CN110311579B - Communication protocol circuit and time-sharing current detection circuit and method thereof - Google Patents
Communication protocol circuit and time-sharing current detection circuit and method thereof Download PDFInfo
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- CN110311579B CN110311579B CN201811066313.1A CN201811066313A CN110311579B CN 110311579 B CN110311579 B CN 110311579B CN 201811066313 A CN201811066313 A CN 201811066313A CN 110311579 B CN110311579 B CN 110311579B
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M3/00—Conversion of dc power input into dc power output
- H02M3/22—Conversion of dc power input into dc power output with intermediate conversion into ac
- H02M3/24—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters
- H02M3/28—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac
- H02M3/325—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal
- H02M3/335—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only
- H02M3/33569—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only having several active switching elements
- H02M3/33576—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only having several active switching elements having at least one active switching element at the secondary side of an isolation transformer
- H02M3/33592—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only having several active switching elements having at least one active switching element at the secondary side of an isolation transformer having a synchronous rectifier circuit or a synchronous freewheeling circuit at the secondary side of an isolation transformer
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M7/00—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
- H02M7/02—Conversion of ac power input into dc power output without possibility of reversal
- H02M7/04—Conversion of ac power input into dc power output without possibility of reversal by static converters
- H02M7/12—Conversion of ac power input into dc power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
- H02M7/21—Conversion of ac power input into dc power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
- H02M7/217—Conversion of ac power input into dc power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only
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Abstract
The invention provides a communication protocol circuit and a time-sharing current detection circuit and method thereof. The time-sharing current detection circuit comprises: a current mirror circuit having a power switch coupled between an internal voltage node and a communication protocol voltage node to supply a communication protocol current; and a sampling switch coupled between the internal voltage node and the reference node for sampling the communication protocol current in a time-division sampling method during a sampling period to generate a sampling current; a bias circuit for providing a reference voltage to the reference node during a sampling period according to a communication protocol voltage of the communication protocol voltage node; the signal conversion circuit is used for generating a time-sharing current detection signal according to the sampling current; and a first switch coupled to the sampling switch for operating to determine a sampling period; wherein the sampling period supplies the power switch with a portion of a full period of the communication protocol current.
Description
Technical Field
The present invention relates to a communication protocol circuit and a time-sharing current detection circuit and method thereof, and more particularly, to a communication protocol circuit sampling a communication protocol current by a time-sharing sampling method and a time-sharing current detection circuit thereof. The invention also relates to a time-sharing current detection method for the communication protocol circuit.
Background
Fig. 1 shows a schematic diagram of a flyback power supply 100 in the prior art, in which an ac voltage Vac is rectified by a rectifier circuit 101 to generate an input voltage Vin. The primary winding W1 of the transformer 102 receives an input voltage Vin. The primary-side power switch PSW controls the on-time of the primary winding W1, and converts the output voltage Vout at the secondary winding W2. The primary-side power switch PSW is controlled by the PWM control circuit 105. The PWM control circuit 105 performs feedback control, and the PWM control circuit 105 generates the PWM signal by obtaining a feedback voltage signal COMP related to the output voltage Vout or the output current through the photo-coupling circuit 104 or an auxiliary winding (not shown) and obtaining a current sense signal CS related to the current flowing through the primary side power switch PSW from the current sensing circuit 106. The PWM control circuit 105 generates a switching signal GATE according to the PWM signal to control the operation of the primary-side power switch PSW. In order to improve the power conversion efficiency, the secondary winding W2 of the flyback power supply 100 is electrically connected to the synchronous rectification switch circuit 108, and is controlled by the synchronous rectification control circuit 107 according to the voltage across the synchronous rectification switch circuit 108, so that the secondary winding W2 is turned on when the primary winding W1 is turned off, so as to convert the input voltage Vin into the output voltage Vout.
Fig. 2 shows a schematic diagram of another prior art flyback power supply 200. Unlike the flyback power supply 100, the flyback power supply 200 further includes a communication protocol circuit 209. When the flyback power supply 200 is used as a charger (e.g., an ac power adapter), the communication protocol circuit 209 exchanges information with the load circuit 211 to generate the communication protocol signal CPS, determines whether to provide the communication protocol current Ibus to the load circuit 211, and provides the charging power at the communication protocol voltage node VBUS of the communication protocol circuit 209. The communication protocol circuit 209 is used to determine whether the specification of the charging power required by the load circuit 211 (e.g., a rechargeable battery) coupled outside the communication protocol voltage node VBUS is consistent with the specification of the charging power provided by the flyback power supply 200, so as to prevent the flyback power supply 200 or the load circuit from being damaged.
