CN113972629B - ACDC converter and management chip thereof - Google Patents

ACDC converter and management chip thereof Download PDF

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Publication number
CN113972629B
CN113972629B CN202111311057.XA CN202111311057A CN113972629B CN 113972629 B CN113972629 B CN 113972629B CN 202111311057 A CN202111311057 A CN 202111311057A CN 113972629 B CN113972629 B CN 113972629B
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voltage
circuit
chip
current
signal
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CN113972629A (en
Inventor
吴智星
农荣真
谭天华
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Shenzhen Zhuoxin Micro Technology Co ltd
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Shenzhen Zhuoxin Micro Technology Co ltd
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Classifications

    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
    • H02H7/00—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions
    • H02H7/10—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for converters; for rectifiers
    • H02H7/12—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for converters; for rectifiers for static converters or rectifiers
    • H02H7/125—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for converters; for rectifiers for static converters or rectifiers for rectifiers
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
    • H02H3/00—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection
    • H02H3/20—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to excess voltage
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
    • H02H5/00—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal non-electric working conditions with or without subsequent reconnection
    • H02H5/04—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal non-electric working conditions with or without subsequent reconnection responsive to abnormal temperature
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
    • H02H7/00—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions
    • H02H7/008—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for protective arrangements according to this subclass
    • 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
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M7/00—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
    • H02M7/02—Conversion of ac power input into dc power output without possibility of reversal
    • H02M7/04—Conversion of ac power input into dc power output without possibility of reversal by static converters
    • H02M7/12—Conversion of ac power input into dc power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
    • H02M7/21—Conversion of ac power input into dc power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
    • H02M7/217—Conversion of ac power input into dc power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only
    • 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)
  • Inverter Devices (AREA)
  • Dc-Dc Converters (AREA)

Abstract

The invention discloses an ACDC converter and a management chip thereof, which comprises a reference generation module, a constant voltage control module, a constant current control module and a logic control module, wherein a high-voltage stabilizer circuit is used for receiving the high voltage of a VDD pin of a chip and converting the high voltage into an internal preset power voltage, providing a stable low-voltage power supply for a low-voltage module in the chip, the reference voltage source circuit is used for generating a reference voltage with a high power supply rejection ratio and a temperature coefficient close to zero at room temperature and providing a reference level for the voltage of an internal circuit of the chip, the reference current source circuit is used for providing a reliable current reference for the internal circuit of the chip, an overvoltage protection circuit is used for determining the minimum working voltage and the maximum switching-off voltage of the chip, and the logic control module judges the current load condition according to sampling signals of all ports, selects the required constant voltage or constant current switching-on or switching-off signals and generates driving signals of a power tube so as to maintain the output voltage or current constant.

Description

ACDC converter and management chip thereof
Technical Field
The invention belongs to the technical field of power management, and particularly relates to an ACDC converter and a management chip thereof.
Background
Nowadays, the power electronic technology becomes an indispensable part of society, electronic equipment is not separated from a power supply, and a switching power supply has the characteristics of small size, high efficiency, light weight, insensitivity to power grid stirring and the like, and is widely applied to household electronic equipment and communication equipment. Switching power supplies can be divided into ACDC and DCDC, the design technology and sound field technology of a DCDC converter are mature at home and abroad, modularization and standardization are realized, and consistent acceptance of users is obtained. However, ACDC converters present some difficulties in achieving modularity due to technical and process manufacturing issues.
The ACDC converter converts alternating current into direct current, because the input of the ACDC converter is 50/60Hz alternating current, the corresponding power consumption is larger and larger, new requirements are put forward on the conversion efficiency and the power consumption of the power supply, the power supply is supplied by using a linear power supply, the linear power supply is simple in structure, good in stability and good in noise resistance, a large amount of heat is generated by an adjusting tube when the linear stabilized power supply works, the efficiency is low and the loss is serious, the linear stabilized power supply generally needs to use an industrial frequency transformer, and the radiating fin of the adjusting tube is added, so that the linear stabilized power supply is huge in volume, and the power supply efficiency is reduced.
Disclosure of Invention
In view of the above, the present invention provides an ACDC converter and a management chip thereof that can improve overvoltage and over-temperature protection and reduce switching loss, so as to solve the above technical problems.
