CN210137278U - Switching power supply control circuit - Google Patents
Switching power supply control circuit Download PDFInfo
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- CN210137278U CN210137278U CN201921312737.1U CN201921312737U CN210137278U CN 210137278 U CN210137278 U CN 210137278U CN 201921312737 U CN201921312737 U CN 201921312737U CN 210137278 U CN210137278 U CN 210137278U
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Abstract
The utility model provides a switching power supply control circuit belongs to the microelectronics technical field. The technical scheme is as follows: a switching power supply control circuit comprises a variable gain network, an output state detection circuit, an error amplifier, a mode control circuit, a slope compensation circuit, a PWM logic circuit and a soft driving circuit. The utility model has the advantages that: the utility model discloses a PWM switching power supply control circuit's periphery with self-adaptation regulation only needs a resistance can detect the output voltage state, according to output voltage's different automatically regulated control circuit loop gain, operating frequency and mode for can all realize best loop gain, operating frequency and mode under output high voltage and the output low voltage state, conversion efficiency reaches the best under the different loads, system conversion efficiency and loop stability under the different output voltage states of improvement that can be very big.
Description
Technical Field
The utility model relates to a microelectronics technical field especially relates to a switching power supply control circuit.
Background
Fast charging switching power supplies are an increasingly popular power supply device, and in many fast charging applications, the switching power supplies are required to have various output voltages, and the output voltages are automatically adjusted to target values according to handshake protocol signals received and transmitted. These applications require primary control circuits, i.e., controlling the switching on and off of the primary power switching tube, to have optimal performance and conversion efficiency under different output voltage conditions, and conventional primary PWM control circuits generally do not have the capability to detect and internally control and adjust the system output voltage. This approach has significant disadvantages in that: when a power supply engineer designs a system scheme, the system efficiency, the loop response performance and the like under different output voltages are difficult to be considered simultaneously, so that the system efficiency is reduced and a large amount of peripheral debugging work is caused.
How to solve the above technical problems is the subject faced by the present invention.
SUMMERY OF THE UTILITY MODEL
An object of the utility model is to provide a switching power supply control circuit, and mode, operating frequency and loop gain etc. all can be according to detected signal automatically regulated, and detected signal can correspond output and be low pressure environment or high-pressure environment, and self-adaptation regulation can make the conversion efficiency of system under different output voltage, different loads reach the best, and loop control is more stable to power engineer's debug time has been saved by a wide margin.
The utility model discloses a realize through following measure: a switching power supply control circuit comprises a rectifying circuit for inputting alternating current, a driving circuit connected to the output end of the rectifying circuit, an output filter circuit connected to the output end of the driving circuit, and a feedback circuit connected between the output filter circuit and the driving circuit;
the rectifier circuit comprises a rectifier bridge BR1 for rectifying an input alternating current power supply into direct current and an input capacitor C1 connected to the output end of one bridge arm of the rectifier bridge BR 1; generally, some filtering devices required to meet the electromagnetic interference index may be included.
The driving circuit comprises a transformer T1, a power switch tube M1, a control circuit, a starting resistor R1, a voltage detection resistor Rdet, a current sampling resistor R4, a power supply diode D1 and a power supply capacitor C2; the drive circuit may also include other components that filter and satisfy emi criteria depending on the design.
The output filter circuit comprises an output rectifying diode D2 and an output capacitor C3, wherein the output rectifying diode D2 is connected between the secondary side winding of the transformer T1 and the output capacitor C3;
the feedback circuit comprises a current-limiting resistor R5, an optocoupler and a protocol chip, wherein one end of the current-limiting resistor R5 is connected with the positive end of the output capacitor C3, the other end of the current-limiting resistor R5 is connected with one input end of the optocoupler, the other input end of the optocoupler is connected with one input end of the protocol chip, and one output end of the optocoupler is connected with the control circuit; the feedback circuit may also include other elements depending on the design.
