, and a reference signal. Based on the above object, the present invention also provides a circuit comprising: a transformer comprising a primary winding and a secondary winding, the primary winding for receiving an input signal of the isolation conversion circuit, the secondary winding Providing a driving signal to the driven component; a main switch coupled to the primary winding, being turned on and off according to the switch driving signal; and a zero-crossing detecting capacitor coupled to the primary winding and the main end at one end a series coupling point of the switch, the other end being coupled to the input end of the zero-crossing detector; an output current calculator calculating the flow according to the current flowing through the main switch and the switch driving signal during the main switch being turned on An equivalent 电流 of the current of the driven component; the zero-crossing detector provides a zero-crossing detection signal according to a current flowing through the zero-crossing detecting capacitor; and a controller, according to the equivalent 値, zero-crossing detection signal, The current flowing through the main switch and a reference signal during the main switch being turned on provide the switch drive signal. Based on the above object, the present invention also proposes a lamp. This luminaire uses the above-described circuit of the present invention. Based on the above object, the present invention also provides a method for a circuit, the circuit comprising: a transformer comprising a primary winding, a secondary winding and a third winding, the primary winding for receiving the An input signal of the isolation conversion circuit, the secondary winding is configured to provide a driving signal to the driven component; and a main switch coupled to the primary winding and turned on and off according to the switching driving signal, the method comprising the steps : calculating an equivalent 电流 of a current flowing through the driven component according to a current flowing through the main switch during the conduction of the main switch and the switch driving signal; according to the two ends of the third winding a voltage, providing a zero crossing detection signal; providing the switching drive signal according to the equivalent 値, zero crossing detection signal, current flowing through the main switch during conduction of the main switch, and a reference signal. The above-mentioned circuit, method and lamp using the same can sample the output current without load sampling resistor and isolation feedback circuit, thereby simplifying the circuit structure. [Embodiment] As shown in Fig. 2, an isolation conversion circuit 200 according to an embodiment of the present invention is shown. This embodiment is used in an AC-DC conversion circuit. However, those skilled in the art will appreciate that the isolation conversion circuit can be used in other circuits, such as DC-DC conversion circuits. The same portion of the isolation conversion circuit 200 and the isolation conversion circuit 100 are given the same reference numerals. The isolation conversion circuit 200 is different from the isolation conversion circuit 100 shown in FIG. 1 in that the isolation conversion circuit 200 does not require a load sampling resistor and The feedback circuit is isolated, and the current sampling and feedback of the LED load is implemented by the output current calculator 104. The equivalent output current ΙΕ (? reflected by the output current calculator 104 reflects the secondary current. Specifically, the isolation conversion circuit 200 includes the rectifier bridge 101, the input capacitor CIN, and the transformer T (including the primary winding T!, the vice The side winding 2 and the third winding T3), the main switch Μ, the first sampling resistor RS, the diode D, the output capacitor C〇, and the LED are coupled in the same manner as the isolation conversion circuit 100, for the sake of brevity, here is not Further, the isolation conversion circuit 200 further includes a zero-crossing -9 - 201220655 detector 103, the input end of which is coupled to one end of the third winding Τ3 to detect the voltage vT3 across the third winding τ3, and according to the third winding The zero-crossing condition of the voltage VT3 across the τ3 provides a zero-crossing detection signal 20^ to the first input of the controller 102; the output current calculator 104 has a first input coupled to the first sampling resistor Rs and the main switch The series coupling point is for receiving the current sampling signal Isense, the second input end is coupled to the output end of the controller 102 to receive the switch driving signal CTR, and providing according to the current sampling signal Isense and the switch driving signal CTR, etc. Output current IE (3 to controller 102; controller 102, the first input is coupled to the zero-crossing detector 103 to receive the zero-cross detection signal ZDET, and the second input is coupled to the output current calculation The output end of the device 104 is configured to receive an equivalent output current IEQ, the third input end of which is coupled to the series coupling point of the first sampling resistor Rs and the main switch , to receive the current sampling signal Isense, and the fourth input end thereof receives The reference signal REF is used to provide a switch drive signal (: to the output current calculator 104 and the control terminal of the main switch 根据 according to the equivalent