CN116760286A - Switching power supply driving circuit and switching power supply - Google Patents
Switching power supply driving circuit and switching power supply Download PDFInfo
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- CN116760286A CN116760286A CN202311053595.2A CN202311053595A CN116760286A CN 116760286 A CN116760286 A CN 116760286A CN 202311053595 A CN202311053595 A CN 202311053595A CN 116760286 A CN116760286 A CN 116760286A
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- 238000004146 energy storage Methods 0.000 claims abstract description 64
- 238000001514 detection method Methods 0.000 claims description 19
- 230000000087 stabilizing effect Effects 0.000 claims description 14
- 230000007274 generation of a signal involved in cell-cell signaling Effects 0.000 claims description 12
- 238000005070 sampling Methods 0.000 claims description 9
- 230000005611 electricity Effects 0.000 claims description 5
- 239000013589 supplement Substances 0.000 claims 1
- 230000000694 effects Effects 0.000 abstract description 6
- 238000004804 winding Methods 0.000 description 21
- 230000001276 controlling effect Effects 0.000 description 11
- 239000003990 capacitor Substances 0.000 description 9
- 230000002265 prevention Effects 0.000 description 6
- 238000006243 chemical reaction Methods 0.000 description 3
- 238000010586 diagram Methods 0.000 description 3
- 230000001105 regulatory effect Effects 0.000 description 3
- 229920006395 saturated elastomer Polymers 0.000 description 2
- 229910002601 GaN Inorganic materials 0.000 description 1
- JMASRVWKEDWRBT-UHFFFAOYSA-N Gallium nitride Chemical compound [Ga]#N JMASRVWKEDWRBT-UHFFFAOYSA-N 0.000 description 1
- 230000000903 blocking effect Effects 0.000 description 1
- 230000008878 coupling Effects 0.000 description 1
- 238000010168 coupling process Methods 0.000 description 1
- 238000005859 coupling reaction Methods 0.000 description 1
- 238000005265 energy consumption Methods 0.000 description 1
- 230000005669 field effect Effects 0.000 description 1
- 229910044991 metal oxide Inorganic materials 0.000 description 1
- 150000004706 metal oxides Chemical class 0.000 description 1
- 230000000630 rising effect Effects 0.000 description 1
- 239000004065 semiconductor Substances 0.000 description 1
Classifications
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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
- H02M3/02—Conversion of dc power input into dc power output without intermediate conversion into ac
- H02M3/04—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters
- H02M3/10—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
- H02M3/145—Conversion of dc power input into dc power output without intermediate conversion into ac 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
- H02M3/155—Conversion of dc power input into dc power output without intermediate conversion into ac 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
- H02M3/156—Conversion of dc power input into dc power output without intermediate conversion into ac 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 with automatic control of output voltage or current, e.g. switching regulators
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H11/00—Emergency protective circuit arrangements for preventing the switching-on in case an undesired electric working condition might result
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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
- H02M1/00—Details of apparatus for conversion
- H02M1/08—Circuits specially adapted for the generation of control voltages for semiconductor devices incorporated in static converters
- H02M1/088—Circuits specially adapted for the generation of control voltages for semiconductor devices incorporated in static converters for the simultaneous control of series or parallel connected semiconductor devices
-
- 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
- H02M1/00—Details of apparatus for conversion
- H02M1/36—Means for starting or stopping converters
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
- Y02B70/00—Technologies for an efficient end-user side electric power management and consumption
- Y02B70/10—Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes
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- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Dc-Dc Converters (AREA)
Abstract
The application relates to a switching power supply driving circuit and a switching power supply, and belongs to the technical field of electronic circuits. In detail, the switching power supply driving circuit comprises a voltage clamping circuit, a starting circuit, an energy storage circuit, a signal generating circuit and a control circuit; the voltage clamping circuit clamps the voltage of the primary coil to output clamping voltage, the starting circuit charges the energy storage circuit, the energy storage circuit supplies power to the signal generating circuit, the signal generating circuit samples the current of the primary coil, and the signal generating circuit outputs a driving control signal according to the current of the primary coil and controls the on-off of the primary coil based on the driving control signal. The energy storage circuit is charged and controlled by the starting circuit so that the energy storage circuit can stably supply power to the signal generating circuit, and the signal generating circuit drives the control circuit based on the current output driving control signal of the primary coil, so that the effect that the control circuit is convenient to control the output voltage of the switching power supply is achieved.
Description
Technical Field
The present application relates to the field of electronic circuits, and in particular, to a switching power supply driving circuit and a switching power supply.
Background
The switching power supply is one of electric energy conversion equipment and comprises a transformer, a driving chip, a switching tube and other components, and the switching tube is controlled to be switched on and off through the driving chip, so that the switching tube can regulate the output voltage of the transformer T1, and the switching power supply can realize conversion and output between different voltage levels.
In the related art, the operating voltage of the driving chip and the input voltage of the switching power supply are generally different from each other, so the driving chip is generally supplied by providing an auxiliary coil of a transformer. However, since the transformer has a coupling relationship between the coils, the power supply voltage output by the auxiliary coil is affected by the secondary coil of the transformer, so that the power supply voltage provided by the auxiliary coil is not stable enough, and the driving chip cannot work stably under the required working voltage, so that the driving chip cannot output a stable control signal to control the on-off of the switching tube, and the output voltage of the switching power supply is difficult to control effectively.