As a further optimization scheme of the switching power supply control circuit provided by the utility model, the transformer T1 comprises a transformer primary side winding, a transformer secondary side winding and a transformer auxiliary winding;
the drain of the power switch tube M1 is connected with one end of the primary side winding of the transformer T1, and the other end of the primary side winding of the transformer T1 is connected with an input capacitor C1; the source terminal of the power switch tube M1 is connected to the resistor R4 and is used for sampling the current in the power switch tube M1;
the starting resistor R1 is connected between the positive end of the input capacitor C1 and the power supply capacitor C2, and the power supply capacitor C2 is also connected with the power supply input end of the control circuit and used for supplying power to the control circuit;
the anode of the power supply diode D1 is connected to one end of the auxiliary winding of the transformer T1, the other end of the auxiliary winding of the transformer T1 is connected to the reference ground, and the cathode of the power supply diode D2 is connected to the power supply capacitor C2;
one end of a primary side winding of the transformer T1 is connected with the anode of the capacitor C1, and the other end of the primary side winding is connected with the drain of the power switch tube M1;
one end of the secondary side winding of the transformer T1 is connected with the positive end of an output rectifying diode D2, the other end of the output rectifying diode is connected with one end of an output capacitor C3, and the other end of the secondary side winding of the transformer T1 is connected with the other end of the output capacitor.
The utility model provides a switching power supply control circuit further optimizes the scheme, transformer T1's auxiliary winding one end is connected power supply diode D1's positive pole and voltage detection resistance Rdet one end, power supply diode D1's negative pole is connected supply capacitor C2, voltage detection resistance Rdet's the other end connect in control circuit, transformer T1's auxiliary winding other end ground connection.
As the utility model provides a further optimization scheme of switching power supply control circuit, control circuit includes variable gain network, output state detection circuitry, error amplifier, mode control circuit, pulse generator, slope compensation circuit, PWM logic circuit, soft drive circuit, OCP circuit and internal power supply;
the output state detection circuit generates control signals of the variable gain network and the mode control circuit; the variable gain network generates an input signal of the error amplifier and a control signal of the mode control circuit;
the mode control circuit generates a control signal of the pulse generator;
the pulse generator generates an input signal of the slope compensation circuit and an input signal of the PWM logic circuit;
the PWM logic circuit generates an input signal for a soft drive circuit that controls the power switch M1 to turn on and off.
The variable gain network comprises: the circuit comprises an upper bias resistor R10, a diode D3, a voltage-dividing resistor R11, a voltage-dividing resistor R12, a voltage-dividing resistor R13, a voltage-dividing resistor R14, a switch tube M11, a switch tube M12, a switch tube M13, a switch tube M14, a switch tube M15, a switch tube M16, a switch tube M17, an inverter U1, an inverter U2, an inverter U3, an inverter U7, a NOR logic gate U4, an AND logic gate U5 and an AND logic gate U6.
As the utility model provides a switching power supply control circuit further optimizes the scheme, output state detection circuitry includes: the resistor R20, the resistor R21, the resistor R22, the resistor R23 and the resistor R24 are connected in series or in parallel, and R20, R21, R22, R23 and R24 have the same resistor type and the same width, and the lengths of R21, R22, R23 and R24 are all integer multiples of R20 or R21, R22, R23 and R24 are all formed by connecting n R20 in series or in parallel;
the circuit also comprises NMOS switching tubes M21, M22, M24, a PMOS switching tube M23, a capacitor C11, a capacitor C12, Schmitt triggers U11 and U16, an inverter U12, an inverter U15, an AND logic gate U13, an AND logic gate U14, or logic gate U17, current sources Ir0, Ir1, Ir2, Ir3, Ir4 and Ir5, and Ir1, Ir2 and Ir3 are mirror current sources of Ir0, a first comparator, a second comparator, a third comparator and a fourth comparator.
As a further optimization scheme of the switching power supply control circuit, the mode control circuit includes a current synthesis controller and an FB voltage detection circuit, the current synthesis controller includes current sources Ir6, Ir7 and Ir8, switches S1, S2 and S3, a current adder, and a V-I control circuit, the FB voltage detection circuit includes a fifth comparator and a sixth comparator;
the negative input terminals of the fifth comparator and the sixth comparator are connected with a terminal 204, and the voltage of the terminal 204 is VFB-VBE(D3)，VFBIs the FB port voltage, VBE(D3)Is the forward voltage drop of diode D3; the positive input terminal of the fifth comparator is connected to the fourth reference voltage, the positive input terminal of the sixth comparator is connected to the fifth reference voltage, and the fourth reference voltage is greater than the fifth reference voltage.