output current IE (3, the zero-cross detection signal ZDET, the current sampling signal Isense, and the reference signal REF) To control the conduction and disconnection of the output current calculator 104 and the main switch 。. In one embodiment, the diode D can be replaced with a rectifier. The main switch Μ can be any controllable semiconductor switching device, such as a metal oxide semiconductor. Field effect transistor (MOSFET), insulated gate bipolar transistor (IGBT), etc. In circuit practical applications, the isolation feedback circuit 110 of the prior art isolation conversion circuit 1 通常 usually needs The plurality of peripheral discrete components are implemented. However, the isolation conversion circuit 200 of the present embodiment does not need to isolate the feedback circuit. Therefore, the isolation conversion circuit 200 of the -10-201220655 is not only reduced in loss but also simplifies the peripheral circuit. The working principle of the conversion circuit 200. When the circuit 2 is running, when the controller 102 provides a high level switch drive signal CTR to the control terminal of the main switch ,, the main switch Μ is closed and the AC input voltage VIN is passed through the rectifier bridge 101. Input capacitor CIN, primary winding Τ, main switch Μ, first sampling resistor Rs to ground. The current flowing through the main switch 线性 rises linearly under the action of the primary winding's magnetizing inductance. Accordingly, the voltage across the first sampling resistor Rs also rises linearly. When the current flowing through the main switch 上升 rises to the set peak Ι current Ιρκ, the switch drive signal CTR output from the controller 102 goes low. Accordingly, the main switch Μ is turned off. At this time, the voltage polarity across the third winding Τ3 is upper and lower, that is, the voltage VT3 is positive, and the voltage polarity across the secondary winding T2 is also positive and negative, and the diode D is turned on and flows through the diode D. The current ID begins to decrease linearly. If the primary winding Τ of the transformer Τ and the transformer turns ratio of the secondary winding T2 are η: 1, the peak 値 current of the diode D is nxIPK. That is, the current ID&nxIPK flowing through the diode D starts to decrease linearly. When it falls to zero, the magnetizing inductance of the primary winding L and the parasitic capacitance (not shown) of the main switch 产生 oscillate. The first zero crossing of the oscillation, that is, when the voltage VT3 is zero for the first time, the zero-crossing detector 103 detects the zero-crossing phenomenon, and outputs a corresponding zero-crossing detection signal ZDET to the controller 102. The controller 102 receives the zero crossing detection signal ZDET and outputs a high level switch drive signal CTR to turn the main switch Μ on. The isolation converter circuit 200 enters a new cycle and operates as previously described. Figure 3 shows the operation of the output current calculator according to the present invention. Flow chart -11 - 201220655 Figure 3 00 shows the method of calculating the output current of the secondary side of the isolation converter circuit. As shown in FIG. 3, the method includes: step 301, starting, that is, periodically turning on and off the main switch 原 of the primary winding of the isolation conversion circuit; step 3 02, determining whether the main switch 导 is in a conducting state, if the main switch is In the on state, proceed to step 3 03, sample the current flowing through the main switch ,, and the equivalent output current Ieq is set to zero. If the main switch Μ is in the off state, proceed to step 304 to maintain the peak current of the main switch 并 as the main switch.等效 Equivalent output current IEQ during the off time interval: Step 305, providing an equivalent output current IE < That is to say, the method for calculating the output current of the secondary side of the isolation conversion circuit comprises: periodically turning on and off the main switch 原 of the primary winding of the isolation conversion circuit; during the time interval when the main switch 导 is turned on, sampling flows through the main switch Μ Current, equivalent output current IEQ is set to zero: during the time interval when the main switch 断开 is turned off, the peak current of the main switch μ is maintained and used as the equivalent output current Ieq in the main switch Μ off time interval. An isolation conversion circuit 400 for calculating the output current of the secondary side of the isolation conversion circuit shown in FIG. 3 is used according to an embodiment of the present invention. The circuit module of the isolation conversion circuit 400 and the same portion of the isolation conversion circuit 200 are given the same reference numerals. For the sake of brevity, the circuit-contact mode of the same part will not be described in detail here. As shown in FIG. 4, the output current calculator 1〇4 includes: a first switch S!, one end coupled to the first sampling resistor Rs and the series connection junction of the main switch , to receive the current sampling signal Isense; the first capacitor (:1, said to be connected between the other end of the first switch S! and the primary side reference ground; the second switch S2, % is connected to the first switch S| and the table to the capacitor of the capacitor C; the third switch S3' is coupled between the other end of the second switch S2 and the primary side reference