Disclosure of Invention
In order to facilitate control of the output voltage of a switching power supply, the application provides a switching power supply driving circuit and a switching power supply.
In a first aspect, the present application provides a switching power supply driving circuit, which adopts the following technical scheme:
a switching power supply driving circuit comprises a voltage clamping circuit, a starting circuit, an energy storage circuit, a signal generating circuit and a control circuit;
the voltage clamping circuit is connected with a primary coil of the transformer T1, clamps the voltage of the primary coil and outputs clamping voltage;
the starting circuit is arranged between the voltage clamping circuit and the energy storage circuit and is used for controlling the charging of the energy storage circuit;
the energy storage circuit is connected with the signal generation circuit and is used for supplying power to the signal generation circuit;
the signal generating circuit is connected with the primary coil, and is used for sampling the current of the primary coil and outputting a driving control signal according to the current of the primary coil;
the control circuit is connected with the primary coil and the signal generation circuit and controls the on-off of the primary coil based on the driving control signal.
Through adopting above-mentioned technical scheme, utilize voltage clamp circuit to carry out the clamp with the voltage of the primary coil of transformer T1, keep apart the voltage on the primary coil, prevent the direct flow of voltage of primary coil to start circuit, rethread start circuit carries out charge control to tank circuit, so that tank circuit can be to signal generation circuit stable power supply, the current output drive control signal based on the primary coil drives control circuit by signal generation circuit again, make control circuit control the break-make of primary coil, thereby realized the effect to the output voltage of switching power supply control.
Optionally, the starting circuit includes a first charging branch, a second charging branch, and a switching sub-circuit;
the switching sub-circuit is connected between the second charging branch circuit and the energy storage circuit, and is used for detecting the charging current of the second charging branch circuit and the charging voltage of the energy storage circuit, and controlling the on-off of the second charging branch circuit according to the charging current and the charging voltage;
the first charging branch circuit and the second charging branch circuit are arranged between the energy storage circuit and the voltage clamping circuit in parallel, and the power supply voltage of the first charging branch circuit is larger than that of the second charging branch circuit.
Through adopting above-mentioned technical scheme, because the power supply voltage of first branch circuit and the second branch circuit that charges is different, utilizes the switching sub-circuit to control the break-make of second branch circuit that charges based on the charge current of second branch circuit and the charge voltage of tank circuit, the first branch circuit or the second branch circuit that charges that are convenient for select corresponding according to the actual conditions of tank circuit to mend the electricity to make the tank circuit can stabilize to signal generation circuit power supply.
Optionally, the first charging branch includes a voltage stabilizing first diode D1 and a first resistor R1;
the cathode of the voltage stabilizing first diode D1 is connected with the voltage clamping circuit, the anode of the voltage stabilizing first diode D1 is connected with one end of the first resistor R1, and the other end of the first resistor R1 is connected with the energy storage circuit.
Through adopting above-mentioned technical scheme, when transformer T1 just goes up, the voltage of tank circuit is zero, the clamp voltage of voltage clamp circuit output, the voltage difference at steady voltage first diode D1 both ends is the clamp voltage, steady voltage first diode D1 reverse switch-on this moment, in order to input the clamp voltage to tank circuit, charge tank circuit, along with the rising of tank circuit voltage, the voltage difference between tank circuit's voltage and the clamp voltage is less than steady voltage first diode D1's reverse switch-on voltage, cut off clamp voltage and pass through steady voltage first diode D1 and supply power to tank circuit, thereby can be automatically according to tank circuit's voltage control voltage clamp circuit and tank circuit's break-make through steady voltage first diode D1.
Optionally, the second charging branch includes a first diode D1 and a second resistor R2;
the anode of the first diode D1 is connected with the voltage clamping circuit, the cathode of the first diode D1 is connected with one end of the second resistor R2, the other end of the second resistor R2 is connected with the energy storage circuit, and the resistance value of the second resistor R2 is larger than that of the first resistor R1.
Through adopting above-mentioned technical scheme, the clamp voltage of voltage clamp circuit output charges to the tank circuit through first diode D1 and second resistor R2 to the resistance of second resistor R2 is greater than the resistance of first resistor R1 makes the clamp voltage of voltage clamp circuit output charge to the tank circuit through first diode D1 and second resistor R2's power supply voltage that charges to the tank circuit through steady voltage first diode D1 and first resistor R1 compare lower.
Optionally, the switching sub-circuit includes a current sampler CS, a current comparator ICMP, a voltage comparator VCMP, an AND gate AND an electronic switch K1;
the sampling end of the current sampler CS is connected with the second charging branch in series, and the output end of the current sampler CS is connected with the current comparator ICMP;
a first input end of the current comparator ICMP is connected with an output end of the current sampler CS, a second input end of the current comparator ICMP is connected with a reference current signal Iref, AND an output end of the current comparator ICMP is connected with a first input end of the AND gate;
a first input end of the voltage comparator VCMP is connected with the energy storage circuit, a second input end of the voltage comparator VCMP is connected with the reference voltage signal Vref, AND an output end of the voltage comparator VCMP is connected with a second input end of the AND gate;
the output end of the AND gate AND is connected with the control end of the electronic switch K1, AND the electronic switch K1 is connected with the second charging branch in series.