As the further optimization scheme of the switching power supply control circuit provided by the utility model, one output end of the variable gain network is connected with the negative input end of the error amplifier, and the other output end is connected with the input end of the mode control circuit; one output end of the output state detection circuit is connected with the input end of the variable gain network, and the other output end of the output state detection circuit is connected with the input end of the mode control circuit;
the output end of the mode control circuit is connected with the input end of a pulse generator, one output end of the pulse generator is connected with the input end of the slope compensation circuit, and the other output end of the pulse generator is connected with the input end of the PWM logic circuit;
one output end of the OCP circuit is connected with the input end of the slope compensation circuit, and the other output end of the OCP circuit is connected with the PWM logic circuit;
the output end of the slope compensation circuit is connected with the positive input end of the error amplifier; the output end of the error amplifier is connected with the input end of the PWM logic circuit; the output end of the PWM logic circuit is connected with the input end of the soft driving circuit, and the output of the soft driving circuit controls the on and off of the power switch tube M1.
In order to better achieve the object of the present invention, the present invention further provides a control method of a switching power supply control circuit, which specifically includes the following steps:
1) setting a peripheral voltage detection resistor Rdet of a control circuit DET pin, flowing current of the voltage detection resistor Rdet, internal reference current Ir1, Ir2, Ir3 and Ir0 in an output state detection circuit, generating voltages on resistors R20, R21, R22, R23 and R24 which are of the same type and have proportional resistance, respectively, comparing the voltage on the resistor R20 with the voltages on the resistors R21, R22, R23 and R24 through a first comparator to a fourth comparator, and detecting the state of the output voltage;
2) and the mode control circuit detects a signal representing the FB voltage of the feedback pin from the variable gain network in real time.
Further, the step 1) specifically comprises the following steps:
① when the output voltage is low voltage output, the first comparator and the second comparator both output low level, the variable gain network adjusts the input gain impedance to R11+ R14, the mode control circuit controls the pulse generator output frequency Switch 1;
② when the output voltage is middle voltage output, the first comparator outputs high level, the second comparator outputs low level, the variable gain network adjusts the input gain impedance to R11+ R12+ R14, the mode control circuit controls the pulse generator output frequency Switch 2;
③ when the output voltage is high voltage output, the first comparator and the second comparator both output high level, the variable gain network adjusts the input gain impedance to R11+ R12+ R13+ R14, the mode control circuit controls the pulse generator output frequency Switch 3;
further, the step 2) specifically comprises the following steps:
① when the FB voltage is higher, the fifth comparator and the sixth comparator both output low level, the mode control circuit controls the pulse generator to work in the constant frequency mode;
② when the FB voltage decreases to the high level output by the fifth comparator and the low level output by the sixth comparator, the mode control circuit controls the pulse generator to work in the frequency modulation mode;
③ when the FB voltage drops to the high level output by the fifth comparator and the sixth comparator, the mode control circuit controls the pulse generator to work in the standby mode.
The utility model has the advantages that: the utility model discloses a PWM switching power supply control circuit's periphery with self-adaptation regulation only needs a resistance can detect the output voltage state, different automatically regulated control circuit loop gain according to output voltage, operating frequency and mode, make output high voltage and output low voltage state down all can realize the best loop gain, operating frequency and mode, conversion efficiency reaches the best under the different loads, system conversion efficiency and loop stability under the different output voltage states of improvement that can be very big to the quick charge switching power supply that provides multiple output voltage, and system's debugging time has been reduced by a wide margin, higher engineering application value has.
Drawings
Fig. 1 is a schematic structural diagram of an overall system according to an embodiment of the present invention;
fig. 2 is a circuit diagram of the PWM switching power supply of the present invention;
fig. 3 is a circuit diagram of a variable gain network according to an embodiment of the present invention;
fig. 4 is a circuit diagram of an output state detection circuit according to an embodiment of the present invention;
FIG. 5 is a circuit diagram of a mode control circuit according to an embodiment of the present invention;
fig. 6 is a circuit diagram of a current synthesizer according to an embodiment of the present invention;
fig. 7 is a circuit diagram of FB voltage detection according to an embodiment of the present invention;
FIG. 8 is a timing diagram illustrating an embodiment of the present invention;
fig. 9 is a flowchart of an embodiment of the present invention.
Wherein the reference numerals are: 1. a rectifying circuit; 2. a drive circuit; 3. an output filter circuit; 4. a feedback circuit; 5. a control circuit.
Detailed Description
In order to clearly illustrate the technical features of the present solution, the present solution is explained below by way of specific embodiments.
