CN213602561U - Control circuit of switch circuit and switch circuit - Google Patents
Control circuit of switch circuit and switch circuit Download PDFInfo
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- CN213602561U CN213602561U CN202022322315.1U CN202022322315U CN213602561U CN 213602561 U CN213602561 U CN 213602561U CN 202022322315 U CN202022322315 U CN 202022322315U CN 213602561 U CN213602561 U CN 213602561U
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Abstract
The utility model discloses a switch circuit's control circuit through predetermineeing a time threshold value that is greater than main power switch tube minimum on-time, through the long length of time size of actual on-time in the logical operation mode comparison main power switch tube current cycle and predetermined time threshold value, then according to the comparative result adjustment main power switch tube's turn-off time, in order to adjust main power switch tube's next switch cycle time. Through the control circuit of the scheme, extra current detection circuits and comparators are not needed to be added, and the self-adaptive adjustment of the switching period of the switching circuit is achieved.
Description
Technical Field
The utility model relates to a power electronic technology field, more specifically say, relate to a switch circuit's control circuit.
Background
The BOOST switch circuit is a circuit commonly used in circuit design, and as shown in fig. 1, the BOOST switch circuit generally includes a first switch M1, a second switch M2, and an inductor L3, where the first switch may be a MOS transistor, the second switch may be a rectifier diode or a synchronous rectifier switch, VIN is an input signal of the BOOST switch circuit, and VOUT is an output signal of the BOOST switch circuit. For the BOOST circuit, when the on-state signal BON of the first switch tube is greater than the minimum on-state time allowed by the first switch tube, the switching period of the first switch tube can be set to be a fixed time by setting a timing circuit, so that the fixed frequency of the switch circuit is realized, and when the on-state time of the first switch tube is reduced, the switching period of the first switch tube is still kept unchanged.
However, under the influence of the variation of the voltage gain or the load current, the on signal BON of the first switch tube is continuously shortened to the minimum on time allowed by the first switch tube, and the control circuit cannot further adjust the output voltage or the load current due to the limitation of the minimum on time. The current value of the first switching tube needs to be sampled, the sampling current and a preset specific value are connected into the comparator, when the sampling current value is smaller than the specific value, the switching circuit starts to spread frequency, extra current detection circuits and the comparator need to be added in the mode, and the cost is high.
SUMMERY OF THE UTILITY MODEL
In view of this, an object of the present invention is to provide a control circuit of a switch circuit and a switch circuit, so as to solve the technical problems of complex circuit and high cost existing in the prior art.
The technical solution of the utility model is that, a control circuit of switch circuit is provided, switch circuit includes inductance and the main power switch tube of being connected with the inductance, include
The first logic circuit compares the conduction time of a main power switch tube in the current switching period with the duration of the preset time threshold value through logic operation to obtain a comparison result, wherein the value of the preset time threshold value is greater than the minimum conduction time value of the main power switch tube;
and the switching period adjusting circuit receives the comparison result and adjusts the turn-off time of the main power switching tube according to the comparison result so as to adjust the time of the next switching period of the main power switching tube.
Preferably, the switching period adjusting circuit prolongs the turn-off time of the main power switching tube according to the comparison result, so as to prolong the time of the next switching period of the main power switching tube.
Preferably, the logic circuit includes an exclusive or logic circuit and an and logic circuit,
the exclusive-or logic circuit receives a conducting time signal of the main power switch tube in the current switching period and a preset time threshold value to generate a first logic signal;
the AND logic circuit receives the first logic signal and performs AND logic operation on the first logic signal and the conduction time of the main power switch tube in the current switching period to obtain a second logic signal, or performs AND logic operation on the first logic signal and the preset time threshold to obtain a second logic signal, wherein the second logic signal is used as the comparison result.
Preferably, the switching cycle adjusting circuit includes a first voltage generating circuit and an off-time generating circuit,
the first voltage generating circuit comprises a first capacitor, the first voltage generating circuit receives the comparison result to control the charging and discharging of the first capacitor according to the comparison result so as to obtain a first voltage signal at two ends of the first capacitor,
the turn-off time generation circuit receives the first voltage signal to generate a turn-off time control signal according to the first voltage signal, and the turn-off time control signal regulates the turn-off time of the main power switch tube.