In a first aspect, the invention provides an ACDC converter, which comprises a reference generating module, a constant voltage control module, a constant current control module and a logic control module, wherein the reference generating module, the constant voltage control module and the constant current control module are connected with the logic control module;
the reference generating module comprises a high-voltage regulator circuit, a reference voltage source circuit, a reference current source circuit and an overvoltage protection circuit, wherein the high-voltage regulator circuit is used for receiving the high voltage of a VDD pin of a chip and converting the high voltage into an internal preset power voltage, providing stable low-voltage power for all low-voltage modules in the chip, the reference voltage source circuit is used for generating a reference voltage with a high power supply rejection ratio and a temperature coefficient close to zero at room temperature and providing a reference level for the voltage of the circuit in the chip, the reference current source circuit is used for providing a reliable current reference for the circuit in the chip, and the overvoltage protection circuit is used for determining a protection circuit of the minimum working voltage and the maximum turn-off voltage of the chip;
the constant voltage control module comprises a constant voltage start signal and a constant voltage turn-off signal control loop, the constant voltage start signal control loop samples output voltage and forms an error amplifier with fixed gain through an FB sampling circuit, an error amplifier and a negative feedback resistor, the FB sampling voltage is connected to an inverting input end of the error amplifier through the resistor, and a non-inverting input end of the error amplifier is connected with a preset reference voltage; the output voltage of the error amplifier is sent to a first comparator and used for generating a starting signal of the power tube, and the output voltage signal is sent to an overvoltage protection circuit after being processed by a resistor voltage division and a filter so as to generate a switching-off signal of the power tube in a constant voltage mode;
the constant current control module is used for generating a constant current on signal and a constant current off signal, the current sampling signal is compared with a reference voltage crossing to an operational amplifier through the CS sampling circuit, the current sampling signal is scaled according to a preset proportion through the buffer and then is sent to the second comparator, and the second comparator generates a corresponding constant current off signal according to the comparison between the output of the front-stage circuit and the corresponding reference voltage; the switching tube completes switching conversion when the voltage crosses zero by adopting a valley conduction mode so as to realize valley conduction and generate a corresponding constant current starting signal;
the logic control module judges the current load condition according to the sampling signals of all ports, selects the required constant voltage or constant current on or off signals, and generates the driving signals of the power tube so as to maintain the output voltage or current constant.
As a further improvement of the technical scheme, the overvoltage protection circuit is connected with a load, when the voltage acquired by the FB sampling circuit is larger than the preset power supply voltage, the voltage division of the FB pin is detected through the negative input end of the error amplifier, and the first comparator outputs a low level.
As a further improvement of the above technical solution, the valley conduction mode includes that when the switching tube is turned off, the energy of the auxiliary winding with the round edge is completely converted to the secondary winding, the auxiliary winding and the drain electrode of the switching tube are two identical-name ends, voltage sampling is performed on the auxiliary winding and the drain electrode of the switching tube through a VS pin, and the auxiliary winding and the drain electrode of the switching tube are compared with the preset reference voltage, and when the output of the second comparator is at a high level, the ACDC converter enters the valley conduction mode.
As a further improvement of the above technical solution, the ACDC converter further includes:
soft startThe dynamic module is connected with the logic control module, performs pulse input after clock frequency eight-division at the CLK input end, and starts the M3 tube for a period of time within each eight clock cycles, I A The current charges the C1 capacitor through the current mirror, and the current passes through the comparison circuit of M7 and M8 and V CS When the input of the pins is compared, when V CS When the voltage on the C1 is exceeded, M11 is turned on, the output of the SS end becomes low, the switching tube is turned off, the reset tube M4 clears the voltage on the two ends of the C1 after the circuit is turned off, and the starting module works normally.
As a further improvement of the above technical solution, the ACDC converter further includes:
and the blanking module is connected with the logic control module, the GATE of the blanking module is used for controlling a driving signal for starting the switching tube, the driving signal is input to the R end of the RS trigger through two inverters, when the voltages input by the enable signal EN and the GATE are high, the XQ end of the RS trigger is arranged at one end, the M3 tube is started, a current mirror formed by M1 and M2 starts to charge the C1 capacitor, when the charge on the C1 reaches a certain degree, the input end of the Schmitt trigger is input high and output high, and LEB signals are output together through the two inverters and the GATE signal from low to high.
