CN112117899A - BOOST converter controlled by current mode - Google Patents

BOOST converter controlled by current mode Download PDF

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Publication number
CN112117899A
CN112117899A CN202010839051.9A CN202010839051A CN112117899A CN 112117899 A CN112117899 A CN 112117899A CN 202010839051 A CN202010839051 A CN 202010839051A CN 112117899 A CN112117899 A CN 112117899A
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voltage
output
module
pin
current
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Inventor
涂才根
张胜
谭在超
罗寅
丁国华
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Suzhou Covette Semiconductor Co ltd
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Suzhou Covette Semiconductor Co ltd
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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M3/00—Conversion of dc power input into dc power output
    • H02M3/02—Conversion of dc power input into dc power output without intermediate conversion into ac
    • H02M3/04—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters
    • H02M3/10—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
    • H02M3/145—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
    • H02M3/155—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only
    • H02M3/156—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only with automatic control of output voltage or current, e.g. switching regulators
    • 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
    • H02M1/00—Details of apparatus for conversion
    • H02M1/0003—Details of control, feedback or regulation circuits

Abstract

The invention relates to a current mode controlled BOOST converter, comprising a control IC and a peripheral circuit, the IC peripheral circuit comprising: VIN is the input voltage of the system; VOUT is the output voltage of the system; l1 is an inductor; d1 is a freewheeling diode; c0 is an output filter capacitor; an N1 power switch tube; c1 is the VCC external pin capacitor of IC; r1 is a resistance, connected with the RT pin of IC, used to control the system working frequency; r2, C2 and C3 are FB pin and COMP pin compensation networks of the IC and play a role in determining the stability of the system; r3 is a current sampling resistor; r4 and R5 form a sampling network of the output voltage, and the proportion of the sampling network determines the height of the output voltage. The current mode BOOST converter provided by the scheme has wide input voltage, output ripples are easy to reduce, subharmonic oscillation is eliminated, and loop stability is convenient to adjust.

Description

BOOST converter controlled by current mode
Technical Field
The invention relates to a converter, in particular to a BOOST converter controlled by a current mode, and belongs to the technical field of power management.
Background
The BOOST circuit is a switched dc BOOST circuit that can make the output voltage higher than the input voltage. The method is widely applied to direct current motor transmission, single-phase Power Factor Correction (PFC) circuits and other alternating current and direct current power supplies. However, the BOOST system is often designed to have the problems of large output ripple, narrow input range, easy generation of subharmonic oscillation due to large duty cycle operation, and difficult loop control. Therefore, a new solution to solve the above technical problems is urgently needed.
Disclosure of Invention
The invention provides a BOOST converter controlled by a current mode aiming at the problems in the prior art, and the technical scheme is the BOOST converter controlled by the current mode and can better solve or improve the defects in the prior art. In order to achieve the above object, an embodiment of the present invention is a BOOST converter controlled in a current mode, the BOOST converter including a control IC and a peripheral circuit.
As an improvement of the present invention, the peripheral circuit includes: VIN is the input voltage of the system; VOUT is the output voltage of the system; l1 is an inductor; d1 is a freewheeling diode; c0 is an output filter capacitor; an N1 power switch tube; c1 is the VCC external pin capacitor of IC; r1 is a resistance, connected with the RT pin of IC, used to control the system working frequency; r2, C2 and C3 are FB pin and COMP pin compensation networks of the IC and play a role in determining the stability of the system; r3 is a current sampling resistor; the R4 and the R5 form a sampling network of the output voltage, the proportion of the sampling network determines the height of the output voltage, and the R4 and the R5 network directly sample the output voltage and are accurate in sampling. The sampled signal FB is sent to the negative input end of an operational amplifier, the operational amplifier is positioned in the whole control loop, the voltage of the two input ends is equal, namely VFBBecause the voltage ratio of R4 and R5 is 1.25V, the output voltage VOUT is determined by the voltage ratio.