ground. The control terminals of the first switch S, the second switch S2 and the third switch S3 are coupled to the output of the control -12-201220 655 And when the switch drive signal Ctr is at a high level, the first switch S and the second switch S 3 are turned on, and the second switch s 3 is turned off; when the switch drive signal CTR is at a low level, the first switch Si and The third switch ^ turns off the first switch S2 is turned on. Assuming that the switch drive signal cTR is at a high level at the beginning, the first switch Si and the third switch S3 are closed and the second switch S2 is turned off, and the second switch S2 is turned off. The high level switch drive signal CTR turns the main switch μ off and on. At this time, the equivalent output current Ieq is Zero, ie IEQ = 0. As mentioned above, the AC input voltage Vin passes through the rectifier bridge 101, the input capacitor c1N, the primary winding L, the main switch M, and the first sampling resistor Rs to ground. The current flowing through the main switch 在 is in the original Side winding Τ! Under the action of the magnetizing inductance, the linear rise, the voltage across the first sampling resistor Rs, that is, the current sampling signal Isense also rises linearly. At this time, since the first switch S! is closed and turned on, therefore, both ends of the capacitor C! The voltage is the current sampling signal Isense. That is to say, during this period of time, the voltage across the capacitor C rises linearly. When it rises to the set peak current Ipk, the switch drive signal CTR goes low. Ground, the first switch S, and the third switch S3 are turned off, the second switch S2 is turned on; the main switch Μ is turned off. At this time, the equivalent output current Ieq is the voltage across the capacitor Ci', that is, Ieq = IpkxRrs 'where Rrs is the resistance 値 of the first sampling resistor RS. The switch drive signal CTR, the current IM flowing through the main switch 、, the current ID flowing through the diode D, the voltage VT3 of the third winding T3, and the equivalent output current IEQ The waveform is shown in Figure 5" by Figure 5 It can be seen that the average output current of the equivalent output current Ieq in one switching cycle is

C -13- 201220655

Ieq(ave)

Ιρκ x Rrs xTOFF T〇N + T〇FF Equation (1) The average 値ID (AVE) of the current ID flowing through the diode in one cycle is LD(AVE) IPK xnxT0FF 2χ(Τ〇ν +T〇 Ff) equation (2)

Where TON is the closed on-time of the main switch 一个 in one cycle, and TOFF is the off-time of the main switch 一个 in one cycle. Available from the above equation (1) and equation (2), 1 EQ(AVE)

2R

RS η :Idi i(AVE) Equation (3 ) It can be seen from equation (3) that when the resistance R rs of the first sampling resistor Rs is given, the average 値 of the equivalent output current IEq flows through the dipole The average 値 of the current Id of the body D is proportional. Since the DC current flowing through the output capacitor C〇 is zero, the average 値 of the current ID flowing through the diode D is equal to the average current flowing through the LED. Therefore, the average 値 of the equivalent output current Ieq is proportional to the average current flowing through the LED, and the equivalent output current Ieq is the equivalent 流 of the average current flowing through the LED, that is, the output current. The output current calculator 104 achieves sampling of the primary side of the secondary LED. FIG. 6 shows an isolation conversion circuit 600 in accordance with one embodiment of the present invention. The circuit blocks of the isolation conversion circuit 600 and the same portions of the isolation conversion circuit 200 are given the same reference numerals. Different from the isolation conversion circuit 200, the -14-201220655 isolation conversion circuit 600 specifically shows an implementation structure of the controller 102. However, those skilled in the art will recognize that the circuit configuration of the controller 102 is not limited to the circuit configuration shown in FIG. As shown in FIG. 6, the controller 102 includes an error amplifier UA having an input (inverting input) coupled to the output of the output current calculator 1-4 to receive the equivalent provided by the output current calculator 104. The output current Ieq, the other input terminal (non-inverting input terminal) receives the reference signal Ref to provide an error amplification signal according to the equivalent output current IEQ and the reference signal REF, that is, the set peak current ΙΡκ to the inverting input of the comparator UC The comparator Uc has an input terminal (inverting input terminal) coupled to the output terminal of the error amplifier UA for receiving the error amplification signal, and another input terminal (non-inverting input terminal) coupled to the first sampling resistor Rs And a series coupling point of the main switch , to receive the current sampling signal Isense to provide a comparison signal SCMP to the logic circuit according to the error amplification signal and the current sampling signal Isense; the logic circuit, one end receives the comparison signal ScMP, and the other end receives the zero cross detection The signal ZDET is used to control the closed turn-on and turn-off of the main switch 提供 by providing the switch drive signal CTR according to the comparison signal SCMP and the zero-cross detection signal ZDET. In this embodiment, the logic circuit is an RS flip-flop, and its set