In a second aspect, the invention also provides a management chip of the ACDC converter, which comprises the ACDC converter, a power supply module and an over-temperature protection module which are sequentially connected;
the power supply module comprises a starting circuit and a power-on reset circuit, wherein the starting circuit monitors VCC in real time, the starting circuit generates a reference voltage OUT after the VCC reaches a starting voltage, the OUT voltage generates a reference voltage VREF, and when the VDD voltage of an internal power supply reaches the voltage requirement required by the chip, the power-on reset circuit generates a reset signal to enable all circuit modules in the chip to start working; when the VCC voltage is under-voltage, the starting circuit does not generate OUT voltage, and the chip stops working at VCC; when a preset protection condition is triggered, the over-temperature protection module generates a protection signal;
the starting circuit comprises a starting resistor, a plurality of switching tubes, a JFET tube and a Schottky diode, when the system starts to be powered on, high-voltage connection generates a power-on completion identification signal to output a low levelThe M2 tube is controlled to be turned off, the grid level of the JFET tube is slowly increased, the JFET tube is turned on, and the high voltage level is supplied to the voltage stabilizing capacitor C through the JFET tube and the Schottky diode D1 vdd Charging; after the capacitor voltage reaches the rated voltage, the inside of the chip starts to work normally; when the M2 tube is kept in an on state, the JFET tube is turned off, and partial current flows through the starting resistor;
the over-temperature protection module comprises three PTAT currents which are proportional to absolute temperature and come from a reference generation module of the ACDC converter, a trigger, three inverters and two resistors with positive temperature coefficients, when the working temperature of a chip is lower than a preset temperature, the voltage of a node C is lower than the on threshold voltage of a switching tube Q1, and the switching tube Q1 is cut off; the level of the node A is high, and the low level is output by the OTP at the output end after passing through the inverter; base-emitter voltage V of Q1 when chip temperature rises BE Decreasing, PTAT current increases, and the resistance of resistors R1 and R2 also increases; when the temperature of the chip reaches the preset temperature, the voltage of the node C is higher than the conduction threshold voltage of the switching tube Q1, the switching tube Q1 is conducted, the voltage of the node A is pulled down, and the output end OTP correspondingly outputs high level.
The invention provides an ACDC converter and a management chip thereof, which have the following beneficial effects compared with the prior art:
through connecting reference generation module, constant voltage control module, constant current control module and logic control module, the high voltage regulator circuit in the reference generation module can be with the input high voltage conversion preset power supply voltage, can reduce circuit overvoltage shock, and the protection of instantaneous voltage is produced to the chip during operation can be ensured to overvoltage protection circuit, and constant temperature control module and constant current control module can provide stable voltage or current output for the load, and first comparator and second comparator be PWM, can provide two kinds of different operating modes to improve ACDC converter's job stabilization nature. The valley conduction mode, the soft start module and the blanking module are added into the circuit, so that switching loss and interference can be reduced, normal operation inside the chip is ensured, and when the working temperature of the chip exceeds the preset temperature, the over-temperature protection module changes the switching of the switching tube, thereby reducing the voltage in the circuit and preventing damage caused by frequent turn-off of the circuit in the chip due to thermal shock.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings that are needed in the embodiments will be briefly described below, it being understood that the following drawings only illustrate some embodiments of the present invention and therefore should not be considered as limiting the scope, and other related drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
Fig. 1 is a block diagram of an ACDC converter according to an embodiment of the present invention;
fig. 2 is a circuit diagram of an ACDC converter according to an embodiment of the present invention;
FIG. 3 is a circuit diagram of an overvoltage protection circuit according to an embodiment of the present invention;
fig. 4 is a circuit diagram of a valley conduction mode according to an embodiment of the present invention;
FIG. 5 is a circuit diagram of a soft start module according to an embodiment of the present invention;
fig. 6 is a circuit diagram of a blanking module according to an embodiment of the present invention;
fig. 7 is a block diagram of a management chip of an ACDC converter according to an embodiment of the present invention.
The main reference numerals are as follows:
a 100-ACDC converter; 110-a reference generation module; 120-a high voltage regulator circuit; 130-a reference voltage source circuit; 140-a reference current source circuit; 150-an overvoltage protection circuit; 160-a constant voltage control module; 170-FB sampling circuit; 180-error amplifier; 190-negative feedback resistance; 200-a first comparator; 210-a second comparator; 220-a constant current control module; 230-CS sampling circuit; 240-a logic control module; 250-soft start module; 260-a blanking module; 270-a power supply module; 280-a start-up circuit; 290-a power-on reset circuit; 300-over temperature protection module.
Detailed Description
Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to like or similar elements or elements having like or similar functions throughout. The embodiments described below by referring to the drawings are illustrative only and are not to be construed as limiting the invention.
It will be understood that when an element is referred to as being "fixed to" another element, it can be directly on the other element or intervening elements may also be present. When an element is referred to as being "connected" to another element, it can be directly connected to the other element or intervening elements may also be present. In contrast, when an element is referred to as being "directly on" another element, there are no intervening elements present. The terms "vertical," "horizontal," "left," "right," and the like are used herein for illustrative purposes only.