Referring to fig. 1, the utility model discloses a: a switching power supply control circuit comprises a rectifying circuit 1 for inputting alternating current, a driving circuit 2 connected with the output end of the rectifying circuit 1, an output filter circuit 4 connected with the output end of the driving circuit 2, and a feedback circuit 4 connected between the output filter circuit 3 and the driving circuit 2;
the rectifier circuit 1 comprises a rectifier bridge BR1 for rectifying an input alternating current power supply into direct current and an input capacitor C1 connected to the output end of one bridge arm of the rectifier bridge BR 1; generally, some filtering devices required to meet the electromagnetic interference index may be included.
The driving circuit 2 comprises a transformer T1, a power switch tube M1, a control circuit 5, a starting resistor R1, a voltage detection resistor Rdet, a current sampling resistor R4, a power supply diode D1 and a power supply capacitor C2; depending on the design, the driver circuit 2 may also include other components for filtering and meeting emi criteria.
The output filter circuit 3 comprises an output rectifying diode D2 and an output capacitor C3, wherein the output rectifying diode D2 is connected between the secondary side winding of the transformer T1 and the output capacitor C3;
the feedback circuit 4 comprises a current-limiting resistor R5, an optical coupler and a protocol chip, wherein one end of the current-limiting resistor R5 is connected with the positive end of the output capacitor C3, the other end of the current-limiting resistor R5 is connected with one input end of the optical coupler, the other input end of the optical coupler is connected with one input end of the protocol chip, and one output end of the optical coupler is connected with the control circuit 5; the feedback circuit 4 may also include other elements depending on the design.
Specifically, the transformer T1 includes a transformer primary side winding, a transformer secondary side winding, and a transformer auxiliary winding;
the drain of the power switch tube M1 is connected with one end of the primary side winding of the transformer T1, and the other end of the primary side winding of the transformer T1 is connected with an input capacitor C1; the source terminal of the power switch tube M1 is connected to the resistor R4 and is used for sampling the current in the power switch tube M1;
the starting resistor R1 is connected between the positive terminal of the input capacitor C1 and the supply capacitor C2, and the supply capacitor C2 is also connected with the power supply input terminal of the control circuit 5 and used for supplying power to the control circuit 5;
the anode of the power supply diode D1 is connected to one end of the auxiliary winding of the transformer T1, the other end of the auxiliary winding of the transformer T1 is connected to the reference ground, and the cathode of the power supply diode D2 is connected to the power supply capacitor C2;
one end of a primary side winding of the transformer T1 is connected with the anode of the capacitor C1, and the other end of the primary side winding is connected with the drain of the power switch tube M1;
one end of the secondary side winding of the transformer T1 is connected with the positive end of an output rectifying diode D2, the other end of the output rectifying diode is connected with one end of an output capacitor C3, and the other end of the secondary side winding of the transformer T1 is connected with the other end of the output capacitor.
Specifically, one end of the auxiliary winding of the transformer T1 is connected to the anode of the power supply diode D1 and one end of the voltage detection resistor Rdet, the cathode of the power supply diode D1 is connected to the power supply capacitor C2, the other end of the voltage detection resistor Rdet is connected to the control circuit 5, and the other end of the auxiliary winding of the transformer T1 is grounded.
Specifically, referring to fig. 2, the control circuit 5 includes a variable gain network, an output state detection circuit, an error amplifier, a mode control circuit, a pulse generator, a slope compensation circuit, a PWM logic circuit, a soft drive circuit, an OCP circuit, and an internal power supply;
the output state detection circuit generates control signals of the variable gain network and the mode control circuit; the variable gain network generates an input signal of the error amplifier and a control signal of the mode control circuit;
the mode control circuit generates a control signal of the pulse generator;
the pulse generator generates an input signal of the slope compensation circuit and an input signal of the PWM logic circuit;
the PWM logic circuit generates an input signal for a soft drive circuit that controls the power switch M1 to turn on and off.
Specifically, referring to fig. 3, the variable gain network includes: the circuit comprises an upper bias resistor R10, a diode D3, a voltage-dividing resistor R11, a voltage-dividing resistor R12, a voltage-dividing resistor R13, a voltage-dividing resistor R14, a switch tube M11, a switch tube M12, a switch tube M13, a switch tube M14, a switch tube M15, a switch tube M16, a switch tube M17, an inverter U1, an inverter U2, an inverter U3, an inverter U7, a NOR logic gate U4, an AND logic gate U5 and an AND logic gate U6.