The communication protocol circuit 209 conforms to, for example, communication protocols such as USBPD, QC, Pumpexpress, and the like. In addition, the flyback power supply 200 is different from the flyback power supply 100 in that in the flyback power supply 100 shown in fig. 1, the feedback voltage signal COMP is related to the output voltage Vout or the output current flowing through the secondary winding W2. In the flyback power supply 200 shown in fig. 2, the feedback voltage signal COMP is related to the communication protocol current Ibus flowing through the power switch coupled between the internal voltage node VDD of the communication protocol circuit 209 and the communication protocol voltage node VBUS (shown as the dashed line power switch inside the communication protocol circuit 209 in fig. 2).
In the prior art flyback power supply 200 shown in fig. 2, it is a common trade-off problem to maintain both accurate current sensing of the communication protocol current Ibus and relatively low power consumption.
In view of the above, the present invention provides a communication protocol circuit and a time-sharing current detection circuit and method thereof, which can accurately sense a communication protocol current Ibus and maintain relatively low power consumption.
Disclosure of Invention
From one aspect, the present invention provides a communication protocol circuit for a flyback power supply, comprising: an information exchange circuit for exchanging information with a load circuit to generate a communication protocol signal to determine whether to provide a communication protocol current to the load circuit; and a time-sharing current detection circuit coupled to the information exchange circuit for generating a time-sharing current detection signal according to the communication protocol current; the flyback power supply converts an input voltage into an output voltage according to the time-sharing current detection signal and supplies the communication protocol current; wherein, this timesharing current detection circuit includes: a current mirror circuit having a power switch coupled between an internal voltage node and a protocol voltage node for supplying the protocol current; and a sampling switch coupled between the internal voltage connection point and a reference node for sampling the communication protocol current in a sampling period by a time-division sampling (discrete time sampling) method to generate a sampling current; a bias circuit coupled to the sampling switch for providing a reference voltage to the reference node during the sampling period according to a communication protocol voltage of the communication protocol voltage node; a signal conversion circuit coupled to the bias circuit for generating a time-sharing current detection signal according to the sampling current; and a first switch coupled to the sampling switch for operating to determine the sampling period; wherein the sampling period supplies the power switch with a portion of a full period of the communication protocol current.
In another aspect, the present invention provides a time-sharing current detection circuit for a communication protocol circuit used in a flyback power supply, the communication protocol circuit having an information exchange circuit for exchanging information with a load circuit to generate a communication protocol signal for determining whether to provide a communication protocol current to the load circuit; and the time-sharing current detection circuit is coupled with the information exchange circuit and used for generating a time-sharing current detection signal according to the communication protocol current; the flyback power supply converts an input voltage into an output voltage according to the time-sharing current detection signal and supplies the communication protocol current; the time-sharing current detection circuit comprises: a current mirror circuit having a power switch coupled between an internal voltage node and a protocol voltage node for supplying the protocol current; and a sampling switch coupled between the internal voltage connection point and a reference node for sampling the communication protocol current in a sampling period by a time-division sampling (discrete time sampling) method to generate a sampling current; a bias circuit coupled to the sampling switch for providing a reference voltage to the reference node during the sampling period according to a communication protocol voltage of the communication protocol voltage node; a signal conversion circuit coupled to the bias circuit for generating the time-sharing current detection signal according to the sampling current; and a first switch coupled to the sampling switch for operating to determine the sampling period; wherein the sampling period supplies the power switch with a portion of a full period of the communication protocol current.
In a preferred embodiment, the time-sharing current detecting circuit further includes a second switch coupled to the signal converting circuit for determining to convert the sampling current into the time-sharing current detecting signal.
In a preferred embodiment, the reference voltage is equal to the communication protocol voltage.
In a preferred embodiment, the signal conversion circuit comprises: a current-voltage conversion circuit coupled to the sampling switch for converting the sampling current into a sampling voltage; and a sample-hold circuit coupled to the current-voltage conversion circuit for sampling and holding the sampled voltage to generate the time-sharing current detection signal.
In a preferred embodiment, the signal conversion circuit comprises: a signal conversion current mirror circuit coupled to the sampling switch for converting the sampling current into a converted sampling current; and a sample-and-hold circuit coupled to the signal conversion current mirror circuit for sampling and holding the converted sample current to generate the time-sharing current detection signal.
