A DC / DC converter clock frequency control circuit
By designing the clock co-frequency control circuit of DC/DC converter, synchronizing with the external clock is achieved by using microcontroller units, complementary push-pull circuits and PWM controllers, the problem of complex phase-locked loops in the prior art is solved, and a simple, flexible and fast clock co-frequency is achieved, and the stability and accuracy of the co-frequency signal is ensured.
Patent Information
- Application Number
- CN202421404114.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-06-19
- Publication Date
- 2025-04-11
- Estimated Expiration
- 2034-06-19
AI Technical Summary
The existing DC/DC converters realize the external clock synchronous function through phase-locked loops, which has the problem of complex circuits, long time and frequency jitter, resulting in insufficient accuracy of the same frequency signals.
A DC/DC converter clock co-frequency control circuit is designed, including a microcontroller unit, a complementary push-pull circuit and a PWM controller. Through the coupling of current limiting resistor and high-frequency capacitance, synchronization with the external clock is achieved, and the output impedance is reduced through the complementary push-pull circuit and the driving capability is enhanced.
It realizes that multiple DC/DC converters are connected in parallel or in series clocks at the same frequency. The circuit is simple, the implementation method is flexible, the clock is achieved at the same frequency for a short time, and the signal is stable and accurate at the same frequency, meeting the strict requirements of electromagnetic interference and switching noise.
Smart Images
Figure CN222750331U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to the technical field of DC / DC converters, in particular to a clock frequency synchronization control circuit for a DC / DC converter. Background Art
[0002] DC / DC converters are widely used in precision instruments and meters such as aerospace, ships, and computer stations due to their advantages such as light weight, small size, and high conversion efficiency. Since DC / DC converters usually operate at frequencies ranging from tens of kilohertz to hundreds of kilohertz, frequency-related problems such as electromagnetic interference and switching noise are inevitable. Especially in a system where multiple DC / DC converters are connected in parallel or in series, the difference frequency noise problem generated by each DC / DC converter is particularly prominent due to errors caused by component accuracy and production accuracy.
[0003] Since the working clock of the DC / DC converter is generally provided by an internal oscillator, a fixed resistor is often used to connect to the RT end of its internal PWM controller. However, the switching frequency provided by the fixed resistance value is fixed and cannot be changed at any time to adapt to different application environments. Therefore, for the DC / DC converter, an external clock is required to replace the internal clock generated by the oscillator as the working clock of the switching power supply to suppress the difference frequency noise and meet the application environment with strict requirements on electromagnetic interference and switching noise. At present, the external clock frequency synchronization function is generally achieved through a phase-locked loop, but the phase-locked loop circuit is relatively complex and not flexible enough, and the time required to achieve clock frequency synchronization is relatively long; in addition, due to the non-ideal characteristics of the phase-locked loop, there is frequency jitter, and the frequency synchronization signal is relatively inaccurate. Utility Model Content
[0004] In view of the fact that the existing DC / DC converter adopts a phase-locked loop method to realize the external frequency synchronization function, the circuit is complex, the time is long, and there is frequency jitter, which leads to the problem that the frequency synchronization signal is not accurate enough. The utility model provides a DC / DC converter clock frequency synchronization control circuit, which can realize clock frequency synchronization in a system of multiple DC / DC converters in parallel or series. The circuit is simple, the implementation method is flexible, the clock frequency synchronization is realized in a short time, and the frequency synchronization signal is stable and accurate.
[0005] The technical solution is as follows: a DC / DC converter clock frequency control circuit, characterized in that it includes a micro control unit, a complementary push-pull circuit and a PWM controller arranged inside the DC / DC converter, the PWM signal emitted by the micro control unit is connected to the input end of the complementary push-pull circuit through a current limiting resistor, the output end of the complementary push-pull circuit is coupled to the RT pin of the PWM controller through a high-frequency capacitor, and the PWM controller synchronizes with the external clock by applying a narrow pulse to its RT pin.