By adopting the technical scheme, the charging current of the second charging branch is sampled by the current sampler CS, the sampling current is input to the first input end of the current comparator ICMP, the sampling current is conveniently compared with the reference current signal Iref, the charging current of the second charging branch is input to the first input end of the voltage comparator VCMP, the charging voltage of the energy storage circuit is conveniently compared with the reference voltage signal Vref, the comparison result of the voltage comparator VCMP AND the current comparator ICMP is input to the AND gate AND, AND the level signal for controlling the electronic switch K1 is output through logic judgment of the AND gate AND, so that the effect of controlling the on-off of the second charging branch through the charging current of the second charging branch AND the charging voltage of the energy storage circuit is realized.
Optionally, the voltage clamping circuit includes a depletion type MOS transistor Q1;
the grid electrode of the depletion type MOS tube Q1 is grounded, the drain electrode is connected with the primary coil, and the source electrode is connected with the starting circuit.
Through adopting above-mentioned technical scheme, depletion type MOS pipe Q1 has the conducting channel when the grid ground, can normally switch on to depletion type MOS pipe Q1 when grid voltage ground, the grid source voltage after switching on changes in a certain range, makes the source voltage after depletion type MOS pipe Q1 switched on be clamped, thereby the source of depletion type MOS pipe Q1 of being convenient for can output the clamp voltage that is fit for the work of later stage circuit.
Optionally, the signal generating circuit includes a driving chip U1, a current detecting sub-circuit OSC, and a first transistor M1;
the current detection subcircuit OSC is connected with the primary coil, so as to detect the current of the primary coil and output a detection signal based on a current detection result;
the receiving end of the driving chip U1 is connected with the current detection subcircuit OSC, and the output end of the driving chip U1 is connected with the grid electrode of the first transistor M1 so as to control the on-off of the first transistor M1;
the drain electrode of the first transistor M1 is connected to the source electrode of the depletion MOS transistor Q1, and the source electrode of the first transistor M1 is connected to the control circuit.
Through adopting above-mentioned technical scheme, detect the electric current of primary coil according to electric current detection sub-circuit OSC to obtain the energy storage condition of primary coil, and the corresponding output high level or low level of control driver chip U1 is outputted to electric current detection sub-circuit OSC according to the energy storage condition of primary coil, thereby control the break-make of first transistor M1, when first transistor M1 switched on, the clamp voltage flow direction control circuit of voltage clamp circuit output, so that control circuit control primary coil switches on, otherwise, control primary coil closure, and then realized the control to primary coil break-make.
Optionally, the signal generating circuit further includes an NOT gate NOT and a second transistor M2;
the input end of the NOT is connected to the output end of the driving chip U1, and the output end of the NOT is connected to the grid electrode of the second transistor M2; the drain of the second transistor M2 is connected to the source of the first transistor M1 and the control circuit, and the source of the second transistor M2 is grounded.
By adopting the technical scheme, the NOT is utilized to enable signals transmitted to the grid electrode of the first transistor M1 and the grid electrode of the second transistor M2 to be opposite, namely, only one of the first transistor M1 and the second transistor M2 can be conducted at the same time, and when the first transistor M1 is turned off and the second transistor M2 is conducted, the second transistor M2 rapidly discharges a driving control signal output to the control circuit so as to rapidly control the on-off of the control circuit.
Optionally, a backflow prevention circuit is further arranged between the starting circuit and the voltage clamping circuit, the backflow prevention circuit comprises a second diode D2, the cathode of the second diode is connected with the starting circuit, and the anode of the second diode is connected with the voltage clamping circuit and the signal generating circuit.
Through adopting above-mentioned technical scheme, utilize preventing flowing backwards circuit and be used for realizing the unidirectional conduction between starting circuit and the voltage clamping circuit to prevent the electric current in the energy storage circuit to flow to voltage clamping circuit and signal generation circuit through starting current, prevent flowing backwards the circuit and adopt the second diode, simple structure, reverse blocking performance is reliable.
In a second aspect, the present application provides a chip, which adopts the following technical scheme:
a chip comprising a start-up circuit as claimed in any one of the preceding claims and a signal generation circuit.
In a third aspect, the present application provides a switching power supply, which adopts the following technical scheme:
a switching power supply comprising a transformer T1 and a switching power supply drive circuit as claimed in any one of the preceding claims.
Drawings
Fig. 1 is a schematic diagram of a switching power supply driving circuit according to an embodiment of the application.
Fig. 2 is a schematic diagram of a switching power supply driving circuit according to an embodiment of the application.
Fig. 3 is a schematic diagram of a start-up circuit according to an embodiment of the application.
Reference numerals illustrate: 1. a voltage clamping circuit; 2. a start-up circuit; 21. a first charging branch; 22. a second charging branch; 23. a switching sub-circuit; 3. a tank circuit; 4. a signal generating circuit; 5. a control circuit; 6. and a backflow prevention circuit.
Detailed Description
The present application will be described in further detail with reference to the drawings and examples, in order to make the objects, technical solutions and advantages of the present application more apparent. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the scope of the application.
Referring to fig. 1 and 2, an embodiment of the present application discloses a switching power supply driving circuit, which includes a voltage clamping circuit 1, a starting circuit 2, a tank circuit 3, a signal generating circuit 4 and a control circuit 5.