Specifically, referring to fig. 4, the output state detection circuit includes: the resistor R20, the resistor R21, the resistor R22, the resistor R23 and the resistor R24 are connected in series or in parallel, and R20, R21, R22, R23 and R24 have the same resistor type and the same width, and the lengths of R21, R22, R23 and R24 are all integer multiples of R20 or R21, R22, R23 and R24 are all formed by connecting n R20 in series or in parallel;
the circuit also comprises NMOS switching tubes M21, M22, M24, a PMOS switching tube M23, a capacitor C11, a capacitor C12, Schmitt triggers U11 and U16, an inverter U12, an inverter U15, an AND logic gate U13, an AND logic gate U14, or logic gate U17, current sources Ir0, Ir1, Ir2, Ir3, Ir4 and Ir5, and Ir1, Ir2 and Ir3 are mirror current sources of Ir0, a first comparator, a second comparator, a third comparator and a fourth comparator.
Specifically, referring to fig. 5, 6, and 7, the mode control circuit includes a current synthesis controller including current sources Ir6, Ir7, and Ir8, switches S1, S2, and S3, a current adder, and a V-I control circuit, and an FB voltage detection circuit including fifth and sixth comparators; the negative input terminals of the fifth comparator and the sixth comparator are connected with a terminal 204, and the voltage of the terminal 204 is VFB-VBE(D3)，VFBIs the FB port voltage, VBE(D3)Is the forward voltage drop of diode D3; the positive input terminal of the fifth comparator is connected to the fourth reference voltage, the positive input terminal of the sixth comparator is connected to the fifth reference voltage, and the fourth reference voltage is greater than the fifth reference voltage.
Specifically, one output end of the variable gain network is connected with a negative input end of the error amplifier, and the other output end of the variable gain network is connected with an input end of the mode control circuit; one output end of the output state detection circuit is connected with the input end of the variable gain network, and the other output end of the output state detection circuit is connected with the input end of the mode control circuit;
the output end of the mode control circuit is connected with the input end of a pulse generator, one output end of the pulse generator is connected with the input end of the slope compensation circuit, and the other output end of the pulse generator is connected with the input end of the PWM logic circuit;
one output end of the OCP circuit is connected with the input end of the slope compensation circuit, and the other output end of the OCP circuit is connected with the PWM logic circuit;
the output end of the slope compensation circuit is connected with the positive input end of the error amplifier; the output end of the error amplifier is connected with the input end of the PWM logic circuit; the output end of the PWM logic circuit is connected with the input end of the soft driving circuit, and the output of the soft driving circuit controls the on and off of the power switch tube M1.
The utility model discloses concrete content is as follows during the actual use:
according to the operating principle of the flyback switching power supply, when the primary side power switching tube is turned off, the auxiliary winding voltage Va and the output voltage Vo have correlation, and Va ═ (NA/NS) × (Vo + VF), wherein NA is the number of turns of the auxiliary winding, NS is the number of turns of the secondary side winding, and VF is the forward voltage drop of the secondary rectifier tube, so that the output voltage information can be detected by detecting Va information.
When the primary side power switch tube is turned off, the peak voltage appears on the auxiliary winding due to the existence of leakage inductance of the primary side winding of the transformer and the existence of parasitic parameters. In order to accurately acquire Va information, the Va information is acquired after a small time delay after the primary side power switch tube is turned off.
Referring to fig. 8, in the time period t0t1, the PWM logic circuit output 207 drives the signal to be high, M22 is turned on, the level on the capacitor C11 is discharged to be low through M22, the schmitt trigger U11 outputs to be high, U12 outputs to be low, U13 outputs to be 301 low, U15 outputs to be low, M23 is turned on, the voltage on the capacitor C12 is to be high, the schmitt trigger U16 outputs to be low, and U17 outputs to be 302 high.
At time t1, the output of the U15 is inverted from high to low, the output of the U15 is inverted to high level, the M23 is cut off, the M24 is turned on, the capacitor C12 discharges through the M24 and the current source Ir5, the discharge current is Ir5, the output of the U16 maintains low level, and the output 302 of the U17 is inverted to low level; with the voltage drop across C12 low, at time t2, the U16 output toggles high and the U17 output 302 high.
At time t1, 207 is inverted from high to low, M22 is cut off, and the current source Ir4 starts to charge C11, at which time the schmitt trigger U11 maintains outputting a high level, U12 outputs a high level, and U13 outputs a 301 high level; as the voltage on capacitor C11 rises, at time t3, the U11 output flips to a low level and the U13 output 301 is low.