From another perspective, the present invention also provides a time-sharing current detection method for a communication protocol circuit, comprising: sampling a communication protocol current in a sampling period by a time-division sampling (discrete time sampling) method to generate a sampling current, wherein a power switch is coupled between an internal voltage connection point and a communication protocol voltage connection point to supply the communication protocol current; providing a reference voltage to a reference node during the sampling period according to a communication protocol voltage of the communication protocol voltage contact, and the sampling current flows through the reference node; generating a time-sharing current detection signal according to the sampling current; and operating a first switch to determine the sampling period; wherein the sampling period supplies the power switch with a portion of a full period of the communication protocol current.
In a preferred embodiment, the time-sharing current detection method for a communication protocol circuit further comprises operating a second switch to determine to convert the sampled current into the time-sharing current detection signal.
In a preferred embodiment, the reference voltage is equal to the communication protocol voltage.
In a preferred embodiment, the step of generating a time-shared current detection signal according to the sampling current comprises: converting the sampling current into a sampling voltage; and sampling and holding the sampling voltage to generate the time-sharing current detection signal.
In a preferred embodiment, the step of generating a time-shared current detection signal according to the sampling current comprises: converting the sampling current into a converted sampling current; and sampling and holding the converted sampling current to generate the time-sharing current detection signal.
The purpose, technical content, features and effects of the invention will be more easily understood through the following detailed description of specific embodiments.
Drawings
Fig. 1 shows a schematic diagram of a flyback power supply 100 in the prior art.
Fig. 2 shows a schematic diagram of another prior art flyback power supply 200.
Fig. 3 shows a schematic diagram of a flyback power supply 300 according to the present invention.
Fig. 4A and 4B are schematic diagrams illustrating a time-sharing current detection circuit 410 and signal waveforms according to the present invention, respectively.
Fig. 5A and 5B are schematic diagrams illustrating a time-sharing current detection circuit 510 and signal waveforms according to the present invention, respectively.
Fig. 6A and 6B are schematic diagrams illustrating a time-sharing current detection circuit 610 and signal waveforms according to the present invention, respectively.
Fig. 7A and 7B are schematic diagrams illustrating a time-sharing current detection circuit 710 and signal waveforms according to the present invention, respectively.
Detailed Description
The drawings in the present disclosure are schematic and are intended to show the coupling relationship between circuits and the relationship between signal waveforms, and the circuits, signal waveforms and frequencies are not drawn to scale.
Referring to fig. 3, a schematic diagram of a flyback power supply 300 according to the present invention is shown. As shown in the figure, the flyback power supply 300 includes a rectifier circuit 101, a transformer 102, a primary power switch PSW, an optocoupler circuit 104, a Pulse Width Modulation (PWM) control circuit 105, a primary current sensing circuit 106, a synchronous rectification control circuit 107, a synchronous rectification switch circuit 108, and a communication protocol circuit 309.
The transformer 102 has a primary winding W1 and a secondary winding W2, wherein the primary winding W1 is used for receiving an input voltage Vin, and the secondary winding W2 is used for generating an output voltage Vout. In one embodiment, the input voltage Vin may be generated by rectifying the ac voltage Vac by the rectifying circuit 101. The primary-side power switch PSW is coupled to the primary-side winding W1. The PWM control circuit 105 is located at the primary side of the transformer 102, and generates a switch control signal GATE in a modulation manner such as PWM according to the current sensing signal CS and the feedback voltage signal COMP to control the primary-side power switch PSW. In order to improve the power conversion efficiency, the secondary winding W2 of the flyback power supply 300 is electrically connected to the synchronous rectification switch circuit 108, and is controlled by the synchronous rectification control circuit 107 according to the voltage across the synchronous rectification switch circuit 108, so that the secondary winding W2 is turned on when the primary winding W1 is turned off, so as to convert the input voltage Vin into the output voltage Vout.
Referring to fig. 3, the flyback power supply 300 includes a communication protocol circuit 309. The communication protocol voltage terminal VBUS of the communication protocol circuit 309 is used, for example, to provide a charging power source. The communication protocol circuit 309 is used to determine whether the specification of the charging power required by the load circuit 211 (e.g., a rechargeable battery) coupled to the outside of the communication protocol voltage node VBUS matches the specification of the charging power provided by the flyback power supply 300, so as to prevent the flyback power supply 300 or the load circuit 211 from being damaged. The communication protocol circuit 309 conforms to, for example, communication protocols such as USBPD, QC, PumpExpress, etc.