In the present invention, unless explicitly specified and limited otherwise, the terms "mounted," "connected," "secured," and the like are to be construed broadly, and may be, for example, fixedly connected, detachably connected, or integrally formed; can be mechanically or electrically connected; can be directly connected or indirectly connected through an intermediate medium, and can be communicated with the inside of two elements or the interaction relationship of the two elements. The specific meaning of the above terms in the present invention can be understood by those of ordinary skill in the art according to the specific circumstances.
Referring to fig. 1 and 2, the present invention provides an ACDC converter 100, including a reference generating module 110, a constant voltage control module 160, a constant current control module 220, and a logic control module 240, where the reference generating module 110, the constant voltage control module 160, and the constant current control module 220 are connected to the logic control module 240;
the reference generating module 110 includes a high voltage regulator circuit 120, a reference voltage source circuit 130, a reference current source circuit 140 and an overvoltage protection circuit 150, wherein the high voltage regulator circuit 120 is used for receiving the high voltage of the VDD pin of the chip and converting the high voltage into an internal preset power voltage, providing a stable low voltage power supply for all low voltage modules in the chip, the reference voltage source circuit 130 is used for generating a reference voltage with a high power supply rejection ratio and a temperature coefficient close to zero at room temperature and providing a reference level for the circuit voltage in the chip, the reference current source circuit 140 is used for providing a reliable current reference for the circuit in the chip, and the overvoltage protection circuit 150 is used for determining a protection circuit of the minimum working voltage and the maximum turn-off voltage of the chip;
the constant voltage control module 160 includes a constant voltage on signal and a constant voltage off signal control loop, the constant voltage on signal control loop samples the output voltage and forms an error amplifier 180 with fixed gain through an FB sampling circuit 170, an error amplifier 180 and a negative feedback resistor 190, the FB sampling voltage is connected to an inverting input terminal of the error amplifier 180 through a resistor, and a non-inverting input terminal of the error amplifier 180 is connected to a preset reference voltage; the output voltage of the error amplifier 180 is sent to the first comparator 200 for generating a power tube turn-on signal, and the output voltage signal is sent to the overvoltage protection circuit 150 after being processed by resistor voltage division and a filter to generate a power tube turn-off signal in a constant voltage mode;
the constant current control module 220 is configured to generate a constant current on signal and a constant current off signal, compare the current sampling signal with a reference voltage across the operational amplifier through the CS sampling circuit 230, perform scaling in a preset ratio through the buffer, and send the scaled current to the second comparator 210, where the second comparator 210 generates a corresponding constant current off signal according to the comparison between the output of the front stage circuit and the corresponding reference voltage; the switching tube completes switching conversion when the voltage crosses zero by adopting a valley conduction mode so as to realize valley conduction and generate a corresponding constant current starting signal;
the logic control module 240 determines the current load condition according to the sampling signals of the ports, selects a required constant voltage or constant current on or off signal, and generates a driving signal of the power tube to maintain the output voltage or current constant.
In this embodiment, the basic control types of the switching power supply are divided into a voltage control type and a current control type, and the corresponding control types can be selected according to different application occasions. The high-voltage regulator circuit receives high voltage such as 7.6V to 26.2V from a VDD pin of a chip, converts the high voltage into internal 5V power supply voltage, an inverting amplifier with 40 times fixed gain is formed by an error amplifier EA and a negative feedback resistor in a constant voltage loop, the non-inverting input end of the error amplifier is connected with 2.5V reference voltage, the output voltage of the error amplifier is sent to a first comparator, namely a PWM comparator, and is used for generating an ON signal CV_ON of a power tube, and a Vcomp signal is sent to CV_OCP after resistor voltage division and filtering treatment and is used for generating an OFF signal CV_OFF of the power tube in a constant voltage mode. In the constant voltage control loop, the output voltage is sampled and passed through a sample-and-hold circuit, and compared with a preset reference voltage, such as 2.5v, and then the difference between the two is amplified by an error amplifier EA, and the switching frequency and the current limiting point are respectively regulated by an error amplification signal Vcomp through two paths. The identification signal of the system entering the constant voltage working mode is that the output of the PWM comparator is changed from 1 to 0, namely when the system works under the condition of output overcurrent to output low voltage, the feedback input pin FB voltage is lower than 2.5v, the first comparator outputs high level, and the system is controlled by the constant current loop. Along with the gradual load reduction, under the medium load or light load or no load condition within the current limiting point, the output voltage gradually rises, the feedback input pin FB voltage is higher than 2.5v, the first comparator outputs a low level, and the system is controlled by the constant current loop to enter a working state controlled by the constant voltage loop.