At time t0-t1, 301 is low, 302 is high, U14 outputs Sample is low, M21 is off; at time t1-t2, 301 is high, 302 is low, U14 outputs Sample low, and M21 is turned off; at time t2t3, 301 is high, 302 is high, U14 outputs Sample high, M21 is on, and the signal is transmitted from DET to the comparator U18, U19, U20, U21 inputs. After time t3, before the primary side power switch tube is turned on in the next switching period, U13 outputs 301 low level, U14 outputs Sample low level, and M21 is turned off.
At times t2-t3, M21 is turned on and the control circuit 5 collects the auxiliary winding voltage Va information via the DET pin. The current Idet flowing through the DET pin is Va/(Rdet + R20), and the voltage V on R20R20Idet R20 Va R20/(Rdet + R20), voltage V on resistor R21R21Voltage V on R20 ═ Ir 1R 21R20And voltage V on R21R21The comparison is performed by a first comparator. Suppose 20<<Rdet, Idet is determined primarily by Rdet. The output state can be detected by comparing the relation between Idet and Ir0 by setting Ir0 × R24 < Ir1 × R21 < Ir2 × R22 < Ir3 × R23, and R21 ═ R20 × n1, R22 ═ R20 × n2, R23 ═ R20 × n3, R24 ═ R20 ═ n4, Ir1 ═ Ir0 × m1, Ir2 ═ Ir0 × m2, and Ir3 ═ Ir0 × m 3.
When n4 Ir0 < Idet < n1 m1 Ir0, the first comparator output 201 and the second comparator output 202 are both at low level, and the output state is at low voltage; when n1 × m1 × Ir0 < Idet < n2 × m2 × Ir0, the first comparator output 201 is at a high level, the second comparator output 202 is at a low level, and the output state is at a medium voltage; when n2 × m3 × Ir0 < Idet < n3 × m3 × Ir0, the first comparator output 201 is at a high level, the second comparator output 202 is at a high level, and the output state is at a high voltage; when det is more than n3 × m3 × Ir0, the output Ovp of the third comparator is at high level, and the output state is overvoltage; when Idet is less than n4 × Ir0, the output Short of the fourth comparator is high level, and the output state is under-voltage or Short circuit.
When 201 and 202 are both low level, M11 and M12 are on, the input gain resistance is (R11+ R14), when 201 is high level and 202 is low level, M11 is off, M12 is on, the input gain resistance is (R11+ R12+ R14), when 201 and 202 are both high level, M11 and M12 are both off, and the input gain resistance is (R11+ R12+ R13+ R14).
When 201 and 202 are both low, S1 and S2 are turned off, and Iosc is Ir 6; when 201 is high and 202 is low, S1 is closed and S2 is open, and Iosc is Ir6+ Ir 7; when both 201 and 202 are high, S1 and S2 are both closed, and Iosc is Ir6+ Ir7+ Ir 8.
When the voltage 204 is greater thanThe fourth reference voltage Vref4, i.e., the FB port voltage VFB＞Vref4+VBE(D3)The fifth and sixth comparator outputs 301, 302 are both low, M13 is on, and the FB signal is transmitted through the variable gain network to the 203 output. Different Iosc are generated according to different states of 201 and 202, the Iosc is output 209 through the V-I control circuit 5 to control the frequency of the pulse generator, at the moment, S3 is disconnected, and the pulse generator works in a fixed frequency mode; the pulse generator outputs the frequency Switch1 when 201, 202 are both low, 2 when 201 is high and 202 is low, and 3 when 201, 202 are both high.
When the 204 voltage is less than the fourth reference voltage Vref4 and greater than the fifth reference voltage Vref5, i.e., the FB port voltage Vref5+ VBE(D3)＜VFB＜Vref4+VBE(D3)The fifth comparator output 301 is high, the sixth comparator output 302 is low, M13 is on, and the voltage at the junction of R11 and R12 is transmitted to the 203 output. Different Iosc are generated according to different states of the 201 and the 202, the Iosc is output 209 through the V-I control circuit 5 to control the frequency of the pulse generator, at the moment, S3 is closed, the voltage 203 has a modulating effect on the Iosc, and the lower the voltage 203 is, the lower the output current 209 is, the pulse generator works in a frequency modulation mode.