The voltage clamping circuit 1 is connected to a primary winding of the transformer T1, clamps the voltage of the primary winding, and outputs a clamped voltage. The clamping voltage is smaller than a preset clamping value, and referring to fig. 2 and 3, the signal VA is the clamping voltage. Referring again to fig. 2, the transformer T1 may include a primary winding, a secondary winding, an output capacitor C0 connected in parallel to the secondary winding, and an output diode D0, wherein both ends of the output capacitor C0 are connected to a load, and a cathode of the output diode D0 is connected to the output capacitor C0 and an anode is connected to the secondary winding to prevent the output capacitor C0 from being directed to the secondary winding. The primary coil and the secondary coil are mutually coupled and induced. When the primary coil is conducted, the current of the primary coil rises, and at the moment, the primary coil starts to store energy, and the secondary coil does not work; when the primary coil is powered off, the energy stored in the primary coil is converted to the secondary coil to provide the voltage VOUT for the load.
The starting circuit 2 is connected between the voltage clamping circuit 1 and the energy storage circuit 3 and is used for controlling the charging of the energy storage circuit 3.
The tank circuit 3 is connected to the signal generating circuit 4 for supplying power to the signal generating circuit 4.
The signal generating circuit 4 is connected to the primary winding, and is configured to sample a current of the primary winding and output a driving control signal according to the current of the primary winding. The drive control signal may be a pulse width modulated signal (Pulse Width Modulation, PWM), among others. Referring to fig. 2, the signal SW is a driving control signal.
The control circuit 5 is connected to the primary coil and the signal generation circuit 4, and controls the on/off of the primary coil based on the drive control signal. It should be appreciated that by controlling the repeated on and off of the primary coil, the primary coil is constantly charged and energy is transferred to the secondary coil, facilitating the conversion and regulation of the secondary coil output voltage.
In the above embodiment, the voltage clamping circuit 1 clamps the voltage of the primary winding of the transformer T1, so that the voltage on the primary winding is isolated to prevent the voltage of the primary winding from directly flowing to the starting circuit 2, and then the starting circuit 2 performs charging control on the tank circuit 3, so that the tank circuit 3 can stably supply power to the signal generating circuit 4. Finally, the signal generating circuit 4 outputs a driving control signal based on the current of the primary coil to drive the control circuit 5, so that the control circuit 5 controls the on-off of the primary coil, and the effect of controlling the output voltage of the switching power supply is achieved.
In this embodiment, since the power of the tank circuit 3 is derived from the clamp voltage, that is, from the primary winding of the transformer T1, and the tank circuit 3 supplies power to the signal generating circuit 4, the power supply to the signal generating circuit 4 can be realized without providing an auxiliary winding of the transformer T1, and the tank circuit 3 can be automatically charged by the start circuit 2 with the clamp voltage outputted from the voltage clamp circuit 1 after the primary winding is powered on, so that the effect that the high-voltage primary winding directly charges the low-voltage tank circuit 3 to start the signal generating circuit 4 is realized.
In the present embodiment, the signal generating circuit 4, the voltage clamping circuit 1, and the control circuit 5 are independently operated or encapsulated in one package.
With further reference to fig. 2, as an embodiment of the voltage clamp circuit 1, the voltage clamp circuit 1 includes a depletion MOS transistor Q1 (Metal Oxide Semiconductor Field Effect Transistor ). The depletion MOS transistor Q1 has a gate grounded, a drain connected to the primary coil, and a source connected to the start circuit 2.
It should be understood that the preset clamping value of the clamping voltage may be the pinch-off voltage of the depletion type MOS transistor Q1, because the gate of the depletion type MOS transistor Q1 is grounded, that is, is a zero potential, along with the conduction of the depletion type MOS transistor Q1, the source voltage of the depletion type MOS transistor Q1 continuously rises, so that the gate-source voltage of the depletion type MOS transistor Q1 becomes negative, and the conducting channel of the depletion type MOS transistor Q1 becomes smaller and smaller until the gate voltage of the depletion type MOS transistor Q1 reaches the pinch-off voltage of the depletion type MOS transistor Q1, at this time, the depletion type MOS transistor Q1 is turned off, that is, the clamping of the source voltage of the depletion type MOS transistor Q1 is realized, so that the clamping voltage is not greater than the pinch-off voltage of the depletion type MOS transistor Q1 all the time.
It should be noted that, since the preset clamping value of the clamping voltage is the pinch-off voltage of the depletion type MOS transistor Q1, a depletion type MOS transistor Q1 with a suitable model can be selected according to the actual situation by the pinch-off voltage. For example, in this embodiment, the depletion type MOS transistor Q1 may be a gallium nitride transistor, which is a normally-on device, and has advantages of high voltage resistance, small on-resistance, and the like. In other embodiments, the depletion MOS transistor Q1 may also select an appropriate device according to the actual situation.
In the above embodiment, when the gate of the depletion MOS transistor Q1 is grounded, that is, when the gate-source voltage is zero, a conduction channel already exists, so that the depletion MOS transistor Q1 can be normally turned on, and the turned-on gate-source voltage varies within a certain range, so that the turned-on source voltage of the depletion MOS transistor Q1 is clamped, and the source of the depletion MOS transistor Q1 can output a clamping voltage suitable for the operation of a later-stage circuit.
Referring again to fig. 2, as an embodiment of the tank circuit 3, the tank element in the tank circuit 3 includes a capacitor C, one end of which is connected to the starting circuit 2 and the other end of which is grounded.