It should be noted that, the error amplifier compares the FB sampling voltage with the 2.5V reference voltage, and outputs a voltage signal Vcomp capable of reflecting the load condition, and the circuit module generates a series of control signals, such as a power tube on signal, a power tube off signal, and the like, according to the voltage. When the FB sample voltage is lower than 2.4375, the EA output voltage Vcomp is 5v, when the FB sample voltage is higher than 2.5625v, the Vcomp voltage is 0v, when the FB sample voltage increases, the Vcomp voltage correspondingly decreases, and when the FB sample voltage decreases, the Vcomp voltage correspondingly increases. Under the normal working condition of the chip, internal propagation delay exists, an actual current limiting point changes along with the voltage of an input line, and when the voltage of the input line is low, such as 85vAC, the actual current limiting point is low; when the input line voltage is high, such as 265vAC, the actual current limiting point is high; when the constant current operation is performed, the output current is inconsistent, namely the output current is small when 85vAC is input, and the output current is large when 265vAC is input; or the maximum output power of the system is inconsistent in constant voltage operation, and is small in 85vAC input and large in 265vAC input, namely a line voltage compensation circuit is needed. The ACDC converter in this embodiment does not need an outer loop compensation capacitor, and can work in DCM and QR modes, so that the constant current precision is controlled within ±3%, and the constant voltage precision is controlled within ±5%. When the system outputs constant voltage or constant current, the constant voltage and constant current state can not work simultaneously, and when the load changes, the constant voltage and constant current mode is switched according to the load requirement. In a charger application, an uncharged battery is charged first in a constant current state, and when the battery is about to be fully charged, the charging phase is switched to a constant voltage mode. In power adapter applications, the system typically operates only in a constant voltage state. Under the constant-current mode, the system limits the output current, no matter how the output voltage is reduced, the system ensures the output current to be constant, and under the constant-voltage mode, the system regulates the output voltage through primary sampling, so that the working stability of the ACDC converter is improved.
Optionally, the overvoltage protection circuit is connected with a load, when the voltage collected by the FB sampling circuit is greater than a preset power supply voltage, the voltage division of the FB pin is detected through the negative input end of the error amplifier, and the first comparator outputs a low level.
Referring to fig. 3, in this embodiment, when the overvoltage protection circuit detects that the input voltage of the VDD pin exceeds 26.2v, the module drives the logic control module to send a high level, controls the external power tube to be turned off, and the chip stops working, so that the working reliability of the ACDC converter can be improved to a certain extent.
Optionally, the valley conduction mode includes that when the switching tube is turned off, the energy of the auxiliary winding with the round edge is completely converted to the secondary winding, the auxiliary winding and the drain electrode of the switching tube are two identical-name ends, voltage sampling is performed on the auxiliary winding and the drain electrode of the switching tube through a VS pin, and the auxiliary winding and the drain electrode of the switching tube are compared with the preset reference voltage, and when the output of the second comparator is at a high level, the ACDC converter enters the valley conduction mode.
Referring to fig. 4, in this embodiment, valley conduction is a conduction mode, also referred to as quasi-resonant mode, during the on and off processes of the switching tube, the switching power supply will lose a certain amount of energy, and this part of energy accounts for a large part of the total loss, and by detecting the minimum value of the drain voltage of the switching tube, when it is at the lowest point, it is turned on, and when the spike caused by parasitic capacitance is least obvious, it can turn on the switch, so that the efficiency and stability of the chip are greatly improved. The number of windings of the transformer and the size of the generated resonance voltage are used as the reference in actual use, valley conduction is carried out at the tail end of each period, the time of each period is limited, the energy stored in the capacitor cannot be completely released, and the anti-interference performance and stability of the chip can be optimized to a great extent.
Optionally, the ACDC converter further includes:
the soft start module 250 is connected with the logic control module 240, and performs pulse input with clock frequency divided by eight at the CLK input end, and the M3 pipe is opened for a period of time in each eight clock cycles, I A The current charges the C1 capacitor through the current mirror, and the current passes through the comparison circuit of M7 and M8 and V CS When the input of the pins is compared, when V CS When the voltage on the C1 is exceeded, M11 is turned on, the output of the SS end becomes low, the switching tube is turned off, the reset tube M4 clears the voltage on the two ends of the C1 after the circuit is turned off, and the starting module works normally.