As an improvement of the present invention, the IC circuit includes: a Regulator module, OSC is an oscillator module, Slope is a Slope compensation module, MaxDuty is a maximum duty cycle module, AMP is an operational amplifier, a comparator CMP1, a comparator CMP2 and a Logic module, wherein VIN pin generates VCC voltage through the Regulator; VCC generates each Reference voltage through a Reference module; the input end of OSC is RT, the output end is divided into two paths, one path of output is sent to the S end of an RS trigger, the other path of output is sent to a slice and a Maxswitch respectively, the positive input end of AMP is a 1.25V reference, the negative input end is an FB pin, the output end is a COMP pin, the COMP is connected with a 5V internal power supply through a resistor R6, the COMP is connected with a resistor R7 after being subjected to voltage reduction by 1.25V, the other end of the resistor R7 is connected with a resistor R8 and the negative input end of a comparator CMP1, the other end of the resistor R8 is grounded, the positive input end of a comparator CMP1 is connected with the output of the slice, the comparator CMP1 outputs to a Logic module, the positive input end of the comparator 2 is a 0.5V reference voltage, the negative input end of the CMP2 is connected with the output of the slice, the output of the slice is connected with the resistor R9, the other end of the resistor R9 is connected with a pin, the CS end of the comparator 2 outputs to the Logic module, the output of the Logic module is sent to a trigger RS module, the output of, the output of Driver is the OUT pin.
The Regulator is a power supply module, generates a medium-voltage power supply VCC inside the IC through a high-voltage power supply VIN, and the medium-voltage power supply VCC is mainly used for generating a 5V power supply inside the IC and providing power for the driving module; the Reference module generates an internal low-voltage 5V power supply and Reference voltages of 1.25V and 0.5V; the OSC is an oscillator module, the external resistor of the RT pin is convenient for adjusting the frequency of the oscillator, the oscillator module generates a clock signal and a sawtooth wave signal, the clock signal is sent to the RS trigger and used for controlling the conduction of each period, and the sawtooth wave signal is respectively sent to the Slope compensation module Slope and the maximum duty ratio module MaxTracty; the Slope is a Slope compensation module which converts a voltage signal of a sawtooth wave into a current of the sawtooth wave, the sawtooth wave current flows through a resistor R9 to generate a Slope voltage, and the Slope voltage is superposed on a CS pin; the Maxswitch is a maximum duty ratio module, and because a slope compensation function is integrated in the IC, the maximum duty ratio can be usually set to be more than 80%, if the CMP1 and the CMP2 are not turned over, the Maxswitch module controls the forced turn-off of the switching period; the AMP is an operational amplifier, the positive input end of the AMP is connected with 1.25V reference voltage, the negative input end of the AMP is connected with an FB pin, the output end of the AMP is connected with a COMP pin, and the operational amplifier is matched with an external C2, R2 and C3 compensation network and is used for detecting output voltage and adjusting the stability of a system; the output of the operational amplifier is subjected to voltage reduction of 1.25V, then is subjected to voltage division by R7 and R8, and then is sent to the negative input end of a comparator CMP1, and the positive input end of the comparator CMP1 is connected with a voltage obtained by superposing slope compensation on a CS pin; the CMP2 comparator has the function of overcurrent protection, when the detection current of the CS pin is overlarge and the voltage after the slope compensation is superposed exceeds 0.5V, the CMP2 is turned over, and the output is controlled to be turned off; the Logic module mainly processes three signals respectively from MaxDaty, CMP1 and CMP2, and determines which signal controls output to be turned off; the RS trigger controls the output to be switched on or switched off logically; driver is a driving module. By means of the ingeniously designed modules and ingeniously combined, current mode control of the BOOST converter can be achieved, and subharmonic oscillation can be avoided.
As an improvement of the present invention, the Regulator is a power supply module, and includes two pins capable of reaching a wide input voltage range, VIN and VCC are two pins of an IC, R1 is a current-limiting resistor, a typical value is more than 1M, D1 is a clamping diode, N1 is a high-voltage enhanced NMOS, C1 is a VCC external capacitor, and the medium-voltage power supply VCC can be expressed as: VCC is VD1-VGSThe VCC can be increased as needed and the clamping diode of D1 can be added in series. The structure is flexible, VCC is not affected by VIN voltage, VIN can be accessed to a wider voltage range, but N1 devices in the process need to be guaranteed to bear the voltage.