Referring to fig. 3, as an embodiment of the starting circuit 2, the starting circuit 2 includes a first charging branch 21, a second charging branch 22, and a switching sub-circuit 23, and the circuit configuration and the operation principle of the starting circuit 2 are described in detail below.
The switching sub-circuit 23 is connected between the second charging branch circuit 22 and the energy storage circuit 3, and is configured to detect a charging current of the second charging branch circuit 22 and a charging voltage of the energy storage circuit 3, and control on-off of the second charging branch circuit 22 according to the charging current and the charging voltage.
The first charging branch 21 and the second charging branch 22 are arranged in parallel between the energy storage circuit 3 and the voltage clamping circuit 1, and the supply voltage of the first charging branch 21 is greater than the supply voltage of the second charging branch 22.
In the above embodiment, since the power supply voltages of the first charging branch 21 and the second charging branch 22 are different, the switching sub-circuit 23 is used to control the on-off of the second charging branch 22 based on the charging current of the second charging branch 22 and the charging voltage of the tank circuit 3, so that the tank circuit 3 can supply power to the signal generating circuit 4 stably by selecting the corresponding first charging branch 21 or second charging branch 22 according to the actual situation of the tank circuit 3.
As an embodiment of the first charging branch 21, the first charging branch 21 includes a voltage stabilizing first diode D1 and a first resistor R1, which will be described in detail below.
The cathode of the voltage stabilizing first diode D1 is connected with the voltage clamping circuit 1, the anode is connected with one end of the first resistor R1, and the other end of the first resistor R1 is connected with the energy storage circuit 3.
Specifically, the cathode of the voltage stabilizing first diode D1 is also connected to the source of the depletion MOS transistor Q1.
It should be appreciated that the regulated first diode D1 is turned on when the voltage difference between the cathode and the anode of the regulated first diode D1 exceeds the reverse turn-on voltage of the regulated first diode D1. And the reverse conducting voltage of the voltage stabilizing first diode D1 is smaller than the pinch-off voltage of the depletion MOS transistor Q1.
In the above embodiment, when the transformer T1 is just powered on, the voltage of the energy storage circuit 3 is zero, and the clamping voltage output by the voltage clamping circuit 1, that is, the voltage difference between the two ends of the stabilized first diode D1 is the clamping voltage, at this time, the stabilized first diode D1 is turned on reversely, so as to input the clamping voltage to the energy storage circuit 3, and charge the energy storage circuit 3. Along with the rise of the voltage of the energy storage circuit 3, the voltage difference between the charging voltage and the clamping voltage of the energy storage circuit 3 is smaller than the reverse conduction voltage of the voltage stabilizing first diode D1, and the power supply of the clamping voltage to the energy storage circuit 3 through the voltage stabilizing first diode D1 is cut off, so that the on-off of the voltage clamping circuit 1 and the energy storage circuit 3 can be automatically controlled according to the voltage of the energy storage circuit 3 through the voltage stabilizing first diode D1.
As an embodiment of the second charging branch 22, the second charging branch 22 includes a first diode D1 and a second resistor R2, which will be described in detail below.
The anode of the first diode D1 is connected with the voltage clamping circuit 1, the cathode is connected with one end of the second resistor R2, the other end of the second resistor R2 is connected with the energy storage circuit 3, and the resistance value of the second resistor R2 is larger than that of the first resistor R1.
Specifically, the anode of the first diode D1 is connected to the source of the depletion MOS transistor Q1 and the cathode of the voltage stabilizing first diode D1.
In the above embodiment, the clamp voltage output from the voltage clamp circuit 1 charges the tank circuit 3 through the first diode D1 and the second resistor R2, and the resistance value of the second resistor R2 is larger than that of the first resistor R1 so that the supply voltage of the clamp voltage output from the voltage clamp circuit 1 to charge the tank circuit 3 through the first diode D1 and the second resistor R2 is lower than the supply voltage of the clamp voltage to charge the tank circuit 3 through the stabilized first diode D1 and the first resistor R1.
Referring to fig. 3, as an embodiment of the switching sub-circuit 23, the switching sub-circuit 23 includes a current sampler CS, a current comparator ICMP, a voltage comparator VCMP, an AND gate AND, AND an electronic switch K1;
the sampling end of the current sampler CS is connected in series to the second charging branch 22, and the output end is connected to the current comparator ICMP.
The first input terminal of the current comparator ICMP is connected to the output terminal of the current sampler CS, the second input terminal is connected to the reference current signal Iref, AND the output terminal is connected to the first input terminal of the AND gate AND.
The first input terminal of the voltage comparator VCMP is connected to the tank circuit 3, the second input terminal is connected to the reference voltage signal Vref, AND the output terminal is connected to the second input terminal of the AND gate AND.
The output end of the AND gate AND is connected with the control end of the electronic switch K1, AND the electronic switch K1 is connected in series on the second charging branch 22 AND is connected between the first diode D1 AND the voltage clamping circuit 1.
It should be understood that when the energy storage element of the energy storage circuit 3 is the capacitor C, as the charging characteristic of the capacitor C is known, the voltage across the capacitor C becomes larger and the current becomes smaller as the capacitor C is continuously charged. That is, the larger the charging voltage of the energy storage circuit 3, the more the amount of electricity stored in the energy storage circuit 3, and the larger the charging current of the second charging branch 22, the lower the amount of electricity stored in the energy storage circuit 3, and the possible occurrence of power shortage.