Preferably, the off-time generating circuit includes a second voltage generating circuit, a comparing circuit and a timing circuit,
the second voltage generating circuit comprises a voltage-controlled current source and a second capacitor, the voltage-controlled current source is used for charging the second capacitor, the voltage at two ends of the second capacitor is a second voltage signal, and the voltage-controlled current source receives the first voltage signal so as to adjust the magnitude of the second voltage signal according to the first voltage signal;
the comparison circuit receives a comparison of the second voltage signal and a second reference value to obtain a second comparison signal,
the timing circuit times the time when the second voltage signal reaches the second reference value as the turn-off time control signal.
The invention provides a switching circuit which comprises an inductor and a main power switching tube connected with the inductor, and the switching circuit comprises the control circuit, wherein the control circuit controls the switching cycle time of the main power switching tube.
Adopt the utility model discloses a control circuit structure is through predetermineeing a time threshold value that is greater than main power switch tube minimum on-time, through the long length of time of logical operation comparison main power switch tube actual on-time in the current on-off period with predetermined time threshold value, then according to the comparative result adjustment main power switch tube's turn-off time, in order to adjust main power switch tube's on-off period. Through the control circuit of the scheme, extra current detection circuits and comparators are not needed to be added, and the self-adaptive adjustment of the switching period of the switching circuit is achieved.
Drawings
FIG. 1 is a circuit block diagram of a prior art BOOST switch circuit;
fig. 2 is a circuit block diagram of a switching circuit control circuit according to the present invention;
FIG. 3 is a circuit block diagram of one embodiment of the first logic circuit of FIG. 2;
FIG. 4 is a circuit block diagram of one embodiment of the switching cycle adjustment circuit of FIG. 2;
fig. 5 is a waveform diagram of a switching circuit control circuit according to the present invention.
Detailed Description
The preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings, but the present invention is not limited to only these embodiments. The present invention covers any alternatives, modifications, equivalents, and alternatives falling within the spirit and scope of the present invention.
In the following description of the preferred embodiments of the present invention, specific details are set forth in order to provide a thorough understanding of the present invention, and it will be apparent to those skilled in the art that the present invention may be practiced without these specific details.
The invention is described in more detail in the following paragraphs by way of example with reference to the accompanying drawings. It should be noted that the drawings are simplified and in non-precise proportion, and are only used for the purpose of conveniently and clearly assisting in explaining the embodiments of the present invention.
Referring to fig. 2-4, fig. 2 is a circuit block diagram of a switching circuit control circuit according to the present invention, fig. 3 is a circuit block diagram of an embodiment of the first logic circuit in fig. 2, and fig. 4 is a circuit block diagram of an embodiment of the switching period adjusting circuit in fig. 2.
As shown in fig. 2, the switching circuit is exemplified by a boost switching circuit, the boost switching circuit includes an inductor L3 and a main power switch M1 connected to the inductor, and a synchronous rectifier M2 connected to the inductor, the control circuit includes a first logic circuit 1 and a switching period adjusting circuit 2, the first logic circuit 1 compares the conduction time T of the main power switch in the current switching period through logic operationBONAnd the preset time threshold value TREF1To obtain a comparison result VCThe value of the preset time threshold is greater than the minimum on-time value of the main power switch tube; here, the value of the preset time threshold is set to be 0.5-1 times of the minimum on-time value of the main power switch tube. The switching period adjusting circuit 2 receives the comparison result VCAnd adjusting the turn-off time TON of the main power switch tube according to the comparison result so as to adjust the time of the next switching period of the main power switch tube. The utility model discloses but control circuit regulating switch circuit's switching frequency for at the uncontrollable occasion of some output voltage, the size of rapid stabilization output voltage.
In one embodiment, the switching period adjusting circuit 2 extends V according to the comparison resultCAnd the turn-off time TON of the main power switch tube is prolonged, so that the time of the next switching period of the main power switch tube is prolonged.