Referring to fig. 5, in this embodiment, the function of the soft start module 250 is that when the chip is started, the output voltage rises gradually, and the switching tube is controlled by gradually lifting the overcurrent limiting threshold and the sampling voltage of the current, so that the starting speed is relatively stable, the influence on the power grid is small, the service life of the chip can be prolonged, and the load loss is reduced. Pulse input after clock frequency eight division is carried out at the CLK input end, the frequency division circuit is realized by adopting a common D trigger, and an M3 tube is started for a period of time every eight clock cycles, at the moment, I A The current charges the C1 capacitor through the current mirror, but the charging time of each time is shorter, and the voltage at the two ends of the C1 can not reach V DD Voltage through comparison circuit of M7 and M8 and V CS When the input of the pins is compared, when V CS The voltage exceeding C1 will turn on M11, the output of SS terminal will become low, the switch tube will be forced to turn offThe voltage of the load circuit does not reach a very high level directly. After several cycles, the voltage on C1 reaches a maximum, the soft start module will not function, V CS The size of the soft start module is not influenced, after the circuit is closed, the voltage at the two ends of the C1 needs to be cleared by the reset tube M4, and when the chip is started for the next time, the soft start module works normally.
Optionally, the ACDC converter further includes:
and a blanking module 260 connected to the logic control module 240, wherein the GATE of the blanking module 260 is used for controlling the on-off driving signal of the switching tube, the driving signal is input to the R end of the RS trigger through two inverters, when the voltages of the enable signal EN and the GATE input are high, the XQ end of the RS trigger is set to be one, the M3 tube is opened, the current mirror formed by M1 and M2 starts to charge the C1 capacitor, when the charge on the C1 reaches a certain degree, the input end of the schmitt trigger is input to be high and output to be high, and the LEB signal is output from low to high through the two inverters and the GATE signal.
Referring to fig. 6, in this embodiment, the blanking module 260 can reduce the interference of spike signals in the circuit to the internal logic, when the switching tube is turned on and turned off, the voltage change is relatively large, the parasitic capacitance exists in the switching tube to generate spike current signals, after passing through the inductor current detection resistor, the voltage can fluctuate in a short time, if the inaccurate voltage is maintained, the primary current detection can be affected, so that the switching tube cannot work normally, a circuit is required to shield the unstable signal, the signal existence time is relatively short, and the shielding of the blanking module 260 to the signal can not affect the normal work of the rest parts. The GATE is a driving signal for controlling the switch tube to be turned on, the driving signal is input to the R end of the RS trigger through two inverters, when the enable signal EN is high and the voltage of the GATE input is high, the M3 tube is turned on at the moment, a current mirror formed by M1 and M2 starts to charge the C1 capacitor, the charging current is equal to 1A, when the charging on the C1 reaches a certain degree, the input end of the Schmitt trigger is input high and the output is also high, and then the L signal is input into an AND GATE together with the GATE signal after passing through the two inverters, and the output LEB signal is changed from low to high. The signal input of the GATE and the signal output of the LEB have a time difference, which can play a role of leading edge blanking, the time is determined by a plurality of delay devices and the charging time of the capacitor C1, the width of the LEB can be adjusted by adjusting the charging current of the capacitor, and the delay time takes a value of 260ns.
Referring to fig. 7, the present invention further provides a management chip of an ACDC converter, including an ACDC converter 100, a power supply module 270, and an over-temperature protection module 300, which are sequentially connected;
the power supply module 270 includes a start circuit 280 and a power-on reset circuit 290, wherein the start circuit 280 monitors VCC in real time and generates a reference voltage OUT when VCC reaches a start voltage, and then generates a reference voltage VREF from the OUT voltage, and when the VDD voltage of the internal power supply reaches the voltage requirement required by the chip, the power-on reset circuit generates a reset signal to enable all circuit modules in the chip to start working; when the VCC voltage is under-voltage, the starting circuit does not generate OUT voltage, and the chip stops working at VCC; when a preset protection condition is triggered, the over-temperature protection module generates a protection signal;
the starting circuit 280 comprises a starting resistor, a plurality of switching tubes, a JFET tube and a Schottky diode, when the system starts to be electrified, high-voltage connection generates an electrification completion identification signal to output a low level, the M2 tube is controlled to be turned off, the grid level of the JFET tube is slowly increased, the JFET tube is turned on, and the high-voltage level charges the voltage stabilizing capacitor Cvdd through the JFET tube and the Schottky diode D1; after the capacitor voltage reaches the rated voltage, the inside of the chip starts to work normally; when the M2 tube is kept in an on state, the JFET tube is turned off, and partial current flows through the starting resistor;
the over-temperature protection module 300 includes three PTAT currents, a trigger, three inverters, and two resistors with positive temperature coefficients, which are proportional to absolute temperature, from the reference generation module of the ACDC converter, and when the chip operating temperature is lower than a preset temperature, the voltage of the node C is lower than the on threshold voltage of the switching tube Q1, and the switching tube Q1 is turned off; the level of the node A is high, and the low level is output by the OTP at the output end after passing through the inverter; base-emitter voltage V of Q1 when chip temperature rises BE Decreasing PTAT current, increasing resistance of resistors R1 and R2Also rise; when the temperature of the chip reaches the preset temperature, the voltage of the node C is higher than the conduction threshold voltage of the switching tube Q1, the switching tube Q1 is conducted, the voltage of the node A is pulled down, and the output end OTP correspondingly outputs high level.