Further, the switching sub-circuit 23 further includes a reference signal generating device for generating the reference current signal Iref and the reference voltage signal Vref, and the reference signal generating device is powered by the tank circuit 3, and generates the reference current signal Iref and the reference voltage signal Vref when the voltage of the tank circuit 3 reaches a certain value.
Specifically, after the reference current signal Iref AND the reference voltage signal Vref are established, the current of the second charging branch 22 is zero, AND the charging voltage of the tank circuit 3 is smaller than the reference voltage signal Vref, so the current comparator ICMP AND the voltage comparator VCMP both output high-level signals, AND then the AND gate AND outputs high-level signals to the electronic switch K1 to control the electronic switch K1 to be turned on, so that the clamping voltage continuously charges the tank circuit 3 via the first diode D1 AND the second resistor R2. When the charging voltage of the tank circuit 3 is greater than the reference voltage signal Vref, the voltage comparator VCMP outputs a low level signal, AND then outputs the low level signal to the electronic switch K1 through the AND gate AND to control the electronic switch K1 to turn off, thereby cutting off the charging of the tank circuit 3.
It should be noted that, when the charging current of the second charging branch 22 is greater than the reference current signal Iref, it is explained that the tank circuit 3 may be out of charge at this time, but the tank circuit 3 is still being charged by the second charging branch 22 with a smaller supply voltage, so the current comparator ICMP outputs a low level signal, AND the AND gate AND outputs a low level signal, AND the electronic switch K1 is controlled to be turned off, so that the clamping voltage charges the tank circuit 3 through the first charging branch 21.
In the above embodiment, the charging current of the second charging branch 22 is sampled by the current sampler CS, the sampled current is input to the first input end of the current comparator ICMP, the sampled current is conveniently compared with the reference current signal Iref, the charging current of the second charging branch 22 is input to the first input end of the voltage comparator VCMP, the charging voltage of the tank circuit 3 is conveniently compared with the reference voltage signal Vref, the comparison result of the voltage comparator VCMP AND the current comparator ICMP is input to the AND gate AND the level signal for controlling the electronic switch K1 is output through the logic judgment of the AND gate AND, so that the effect of controlling the on-off of the second charging branch 22 by the charging current of the second charging branch 22 AND the charging voltage of the tank circuit 3 is realized, AND further, one of the first charging branch 21 AND the second charging branch 22 charges the tank circuit 3.
With continued reference to fig. 2, as an embodiment of the signal generating circuit 4, the signal generating circuit 4 includes a driving chip U1, a current detecting sub-circuit OSC, and a first transistor M1;
the current detection sub-circuit OSC is connected to the primary coil to detect a current of the primary coil and outputs a detection signal based on a current detection result. Specifically, a sampling resistor Rs is connected in series to the primary winding, one end of the sampling resistor Rs is connected to the control circuit 5 and the current detection sub-circuit OSC, and the other end is grounded.
The receiving end of the driving chip U1 is connected with the current detection sub-circuit OSC, and the output end of the driving chip U1 is connected with the grid electrode of the first transistor M1 so as to control the on-off state of the first transistor M1. The drain of the first transistor M1 is connected to the source of the depletion MOS transistor Q1, and the source of the first transistor M1 is connected to the control circuit 5.
It should be understood that when the detection signal reaches the preset value, the driving chip U1 outputs the PWM signal, and the first transistor M1 is turned off and the control circuit 5 is turned off during a period in which the PWM signal output by the driving chip U1 is at a low level. At this time, the voltage of the primary coil flows to the voltage clamp circuit 1 and the voltage clamp circuit 1 outputs the clamp voltage, so that the switching sub-circuit 23 performs charge control on the tank circuit 3 according to the charge current of the second charging branch 22 and the charge voltage of the tank circuit 3. During the period when the driving chip U1 outputs a high level, the first transistor M1 is turned on, and the clamping voltage output by the voltage clamping circuit 1 is input to the control circuit 5 through the first transistor M1, so that the control circuit 5 is turned on, and the clamping voltage is pulled down at this time, so that the energy storage circuit 3 cannot be charged.
It should also be appreciated that, since the energy storage circuit 3 can be charged only during the period when the driving chip U1 outputs a low level, that is, the duration of charging the energy storage circuit 3 is limited, by detecting the charging current of the second charging branch 22, when the energy storage circuit 3 is out of charge and still is charged with the second charging branch 22, the second charging branch 22 needs to be disconnected to switch to the first charging branch 21 with a higher power supply voltage to charge the energy storage circuit 3.
In the above embodiment, the current of the primary coil is detected according to the current detection sub-circuit OSC, so as to obtain the energy storage condition of the primary coil, and the current detection sub-circuit OSC outputs a detection signal according to the energy storage condition of the primary coil, so as to control the corresponding output high level or low level of the driving chip U1, thereby controlling the on-off of the first transistor M1, when the first transistor M1 is turned on, the clamping voltage output by the voltage clamping circuit 1 flows to the control circuit 5, so that the control circuit 5 controls the primary coil to be turned on, otherwise, controls the primary coil to be turned off, and further realizes the control of the on-off of the primary coil.
