CN113972629A - ACDC converter and management chip thereof - Google Patents

ACDC converter and management chip thereof Download PDF

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Publication number
CN113972629A
CN113972629A CN202111311057.XA CN202111311057A CN113972629A CN 113972629 A CN113972629 A CN 113972629A CN 202111311057 A CN202111311057 A CN 202111311057A CN 113972629 A CN113972629 A CN 113972629A
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voltage
circuit
signal
current
tube
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CN202111311057.XA
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CN113972629B (en
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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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    • 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)
  • Dc-Dc Converters (AREA)
  • Inverter Devices (AREA)

Abstract

The invention discloses an ACDC converter and a management chip thereof, comprising 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 chip VDD pin and converting the high voltage into an internal preset power voltage to provide a stable low voltage power supply for a chip internal low voltage module, a reference voltage source circuit is used for generating a high power supply rejection ratio, has a reference voltage close to a zero temperature coefficient at room temperature and provides a reference level for the chip internal circuit voltage, a reference current source circuit is used for providing a reliable current reference for the chip internal circuit, an overvoltage protection circuit is used for determining a chip minimum working voltage and a chip maximum turn-off voltage protection circuit, the logic control module judges the current load condition according to sampling signals of various ports, selects required constant voltage or constant current turn-on or turn-off signals and generates driving signals of a power tube, 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, power electronic technology becomes an indispensable part in society, electronic equipment can not be powered on, and a switching power supply has the characteristics of small volume, high efficiency, light weight, insensitivity to power grid shifting and the like, and is widely applied to household electronic equipment and communication equipment. The switch power supply can be divided into two categories of ACDC and DCDC, the design technology and the sound field process of the DCDC converter are mature at home and abroad, the modularization and the standardization are realized, and the consistent approval of users is obtained. However, ACDC converters present some difficulties in achieving modularity due to limitations in technology and process manufacturing issues.
The ACDC converter converts alternating current into direct current, because ACDC converter input often is 50/60 Hz's alternating current, the power consumption that corresponds is bigger and bigger, and conversion efficiency to the power, the consumption has proposed new requirement, the power uses linear power to supply power mostly, linear power simple structure, good stability and noise immunity are good, but linear constant voltage power supply during operation regulating tube can produce a large amount of heat, lead to the efficiency not high and the loss serious, and linear constant voltage power supply generally need use power frequency transformer, in addition the fin of regulating tube, it is bulky to cause linear steady voltage power supply, lead to power efficiency to reduce.
Disclosure of Invention
In view of the above, the present invention provides an ACDC converter and a management chip thereof, which can improve overvoltage and over-temperature protection and reduce switching loss, so as to solve the above technical problems.
In a first aspect, the present invention provides an ACDC converter, including a reference generation module, a constant voltage control module, a constant current control module, and a logic control module, where the reference generation module, the constant voltage control module, and the constant current control module are connected to the logic control module;
the reference generation 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 chip VDD pin and converting the high voltage into an internal preset power voltage to provide a stable low-voltage power supply for all low-voltage modules in the chip;
the constant voltage control module comprises a constant voltage starting signal control loop and a constant voltage stopping signal control loop, the constant voltage starting 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 the inverting input end of the error amplifier through a resistor, and the 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 divider and a filter so as to generate a turn-off signal of the power tube in a constant voltage mode;
the constant current control module is used for generating a constant current starting signal and a constant current stopping signal, the current sampling signal is compared with a reference voltage spanning to the operational amplifier through the CS sampling circuit, the current sampling signal is subjected to scaling of a preset proportion through the buffer and then is sent to the second comparator, and the second comparator generates a corresponding constant current stopping signal according to the comparison between the output of the preceding stage circuit and the corresponding reference voltage; a valley bottom conduction mode is adopted to enable the switching tube to complete switching conversion when the voltage is over zero so as to realize valley bottom 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 the ports, selects the required constant voltage or constant current on or off signal, and generates the driving signal of the power tube to maintain the constancy of the output voltage or current.