When the voltage 204 is less than the fifth reference voltage Vref5, i.e., the FB port voltage VFB＜Vref5+VBE(D3)The fifth comparator output 301 is high, the sixth comparator output 302 is high, M13 is off, M14 is on, and the first reference voltage Vref1, the second reference voltage Vref2, or the third reference voltage Vref3 are transmitted to the 203 output according to the different states of 201, 202. Different Iosc are generated according to different states of the 201 and the 202, the Iosc is output 209 through the V-I control circuit 5 to control the frequency of the pulse generator, at the moment, S3 is closed, the 203 voltage has a modulation effect on the Iosc, and the pulse generator works in a standby mode.
The technical features that the utility model has not been described can be realized through or adopt prior art, and no longer give unnecessary details here, and of course, the above-mentioned explanation is not right the utility model discloses a restriction, the utility model discloses also not only be limited to the above-mentioned example, ordinary skilled person in this technical field is in the utility model discloses a change, modification, interpolation or replacement made in the essential scope also should belong to the utility model discloses a protection scope.
Claims (7)
1. A switching power supply control circuit is characterized by comprising a rectifying circuit for inputting alternating current, a driving circuit connected to the output end of the rectifying circuit, an output filter circuit connected to the output end of the driving circuit, and a feedback circuit connected between the output filter circuit and the driving circuit;
the rectifier circuit comprises a rectifier bridge BR1 for rectifying an input alternating current power supply into direct current and an input capacitor C1 connected to the output end of one bridge arm of the rectifier bridge BR 1;
the driving circuit comprises a transformer T1, a power switch tube M1, a control circuit, a starting resistor R1, a voltage detection resistor Rdet, a current sampling resistor R4, a power supply diode D1 and a power supply capacitor C2;
the output filter circuit comprises an output rectifying diode D2 and an output capacitor C3, wherein the output rectifying diode D2 is connected between the secondary side winding of the transformer T1 and the output capacitor C3;
the feedback circuit includes current-limiting resistor R5, opto-coupler, agreement chip, current-limiting resistor R5 one end is connected the positive end of output electric capacity C3, the one end of opto-coupler input is connected to the current-limiting resistor R5 other end, the one end of agreement chip input is connected to the other end of opto-coupler input, the one end connection control circuit of the output of opto-coupler.
2. The switching power supply control circuit according to claim 1, wherein the transformer T1 includes a transformer primary side winding, a transformer secondary side winding, and a transformer auxiliary winding;
the drain of the power switch tube M1 is connected with one end of the primary side winding of the transformer T1, and the other end of the primary side winding of the transformer T1 is connected with an input capacitor C1; the source terminal of the power switch tube M1 is connected to the resistor R4 and is used for sampling the current in the power switch tube M1;
the starting resistor R1 is connected between the positive end of the input capacitor C1 and the power supply capacitor C2, and the power supply capacitor C2 is also connected with the power supply input end of the control circuit and used for supplying power to the control circuit;
the anode of the power supply diode D1 is connected to one end of the auxiliary winding of the transformer T1, the other end of the auxiliary winding of the transformer T1 is connected to the reference ground, and the cathode of the power supply diode D2 is connected to the power supply capacitor C2;
one end of a primary side winding of the transformer T1 is connected with the anode of the capacitor C1, and the other end of the primary side winding is connected with the drain of the power switch tube M1;
one end of the secondary side winding of the transformer T1 is connected with the positive end of an output rectifying diode D2, the other end of the output rectifying diode is connected with one end of an output capacitor C3, and the other end of the secondary side winding of the transformer T1 is connected with the other end of the output capacitor.
3. The switching power supply control circuit according to claim 1, wherein one end of the auxiliary winding of the transformer T1 is connected to an anode of a power supply diode D1 and one end of the voltage detection resistor Rdet, a cathode of the power supply diode D1 is connected to the power supply capacitor C2, the other end of the voltage detection resistor Rdet is connected to the control circuit, and the other end of the auxiliary winding of the transformer T1 is grounded.
4. The switching power supply control circuit according to claim 1, wherein the control circuit comprises a variable gain network, an output state detection circuit, an error amplifier, a mode control circuit, a pulse generator, a slope compensation circuit, a PWM logic circuit, a soft drive circuit, an OCP circuit, and an internal power supply;
the output state detection circuit generates control signals of the variable gain network and the mode control circuit; the variable gain network generates an input signal of the error amplifier and a control signal of the mode control circuit;
the mode control circuit generates a control signal of the pulse generator;
the pulse generator generates an input signal of the slope compensation circuit and an input signal of the PWM logic circuit;
the PWM logic circuit generates an input signal for a soft drive circuit that controls the power switch M1 to turn on and off.
