Highly integrated current mode PWM controller

Abstract

A highly integrated current mode PWM controller disclosed by the present invention comprises a reference power supply, a Vcc undervoltage limiter, an oscillator, a PWM latch, an error amplifier, a driver and a current detection comparator, one end of the reference power supply is electrically connected with the Vcc undervoltage limiter, one end of the oscillator is electrically connected with the PWM latch, one end of the PWM latch is electrically connected with the driver, and the other end of the PWM latch is electrically connected with the error amplifier. The current mode PWM controller has the advantages that the defects that a voltage control type pulse width modulation switch voltage-stabilized power supply is slow in frequency response and low in voltage regulation rate and load regulation rate can be stably overcome by the aid of the designed current mode PWM controller, and the voltage-stabilized power supply is high in voltage regulation rate and load regulation rate. The circuit is simple in structure, low in cost, small in size and easy to implement, and has a great development prospect.

Description

Technical Field

[0001] The present invention relates to the technical field of power electronics control, and particularly relates to a highly integrated current-mode PWM controller. Background Art

[0002] In many power electronics application scenarios such as switched-mode power supplies and motor drives, the PWM controller is a core component. The traditional PWM controller has poor integration, and each functional module is relatively scattered. Modules such as current detection, error amplification, and PWM signal generation are independent of each other. This not only leads to a significant increase in the hardware cost of the system, but also occupies a large amount of circuit board space, resulting in a large overall volume, which is not conducive to the miniaturization development of equipment. At the same time, the connection of numerous external components increases the risk of signal transmission interference, reduces the reliability and stability of the system. In the face of load mutations and input voltage fluctuations, the traditional controller has a slow dynamic response and cannot adjust the output accurately and in a timely manner, resulting in a decrease in power supply efficiency and affecting the normal operation of the equipment. In addition, its complex design and debugging process also increase the development difficulty and cycle, and it is difficult to meet the requirements of modern high-efficiency and intelligent power systems. Therefore, a highly integrated current-mode PWM controller is provided to solve the above problems. Summary of the Invention

[0003] To solve the problems raised in the above background art, the technical solution adopted by the present invention to solve the technical problems is: a highly integrated current-mode PWM controller, which includes: a reference power supply, a Vcc undervoltage limit, an oscillator, a PWM latch, an error amplifier, a driver, and a current detection comparator. One end of the reference power supply is electrically connected to the Vcc undervoltage limit, one end of the oscillator is electrically connected to the PWM latch, one end of the PWM latch is electrically connected to the driver, the other end of the PWM latch is electrically connected to the current detection comparator, and the error amplifier is electrically connected to the reference power supply.

[0004] As a preferred technical solution of the present invention, one end of the Vcc undervoltage limit is electrically connected to a first triode, and a second triode is connected to one end of the first triode. Both the first triode and the second triode are connected to one end of the driver.

[0005] As a preferred technical solution of the present invention, a first zener diode is connected between the Vcc undervoltage limit and one end of the first triode. One end of the first zener diode is connected to pin G. Pin G is the DC power supply input terminal, which has undervoltage and overvoltage lock functions, and the power consumption is 15 mW.

[0006] As a preferred technical solution of the present invention, one end of the first triode and the second triode is electrically connected to pin F. Pin F is a push-pull output terminal, and the rise or fall time is only 50 ns, and the driving ability is 1 A.

[0007] As a preferred technical solution of the present invention, one end of the second triode is electrically connected to a pin E, and the pin E is a common ground terminal. One end of the oscillator is electrically connected to a pin D, and the pin D is a timing terminal.

[0008] As a preferred technical solution of the present invention, one end of the current detection comparator is connected to a pin C, and the pin C is a current detection input terminal. When the detected voltage exceeds V, the pulse width is reduced to make the power supply in an intermittent working state.

[0009] As a preferred technical solution of the present invention, one end of the error amplifier is connected to a pin B, and the pin B is the output terminal of the error amplifier. External resistance-capacitance elements are used to improve the gain and frequency characteristics of the error amplifier. The other end of the error amplifier is connected to a pin A, and the pin A is a feedback voltage input terminal. The voltage of the pin A is compared with the 1V reference voltage at the in-phase terminal of the error amplifier to generate an error voltage to control the pulse width.

[0010] As a preferred technical solution of the present invention, one end of the reference power supply is connected to a pin H, and the pin H is a reference voltage output terminal, and the load capacity is 50 mA.

[0011] As a preferred technical solution of the present invention, a first diode, a second diode, and a first resistor are connected in series in the circuit between the error amplifier and the current detection comparator. A second resistor and a second zener diode are connected in the circuit between the first resistor and the current detection comparator.

[0012] As a preferred technical solution of the present invention, a third resistor is connected in the circuit between the reference power supply and the pin H, and a fourth resistor is connected in the circuit between the reference power supply and the error amplifier.