In addition, in the flyback power supply 300 shown in fig. 3, the feedback voltage signal COMP is related to the communication protocol current Ibus flowing through the power switch SW1 coupled between the internal voltage node VDD and the communication protocol voltage node VBUS of the communication protocol circuit 309. It should be noted that the communication protocol circuit 309 may also select a charging power source with a fixed specification, such as a fixed current of 5 volts (V) and 0-2 amperes (a), according to the result of no response of the load circuit 211.
The communication protocol circuit 309 generates an optical coupling signal at the optical coupling node OPT according to the time-sharing current detection signal TDCS, and generates a feedback voltage signal COMP in an optical coupling manner, and transmits the feedback voltage signal COMP to the Pulse Width Modulation (PWM) control circuit 105 through the optical coupling circuit 104. The PWM control circuit 105 operates the primary power switch PSW according to the feedback voltage signal COMP (the photo coupling signal), converts the input voltage Vin into an output voltage Vout to the internal voltage node VDD of the communication protocol circuit 309, and supplies a communication protocol current Ibus to flow between the internal voltage node VDD and the communication protocol voltage node VBUS.
The communication protocol circuit 309 includes a time-sharing current detecting circuit 310 and an information exchanging circuit 312. The message exchange circuit 312 is used for exchanging messages with the load circuit 211 and generating a communication protocol signal CPS to determine whether to provide the communication protocol current Ibus to the load circuit 211. The time-sharing current detecting circuit 310 is coupled to the message exchange circuit 312 for generating the time-sharing current detecting signal TDCS according to the communication protocol current Ibus. The current detection circuit 310 includes a current mirror circuit 3101, a bias circuit 3102, a signal conversion circuit 3103, and a first switch S1.
The current mirror circuit 3101 includes a power switch SW1 and a sampling switch SW 2. The power switch SW1 is coupled between the internal voltage node VDD and the communication protocol voltage node VBUS to operate according to the communication protocol signal CPS to supply the communication protocol current Ibus. The sampling switch SW2 is coupled between the internal voltage node VDD and the reference node VBR for sampling the protocol current Ibus in a time-sharing sampling method during a sampling period (e.g., the period between time points t1 and t2, and t3 and t4 shown in fig. 4B) to generate a sampling current ISEN. The bias circuit 3102 is coupled to the sampling switch SW2 for providing a reference voltage VREF to the reference node VBR during the sampling period according to the communication protocol voltage of the communication protocol voltage node VBUS.
The signal conversion circuit 3103 is coupled to the bias circuit 3102 for generating the time-sharing current detection signal TDCS according to the sampling current ISEN. The first switch S1 is coupled to the sampling switch SW2 for determining a sampling period (e.g., the period between time points t1 and t2, t3 and t4 shown in fig. 4B). Wherein the sample period supplies power switch SW1 with a portion of a full period of the communication protocol current Ibus.
The invention utilizes a time-sharing sampling method to sample the communication protocol current Ibus during the sampling period; thus, compared with the full-time sampling method, the power consumption can be reduced. In another aspect, the present invention utilizes a time-sharing sampling method to sample the communication protocol current Ibus during the sampling period, and can also reduce the current conversion ratio (M: 1 as shown in fig. 4A) to increase the sensing accuracy. For example, the current conversion ratio can be set to be M:1 equal to 100:1, because time-sharing sampling is adopted, compared with a full-time sampling method, the electric energy waste can be avoided, the efficiency is improved, and the system overheating is also avoided; compared with the method of setting the current conversion ratio to be M:1 or 1000:1, the method of full time sampling has relatively high accuracy.
Fig. 4A and 4B are schematic diagrams illustrating a time-sharing current detection circuit 410 and signal waveforms according to the present invention, respectively. Fig. 4A shows an embodiment of a time-sharing current detection circuit 410 for a flyback power supply according to the present invention. As shown, the current detection circuit 410 includes a current mirror circuit 4101, a bias circuit 4102, a signal conversion circuit 4103, a first switch S1 and a second switch S2.
The current mirror circuit 4101 has a power switch SW1 and a sampling switch SW 2. The power switch SW1 is coupled between the internal voltage node VDD and the communication protocol voltage node VBUS to operate according to the communication protocol signal CPS to supply the communication protocol current Ibus. The sampling switch SW2 is coupled between the internal voltage node VDD and the reference node VBR for sampling the protocol current Ibus in a time-sharing sampling method during a sampling period (e.g., the period between time points t1 and t2, and t3 and t4 shown in fig. 4B) to generate a sampling current ISEN.