As an improvement of the present invention, the slope compensation function is specially designed, a slope voltage is superimposed on the CS pin, and the superimposed voltage will increase as the conduction time increases. An input signal of a Slope compensation module (Slope) is a sawtooth wave signal generated by an oscillator OSC, an output signal is a Slope current Islope, symmetry of two paths is forced by P3, P4, N1 and N2, Vgs of N1 and N2 are equal, due to common Gate of N1 and N2, Source voltages of all N1 and N2 are equal, for P1 and P2, due to symmetry, Vsg is equal, Source voltages of P1 and P2 are equal, Gate voltages of P1 and P2 are equal, and due to Gate voltage of P2 being equal to R1 voltage, Gate voltage of P1 being equal to R1 voltage; so that the currents in both branches of the current mirror are equal to
Figure BDA0002640745870000031
The output current of P5 can be designed according to the current mirror ratio to generate a current Islope proportional to Vslope, and the module generates a ramp voltage Islope R9, which is superimposed on the CS pin. Current modeWhen the duty ratio exceeds 50%, subharmonic oscillation is likely to occur, and the larger the duty ratio is, the more likely subharmonic oscillation is to occur. Therefore, it is desirable that the larger the on-time, the larger the compensation amount, and the more preferable the ramp method is. The general slope compensation method has two types, one is to superpose a certain compensation amount on the positive input end (CS) of the comparator, and the other is to reduce a certain compensation amount on the negative input end (COMP indirect reflection) of the comparator, and the first method is adopted in the text.
Compared with the prior art, the current mode BOOST converter has the advantages that the current mode BOOST converter provided by the technical scheme has wide input voltage, output ripples are easy to reduce, and loop stability is convenient to adjust. By means of the ingeniously designed modules and ingeniously combined, current mode control of the BOOST converter can be achieved, and subharmonic oscillation can be avoided.
Drawings
FIG. 1 is a schematic diagram of a BOOST converter controlled in current mode;
FIG. 2 is a schematic diagram of a Regulator module;
FIG. 3 is a schematic structural diagram of an OSC module;
fig. 4 is a schematic structural diagram of a Slope compensation module (Slope).
The specific implementation mode is as follows:
for the purpose of enhancing an understanding of the present invention, the present embodiment will be described in detail below with reference to the accompanying drawings.
Example 1: referring to fig. 1, the present invention provides a BOOST converter controlled in a current mode, as shown in fig. 1, the whole system includes a control IC and peripheral circuits. IC peripheral devices: VIN is the input voltage of the system; VOUT is the output voltage of the system; l1 is an inductor; d1 is a freewheeling diode; c0 is an output filter capacitor; an N1 power switch tube; c1 is the VCC external pin capacitor of IC; r1 is a resistance, connected with the RT pin of IC, used to control the system working frequency; r2, C2 and C3 are FB pin and COMP pin compensation networks of the IC and play a role in determining the stability of the system; r3 is a current sampling resistor; r4 and R5 form a sampling network of the output voltage, and the proportion of the sampling network determines the height of the output voltage. The IC mainly illustrates several core modules: a Regulator module, OSC is an oscillator module, Slope is a Slope compensation module, MaxDuty is a maximum duty cycle module, AMP is an operational amplifier, a comparator CMP1, a comparator CMP2 and a Logic module, wherein VIN pin generates VCC voltage through the Regulator; VCC generates each Reference voltage through a Reference module; the input end of OSC is RT, the output end is divided into two paths, one path of output is sent to the S end of an RS trigger, the other path of output is sent to a slice and a Maxswitch respectively, the positive input end of AMP is a 1.25V reference, the negative input end is an FB pin, the output end is a COMP pin, the COMP is connected with a 5V internal power supply through a resistor R6, the COMP is connected with a resistor R7 after being subjected to voltage reduction by 1.25V, the other end of the resistor R7 is connected with a resistor R8 and the negative input end of a comparator CMP1, the other end of the resistor R8 is grounded, the positive input end of a comparator CMP1 is connected with the output of the slice, the comparator CMP1 outputs to a Logic module, the positive input end of the comparator 2 is a 0.5V reference voltage, the negative input end of the CMP2 is connected with the output of the slice, the output of the slice is connected with the resistor R9, the other end of the resistor R9 is connected with a pin, the CS end of the comparator 2 outputs to the Logic module, the output of the Logic module is sent to a trigger RS module, the output of, the output of Driver is the OUT pin. The Regulator is a power supply module, generates a medium-voltage power supply VCC inside the IC through a high-voltage power supply VIN, and the medium-voltage power supply VCC is mainly used for generating a 5V power supply inside the IC and providing power for the driving module; the Reference module generates an internal low-voltage 5V power supply and Reference voltages of 1.25V and 0.5V; the OSC is an oscillator module, the external resistor of the RT pin is convenient for adjusting the frequency of the oscillator, the oscillator module generates