[0013] The present invention has the following advantages: This article uses the designed current-mode PWM controller to stably overcome the disadvantages of slow frequency response, low voltage regulation rate, and low load regulation rate of the voltage-controlled pulse-width modulation switching power supply. The circuit structure is simple, the cost is low, the volume is small, and it is easy to implement, and it has great development prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 is a schematic diagram of the operation circuit of the PWM controller of the preferred embodiment of the present invention;

[0015] Figure 2 is a schematic diagram of the application power circuit of the PWM controller of the preferred embodiment of the present invention.

[0016] Description of the reference numerals: 1, reference power supply; 2, Vcc undervoltage limit; 3, oscillator; 4, PWM latch; 5, driver; 6, current detection comparator; 7, error amplifier; 8, first triode; 9, second triode; 10, first zener diode; 11, pin G; 12, pin F; 13, pin E; 14, pin D; 15, pin C; 16, pin B; 17, pin A; 18, pin H; 19, first diode; 20, second diode; 21, first resistor; 22, second resistor; 23, second zener diode; 24, third resistor; 25, fourth resistor. Detailed implementation manners

[0017] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention. Many specific details are set forth in the following description in order to fully understand the present invention. However, the present invention may be implemented in other ways different from those described herein. Therefore, the protection scope of the present invention is not limited by the specific embodiments disclosed below.

[0018] In order to more clearly understand the above objects, features and advantages of the present invention, the present invention will be further described in detail below with reference to the drawings and specific implementation manners.

[0019] Please refer to Figure 1 , a highly integrated current-mode PWM controller of the present invention includes: a reference power supply 1, a Vcc undervoltage limit 2, an oscillator 3, a PWM latch 4, an error amplifier 7, a driver 5, and a current detection comparator 6. One end of the reference power supply 1 is electrically connected to the Vcc undervoltage limit 2, one end of the oscillator 3 is electrically connected to the PWM latch 4, one end of the PWM latch 4 is electrically connected to the driver 5, the other end of the PWM latch 4 is electrically connected to the current detection comparator 6, and the error amplifier 7 is electrically connected to the reference power supply 1.

[0020] Among them, one end of the Vcc undervoltage limit 2 is electrically connected to the first triode 8. One end of the first triode 8 is connected to the second triode 9. Both the first triode 8 and the second triode 9 are connected to one end of the driver 5. One end of the Vcc undervoltage limit 2 and the first triode 8 are connected to a first zener diode 10. One end of the first zener diode is connected to the pin G11. The pin G11 is the DC power supply terminal, with undervoltage and overvoltage lockout functions, and the power consumption is 15 mW. One end of the first triode 8 and the second triode 9 are electrically connected to the pin F12. The pin F12 is a push-pull output terminal, and the rise or fall time is only 50 ns. The driving ability of the driver 5 is 1 A. One end of the second triode 9 is electrically connected to the pin E13. The pin E13 is the common ground terminal. One end of the oscillator 3 is electrically connected to the pin D14. The pin D14 is the timing terminal.

[0021] Among them, one end of the current detection comparator 6 is connected to the pin C15. The pin C15 is the current detection input terminal. When the detected voltage exceeds 1 V, the pulse width is reduced to make the power supply operate in an intermittent state. One end of the error amplifier 7 is connected to the pin B16. The pin B16 is the output terminal of the error amplifier 7. External resistor-capacitor elements are used to improve the gain and frequency characteristics of the error amplifier 7. The other end of the error amplifier 7 is connected to the pin A17. The pin A17 is the feedback voltage input terminal. And the voltage of the pin A17 is compared with the 2.5 V reference voltage at the non-inverting terminal of the error amplifier 7 to generate an error voltage to control the pulse width. One end of the reference power supply 1 is connected to the pin H18. The pin H18 is the reference voltage output terminal, and the load capacity is 50 mA. A first diode 19, a second diode 20 and a first resistor 21 are connected in series in the circuit between the error amplifier 7 and the current detection comparator 6. A second resistor 22 and a second zener diode 23 are connected to the circuit between the first resistor 21 and the current detection comparator 6. A third resistor 24 is connected to the circuit between the reference power supply 1 and the pin H18. A fourth resistor 25 is connected to the circuit between the reference power supply 1 and the error amplifier 7.

[0022] Combined with Figure 2It is a switching power supply circuit composed of an integrated current mode PWM controller. Electromagnetic interference is filtered by C1 and L1, and the negative temperature coefficient thermistor Rt1 limits the current. After VC rectification and C2 filtering, the resistor R1 and potentiometer RP1 step down the voltage and add it to the power supply terminal ⑦ pin (pin G11) of the PWM controller to provide the starting voltage for the PWM controller. After the circuit is started, the rectified and filtered voltage of the auxiliary winding ③ pin (pin C15) and ④ pin (pin D14) of the transformer provides the normal working voltage for the PWM controller on the one hand, and on the other hand, it is added to the inverting input terminal ② pin (pin B16) of the error amplifier through the voltage division of R1 and R4 to provide the negative feedback voltage for the PWM controller. The rule is that the higher the voltage of this pin, the smaller the duty cycle of the driving pulse, so as to stabilize the output voltage. The oscillation frequency is determined by the ④ pin (pin D14) and the external R6 and C8 of the pin. The maximum value of the oscillation frequency can reach 500KHz. R5 and C6 are used to improve the gain and frequency characteristics. The square wave signal output from pin ⑥ (pin F12) drives the MOS FEF power tube after being divided by R7 and R8. The energy of pins ① and ② of the primary winding of the transformer is transferred to the secondary windings. After rectification and filtering, DC voltages of different values ​​are output for use by the load. Resistor R10 is used for current detection. After being filtered by R9 and C9, it is sent to pin ③ (pin C15) of the PWM controller to form a current feedback loop. Therefore, the power supply composed of the PWM controller is a double closed-loop control system with very high voltage stability. When the voltage of pin ③ (pin C15) of the PWM controller is higher than 1V, the oscillator stops oscillating to protect the power tube from being damaged by overcurrent.