As a further improvement of the above technical solution, the overvoltage protection circuit is connected to a load, when the voltage collected by the FB sampling circuit is greater than the preset power supply voltage, the divided voltage of the FB pin is detected by the negative input terminal of the error amplifier, and the first comparator outputs a low level.
As a further improvement of the above technical solution, the valley bottom conduction mode includes that when the switch tube is turned off, the energy of the auxiliary winding on the round side is completely converted to the secondary winding, the auxiliary winding and the drain of the switch tube are two terminals with the same name, the auxiliary winding and the drain of the switch tube are subjected to voltage sampling through the VS pin and 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 bottom conduction mode.
As a further improvement of the above technical solution, the ACDC converter further includes:
a soft start module connected with the logic control module for inputting pulse with eight-frequency clock frequency division at the CLK input end, and opening the M3 tube for a period of time every eight clock periods, IACurrent is charged to the C1 capacitor through a current mirror, and passes through a comparison circuit of M7 and M8 and VCSWhen the inputs of the pins are compared, V isCSWhen the voltage of the C1 is exceeded, the M11 is turned on, the output of the SS end becomes low, the switch tube is turned off, and after the circuit is turned off, the reset tube M4 clears the voltage at the two ends of the C1, so that 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 opening a 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, the M3 tube is opened, a current mirror consisting of the M1 and the M2 starts to charge the C1 capacitor, when the charging on the C1 reaches a certain degree, the input end of the Schmidt trigger is high and the output of the Schmidt trigger is high, and an LEB signal is output together with the GATE signal through the two inverters and is changed from low to high.
In a second aspect, the invention further 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 connected in sequence;
the power supply module comprises a starting circuit and a power-on reset circuit, wherein the starting circuit monitors VCC in real time, generates a reference voltage OUT when VCC reaches a starting voltage, generates a reference voltage VREF from the OUT voltage, and generates a reset signal to enable all circuit modules in the chip to start working when the VDD voltage of the internal power supply reaches the voltage requirement required by the chip; when the voltage of VCC is undervoltage, 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 access generates an electrifying completion identification signal to output low level, the M2 tube is controlled to be switched off, the grid level of the JFET tube is slowly increased, the JFET tube is switched on, and the high-voltage level supplies a voltage stabilizing capacitor C through the JFET tube and the Schottky diode D1vddCharging; when the voltage of the capacitor reaches the rated voltage, the interior of the chip starts to work normally; when the M2 tube is kept in an open 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 from a reference generation module of the ACDC converter and are in direct proportion to absolute temperature, a trigger, three phase 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 conduction 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 output end OTP outputs low level after passing through the inverter; base-emitter voltage V of Q1 when chip temperature risesBEDecreasing, increasing the PTAT current, and increasing the resistance of the resistors R1 and R2; when the temperature of the chip reaches a 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 low, and the output end OTP correspondingly outputs a high level。
Compared with the prior art, the ACDC converter and the management chip thereof provided by the invention have the following beneficial effects:
through producing the module with the benchmark, the constant voltage control module, constant current control module and logic control module are connected, the high voltage regulator circuit in the benchmark production module can convert the input high pressure into predetermineeing mains voltage, can reduce circuit overvoltage crowning, the protection that the chip during operation produced instantaneous voltage can be guaranteed to the overvoltage crowning, constant temperature control module and constant current control module can provide stable voltage or current output for the load, first comparator and second comparator are PWM, can provide two kinds of different mode of operation, with the job stabilization who improves the ACDC converter. The valley bottom 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 work inside the chip is guaranteed, the switching on and off of the switching tube is changed when the working temperature of the chip exceeds the preset temperature through the over-temperature protection module, voltage in the circuit is reduced, and damage caused by frequent switching off of circuits in the chip due to thermal shock can be prevented.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings needed to be used in the embodiments will be briefly described below, it should be understood that the following drawings only illustrate some embodiments of the present invention and therefore should not be considered as limiting the scope, and for those skilled in the art, other related drawings can be obtained according to the drawings without inventive efforts.
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 over-voltage protection circuit according to an embodiment of the present invention;
fig. 4 is a circuit diagram of a valley bottom 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 the ACDC converter according to the embodiment of the present invention.