Note that the current mirror circuit 4101 is different from a typical current mirror circuit generally having diode-connected MOS elements. In a typical current mirror circuit, the power switch SW1 is electrically connected to a diode-type MOS device, but in this embodiment, the power switch SW1 is not electrically connected to a diode-type MOS device, but the current flowing end (reference node VBR) of the sampling switch SW2 is adjusted to the same voltage as the communication protocol voltage node VBUS to implement the function of the current mirror circuit.
The bias circuit 4102 is coupled to the sampling switch SW2 for providing a reference voltage VREF to the reference node VBR during the sampling period according to the communication protocol voltage of the communication protocol voltage node VBUS. The signal conversion circuit 4103 is coupled to the bias circuit 4102 for generating a time-sharing current detection signal TDCS according to the sampling current ISEN. The first switch S1 is coupled to the sampling switch SW2 for determining a sampling period (e.g., the period between time points t1 and t2, t3 and t4 shown in fig. 4B). Wherein the sample period supplies power switch SW1 with a portion of a full period of the communication protocol current Ibus. In a preferred embodiment, the sampling period is, for example, but not limited to, less than one tenth of the full period.
In the present embodiment, the first switch S1 is coupled between the reference node VBR and the switch SW3 of the bias circuit 4102. Compared to the time-sharing current detecting circuit 310 shown in fig. 3, the time-sharing current detecting circuit 410 further includes a second switch S2 coupled to the signal converting circuit 4103 for determining to convert the sampling current ISEN into the time-sharing current detecting signal TDCS.
As shown in fig. 4A, the bias circuit 4102 has, for example, an operational amplifier Q1 and a switch SW 3. The operational amplifier Q1 controls the switch SW3 according to the voltage of the communication protocol voltage node VBUS and electrically connects the inverting input terminal to the reference node VBR, and the output terminal of the operational amplifier Q1 controls the switch VREF to adjust the reference voltage VREF of the reference node VBR to be equal to the voltage of the communication protocol voltage node VBUS during the sampling period.
In a preferred embodiment, the signal conversion circuit 4103 includes, for example, a current-voltage conversion circuit (such as, but not limited to, a resistor R1 as shown in the figure) and a sample-and-hold circuit. The current-voltage conversion circuit is coupled to the sampling switch SW2 during the sampling period for converting the sampled current ISEN into the sampled voltage VSEN. As shown, during the sampling period, i.e. between time points t1 and t2 or between time points t3 and t4, the current-voltage conversion circuit, i.e. the resistor R1, is coupled between the sampling switch SW2 and the ground potential GND, and the sampling current ISEN flows through the resistor R1 to generate the sampling voltage VSEN.
A sample-and-hold circuit, such as but not limited to a capacitor C1 as shown in the figure, is coupled to the current-to-voltage conversion circuit for sampling and holding the sampling voltage VSEN to generate a time-sharing current detection signal TDCS, so that the communication protocol circuit 309 generates an optical coupling signal according to the time-sharing current detection signal TDCS to the optical coupling node OPT, and generates a feedback voltage signal COMP in an optical coupling manner, which is transmitted to the Pulse Width Modulation (PWM) control circuit 105 through the optical coupling circuit 104.
Fig. 5A and 5B are schematic diagrams illustrating a time-sharing current detection circuit 510 and signal waveforms according to the present invention, respectively. Fig. 5A shows an embodiment of a time-sharing current detection circuit 510 for a flyback power supply according to the present invention. As shown, the current detection circuit 510 includes a current mirror circuit 5101, a bias circuit 5102, a signal conversion circuit 5103, a first switch S1, and a second switch S2.
The current mirror circuit 5101 includes a power switch SW1 and a sampling switch SW 2. The power switch SW1 is coupled between the internal voltage node VDD and the communication protocol voltage node VBUS to operate according to the communication protocol signal CPS to supply the communication protocol current Ibus. The sampling switch SW2 is coupled between the internal voltage node VDD and the reference node VBR for sampling the protocol current Ibus in a time-sharing sampling method during a sampling period (e.g., the period between time points t1 and t2, and t3 and t4 shown in fig. 5B) to generate a sampling current ISEN.