terminal R is coupled to the output end of the comparator Uc to receive the comparison signal SCMP: its reset end is coupled to the output end of the zero-crossing detector 1 0 3 To receive the zero-cross detection signal ZDET: its output terminal Q is coupled to the control terminal of the main switch 以 to provide the switch drive signal CTR. In this embodiment, a compensation circuit Zc is coupled between the output of the error amplifier uA and the primary reference ground. In one embodiment, the compensation circuit zc may be a capacitive compensation network or a resistive, capacitive compensation network, the structure of which is well known to those skilled in the art. For the sake of simplicity -15-201220655, the circuit structure of the compensation circuit ZC will not be described in detail here. As shown in FIG. 6, due to the coupling mode of the error amplifier UA, the set peak current Ιρκ, that is, the error amplification signal is determined by the equivalent output current IEQ and the reference signal Ref. From equation (3), the equivalent output current IEQ is proportional to the average current flowing through the LED, and the reference signal REF is a given signal. Therefore, the set peak current Ιρκ is determined by the average current flowing through the LED. During the period when the main switch Μ is closed and turned on, when the sampling current lsense reaches the set peak current Ιρκ, the comparison signal SCMP outputted by the comparator goes high, thereby resetting the output of the RS flip-flop, and the switch drive signal CTR is reset. It is low to disconnect the main switch Μ. Therefore, the average current flowing through the LED determines the set peak current Ιρκ, that is, the time point at which the main switch Μ is controlled to be turned off. When the main switch Μ is turned off, when the zero-crossing detector detects that the voltage VT3 of the third winding Τ3 is zero, the high-level zero-cross detection signal ZDET is output, thereby setting the output of the meta-RS flip-flop, so that the switch The drive signal CTR goes high. Accordingly, the main opening threshold is closed and the isolation conversion circuit 600 enters a new duty cycle. FIG. 7 shows an isolation conversion circuit 700 in accordance with another embodiment of the present invention. The circuit module of the isolation conversion circuit 700 and the same portion of the isolation conversion circuit 400 are given the same reference numerals. For the sake of brevity, the coupling of the same parts of the two is not detailed here. Different from the isolation conversion circuit 400, in order to avoid the capacitance in the output current calculator 1〇4 (the capacitance 値 is not large enough) to achieve impedance matching in the practical application, the output current calculator 104 of the isolation conversion circuit 700 is A buffer U i is coupled between the capacitor C! and the second switch S2. That is, the output current calculator 1 〇4 includes: a first switch s, a -16-201220655 end coupled to the first sampling resistor Rs and the main The series coupling point of the switch ;; the first - the electric valley Cl ' is connected between the other end of the first switch 3! and the primary side reference ground; the buffer U, 'the input end is coupled to the first switch S! and a coupling point of the first capacitor ci; a second switch S2 coupled to the output of the buffer U; the third switch S3' is in contact between the other end of the second switch S2 and the ground. The first switch Si' When the control ends of the second switch S2 and the third switch S3 are coupled to the output end of the controller 1〇2 and the switch drive signal CTR is at a high level, the first switch S1 and the third switch S3 are closed, and the second switch S3 is closed. Disconnect: When the switch drive signal CTR is low, the first switch S1 and the third switch S3 The second switch S2 is turned on. It will be appreciated by those skilled in the art that the operation of the isolation conversion circuit 700 is the same as that of the isolation conversion circuit 400, and is not described in detail herein. FIG. 8 shows still another detail according to the present invention. The isolation conversion circuit 8 of the embodiment is similar to the isolation conversion circuit 200, and the same reference numerals are used for the same portions of the isolation conversion circuit 8 as the isolation conversion circuit 200. The description is concise, and the coupling of the same parts is not described in detail here. Unlike the isolation conversion circuit 200, the isolation conversion circuit 800 omits the third winding T3, and instead, the isolation conversion circuit 8 00 adopts a zero crossing. The capacitor C2 is detected, and one end of the zero-crossing detecting capacitor C2 is coupled to the input end of the zero-crossing detector 1 。 