The main element symbols are as follows:
100-ACDC converter; 110-a reference generation module; 120-a high voltage regulator circuit; 130-reference voltage source circuit; 140-a reference current source circuit; 150-an overvoltage protection circuit; 160-constant voltage control module; 170-FB sampling circuit; 180-an error amplifier; 190-degeneration resistance; 200-a first comparator; 210-a second comparator; 220-constant current control module; 230-CS sampling circuit; 240-logic control module; 250-a soft start module; 260-blanking module; 270-power supply module; 280-start-up circuit; 290-a power-on reset circuit; 300-over-temperature protection module.
Detailed Description
Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the accompanying drawings are illustrative only for the purpose of explaining the present invention, and are not to be construed as limiting the present invention.
It will be understood that when an element is referred to as being "secured 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 as used herein are for illustrative purposes only.
In the present invention, unless otherwise expressly stated or limited, the terms "mounted," "connected," "secured," and the like are to be construed broadly and can, for example, be fixedly connected, detachably connected, or integrally formed; can be mechanically or electrically connected; either directly or indirectly through intervening media, either internally or in any other relationship. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.
Referring to fig. 1 and fig. 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 generation 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, where the high voltage regulator circuit 120 is configured to receive a high voltage of a chip VDD pin and convert the high voltage into an internal preset power voltage to provide a stable low voltage power for all low voltage modules inside the chip, the reference voltage source circuit 130 is configured to generate a high power rejection ratio, and has a reference voltage close to a zero temperature coefficient at room temperature and provides a reference level for a chip internal circuit voltage, the reference current source circuit 140 is configured to provide a reliable current reference for a chip internal circuit, and the overvoltage protection circuit 150 is configured to determine a protection circuit of a chip minimum working voltage and a chip maximum off voltage;
the constant voltage control module 160 comprises a constant voltage on signal control loop and a constant voltage off signal control loop, the constant voltage on signal control loop samples output voltage and forms an error amplifier 180 with fixed gain through an FB sampling circuit 170, the error amplifier 180 and a negative feedback resistor 190, the FB sampling voltage is connected to the inverting input end of the error amplifier 180 through a resistor, and the non-inverting input end of the error amplifier 180 is connected with a preset reference voltage; the error amplifier 180 outputs a voltage to the first comparator 200 for generating a power tube turn-on signal, and the output voltage signal is processed by a resistor divider and a filter and then sent to the overvoltage protection circuit 150 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 turn-on signal and a constant current turn-off signal, where the current sampling signal is compared with a reference voltage across to the operational amplifier through the CS sampling circuit 230, and is sent to the second comparator 210 after being scaled by a preset proportion through the buffer, and the second comparator 210 generates a corresponding constant current turn-off signal according to the comparison between the output of the previous stage circuit and the corresponding reference voltage; a valley bottom conduction mode is adopted to enable the switching tube to complete switching conversion when the voltage is over zero so as to realize valley bottom conduction and generate a corresponding constant current starting signal;
the logic control module 240 determines the current load condition according to the sampling signal of each port, 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 may be selected according to different application occasions. The high-voltage regulator circuit receives high voltage such as 7.6V to 26.2V from a pin VDD of a chip and converts the high voltage into internal 5V power supply voltage, in a constant voltage loop, an error amplifier EA and a negative feedback resistor jointly form an inverting amplifier with 40 times of fixed gain, 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 the first comparator is used for generating a starting signal CV _ ON of a power tube, and a Vcomp signal is sent to CV _ OCP after being subjected to resistance voltage division and filtering processing and used for generating a closing signal CV _ OFF of the power tube in a constant voltage mode. In the constant voltage control loop, firstly, an output voltage is sampled and passes through a sampling and holding circuit, the output voltage is compared with a preset reference voltage such as 2.5v, then the difference value of the output voltage and the preset reference voltage is amplified through an error amplifier EA, and an error amplification signal Vcomp respectively adjusts the switching frequency and the current limiting point through two paths. The