The bias circuit 5102 is coupled to the sampling switch SW2 for providing a reference voltage VREF to the reference node VBR during the sampling period according to the communication protocol voltage of the communication protocol voltage node VBUS. The signal conversion circuit 5103 is coupled to the bias circuit 5102, and is configured to generate the time-sharing current detection signal TDCS according to the sampling current ISEN. The first switch S1 is coupled to the sampling switch SW2 for determining a sampling period (e.g., the period between time points t1 and t2, t3 and t4 shown in fig. 5B). Wherein the sample period supplies power switch SW1 with a portion of a full period of the communication protocol current Ibus.
The embodiment is different from the embodiment shown in fig. 4A in that in the embodiment, the first switch S1 is coupled between the power switch SW1 and the sampling switch SW2, but it has the same function as the first switch S1 of the embodiment shown in fig. 4A, and is used to determine the sampling period.
Fig. 6A and 6B are schematic diagrams illustrating a time-sharing current detection circuit 610 and signal waveforms according to the present invention, respectively. Fig. 6A shows an embodiment of a time-sharing current detection circuit 610 for a flyback power supply according to the present invention. As shown, the current detection circuit 610 includes a current mirror circuit 6101, a bias circuit 6102, a signal conversion circuit 6103, a first switch S1, and a second switch S2.
The current mirror circuit 6101 has a power switch SW1 and a sampling switch SW 2. The power switch SW1 is coupled between the internal voltage node VDD and the communication protocol voltage node VBUS to operate according to the communication protocol signal CPS to supply the communication protocol current Ibus. The sampling switch SW2 is coupled between the internal voltage node VDD and the reference node VBR for sampling the protocol current Ibus in a time-sharing sampling method during a sampling period (e.g., the period between time points t1 and t2, and t3 and t4 shown in fig. 6B) to generate a sampling current ISEN.
The bias circuit 6102 is coupled to the sampling switch SW2 for providing the reference voltage VREF to the reference node VBR during the sampling period according to the communication protocol voltage of the communication protocol voltage node VBUS. The signal conversion circuit 6103 is coupled to the bias circuit 6102 for generating the time-sharing current detection signal TDCS according to the sampling current ISEN. The first switch S1 is coupled to the sampling switch SW2 for determining a sampling period (e.g., the period between time points t1 and t2, t3 and t4 shown in fig. 6B). Wherein the sampling period is a fraction of a full period of the time that the power switch SW1 supplies the communication protocol current Ibus, in a preferred embodiment, the sampling period is, for example, but not limited to, less than one tenth of the full period.
Unlike the embodiment shown in fig. 4A, in the present embodiment, the current-voltage conversion circuit includes a switch S3 and a capacitor C2, during the sampling period, neither of the switches S2 nor S3 is turned on, and the sampling current ISEN charges the capacitor C2; during the period from time t2 to t5 and from time t4 to t6 after the sampling period, the switch S2 is turned on and the switch S3 is kept off, so that the current IFB charges the capacitor C3 (sampling protection circuit), and the time-sharing current detection signal TDCS is generated.
Fig. 7A and 7B are schematic diagrams illustrating a time-sharing current detection circuit 710 and signal waveforms according to the present invention, respectively. Fig. 7A shows an embodiment of a current sharing detection circuit 710 for a flyback power supply according to the present invention. As shown, the current detection circuit 710 includes a current mirror circuit 7101, a bias circuit 7102, a signal conversion circuit 7103, a first switch S1 and a second switch S2.
The current mirror circuit 7101 has a power switch SW1 and a sampling switch SW 2. The power switch SW1 is coupled between the internal voltage node VDD and the communication protocol voltage node VBUS to operate according to the communication protocol signal CPS to supply the communication protocol current Ibus. The sampling switch SW2 is coupled between the internal voltage node VDD and the reference node VBR for sampling the protocol current Ibus in a time-sharing sampling method during a sampling period (e.g., the period between time points t1 and t2, and t3 and t4 shown in fig. 7B) to generate a sampling current ISEN.
The bias circuit 7102 is coupled to the sampling switch SW2 for providing a reference voltage VREF to the reference node VBR during sampling according to the communication protocol voltage of the communication protocol voltage node VBUS. The signal conversion circuit 7103 is coupled to the bias circuit 7102 for generating the time-sharing current detection signal TDCS according to the sampling current ISEN. The first switch S1 is coupled to the sampling switch SW2 for determining a sampling period (e.g., the period between time points t1 and t2, t3 and t4 shown in fig. 7B). Wherein the sampling period is a fraction of a full period of the time that the power switch SW1 supplies the communication protocol current Ibus, in a preferred embodiment, the sampling period is, for example, but not limited to, less than one tenth of the full period.