As an embodiment of the signal generating circuit 4, the signal generating circuit 4 further includes an NOT gate NOT and a second transistor M2.
The input end of the NOT gate NOT is connected to the output end of the driving chip U1, and the output end of the NOT gate is connected to the grid electrode of the second transistor M2; the drain of the second transistor M2 is connected to the source of the first transistor M1 and the control circuit 5, and the source of the second transistor M2 is grounded.
It should be appreciated that since the voltage clamping circuit 1 clamps the voltages flowing to the first transistor M1 and the second transistor M2, both the first transistor M1 and the second transistor M2 may employ low-voltage MOS transistors.
In the above embodiment, the NOT is utilized to make the signals transmitted to the gate of the first transistor M1 and the gate of the second transistor M2 opposite, that is, only one of the first transistor M1 and the second transistor M2 can be turned on at the same time, and when the first transistor M1 is turned off and the second transistor M2 is turned on, the second transistor M2 rapidly discharges the driving control signal output to the control circuit 5, so as to rapidly control the on/off of the control circuit 5.
Referring to fig. 2, as an embodiment of the control circuit 5, the control circuit 5 includes a transistor Q2, a base of the transistor Q2 is connected to a source of the first transistor M1 and a drain of the second transistor M2, a collector is connected to the primary winding, and an emitter is grounded. The triode Q2 can be a high-voltage resistant triode.
It can be seen that, in the present embodiment, the transistor Q2 is turned on after the first transistor M1 is turned on, and the clamp voltage is derived from the primary winding, so that the driving control signal for controlling the transistor Q2 to be turned on is also provided by the primary winding; on the one hand, the driving chip U1 outputs smaller voltage, namely, the first transistor M1 can be controlled to be conducted, and after the first transistor M1 is conducted, the primary coil provides driving current for the triode Q2, and the driving chip U1 is not required to provide driving current for the triode Q2, so that the power consumption of the driving chip is reduced, and the situations of too fast electricity consumption, unstable voltage and the like of the energy storage circuit 3 caused by too large power consumption of the driving chip U1 are avoided, so that the reliable starting under the condition of a larger capacitive load is not facilitated. On the other hand, the drive control signal from the clamping voltage can enable the triode Q2 to be fully saturated and conducted after being turned on, and is not influenced by current in the energy storage circuit 3, so that the working state of the triode Q2 is more stable.
It should also be appreciated that in this embodiment, the transistor Q2 needs to be driven in supersaturation, and a large amount of charges are accumulated in the base stage of the transistor Q2 at this time, so that the turn-off speed of the transistor Q2 is slow, and the charges accumulated in the base stage of the transistor Q2 can be discharged to the ground by turning on the second transistor M2, so that the transistor Q2 can be turned off quickly, which helps to increase the switching frequency of the transistor Q2.
Referring to fig. 2 and 3, as a further embodiment of the switching power supply driving circuit, a backflow prevention circuit 6 is further provided between the starting circuit 2 and the voltage clamping circuit 1, and the backflow prevention circuit 6 includes a second diode D2, and a cathode of the second diode D2 is connected to the starting circuit 2 and an anode thereof is connected to the voltage clamping circuit 1 and the signal generating circuit 4.
Specifically, the cathode of the second diode D2 is connected to one end of the electronic switch K1 and the cathode of the zener diode D, and the anode is connected to the gate of the depletion MOS transistor Q1 and the source of the first transistor M1.
It should be understood that, in this embodiment, since the driving control signal of the transistor Q2 is derived from the clamping voltage, the clamping voltage can already provide enough base current to make the transistor Q2 fully saturated and conductive after being turned on to control the primary coil energy storage, so that the energy storage circuit 3 is prevented from providing the base current to the transistor Q2 during the primary coil energy storage by providing the backflow prevention circuit 6, so as to prevent unnecessary energy consumption of the energy storage circuit 3 from being increased.
In the above embodiment, the anti-backflow circuit is used for realizing unidirectional conduction between the starting circuit and the voltage clamping circuit so as to prevent the current in the energy storage circuit from flowing to the voltage clamping circuit and the signal generating circuit through the starting current, and the anti-backflow circuit adopts the second diode D2, so that the anti-backflow circuit has a simple structure and reliable reverse cut-off performance.
In addition, on the basis of the above, the embodiment of the application also discloses a chip, which comprises the starting circuit 2 and the signal generating circuit 4.
In addition, the embodiment of the application also discloses a switching power supply which comprises the transformer T1 and the switching power supply driving circuit.
In the foregoing embodiments, the descriptions of the embodiments are focused on, and for those portions of one embodiment that are not described in detail, reference may be made to the related descriptions of other embodiments.
The foregoing description of the preferred embodiments of the application is not intended to limit the scope of the application in any way, including the abstract and drawings, in which case any feature disclosed in this specification (including abstract and drawings) may be replaced by alternative features serving the same, equivalent purpose, unless expressly stated otherwise. That is, each feature is one example only of a generic series of equivalent or similar features, unless expressly stated otherwise.