5. The switching power supply control circuit according to claim 4, wherein the output state detection circuit comprises: the resistor R20, the resistor R21, the resistor R22, the resistor R23 and the resistor R24 are connected in series or in parallel, and R20, R21, R22, R23 and R24 have the same resistor type and the same width, and the lengths of R21, R22, R23 and R24 are all integer multiples of R20 or R21, R22, R23 and R24 are all formed by connecting n R20 in series or in parallel;
the circuit also comprises NMOS switching tubes M21, M22, M24, a PMOS switching tube M23, a capacitor C11, a capacitor C12, Schmitt triggers U11 and U16, an inverter U12, an inverter U15, an AND logic gate U13, an AND logic gate U14, or logic gate U17, current sources Ir0, Ir1, Ir2, Ir3, Ir4 and Ir5, and Ir1, Ir2 and Ir3 are mirror current sources of Ir0, a first comparator, a second comparator, a third comparator and a fourth comparator.
6. The switching power supply control circuit according to claim 4, wherein the mode control circuit includes a current synthesis controller including current sources Ir6, Ir7 and Ir8, switches S1, S2 and S3, a current adder, a V-I control circuit, and an FB voltage detection circuit including a fifth comparator and a sixth comparator;
the negative input terminals of the fifth comparator and the sixth comparator are connected with a terminal 204, and the voltage of the terminal 204 is VFB-VBE(D3),VFBIs the FB port voltage, VBE(D3)Is the forward voltage drop of diode D3; the positive input terminal of the fifth comparator is connected to a fourth reference voltage, the positive input terminal of the sixth comparator is connected to a fifth reference voltage, and the fourth reference voltage is greater than the fifth reference voltage.
7. The switching power supply control circuit according to claim 4, wherein one output terminal of the variable gain network is connected to the negative input terminal of the error amplifier, and the other output terminal is connected to the input terminal of the mode control circuit; one output end of the output state detection circuit is connected with the input end of the variable gain network, and the other output end of the output state detection circuit is connected with the input end of the mode control circuit;
the output end of the mode control circuit is connected with the input end of a pulse generator, one output end of the pulse generator is connected with the input end of the slope compensation circuit, and the other output end of the pulse generator is connected with the input end of the PWM logic circuit;
one output end of the OCP circuit is connected with the input end of the slope compensation circuit, and the other output end of the OCP circuit is connected with the PWM logic circuit;
the output end of the slope compensation circuit is connected with the positive input end of the error amplifier; the output end of the error amplifier is connected with the input end of the PWM logic circuit; the output end of the PWM logic circuit is connected with the input end of the soft driving circuit, and the output of the soft driving circuit controls the on and off of the power switch tube M1.
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| CN201921312737.1U CN210137278U (en) | 2019-08-13 | 2019-08-13 | Switching power supply control circuit |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110365218A (en) * | 2019-08-13 | 2019-10-22 | 无锡博通微电子技术有限公司 | A kind of PWM switching power source control circuit and method with automatic adjusument |
| CN112524655A (en) * | 2020-12-08 | 2021-03-19 | 珠海格力电器股份有限公司 | Magnetic field control circuit, ion flame control method and device and plasma cooker |
| CN115864858A (en) * | 2023-03-01 | 2023-03-28 | 恩赛半导体(成都)有限公司 | Auxiliary power supply, power supply system and electronic device |
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2019
- 2019-08-13 CN CN201921312737.1U patent/CN210137278U/en active Active
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110365218A (en) * | 2019-08-13 | 2019-10-22 | 无锡博通微电子技术有限公司 | A kind of PWM switching power source control circuit and method with automatic adjusument |
| CN110365218B (en) * | 2019-08-13 | 2024-04-02 | 无锡博通微电子技术有限公司 | PWM switching power supply control circuit and method with self-adaptive adjustment |
| CN112524655A (en) * | 2020-12-08 | 2021-03-19 | 珠海格力电器股份有限公司 | Magnetic field control circuit, ion flame control method and device and plasma cooker |
| CN115864858A (en) * | 2023-03-01 | 2023-03-28 | 恩赛半导体(成都)有限公司 | Auxiliary power supply, power supply system and electronic device |
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