Unlike the embodiment shown in fig. 4A, in the present embodiment, the signal conversion circuit 7103 includes a signal conversion current mirror circuit (e.g., formed by switches SW4 and SW5 in fig. 7A) and a sample-and-hold circuit (e.g., capacitor C3 in fig. 7A). The signal conversion current mirror circuit is coupled to the sampling switch SW2 for converting the sampling current ISEN into the converted sampling current ITD. The sample-hold circuit is coupled to the signal conversion current mirror circuit, and is configured to sample-hold the converted sampling current ITD to generate the time-sharing current detection signal TDCS.
In detail, the switching sampling current ITD is determined by the gate-source voltage (Vgs) of the switch SW 5; during sampling, switch S2 is turned on, and the sampling current ISEN determines the gate-source voltage (Vgs) of switch SW4, i.e., diode-connected MOS device shown in fig. 7A, and switch SW5, and thus the communication protocol current Ibus determines the converted sampling current ITD, which in a preferred embodiment is proportional to the communication protocol current Ibus. When the switch S2 is turned off, the gate-source voltage (Vgs) of the switch SW5 is held due to the capacitor C3, so that the sample-hold-converted sample current ITD and its associated time-shared current detection signal TDCS are held, and in a preferred embodiment, the sample-hold-converted sample current ITD is equal to the time-shared current detection signal TDCS.
The present invention has been described with respect to the preferred embodiments, but the above description is only for the purpose of making the content of the present invention easy to understand for those skilled in the art, and is not intended to limit the scope of the present invention. The embodiments described are not limited to single use, but may be used in combination, for example, two or more embodiments may be combined, and some components in one embodiment may be substituted for corresponding components in another embodiment. In addition, equivalent variations and combinations can be conceived by those skilled in the art within the same spirit of the present invention, for example, the current mirror circuit in the foregoing embodiments is not limited to the illustrated MOS transistor, and it can be replaced by various switches such as BJT or JFET. The term "processing or calculating or generating an output result based on a signal" in the present invention is not limited to the signal itself, and includes, if necessary, performing voltage-to-current conversion, current-to-voltage conversion, and/or scaling on the signal, and then performing processing or calculation based on the converted signal to generate an output result. It is understood that equivalent variations and combinations are possible and will occur to those skilled in the art, which combinations are not intended to be exhaustive, within the same spirit of the invention. Accordingly, the scope of the present invention should be determined to encompass all such equivalent variations as described above.
Claims (15)
1. A communication protocol circuit for use in a flyback power supply, comprising:
an information exchange circuit for exchanging information with a load circuit to generate a communication protocol signal to determine whether to provide a communication protocol current to the load circuit; and
a time-sharing current detection circuit coupled to the information exchange circuit for generating a time-sharing current detection signal according to the communication protocol current;
the flyback power supply converts an input voltage into an output voltage according to the time-sharing current detection signal and supplies the communication protocol current;
wherein, this timesharing current detection circuit includes:
a current mirror circuit having a power switch coupled between an internal voltage node and a communication protocol voltage node for supplying the communication protocol current; and a sampling switch coupled between the internal voltage connection point and a reference node for sampling the communication protocol current in a sampling period by a time-sharing sampling method to generate a sampling current;
a bias circuit coupled to the sampling switch for providing a reference voltage to the reference node during the sampling period according to a communication protocol voltage of the communication protocol voltage node;
a signal conversion circuit coupled to the bias circuit for generating the time-sharing current detection signal according to the sampling current; and
a first switch coupled to the sampling switch for operating to determine the sampling period;
wherein the sampling period supplies the power switch with a portion of a full period of the communication protocol current.
2. The communication protocol circuit of claim 1, wherein the time-shared current detection circuit further comprises a second switch coupled to the signal conversion circuit for determining to convert the sampled current to the time-shared current detection signal.
3. The communication protocol circuit of claim 1 wherein the reference voltage is equal to the communication protocol voltage.
4. The communication protocol circuit of claim 1, wherein the signal conversion circuit comprises:
a current-voltage conversion circuit, coupled to the sampling switch during the sampling period, for converting the sampling current into a sampling voltage; and
a sample-hold circuit coupled to the current-voltage conversion circuit for sampling and holding the sample voltage to generate the time-sharing current detection signal.
5. The communication protocol circuit of claim 1, wherein the signal conversion circuit comprises:
a signal conversion current mirror circuit, coupled to the sampling switch during the sampling period, for converting the sampling current into a converted sampling current; and
a sample-hold circuit coupled to the signal conversion current mirror circuit for sampling and holding the converted sample current to generate the time-sharing current detection signal.