identification signal that the system enters 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, the output voltage of a feedback input pin FB is lower than 2.5v, the first comparator outputs high level, and the system is controlled by a constant current loop. Along with the gradual lightening of the load, under the condition of medium load, light load or no load within a current limiting point, the output voltage is gradually increased, the voltage of a feedback input pin FB is higher than 2.5v, the first comparator outputs low level, and at the moment, the system is controlled by a constant current loop to enter a working state controlled by a 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 according to the voltage, such as a power tube on signal, a power tube off signal, and the like. The EA output voltage Vcomp is 5v when the FB sample voltage is below 2.4375, 0v when the FB sample voltage is above 2.5625v, a corresponding decrease in Vcomp voltage when the FB sample voltage increases, and a corresponding increase in Vcomp voltage when the FB sample voltage decreases. Under the normal working condition of the chip, internal propagation delay exists, the actual current limiting point changes along with the input line voltage, and when the input line voltage 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 limit point is high; when the constant current operation is performed, the output currents are inconsistent, namely the output current at 85vAC input is small, and the output current at 265vAC input is large; or the maximum output power of the system is inconsistent when the system works at constant voltage, the maximum output power is small at 85vAC input, and the maximum output power is large at 265vAC input, namely the line voltage compensation circuit is needed. The ACDC converter in the embodiment does not need an external loop compensation capacitor, can work in DCM and QR modes, and can control the constant current precision within +/-3% and the constant voltage precision within +/-5%. When the system outputs constant voltage or constant current, the constant voltage and constant current states can not work simultaneously, and when the load changes, the constant voltage and constant current modes are switched according to the load requirement. In a charger application, an uncharged battery is charged with a constant current, 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, the system ensures that the output current is constant no matter how the output voltage drops, and under the constant-voltage mode, the system regulates the output voltage through primary side sampling, so that the working stability of the ACDC converter is improved.
Optionally, the overvoltage protection circuit is connected to a load, when the voltage collected by the FB sampling circuit is greater than a preset power supply voltage, the divided voltage of the FB pin is detected through the negative input terminal 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 to control the external power tube to turn 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 bottom conduction mode includes that when the switch tube is turned off, energy of the auxiliary winding on the round side is completely converted to the secondary winding, the auxiliary winding and the drain of the switch tube are two dotted terminals, voltage sampling is performed on the auxiliary winding and the drain of the switch tube through a VS pin, the auxiliary winding and the drain of the switch tube are compared with the preset reference voltage, and when the output of the second comparator is a high level, the ACDC converter enters the valley bottom conduction mode.
Referring to fig. 4, in this embodiment, the valley-bottom conduction mode is a conduction mode, which is also called a quasi-resonant mode, during the turning on and off of the switch tube, the switch power supply may lose a certain amount of energy, which accounts for a large portion of the total loss, and the minimum value of the drain terminal voltage of the switch tube may be detected and conducted when the minimum value is at the lowest point, so that the switch may be turned on when the spike caused by the parasitic capacitance is least significant, and the efficiency and the stability of the chip may be greatly improved. The number of windings of the transformer and the size of the generated resonant voltage are used as references in practical use, valley conduction is carried out at the tail end of each period, the time of each period is limited, energy stored in a capacitor cannot be completely released, and the anti-interference performance and the stability of a chip can be optimized to a great extent.
Optionally, the ACDC converter further comprises:
a soft start module 250 connected to the logic control module 240, for inputting pulses with a clock frequency divided by eight at the CLK input end, and turning on the M3 transistor for a period of time, I, every eight clock cyclesACurrent is charged to the C1 capacitor through a current mirror, and passes through a comparison circuit of M7 and M8 and VCSWhen the inputs of the pins are compared, V isCSOver the voltage at C1And the M11 is enabled to be started, the output of the SS end becomes low, the switching tube is enabled to be closed, and after the circuit is closed, the reset tube M4 clears the voltage at the two ends of the C1, so that the starting module works normally.