a clock signal and a sawtooth wave signal, the clock signal is sent to the RS trigger and used for controlling the conduction of each period, and the sawtooth wave signal is respectively sent to the Slope compensation module Slope and the maximum duty ratio module MaxTracty; the Slope is a Slope compensation module which converts a voltage signal of a sawtooth wave into a current of the sawtooth wave, the sawtooth wave current flows through a resistor R9 to generate a Slope voltage, and the Slope voltage is superposed on a CS pin; the Maxswitch is a maximum duty ratio module, and because a slope compensation function is integrated in the IC, the maximum duty ratio can be usually set to be more than 80%, if the CMP1 and the CMP2 are not turned over, the Maxswitch module controls the forced turn-off of the switching period; the AMP is an operational amplifier, the positive input end of the AMP is connected with 1.25V reference voltage, the negative input end of the AMP is connected with an FB pin, the output end of the AMP is connected with a COMP pin, and the operational amplifier is matched with an external C2, R2 and C3 compensation network and is used for detecting output voltage and adjusting the stability of a system; the output of the operational amplifier is subjected to voltage reduction of 1.25V, then is subjected to voltage division by R7 and R8, and then is sent to the negative input end of a comparator CMP1, and the positive input end of the comparator CMP1 is connected with a voltage obtained by superposing slope compensation on a CS pin; the CMP2 comparator has the function of overcurrent protection, when the detection current of the CS pin is overlarge and the voltage after the slope compensation is superposed exceeds 0.5V, the CMP2 is turned over, and the output is controlled to be turned off; the Logic module mainly processes three signals respectively from MaxDaty, CMP1 and CMP2, and determines which signal controls output to be turned off; the RS trigger controls the output to be switched on or switched off logically; driver is a driving module.
The working process is as follows: referring to fig. 1-4, upon system startup: the input pin VIN supplies power to VCC through a Regulator, the IC starts to work, a 5V low-voltage power supply and other biases are generated, an internal low-voltage power supply 5V charges a COMP pin external capacitor C2 through a resistor R6, the COMP voltage rises, after the COMP voltage exceeds 1.25V at a certain time, voltage starts to be generated on a resistor R8, it should be noted that when the COMP voltage is lower than 1.25V, the R8 voltage is 0V, the CMP1 output is kept at a high level, the output is always turned off at the moment, even if a signal is sent to control the IC to be turned on in each oscillator period, the on time is also 0, namely the output is always turned off. When a voltage is applied to the R8, the oscillator OSC control IC is turned on, the CS voltage rises, the voltage after the superposition slope compensation exceeds the voltage of the R8, and the output is turned off.
After the system works stably: when the power switch tube N1 is turned on, that is, the oscillator OSC is clocked on, the inductor input signal VIN charges the inductor L1, the voltage on the right side of the inductor is close to 0V due to the conduction of N1, the voltage on the right side of the inductor D1 is high, the voltage on the left side is low, D1 is not turned on, the current of the inductor L1 is equal to the current of the current sampling resistor R3, therefore, the CS voltage gradually increases, and the CS voltage superposed with the slope compensation at a certain time exceeds the voltage at the negative input end of the CMP1, so that the CMP1 is inverted, and the IC is controlled to be turned off, that is. After N1 is turned off, the inductor L1 reverses polarity and begins to discharge the output through D1 until the next oscillator cycle again turns on the power transistor N1.
Based on the above analysis, the magnitude of the on time of N1 is directly controlled by the voltage of R8, with higher R8 voltage, longer on time, higher duty cycle, and more energy transferred to the output. For the system, if the output voltage VOUT decreases, the FB voltage becomes low, the operational amplifier AMP controls the COMP voltage to increase, so that the voltage of R8 increases, the duty ratio increases, and the output voltage VOUT is controlled to increase; similarly, if the output voltage VOUT rises, the FB voltage rises, the operational amplifier AMP controls the COMP voltage to decrease, the R8 voltage decreases, the duty cycle decreases, and the output voltage VOUT is controlled to decrease. Therefore, the system can well realize the constant voltage control of the output voltage and is convenient to control. The target value of the output voltage can be designed by adjusting the proportion of R4 and R5.
The system is specially designed for a high-voltage power supply module (Regulator) of an IC, and can achieve a wide input voltage range, the structure of the Regulator module is shown in figure 2, VIN and VCC are two pins of the IC, R1 is a current-limiting resistor with a typical value of more than 1M, D1 is a clamping diode, N1 is a high-voltage enhanced NMOS, and C1 is a VCC external capacitor. The medium voltage supply VCC may be expressed as: VCC is VD1-VGSThe VCC can be increased as needed and the clamping diode of D1 can be added in series. The structure is flexible, VCC is not affected by VIN voltage, VIN can be accessed to a wider voltage range, but N1 devices in the process need to be guaranteed to bear the voltage.