Claims (10)
1. A switching power supply driving circuit, characterized in that: the power supply comprises a voltage clamping circuit (1), a starting circuit (2), a tank circuit (3), a signal generating circuit (4) and a control circuit (5);
the voltage clamping circuit (1) is connected with a primary coil of the transformer T1, clamps the voltage of the primary coil and outputs clamping voltage;
the starting circuit (2) is connected between the voltage clamping circuit (1) and the energy storage circuit (3) and is used for controlling the charging of the energy storage circuit (3);
the energy storage circuit (3) is connected with the signal generation circuit (4) and is used for supplying power to the signal generation circuit (4);
the signal generating circuit (4) is connected with the primary coil, and is used for sampling the current of the primary coil and outputting a driving control signal according to the current of the primary coil;
the control circuit (5) is connected with the primary coil and the signal generation circuit (4) and controls the on-off of the primary coil based on the driving control signal.
2. A switching power supply driving circuit according to claim 1, wherein: the starting circuit (2) comprises a first charging branch circuit (21), a second charging branch circuit (22) and a switching sub-circuit (23);
the switching sub-circuit (23) is connected between the second charging branch circuit (22) and the energy storage circuit (3) and is used for detecting the charging current of the second charging branch circuit (22) and the charging voltage of the energy storage circuit (3), and controlling the on-off of the second charging branch circuit (22) according to the charging current and the charging voltage so that the energy storage circuit (3) can supplement electricity through the first charging branch circuit (21) or the second charging branch circuit (22);
the first charging branch circuit (21) and the second charging branch circuit (22) are arranged in parallel between the energy storage circuit (3) and the voltage clamping circuit (1), and the power supply voltage of the first charging branch circuit (21) is larger than that of the second charging branch circuit (22).
3. A switching power supply driving circuit according to claim 2, wherein: the first charging branch (21) comprises a voltage stabilizing first diode D1 and a first resistor R1;
the cathode of the voltage stabilizing first diode D1 is connected with the voltage clamping circuit (1), the anode of the voltage stabilizing first diode D1 is connected with one end of the first resistor R1, and the other end of the first resistor R1 is connected with the energy storage circuit (3).
4. A switching power supply driving circuit according to claim 3, wherein: the second charging branch (22) comprises a first diode D1 and a second resistor R2;
the anode of the first diode D1 is connected with the voltage clamping circuit (1), the cathode of the first diode D1 is connected with one end of the second resistor R2, the other end of the second resistor R2 is connected with the energy storage circuit (3), and the resistance value of the second resistor R2 is larger than that of the first resistor R1.
5. A switching power supply driving circuit according to claim 2, wherein: the switching sub-circuit (23) comprises a current sampler CS, a current comparator ICMP, a voltage comparator VCMP, an AND gate AND AND an electronic switch K1;
the sampling end of the current sampler CS is connected with the second charging branch (22) in series, and the output end of the current sampler CS is connected with the current comparator ICMP;
a first input end of the current comparator ICMP is connected with an output end of the current sampler CS, a second input end of the current comparator ICMP is connected with a reference current signal Iref, AND an output end of the current comparator ICMP is connected with a first input end of the AND gate;
a first input end of the voltage comparator VCMP is connected with the energy storage circuit (3), a second input end of the voltage comparator VCMP is connected with a reference voltage signal Vref, AND an output end of the voltage comparator VCMP is connected with a second input end of the AND gate;
the output end of the AND gate AND is connected with the control end of the electronic switch K1, AND the electronic switch K1 is connected with the second charging branch (22) in series.
6. A switching power supply driving circuit according to claim 1, wherein: the voltage clamping circuit (1) comprises a depletion type MOS tube Q1;
the grid electrode of the depletion type MOS tube Q1 is grounded, the drain electrode is connected with the primary coil, and the source electrode is connected with the starting circuit (2).
7. The switching power supply driving circuit according to claim 6, wherein: the signal generating circuit (4) includes a driving chip U1, a current detecting sub-circuit OSC, and a first transistor M1;
the current detection subcircuit OSC is connected with the primary coil, so as to detect the current of the primary coil and output a detection signal based on a current detection result;
the receiving end of the driving chip U1 is connected with the current detection subcircuit OSC, and the output end of the driving chip U1 is connected with the grid electrode of the first transistor M1 so as to control the on-off of the first transistor M1;
the drain of the first transistor M1 is connected to the source of the depletion MOS transistor Q1, and the source of the first transistor M1 is connected to the control circuit (5).
8. The switching power supply driving circuit according to claim 7, wherein: the signal generating circuit (4) further comprises a NOT gate NOT and a second transistor M2;
the input end of the NOT is connected to the output end of the driving chip U1, and the output end of the NOT is connected to the grid electrode of the second transistor M2; the drain electrode of the second transistor M2 is connected to the source electrode of the first transistor M1 and the control circuit (5), and the source electrode of the second transistor M2 is grounded.
9. A switching power supply driving circuit according to claim 1, wherein: the anti-backflow circuit (6) is further arranged between the starting circuit (2) and the voltage clamping circuit (1), the anti-backflow circuit (6) comprises a second diode D2, the cathode of the second diode D2 is connected with the starting circuit (2), and the anode of the second diode D2 is connected with the voltage clamping circuit (1) and the signal generating circuit (4).
10. A switching power supply, characterized by: a switching power supply driving circuit as claimed in any one of claims 1 to 9, comprising a transformer T1.
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| CN202311053595.2A CN116760286B (en) | 2023-08-21 | 2023-08-21 | Switching power supply driving circuit and switching power supply |
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| CN202311053595.2A CN116760286B (en) | 2023-08-21 | 2023-08-21 | Switching power supply driving circuit and switching power supply |
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