In the embodiment, constant voltage and constant current output is realized by combining primary side feedback and secondary side feedback, and the modules such as valley conduction, blanking and soft start are added, so that the efficiency of the chip is improved. The modulation mode of the switching power supply chip comprises a pulse width modulation mode PWM, a pulse modulation mode PFM and a working mode of mixing the pulse modulation mode PFM and the pulse modulation mode PFM, wherein the PWM fixes the working period of the system and only adjusts the on time of a switching tube to control and output, the PWM modulation module generally comprises an oscillator, a comparator, an error amplifier, a reference voltage generation module and the like, the voltage fed back is compared and amplified with the reference voltage, the signal is input into the comparator with triangular wave to be compared, when the error signal is larger than the triangular wave, a PWM signal is output, when the triangular wave is larger than the error signal, a low level is output, and if the feedback signal is lower at the moment, the error amplification signal is higher, so that the pulse of the output PWM signal is widened, the transmitted power is increased, the output voltage is increased, and the purpose of constant voltage is achieved. The rectifier diode with forward bias on the secondary side exists, the FB voltage fed back by the auxiliary winding can be affected by temperature to enable the sampling voltage to be inaccurate, and the voltage related to the temperature coefficient of the secondary side diode is used as the reference voltage, so that the temperature drift effect of the voltage drop of the secondary side conduction diode can be counteracted.
The invention provides an ACDC converter and a management chip thereof, which are characterized in that a reference generating module, a constant voltage control module, a constant current control module and a logic control module are connected, a high-voltage regulator circuit in the reference generating module can convert input high voltage into preset power supply voltage, overvoltage impact of the circuit can be reduced, an overvoltage protection circuit can ensure that instantaneous voltage is generated when the chip works, the constant temperature control module and the constant current control module can provide stable voltage or current output for a load, a first comparator and a second comparator are PWM, and two different working modes can be provided to improve the working stability of the ACDC converter. The valley conduction mode, the soft start module and the blanking module are added into the circuit, so that switching loss and interference can be reduced, normal operation inside the chip is ensured, and when the working temperature of the chip exceeds the preset temperature, the over-temperature protection module changes the switching of the switching tube, thereby reducing the voltage in the circuit and preventing damage caused by frequent turn-off of the circuit in the chip due to thermal shock.
Any particular values in all examples shown and described herein are to be construed as merely illustrative and not a limitation, and thus other examples of exemplary embodiments may have different values.
It should be noted that: like reference numerals and letters denote like items in the following figures, and thus once an item is defined in one figure, no further definition or explanation thereof is necessary in the following figures.
The above examples merely represent a few embodiments of the present invention, which are described in more detail and are not to be construed as limiting the scope of the present invention. It should be noted that it will be apparent to those skilled in the art that several variations and modifications can be made without departing from the spirit of the invention, which are all within the scope of the invention.

Claims (5)

1. The ACDC converter is characterized by comprising a reference generation module, a constant voltage control module, a constant current control module and a logic control module, wherein the reference generation module, the constant voltage control module and the constant current control module are connected with the logic control module;
the reference generating module comprises a high-voltage regulator circuit, a reference voltage source circuit, a reference current source circuit and an overvoltage protection circuit, wherein the high-voltage regulator circuit is used for receiving the high voltage of a VDD pin of a chip and converting the high voltage into an internal preset power voltage, providing stable low-voltage power for all low-voltage modules in the chip, the reference voltage source circuit is used for generating a reference voltage with a high power supply rejection ratio and a temperature coefficient close to zero at room temperature and providing a reference level for the voltage of the circuit in the chip, the reference current source circuit is used for providing a reliable current reference for the circuit in the chip, and the overvoltage protection circuit is used for determining a protection circuit of the minimum working voltage and the maximum turn-off voltage of the chip;
the constant voltage control module comprises a constant voltage start signal and a constant voltage turn-off signal control loop, the constant voltage start signal control loop samples output voltage and forms an error amplifier with fixed gain through an FB sampling circuit, an error amplifier and a negative feedback resistor, the FB sampling voltage is connected to an inverting input end of the error amplifier through the resistor, and a non-inverting input end of the error amplifier is connected with a preset reference voltage; the output voltage of the error amplifier is sent to a first comparator and used for generating a starting signal of the power tube, and the output voltage signal is sent to an overvoltage protection circuit after being processed by a resistor voltage division and a filter so as to generate a switching-off signal of the power tube in a constant voltage mode;
the constant current control module is used for generating a constant current on signal and a constant current off signal, the current sampling signal is compared with a reference voltage crossing to an operational amplifier through the CS sampling circuit, the current sampling signal is scaled according to a preset proportion through the buffer and then is sent to the second comparator, and the second comparator generates a corresponding constant current off signal according to the comparison between the output of the front-stage circuit and the corresponding reference voltage; the switching tube completes switching conversion when the voltage crosses zero by adopting a valley conduction mode so as to realize valley conduction and generate a corresponding constant current starting signal;
the logic control module judges the current load condition according to the sampling signals of all ports, selects the required constant voltage or constant current on or off signals, and generates a driving signal of the power tube so as to maintain the output voltage or current constant;
the soft start module is connected with the logic control module, pulse input is carried out after clock frequency is divided by eight at the CLK input end, the M3 tube is started for a period of time in each eight clock periods, IA current charges the C1 capacitor through the current mirror, when the input of the comparison circuit of M7 and M8 and the VCS pin is compared, when VCS exceeds the voltage on the C1, the M11 is started, the output of the SS end is lowered to enable the switching tube to be closed, the reset tube M4 clears the voltage at the two ends of the C1 after the circuit is closed, and the start module works normally.