The OSC module determines the operating frequency of the system, and can be conveniently adjusted by changing the resistance of the RT pin external resistor R1, the structure of the OSC module is schematically shown in fig. 3, and a simple negative feedback structure fixes the voltage of the RT pin to 1.25V, so that the RT pin external resistor determines the current of the current mirror, and the ratio of the PMOS current above is 1: 1: 1, the following NMOS current mirror ratio is 1: n, the charge-discharge current ratio of the following capacitor is 1: n, the ramp generated on the capacitor rises slowly and falls quickly, and the ramp is sent to a subsequent Slope module. The second half of the diagram shows a typical structure of an oscillator circuit for controlling a switching device for charging and discharging a capacitor. The frequency of the OSC is easy to adjust, and under the condition that loop compensation is well adjusted, the working frequency of the system can be set high, so that output ripples can be reduced, and conversion efficiency can be improved.
Aiming at the risk that a current mode system is easy to generate subharmonic oscillation under the condition of large duty ratio, the invention specially designs a slope compensation function, a slope voltage is superposed on a CS pin, and the superposed voltage is increased along with the increase of the conduction time. The Slope compensation module (Slope) is schematically shown in fig. 4, and an input signal of the Slope compensation module is a sawtooth wave signal generated by an oscillator OSC, and an output signal of the Slope compensation module is a Slope current Islope. P3, P4, N1 and N2 force the symmetry of two paths, then the Vgs of N1 and N2 are equal, and the Source voltages of N1 and N2 are equal due to the common Gate of N1 and N2. For P1 and P2, also because of symmetry, Vsg is equal, Source voltages of P1 and P2 are equal, Gate voltages of P1 and P2 are equal, and because the Gate voltage of P2 is equal to the voltage of the resistor R1, the Gate voltage of P1 is equal to the voltage of the resistor R1. So that the currents in both branches of the current mirror are equal to
Figure BDA0002640745870000051
The output current of P5 can be designed according to the current mirror ratio to produce a current Islope proportional to Vslope in conjunction with fig. 1, the module produces a ramp voltage Islope R9, which is superimposed on the CS pin.
The current mode BOOST converter provided by the invention has wide input voltage, is easy to reduce output ripple waves, eliminates subharmonic oscillation, and is convenient to adjust loop stability.
It should be noted that the above-mentioned embodiments are not intended to limit the scope of the present invention, and all equivalent modifications and substitutions based on the above-mentioned technical solutions are within the scope of the present invention as defined in the claims.

Claims (6)

1. A current mode controlled BOOST converter is characterized by comprising a control IC and peripheral circuits.
2. The current mode controlled BOOST converter according to claim 1, wherein said peripheral circuit comprises: VIN is the input voltage of the system; VOUT is the output voltage of the system; l1 is an inductor; d1 is a freewheeling diode; c0 is an output filter capacitor; an N1 power switch tube; c1 is the VCC external pin capacitor of IC; r1 is a resistance, connected with the RT pin of IC, used to control the system working frequency; r2, C2 and C3 are FB pin and COMP pin compensation networks of the IC and play a role in determining the stability of the system; r3 is a current sampling resistor; r4 and R5 form a sampling network of the output voltage, and the proportion of the sampling network determines the height of the output voltage.
3. The current-mode controlled BOOST converter according to claim 2, wherein the control IC comprises: a Regulator module, OSC is an oscillator module, a Reference module, Slope is a Slope compensation module, MaxDuty is a maximum duty cycle module, AMP is an operational amplifier, a comparator CMP1, a comparator CMP2 and a Logic module, wherein VIN pin generates VCC voltage through the Regulator; VCC generates each Reference voltage through a Reference module; the input end of OSC is RT, the output end is divided into two paths, one path of output is sent to the S end of an RS trigger, the other path of output is sent to a slice and a Maxswitch respectively, the positive input end of AMP is a 1.25V reference, the negative input end is an FB pin, the output end is a COMP pin, the COMP is connected with a 5V internal power supply through a resistor R6, the COMP is connected with a resistor R7 after being subjected to voltage reduction by 1.25V, the other end of the resistor R7 is connected with a resistor R8 and the negative input end of a comparator CMP1, the other end of the resistor R8 is grounded, the positive input end of a comparator CMP1 is connected with the output of the slice, the comparator CMP1 outputs to a Logic module, the positive input end of the comparator 2 is a 0.5V reference voltage, the negative input end of the CMP2 is connected with the output of the slice, the output of the slice is connected with the resistor R9, the other end of the resistor R9 is connected with a pin, the CS end of the comparator 2 outputs to the Logic module, the output of the Logic module is sent to a trigger RS module, the output of, the output of Driver is the OUT pin.