Referring to fig. 5, in the present embodiment, the soft start module 250 is used for gradually increasing the output voltage when the chip is started, and controlling the switching tube by gradually increasing the sampling voltage of the over-current limiting threshold and the current, so that the start 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 low in price. The pulse input of the clock frequency after eight frequency divisions is carried out at the CLK input end, the frequency division circuit is realized by adopting a common D trigger, the M3 tube is opened for a period of time every eight clock periods, and at the moment, I isAThe current charges the C1 capacitor through the current mirror, but the charging time is short each time, and the voltage at the two ends of the C1 cannot reach VDDVoltage, comparison circuit through M7 and M8 and VCSWhen the inputs of the pins are compared, V isCSWhen the voltage of the C1 is exceeded, the M11 is turned on, the output of the SS terminal goes low, and the switch tube is forced to be closed, so that the voltage of the load circuit does not reach a high level directly. After a few cycles, the voltage at C1 reaches a maximum, the soft start module does not function, VCSThe soft start module is not influenced to be started, after the circuit is closed, the reset tube M4 is needed to reset the voltage at the two ends of the C1, and the soft start module works normally when the chip is easy to start next time.
Optionally, the ACDC converter further comprises:
the blanking module 260 is connected to the logic control module 240, the GATE of the blanking module 260 is used to control a driving signal for switching on the switching tube, the driving signal is input to the R terminal of the RS flip-flop through two inverters, when the voltages input by the enable signal EN and the GATE are high, the XQ terminal of the RS flip-flop is set to be one, the M3 transistor is turned on, the current mirror composed of the M1 and the M2 starts to charge the C1 capacitor, when the charging on the C1 reaches a certain degree, the input end of the schmitt trigger is high and the output is high, and the LEB signal is output together with the GATE signal through the two inverters and changes from low to high.
Referring to fig. 6, in this embodiment, the blanking module 260 may reduce interference of a spike signal in a circuit on internal logic, when a switching tube is turned on and off, a voltage change is large, the switching tube has a parasitic capacitance and may generate a spike current signal, after passing through an inductive current detection resistor, the voltage may fluctuate in a short time, if the inaccurate voltage is retained, primary side current detection may be affected, which may cause the switching tube to fail to operate normally, a circuit is required to shield the unstable signal, the existence time of the unstable signal is short, and shielding of the signal by the blanking module 260 may not affect normal operation of the rest. The GATE is a driving signal for controlling the switching tube to be turned on, the driving signal is input to the R end of the RS trigger through the two inverters, when an enable signal EN is high and the voltage input by the GATE is high, the M3 tube is turned on at the moment, a current mirror consisting of the M1 and the 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 of the input end of the Schmitt trigger is high and the output is also high, the charging current and the GATE signal are input into an AND GATE together after passing through the two inverters, and the output LEB signal can be 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 a capacitor C1, the width of the LEB can be adjusted by adjusting the charging current of the capacitor, and the delay time is 260 ns.
Referring to fig. 7, the present invention further provides a management chip of the ACDC converter, including an ACDC converter 100, a power supply module 270, and an over-temperature protection module 300, which are connected in sequence;
the power supply module 270 includes a start circuit 280 and a power-on reset circuit 290, the start circuit 280 monitors VCC in real time, and when VCC reaches a start voltage, the start circuit generates a reference voltage OUT, and then generates a reference voltage VREF from the OUT voltage, and when VDD voltage of the internal power supply reaches a 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 voltage of VCC is undervoltage, 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 access generates an electrified identification signal to output 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; when the voltage of the capacitor reaches the rated voltage, the interior of the chip starts to work normally; when the M2 tube is kept in an open state, the JFET tube is turned off, and partial current flows through the starting resistor;
the over-temperature protection module 300 comprises three PTAT currents which are from a reference generation module of the ACDC converter and are in direct proportion to absolute temperature, a trigger, three phase 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 conduction threshold voltage of a switch tube Q1, and the switch tube Q1 is cut off; the level of the node A is high, and the output end OTP outputs low level after passing through the inverter; base-emitter voltage V of Q1 when chip temperature risesBEDecreasing, increasing the PTAT current, and increasing the resistance of the resistors R1 and R2; when the temperature of the chip reaches a 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 low, and the output end OTP correspondingly outputs a high level.