3. The other end of the zero-crossing detecting capacitor C2 is coupled to the series coupling of the main switch M and the primary winding T! Point. When the main switch Μ is turned off, the current ID flowing through the diode D starts to drop from nxIPK, and when it falls to zero, the primary winding T, the magnetizing inductance and the main switch Μ The parasitic capacitance (not shown) generates oscillation. When the first zero of the oscillation is -17-201220655, the current flowing through the zero-crossing detection capacitor c2 is reversed, and the zero-pole 103 detects the reverse current and outputs a high level. The zero crossing Zdet ' thus causes the controller 102 to output a high level switch drive signal i main switch IV [closed conduction. The isolation conversion circuit 800 enters a new phase. The remaining operation principle of the isolation conversion circuit 800 is the same as the aforementioned isolation circuit 200, The description is succinct and will not be described in detail here. Although the specific structure of the calculator 105 is not shown in the isolation conversion circuit 800 shown in FIG. 8, in a specific embodiment, the calculator 105 may be as shown in FIG. 4 or FIG. In another embodiment, the circuit Zc as shown in FIG. 6 can also be added on the basis of the above. Although the above description has been made with the LED element as an example of the driven element, those skilled in the art should understand that the embodiment can also be applied to other types of driving elements, sources. The above disclosure is only for the preferred embodiment or the embodiments, and the specific embodiments are not to be construed as limited to the scope of the appended claims. The scope of the invention is to be construed as being limited by the scope of the invention and the scope of the invention. The type of application is covered by the scope of patent application. The cross-detection detection signal Tiger Ctr, which is a specific compensation of the working cycle from the converted electrical output current output current, describes the solution. For example, the current can produce the essence of the invention. This description is the same as the technical staff. . Therefore, it should be attached -18-201220655 [Schematic Description of the Drawing] FIG. 1 shows a conventional isolation conversion circuit 100. Figure 2 shows an isolation conversion circuit 200 in accordance with one embodiment of the present invention. Figure 3 shows a flow chart 300 of the operation of an output current calculator in accordance with the present invention. 4 illustrates an isolation conversion circuit 400 employing the method of calculating the secondary side output current of the isolation conversion circuit of FIG. 3, in accordance with one embodiment of the present invention. 5 shows the waveforms of the switch drive signal, the current flowing through the main switch, the current flowing through the diode, the voltage of the third winding, and the equivalent output current in the isolation conversion circuit 400 shown in FIG. Figure 6 illustrates an isolation conversion circuit 600 that specifically illustrates an implementation of a controller in accordance with one embodiment of the present invention. 7 shows an isolation conversion circuit 700 according to another embodiment of the present invention. FIG. 8 shows an isolation conversion circuit 800 according to still another embodiment of the present invention. [Main Component Symbol Description] 100: Isolated Conversion Circuit 1 0 1 : Rectifier Bridge 1 〇 2 : Controller 1 0 3 : Zero-crossing detector 104 : Output current calculator 1 1 0 : Isolated feedback circuit -19 - 201220655 200 : Isolation conversion circuit 400 : Isolation conversion circuit 600 : Isolation conversion circuit 700 : Isolation conversion Circuit 800: Isolated Conversion Circuit

Claims (1)

201220655 VII. Patent application scope: 1. A circuit comprising: a transformer comprising a primary winding, a secondary winding and a third winding, the primary winding receiving an input signal of the isolation conversion circuit, the secondary winding Providing a driving signal to the driven component; a main switch coupled to the primary winding, being turned on and off according to the switch driving signal; and an output current calculator according to a current flowing through the main switch during the main switch being turned on The switch drive signal calculates an equivalent 値 of a current flowing through the driven component; a zero-crossing detector provides a zero-cross detection signal according to a voltage across the third winding; the controller, according to the equivalent 値, zero crossing The detection signal, the current flowing through the main switch during the conduction of the main switch, and a reference signal provide the switch drive signal. 2. The circuit of claim 1, wherein the output current calculator comprises: a first switch, one end receiving a current flowing through the main switch: a first capacitor coupled to the other of the first switch The second switch has one end coupled to the series coupling point of the first switch and the first capacitor; the second switch is connected to the other end of the second switch and the primary side Reference grounding; -21 - 201220655 The first switch, the second switch and the third switch are controlled to be turned on and off by the switch driving signal; the output current calculator is at the second switch and the third switch A current corresponding to the equivalent 値 is provided at the series coupling point. 3. The circuit of claim 2, wherein the output current calculator further comprises a buffer coupled between the series coupling point of the first switch and the first capacitor and the second switch. 