4. The current-mode controlled BOOST converter according to claim 3, wherein the Regulator is a power supply module, and generates a medium voltage power source VCC inside the IC from the high voltage power source VIN, and the medium voltage power source VCC is mainly used for generating a voltage 5V power source inside the IC and providing power for the driving module; the Reference module generates an internal low-voltage 5V power supply and Reference voltages of 1.25V and 0.5V; the OSC is an oscillator module, the external resistor of the RT pin is convenient for adjusting the frequency of the oscillator, the oscillator module generates a clock signal and a sawtooth wave signal, the clock signal is sent to the RS trigger and used for controlling the conduction of each period, and the sawtooth wave signal is respectively sent to the Slope compensation module Slope and the maximum duty ratio module MaxTracty; the Slope is a Slope compensation module which converts a voltage signal of a sawtooth wave into a current of the sawtooth wave, the sawtooth wave current flows through a resistor R9 to generate a Slope voltage, and the Slope voltage is superposed on a CS pin; the Maxswitch is a maximum duty ratio module, and because a slope compensation function is integrated in the IC, the maximum duty ratio can be usually set to be more than 80%, if the CMP1 and the CMP2 are not turned over, the Maxswitch module controls the forced turn-off of the switching period; the AMP is an operational amplifier, the positive input end of the AMP is connected with 1.25V reference voltage, the negative input end of the AMP is connected with an FB pin, the output end of the AMP is connected with a COMP pin, and the operational amplifier is matched with an external C2, R2 and C3 compensation network and is used for detecting output voltage and adjusting the stability of a system; the output of the operational amplifier is subjected to voltage reduction of 1.25V, then is subjected to voltage division by R7 and R8, and then is sent to the negative input end of a comparator CMP1, and the positive input end of the comparator CMP1 is connected with a voltage obtained by superposing slope compensation on a CS pin; the CMP2 comparator has the function of overcurrent protection, when the detection current of the CS pin is overlarge and the voltage after the slope compensation is superposed exceeds 0.5V, the CMP2 is turned over, and the output is controlled to be turned off; the Logic module mainly processes three signals respectively from MaxDaty, CMP1 and CMP2, and determines which signal controls output to be turned off; the RS trigger controls the output to be switched on or switched off logically; driver is a driving module.
5. The current-mode controlled BOOST converter according to claim 4, wherein the Regulator is a power supply module comprising VIN and VCC are two pins of IC, R1 is a current limiting resistor, D1 is a clamping diode, N1 is a high voltage enhancement NMOS, C1 is a VCC external capacitor, and the medium voltage VCC can be expressed as: VCC is VD1-VGSThe VCC can be increased as needed and the clamping diode of D1 can be added in series.
6. The current mode controlled BOOST converter according to claim 3 or 4,the input signal of the Slope compensation module (Slope) is a sawtooth wave signal generated by an oscillator OSC, the output signal is a Slope current Islope, the symmetry of two paths is forced by P3, P4, N1 and N2, Vgs of N1 and N2 are equal, the Source voltages of N1 and N2 are equal due to the common Gate of N1 and N2, the Vsg of P1 and P2 are equal due to the symmetry, the Source voltages of P1 and P2 are equal, the Gate voltages of P1 and P2 are equal, and the Gate voltage of P2 is equal to the voltage of a resistor R1, the Gate voltage of P1 is equal to the voltage of a resistor R1; so that the currents in both branches of the current mirror are equal to
Figure FDA0002640745860000021
The output current of P5 may be designed according to the current mirror ratio to produce a current Islope proportional to Vslope, and the module produces a ramp voltage Islope R9, which is superimposed on the CS pin.
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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN113791665A (en) * 2021-09-22 2021-12-14 苏州锴威特半导体股份有限公司 Power factor correcting device and control chip
CN114696617A (en) * 2022-05-30 2022-07-01 苏州锴威特半导体股份有限公司 Step-down and push-pull cascade type DC-DC converter and control chip thereof

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN113791665A (en) * 2021-09-22 2021-12-14 苏州锴威特半导体股份有限公司 Power factor correcting device and control chip
CN114696617A (en) * 2022-05-30 2022-07-01 苏州锴威特半导体股份有限公司 Step-down and push-pull cascade type DC-DC converter and control chip thereof

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