[0023] The above shows and describes the basic principles and main features of the present invention and the advantages of the present invention. It is obvious to those skilled in the art that the present invention is not limited to the details of the above exemplary embodiments, and the present invention can be implemented in other specific forms without departing from the spirit or basic features of the present invention. Therefore, no matter from which point of view, the embodiments should be regarded as exemplary and non-restrictive. The scope of the present invention is defined by the attached claims rather than the above description, and it is intended that all changes falling within the meaning and scope of the equivalent elements of the claims are included in the present invention. Any figure mark in the claims should not be regarded as limiting the claims involved.

[0024] Other parts of the present invention not described in detail belong to the prior art and will not be described in detail here.

[0025] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A highly integrated current mode PWM controller, characterized in that: include: A reference power supply (1), a Vcc undervoltage limiter (2), an oscillator (3), a PWM latch (4), an error amplifier (7), a driver (5) and a current detection comparator (6), wherein one end of the reference power supply (1) is electrically connected to the Vcc undervoltage limiter (2), one end of the oscillator (3) is electrically connected to the PWM latch (4), one end of the PWM latch (4) is electrically connected to the driver (5), the other end of the PWM latch (4) is electrically connected to the current detection comparator (6), and the error amplifier (7) is electrically connected to the reference power supply (1).

2. The highly integrated current mode PWM controller according to claim 1, characterized in that: One end of the Vcc undervoltage limiter (2) is electrically connected to a first transistor (8), one end of the first transistor (8) is connected to a second transistor (9), and both the first transistor (8) and the second transistor (9) are connected to one end of the driver (5).

3. The highly integrated current mode PWM controller according to claim 1, characterized in that: The Vcc undervoltage limiter (2) and one end of the first transistor (8) are connected to a first voltage stabilizing diode (10), one end of the first voltage stabilizing diode is connected to a pin G (11), the pin G (11) is a DC power supply terminal, has undervoltage and overvoltage locking functions, and has a power consumption of 15 mW.

4. The highly integrated current mode PWM controller according to claim 2, characterized in that: One end of the first transistor (8) and the second transistor (9) are electrically connected to a pin F (12), and the pin F (12) is a push-pull output terminal, the rise or fall time is only 50ns, and the driving (5) capability is 1A.

5. The highly integrated current mode PWM controller according to claim 1, characterized in that: One end of the second transistor (9) is electrically connected to a pin E (13), and the pin E (13) is a common ground terminal. One end of the oscillator (3) is electrically connected to a pin D (14), and the pin D (14) is a timing terminal.

6. The highly integrated current mode PWM controller according to claim 1, characterized in that: One end of the current detection comparator (6) is connected to a pin C (15), which is a current detection input terminal. When the detection voltage exceeds 1V, the pulse width is reduced so that the power supply is in an intermittent working state.

7. The highly integrated current mode PWM controller according to claim 1, characterized in that: One end of the error amplifier (7) is connected to a pin B (16), which is the output end of the error amplifier (7). The external resistor and capacitor are used to improve the gain and frequency characteristics of the error amplifier (7). The other end of the error amplifier (7) is connected to a pin A (17), which is the feedback voltage input end. The voltage of the pin A (17) is compared with a 2.5V reference voltage at the in-phase end of the error amplifier (7) to generate an error voltage to control the pulse width.

8. The highly integrated current mode PWM controller according to claim 1, characterized in that: One end of the reference power supply (1) is connected to a pin H (18), and the pin H (18) is a reference voltage output end with a load capacity of 50 mA.

9. The highly integrated current mode PWM controller according to claim 1, characterized in that: A first diode (19), a second diode (20) and a first resistor (21) are connected in series in a circuit between the error amplifier (7) and the current detection comparator (6); a second resistor (22) and a second voltage-stabilizing diode (23) are connected in a circuit between the first resistor (21) and the current detection comparator (6).

10. The highly integrated current mode PWM controller according to claim 1, characterized in that: A third resistor (24) is connected in a circuit between the reference power supply (1) and the pin H (18), and a fourth resistor (25) is connected in a circuit between the reference power supply (1) and the error amplifier (7).

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