In particular, with reference to figures 3 and 4,the logic circuit comprises an exclusive-OR logic circuit and an AND logic circuit, and the exclusive-OR logic circuit receives the conduction time T of the main power switch tube in the current switching periodBONAnd a preset time threshold TREF1To generate a first logic signal T1; the AND logic circuit receives the first logic signal T1 and leads the first logic signal and the conduction time T of the main power switch tube in the current switching periodBONPerforming an AND operation to obtain a second logic signal, or performing an AND operation on the first logic signal T1 and the predetermined time threshold TREF1Performing an AND logic operation to obtain a second logic signal as the comparison result VC。
It should be noted here that the on-time T of the main power switch tubeBONAnd a preset time threshold TREF1Are all characteristic of the on-time TBONAnd a preset time threshold TREF1Is, at the on-time TBONDuring an effective time period of (c), the on-time TBONThe signal is high level, the other time is low level, and a preset time threshold value TREF1All the same. According to the logic circuit described above, the first logic signal T1 is characterized by the on-time TBONAnd a preset time threshold TREF1I.e., the time period during which the first logic signal T1 is at a high level and the other time is at a low level during the difference between the two valid time periods. Then the first logic signal T1 is coupled to the on-time TBONThe AND operation of the signals can result in the effective time period of high level, the conduction time T of the first logic signal T1BONWhether the signal is high or a predetermined time threshold TREF1High when the first logic signal T1 is on for a time TBONHigh after the signal and logic operation, the conduction time TBONThe effective duration of the signal is greater than a preset time threshold TREF1Is not detected, otherwise a preset time threshold value T is setREF1The effective duration of the signal is greater than the on-time TBONThe effective duration of the signal. Thus, the comparison of the time values is realized through the logic operation without samplingThe circuit and the comparator are simple and low in cost.
In another embodiment, the first logic signal T1 and the preset time threshold T are combinedREF1The and logic operation is performed to obtain the second logic signal, and the above result can be obtained as well, and the determination principle is the same, which is not repeated herein.
Referring to fig. 4, the switching period adjusting circuit 2 includes a first voltage generating circuit 2-1 and an off-time generating circuit 2-1, and specifically, the first voltage generating circuit 2-1 includes a first capacitor C1, a first current source I1 and a second current source respectively charge and discharge the first capacitor C1, a first switch K1 and a second switch K2 control charge and discharge operations of the first current source I1 and the second current source, a first switch K1 controls a switching operation of the first current source I1 according to the comparison result Vc, a second switch K2 controls a switching operation of the second current source I3538 according to the comparison result Vc, and a voltage across the first capacitor is used as a first voltage signal V1.
The off time generating circuit 2-2 includes a second voltage generating circuit, a comparing circuit, and a timing circuit. The second voltage generating circuit comprises a voltage-controlled current source I3 and a second capacitor C2, the voltage-controlled current source is used for charging the second capacitor, the voltage across the second capacitor is a second voltage signal V2, and the voltage-controlled current source receives the first voltage signal V1 so as to adjust the magnitude of the second voltage signal according to the first voltage signal; the comparison circuit receives a second voltage signal V2 and a second reference valueVREF2To obtain a second comparison signal Vc2, the timing circuit timing the time when the second voltage signal reaches the second reference value as the off-time control signal TONSaid off-time control signal TONThe switching period adjusting circuit is used for controlling the turn-off time of the main power tube, namely, the turn-off time of the main power tube is controlled to be consistent with the time when the second voltage signal reaches the second reference value, so that the switching period can be adjusted, and the adjustment of the switching period of the main power tube can be realized through the switching period adjusting circuit.
Fig. 5 is a diagram of an operating waveform according to the present invention, I is an inductor current waveform,in the comparison process, if the on-time of the main power transistor is greater than the preset threshold time, and the comparison result is a high level, the first switch K1 is turned on, the first current source I1 charges the first capacitor C1, the first voltage signal V1 increases, the controllable current source I3 decreases, the second voltage signal V2 decreases, and the second voltage signal V2 reaches the second reference value V2REF2The time of the power supply is prolonged, so that the turn-off time is prolonged, the turn-off time of the main power tube is prolonged, the switching period is prolonged, and the switching frequency is spread.