4. The circuit of claim 2, wherein when the switch drive signal is at a high level, the first switch and the third switch are controlled to conduct 'the second switch is controlled to open; when the switch When the driving signal is low, the first switch and the third switch are controlled to be turned off, and the second switch is controlled to be turned on. 5. The circuit of claim 1, wherein the controller comprises: an error amplifier that provides an error amplification signal based on the equivalent output current and the reference signal; a comparator that amplifies the signal and the main according to the error The current flowing through the main switch during the on period of the switch provides a comparison signal; and the logic circuit provides the switch drive signal according to the comparison signal and the zero crossing detection signal. 6. The circuit of claim 1 wherein the controller further comprises a compensation circuit coupled between the error amplifier and the primary side reference ground. 7. A circuit comprising: -22-201220655 a transformer comprising a primary winding and a secondary winding, the primary winding for receiving an input signal of the isolation converter circuit, the secondary winding for providing a drive signal to a driven component; a main switch coupled to the primary winding, turned on and off according to a switch driving signal; a zero-crossing detecting capacitor, one end coupled to the primary winding and the series coupling point of the main switch, and the other end An output coupled to the zero-crossing detector; an output current calculator that calculates an equivalent 电流 of a current flowing through the driven component according to a current flowing through the main switch during the main switch being turned on and the switch driving signal; a cross detector that provides a zero crossing detection signal according to a current flowing through the zero crossing detection capacitor; a controller, according to the equivalent 値, a zero crossing detection signal, a current flowing through the main switch during the main switch conduction period, and a reference A signal that provides the switch drive signal. 8. The circuit of claim 7, wherein the output current calculator comprises: a first switch, one end receiving a current flowing through the main switch; and a first capacitor coupled to the other of the first switch The second switch is coupled to the series coupling point of the first switch and the first capacitor; the third switch is coupled to the other end of the second switch and the primary side Between reference ground; -23- 201220655 The output current calculator provides the corresponding current corresponding to the series connection of the second switch and the third switch. 9. The circuit of claim 8, wherein the output current calculator further comprises a buffer coupled between the series coupling point of the first switch and the first capacitor and the second switch. 10. The circuit of claim 8 wherein when the switch drive signal is at a high level, the first switch and the third switch are controlled to conduct 'the second switch is controlled to open; when the switch When the driving signal is low, the first switch and the third switch are controlled to be turned off, and the second switch is controlled to be turned on. The circuit of claim 7, wherein the controller comprises: an error amplifier 'providing an error amplification signal according to an equivalent 値 of the output current and the reference signal'; and a comparator amplifying the signal according to the error And a current flowing through the main switch during the on-time of the main switch to provide a comparison signal; the logic circuit 'provides the switch drive signal according to the comparison signal and the zero-cross detection signal. 12. The circuit of claim 7 wherein the controller further comprises a compensation circuit 'coupled between the error amplifier and the primary side reference ground. 13. A luminaire </ RTI> The luminaire uses the circuit described in claim 1 or the scope of claim 7 of the patent application. 14. A method for a circuit comprising: a transformer, -24 - 201220655 the transformer comprising a primary winding, a secondary winding and a third winding, the primary winding receiving an input signal of the isolation conversion circuit, The secondary winding is configured to provide a driving signal to the driven component; and the main switch is coupled to the primary winding, and is turned on and off according to the switching driving signal, the method comprising the steps of: flowing according to the main switch during the conducting period a current of the main switch and the switch drive signal, calculating an equivalent 电流 of the current flowing through the driven component; providing a zero-cross detection signal according to the voltage across the third winding; according to the equivalent 値, zero-cross detection signal, The current flowing through the main switch and a reference signal during the period in which the main switch is turned on provides the switch drive signal. The method of claim 14, wherein the method of terminating the primary winding of the isolation conversion circuit is periodically turned on and off. Main switch. The method of claim 15, wherein the current flowing through the main switch is sampled during the time interval in which the main switch is turned on, and the equivalent is set to zero. 17. The method of claim 16, wherein the peak current flowing through the main switch is kept in a time interval during which the main switch is turned off, and the peak current is broken as the main switch. The equivalent 値 within the open time interval. 1 8 _ According to the method of claim 14, the further step of determining the conduction state of the main switch. -25-