In the embodiment, constant voltage and constant current output is realized by combining primary side feedback and secondary side feedback, and modules such as valley bottom conduction, blanking, soft start and the like 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 mixed working mode of the PWM and the PFM, wherein the PWM fixes the working period of a system and only adjusts the conduction time of a switching tube for controlling and outputting, a PWM modulation module generally comprises an oscillator, a comparator, an error amplifier, a reference voltage generation module and the like, a feedback voltage and a reference voltage are compared and amplified, then a signal and a triangular wave are input into the comparator for comparison, a PWM signal is output when an error signal is larger than the triangular wave, a low level is output when the triangular wave is larger than the error signal, if the feedback signal becomes low, the error amplification signal becomes high, 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. A forward biased rectifier diode exists on the secondary side, the FB voltage fed back by the auxiliary winding can be influenced by temperature to enable the sampling voltage to be inaccurate, and one voltage related to the temperature coefficient of the secondary side diode is used as a reference voltage to offset the temperature drift influence of the voltage drop of the secondary side conduction diode.
The invention provides an ACDC converter and a management chip thereof.A reference generation module, a constant voltage control module, a constant current control module and a logic control module are connected, a high-voltage stabilizer circuit in the reference generation 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 the protection of instantaneous voltage generated when the chip works, a constant temperature control module and a constant current control module can provide stable voltage or current output for a load, a first comparator and a second comparator are PWM and can provide two different working modes so as to improve the working stability of the ACDC converter. The valley bottom 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 work inside the chip is guaranteed, the switching on and off of the switching tube is changed when the working temperature of the chip exceeds the preset temperature through the over-temperature protection module, voltage in the circuit is reduced, and damage caused by frequent switching off of circuits in the chip due to thermal shock can be prevented.
In all examples shown and described herein, any particular value should be construed as merely exemplary, and not as a limitation, and thus other examples of example embodiments may have different values.
It should be noted that: like reference numbers and letters refer to like items in the following figures, and thus, once an item is defined in one figure, it need not be further defined and explained in subsequent figures.
The above examples are merely illustrative of several embodiments of the present invention, and the description thereof is more specific and detailed, but not to be construed as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention.

Claims (6)

1. An 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 generation 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 chip VDD pin and converting the high voltage into an internal preset power voltage to provide a stable low-voltage power supply for all low-voltage modules in the chip;
the constant voltage control module comprises a constant voltage starting signal control loop and a constant voltage stopping signal control loop, the constant voltage starting 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 the inverting input end of the error amplifier through a resistor, and the 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 divider and a filter so as to generate a turn-off signal of the power tube in a constant voltage mode;
the constant current control module is used for generating a constant current starting signal and a constant current stopping signal, the current sampling signal is compared with a reference voltage spanning to the operational amplifier through the CS sampling circuit, the current sampling signal is subjected to scaling of a preset proportion through the buffer and then is sent to the second comparator, and the second comparator generates a corresponding constant current stopping signal according to the comparison between the output of the preceding stage circuit and the corresponding reference voltage; a valley bottom conduction mode is adopted to enable the switching tube to complete switching conversion when the voltage is over zero so as to realize valley bottom 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 the ports, selects the required constant voltage or constant current on or off signal, and generates the driving signal of the power tube to maintain the constancy of the output voltage or current.
2. The ACDC converter according to claim 1, wherein the over-voltage protection circuit is connected to a load, and when the voltage collected by the FB sampling circuit is greater than the preset power supply voltage, the divided voltage of the FB pin is detected through the negative input terminal of the error amplifier, and the first comparator outputs a low level.
3. The ACDC converter of claim 1, wherein the valley conduction mode comprises when the switch is turned off and the energy of the auxiliary winding on the rounded side is fully converted to the secondary winding, the auxiliary winding and the drain of the switch are two terminals with the same name, the voltage of the auxiliary winding and the drain of the switch is sampled by a VS pin and compared with the predetermined reference voltage, and when the output of the second comparator is high, the ACDC converter enters the valley conduction mode.