Finally, the utility model also discloses a switch circuit, including inductance and the main power switch tube of being connected with the inductance, still include foretell control circuit, control circuit control the on-off cycle time of main power switch tube.
The above-mentioned switch circuit is illustrated by using boost as an example, and those skilled in the art will appreciate that the control circuit of the present application can also be applied to other suitable topologies.
The above-described embodiments do not limit the scope of the present invention. Any modification, equivalent replacement, and improvement made within the spirit and principle of the above-described embodiments should be included in the protection scope of the technical solution.
Claims (6)
1. A control circuit of a switching circuit, the switching circuit comprises an inductor and a main power switch tube connected with the inductor, and the control circuit is characterized by comprising
The first logic circuit compares the conduction time of a main power switch tube in the current switching period with the duration of a preset time threshold value through logic operation to obtain a comparison result, wherein the value of the preset time threshold value is greater than the minimum conduction time value of the main power switch tube;
and the switching period adjusting circuit receives the comparison result and adjusts the turn-off time of the main power switching tube according to the comparison result so as to adjust the time of the next switching period of the main power switching tube.
2. The control circuit of claim 1, wherein the switching cycle adjustment circuit extends the turn-off time of the main power switch tube according to the comparison result, thereby extending the time of the next switching cycle of the main power switch tube.
3. The control circuit of claim 1, wherein the logic circuit comprises an exclusive OR logic circuit and an AND logic circuit,
the exclusive-or logic circuit receives a conducting time signal of the main power switch tube in the current switching period and a preset time threshold value to generate a first logic signal;
the AND logic circuit receives the first logic signal and performs AND logic operation on the first logic signal and the conduction time of the main power switch tube in the current switching period to obtain a second logic signal, or performs AND logic operation on the first logic signal and the preset time threshold to obtain a second logic signal, wherein the second logic signal is used as the comparison result.
4. The control circuit of claim 1, wherein the switching cycle adjustment circuit comprises a first voltage generation circuit and an off-time generation circuit,
the first voltage generating circuit comprises a first capacitor, the first voltage generating circuit receives the comparison result to control the charging and discharging of the first capacitor according to the comparison result so as to obtain a first voltage signal at two ends of the first capacitor,
the turn-off time generation circuit receives the first voltage signal to generate a turn-off time control signal according to the first voltage signal, and the turn-off time control signal regulates the turn-off time of the main power switch tube.
5. The control circuit of claim 4, wherein the off-time generating circuit includes a second voltage generating circuit, a comparing circuit, and a timing circuit,
the second voltage generating circuit comprises a voltage-controlled current source and a second capacitor, the voltage-controlled current source is used for charging the second capacitor, the voltage at two ends of the second capacitor is a second voltage signal, and the voltage-controlled current source receives the first voltage signal so as to adjust the magnitude of the second voltage signal according to the first voltage signal;
the comparison circuit receives a comparison of the second voltage signal and a second reference value to obtain a second comparison signal,
the timing circuit times the time when the second voltage signal reaches the second reference value as the turn-off time control signal.
6. A switching circuit comprising an inductor and a main power switch connected to the inductor, comprising the control circuit of any of claims 1-5, wherein the control circuit controls a switching cycle time of the main power switch.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202022322315.1U CN213602561U (en) | 2020-10-19 | 2020-10-19 | Control circuit of switch circuit and switch circuit |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202022322315.1U CN213602561U (en) | 2020-10-19 | 2020-10-19 | Control circuit of switch circuit and switch circuit |
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| CN213602561U true CN213602561U (en) | 2021-07-02 |
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| CN202022322315.1U Active CN213602561U (en) | 2020-10-19 | 2020-10-19 | Control circuit of switch circuit and switch circuit |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113517814A (en) * | 2021-08-26 | 2021-10-19 | 上海泰矽微电子有限公司 | BOOST switch converter and minimum closing time control circuit |
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2020
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113517814A (en) * | 2021-08-26 | 2021-10-19 | 上海泰矽微电子有限公司 | BOOST switch converter and minimum closing time control circuit |
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