6. A time-sharing current detection circuit is used for a communication protocol circuit which is used in a flyback power supply and is provided with an information exchange circuit which is used for exchanging information with a load circuit to generate a communication protocol signal and determine whether to provide a communication protocol current for the load circuit or not; and the time-sharing current detection circuit is coupled with the information exchange circuit and used for generating a time-sharing current detection signal according to the communication protocol current; the flyback power supply converts an input voltage into an output voltage according to the time-sharing current detection signal and supplies the communication protocol current; the time-sharing current detection circuit comprises:
a current mirror circuit having a power switch coupled between an internal voltage node and a communication protocol voltage node for supplying the communication protocol current; and a sampling switch coupled between the internal voltage connection point and a reference node for sampling the communication protocol current in a sampling period by a time-sharing sampling method to generate a sampling current;
a bias circuit coupled to the sampling switch for providing a reference voltage to the reference node during the sampling period according to a communication protocol voltage of the communication protocol voltage node;
a signal conversion circuit coupled to the bias circuit for generating the time-sharing current detection signal according to the sampling current; and
a first switch coupled to the sampling switch for operating to determine the sampling period;
wherein the sampling period supplies the power switch with a portion of a full period of the communication protocol current.
7. The time-sharing current detecting circuit as claimed in claim 6, further comprising a second switch coupled to the signal converting circuit for determining to convert the sampled current into the time-sharing current detecting signal.
8. The time-sharing current detecting circuit as claimed in claim 6, wherein the reference voltage is equal to the communication protocol voltage.
9. The time-sharing current detecting circuit as claimed in claim 6, wherein the signal converting circuit comprises:
a current-voltage conversion circuit, coupled to the sampling switch during the sampling period, for converting the sampling current into a sampling voltage; and
a sample-hold circuit coupled to the current-voltage conversion circuit for sampling and holding the sample voltage to generate the time-sharing current detection signal.
10. The time-sharing current detecting circuit as claimed in claim 6, wherein the signal converting circuit comprises:
a signal conversion current mirror circuit, coupled to the sampling switch during the sampling period, for converting the sampling current into a converted sampling current; and
a sample-hold circuit coupled to the signal conversion current mirror circuit for sampling and holding the converted sample current to generate the time-sharing current detection signal.
11. A method for time-shared current detection for a communication protocol circuit, comprising:
sampling a communication protocol current in a sampling period by a time-sharing sampling method to generate a sampling current, wherein a power switch is coupled between an internal voltage contact and a communication protocol voltage contact to supply the communication protocol current;
providing a reference voltage to a reference node during the sampling period according to a communication protocol voltage of the communication protocol voltage contact, and the sampling current flows through the reference node;
generating a time-sharing current detection signal according to the sampling current; and
operating a first switch to determine the sampling period;
wherein the sampling period supplies the power switch with a portion of a full period of the communication protocol current.
12. The method of claim 11, further comprising operating a second switch to determine conversion of the sampled current to the time-shared current detection signal.
13. The method of claim 11, wherein the reference voltage is equal to the communication protocol voltage.
14. The method of claim 11, wherein the step of generating a time-shared current detection signal based on the sampled current comprises:
converting the sampling current into a sampling voltage; and
the sampling voltage is sampled and held to generate the time-sharing current detection signal.
15. The method of claim 11, wherein the step of generating a time-shared current detection signal based on the sampled current comprises:
converting the sampling current into a converted sampling current; and
the converted sampling current is sampled and held to generate the time-sharing current detection signal.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US16/219,831 US10505464B2 (en) | 2018-03-25 | 2018-12-13 | Communication protocol circuit and discrete-time current sense circuit and method thereof |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US201862647805P | 2018-03-25 | 2018-03-25 | |
| US62/647,805 | 2018-03-25 |
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| US8717785B2 (en) * | 2011-09-30 | 2014-05-06 | Power Integrations, Inc. | Multi-stage sampling circuit for a power converter controller |
| CN103135024A (en) * | 2011-11-29 | 2013-06-05 | 立锜科技股份有限公司 | Short circuit detection circuit and short circuit detection method |
| CN203827167U (en) * | 2014-03-13 | 2014-09-10 | 昂宝电子（上海）有限公司 | Novel output voltage and current-variable switching power source circuit |
| CN107196530A (en) * | 2016-03-14 | 2017-09-22 | 恩智浦有限公司 | Load current is measured |
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