2. The ACDC converter of claim 1 wherein the overvoltage protection circuit is connected to a load, and when the voltage collected by the FB sampling circuit is greater than a preset supply voltage, the divided voltage of the FB pin is detected through the negative input of the error amplifier, and the first comparator outputs a low level.
3. The ACDC converter of claim 1 wherein the valley conduction mode includes switching all energy of the auxiliary winding to the secondary winding at the rounded edge after the switching tube is turned off, the auxiliary winding being at two identical ends to the switching tube drain, voltage sampling it via a VS pin and comparing it to the preset reference voltage, and the ACDC converter entering the valley conduction mode when the second comparator output is high.
4. The ACDC converter of claim 1 further comprising:
and the blanking module is connected with the logic control module, the GATE of the blanking module is used for controlling a driving signal for starting the switching tube, the driving signal is input to the R end of the RS trigger through two inverters, when the voltages input by the enable signal EN and the GATE are high, the XQ end of the RS trigger is arranged at one end, the M3 tube is started, a current mirror formed by M1 and M2 starts to charge the C1 capacitor, when the charge on the C1 reaches a certain degree, the input end of the Schmitt trigger is input high and output high, and LEB signals are output together through the two inverters and the GATE signal from low to high.
5. A management chip of an ACDC converter according to any one of claims 1 to 4, comprising an ACDC converter, a power supply module and an overtemperature protection module connected in this order;
the power supply module comprises a starting circuit and a power-on reset circuit, wherein the starting circuit monitors VCC in real time, the starting circuit generates a reference voltage OUT after the VCC reaches a starting voltage, the OUT voltage generates a reference voltage VREF, and when the VDD voltage of an internal power supply reaches the voltage requirement required by the chip, the power-on reset circuit generates a reset signal to enable all circuit modules in the chip to start working; when the VCC voltage is under-voltage, the starting circuit does not generate OUT voltage, and the chip stops working at VCC; when a preset protection condition is triggered, the over-temperature protection module generates a protection signal;
the starting circuit comprises a starting resistor, a plurality of switching tubes, a JFET tube and a Schottky diode, when the system starts to be electrified, high-voltage connection generates an electrified finishing identification signal to output a low level, the M2 tube is controlled to be turned off, the grid level of the JFET tube is slowly increased, the JFET tube is turned on, and the high-voltage level charges a voltage stabilizing capacitor Cvdd through the JFET tube and the Schottky diode D1; after the capacitor voltage reaches the rated voltage, the inside of the chip starts to work normally; when the M2 tube is kept in an on state, the JFET tube is turned off, and partial current flows through the starting resistor;
the over-temperature protection module comprises three PTAT currents which are proportional to absolute temperature and come from a reference generation module of the ACDC converter, a trigger, three inverters and two resistors with positive temperature coefficients, when the working temperature of a chip is lower than a preset temperature, the voltage of a node C is lower than the on threshold voltage of Q1, and a Q1 pipe is cut off; the level of the node A is high, and the low level is output by the OTP at the output end after passing through the inverter; when the chip temperature rises, the base-emitter voltage VBE of the Q1 is reduced, the PTAT current rises, and the resistance values of the resistors R1 and R2 also rise; when the temperature of the chip reaches the preset temperature, the voltage of the node C is higher than the conduction threshold voltage of the Q1, the Q1 pipe is conducted, the voltage of the node A is pulled down, and the output end OTP correspondingly outputs high level.
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