4. The ACDC converter of claim 1, further comprising:
a soft start module connected with the logic control module for inputting pulse with eight-frequency clock frequency division at the CLK input end, and opening the M3 tube for a period of time every eight clock periods, IACurrent is charged to the C1 capacitor through a current mirror, and passes through a comparison circuit of M7 and M8 and VCSWhen the inputs of the pins are compared, V isCSWhen the voltage of the C1 is exceeded, the M11 is turned on, the output of the SS end becomes low, the switch tube is turned off, and after the circuit is turned off, the reset tube M4 clears the voltage at the two ends of the C1, so that the starting module works normally.
5. 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 opening a 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, the M3 tube is opened, a current mirror consisting of the M1 and the M2 starts to charge the C1 capacitor, when the charging on the C1 reaches a certain degree, the input end of the Schmidt trigger is high and the output of the Schmidt trigger is high, and an LEB signal is output together with the GATE signal through the two inverters and is changed from low to high.
6. A management chip of an ACDC converter according to any one of claims 1 to 5, comprising the ACDC converter, a power supply module and an over-temperature protection module which are connected in sequence;
the power supply module comprises a starting circuit and a power-on reset circuit, wherein the starting circuit monitors VCC in real time, generates a reference voltage OUT when VCC reaches a starting voltage, generates a reference voltage VREF from the OUT voltage, and generates a reset signal to enable all circuit modules in the chip to start working when the VDD voltage of the internal power supply reaches the voltage requirement required by the chip; when the voltage of VCC is undervoltage, 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 access generates an electrified identification signal to output low level, the M2 tube is controlled to be switched off, the grid level of the JFET tube is slowly increased, the JFET tube is switched on, and the high-voltage level charges the voltage stabilizing capacitor Cvdd through the JFET tube and the Schottky diode D1; when the voltage of the capacitor reaches the rated voltage, the interior of the chip starts to work normally; when the M2 tube is kept in an open state, the JFET tube is turned off, and partial current flows through the starting resistor;
the over-temperature protection module comprises three and absolute reference generation modules from the ACDC converterThe temperature-proportional PTAT circuit comprises a PTAT current, a trigger, three phase 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 Q1 conduction threshold voltage, and a Q1 tube is cut off; the level of the node A is high, and the output end OTP outputs low level after passing through the inverter; base-emitter voltage V of Q1 when chip temperature risesBEDecreasing, increasing the PTAT current, and increasing the resistance of the resistors R1 and R2; when the temperature of the chip reaches a preset temperature, the voltage of the node C is higher than the conduction threshold voltage of the Q1, the Q1 tube is conducted, the voltage of the node A is pulled low, and the output end OTP correspondingly outputs a high level.
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CN116131219A (en) * 2023-02-16 2023-05-16 恩赛半导体(成都)有限公司 Overvoltage protection circuit and electronic device
CN116403517A (en) * 2023-06-09 2023-07-07 中科(深圳)无线半导体有限公司 Self-adaptive control method for power source of LED display system

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CN104917411A (en) * 2015-06-26 2015-09-16 深圳市稳先微电子有限公司 AC-DC control chip of single-stage high power factor correction (PFC) and switching power supply circuit
CN207782663U (en) * 2018-01-29 2018-08-28 深圳市创新微源半导体有限公司 A kind of constant pressure and flow mode switching circuit

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CN103401428A (en) * 2013-07-31 2013-11-20 普缘芯半导体科技(上海)有限公司 Switch power supply control chip and switch power supply control system
CN104917411A (en) * 2015-06-26 2015-09-16 深圳市稳先微电子有限公司 AC-DC control chip of single-stage high power factor correction (PFC) and switching power supply circuit
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CN116131219A (en) * 2023-02-16 2023-05-16 恩赛半导体(成都)有限公司 Overvoltage protection circuit and electronic device
CN116403517A (en) * 2023-06-09 2023-07-07 中科(深圳)无线半导体有限公司 Self-adaptive control method for power source of LED display system
CN116403517B (en) * 2023-06-09 2023-08-29 中科(深圳)无线半导体有限公司 Self-adaptive control method for power source of LED display system

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