[0006] Its further characteristics are: the microcontroller unit comprises a single-chip microcomputer N1, the single-chip microcomputer N1 uses a single-chip microcomputer of model KF8F2020MB-S, the PWM controller comprises a PWM controller N2, and the PWM controller N2 uses a PWM controller of CYT5035;
[0007] The complementary push-pull circuit includes an NPN transistor Q1 and a PNP transistor Q2. Pin 1 of the single-chip microcomputer N1 is connected to one end of a resistor R1, one end of a capacitor C1 and a P5V1 power supply. The other end of the resistor R1 is connected to the P5V power supply. The other end of the capacitor C1 is grounded. Pin 5 of the single-chip microcomputer N1 is connected to one end of a resistor R3. The other end of the resistor R3 is connected to the base of the transistor Q1 and the base of the transistor Q2. The collector of the transistor Q1 is connected to the P5V1 power supply. The collector of the transistor Q2 is grounded. The emitter of the transistor Q1 is connected to the emitter of the transistor Q2. The first and second electrodes are connected to each other and then connected to one end of a capacitor C3. The other end of the capacitor C3 is connected to one end of a resistor R4 and pin 4 of the PWM controller N2. Pin 5 of the PWM controller N2 is connected to the other end of the resistor R4 and then grounded. Pin 15 of the PWM controller N2 is connected to one end of the capacitor C4 and grounded. Pin 19 of the PWM controller N2 is connected to the other end of the capacitor C4 and connected to a VREF power supply. Pin 16 of the PWM controller N2 is connected to one end of the capacitor C2 and one end of the resistor R2. The other end of the resistor R2 is connected to a P10V power supply, and the other end of the capacitor C2 is grounded.
[0008] After adopting the above structure, since the same-frequency PWM signal sent by the primary MCU is connected to the complementary push-pull circuit through the current-limiting resistor, the complementary push-pull circuit is coupled to the RT pin of the PWM controller through the high-frequency capacitor, and the PWM controller can synchronize with the external clock by applying a narrow pulse to its RT pin. When multiple DC / DC converters are connected in parallel or in series, a DC / DC converter clock same-frequency control circuit is adopted, and the same-frequency frequency can be flexibly adjusted by configuring the internal timer of the MCU, so that each DC / DC converter works at the same switching frequency, reducing the difference frequency interference caused by the accuracy of components and production accuracy. The complementary push-pull circuit can reduce the output impedance, enhance the output driving capability, and improve the anti-interference ability of the same-frequency signal, so as to meet the application environment with strict requirements on electromagnetic interference and switching noise. The circuit of the utility model is simple, the implementation method is flexible, the clock same-frequency implementation time is short, and the same-frequency signal is stable and accurate. BRIEF DESCRIPTION OF THE DRAWINGS
[0009] Figure 1 This is a circuit schematic diagram of the utility model. DETAILED DESCRIPTION
[0010] A DC / DC converter clock frequency control circuit comprises a microcontroller unit, a complementary push-pull circuit and a PWM controller arranged inside the DC / DC converter. The PWM signal emitted by the microcontroller unit is connected to the input end of the complementary push-pull circuit through a current limiting resistor. The output end of the complementary push-pull circuit is coupled to the RT pin of the PWM controller through a high-frequency capacitor. The PWM controller synchronizes with an external clock by applying a narrow pulse to its RT pin. The microcontroller unit includes a single-chip microcomputer N1, which uses a single-chip microcomputer of model KF8F2020MB-S; the PWM controller includes a PWM controller N2, which uses a PWM controller of CYT5035; the complementary push-pull circuit includes an NPN transistor Q1 and a PNP transistor Q2, the 1st pin of the single-chip microcomputer N1 is connected to one end of the resistor R1, one end of the capacitor C1 and the P5V1 power supply, the other end of the resistor R1 is connected to the P5V power supply, the other end of the capacitor C1 is grounded, the 5th pin of the single-chip microcomputer N1 is connected to one end of the resistor R3, the other end of the resistor R3 is connected to the base of the transistor Q1 and the base of the transistor Q2, the transistor Q1 The collector of the transistor Q2 is connected to the P5V1 power supply, the collector of the transistor Q2 is grounded, the emitter of the transistor Q1 is connected to the emitter of the transistor Q2 and then connected to one end of the capacitor C3, the other end of the capacitor C3 is connected to one end of the resistor R4 and pin 4 of the PWM controller N2, the 5th pin of the PWM controller N2 is connected to the other end of the resistor R4 and then grounded, the 15th pin of the PWM controller N2 is connected to one end of the capacitor C4 and grounded, the 19th pin of the PWM controller N2 is connected to the other end of the capacitor C4 and connected to the VREF power supply, the 16th pin of the PWM controller N2 is connected to one end of the capacitor C2 and one end of the resistor R2, the other end of the resistor R2 is connected to the P10V power supply, and the other end of the capacitor C2 is grounded.
[0011] The working principle of the utility model is as follows: the PWM controller N2 inside the DC / DC converter can be synchronized with the external clock by applying narrow pulses to its RT pin. The external clock must be at least 10% higher than the oscillation frequency set by the RT resistor R4. If the external clock frequency is less than the frequency set by the RT resistor R4, the PWM controller will not be able to synchronize the pulses, so the clock frequency pulse signal output by the microcontroller unit MCU is 10% higher than the oscillation frequency set by the RT resistor R4. In addition, the clock signal must be coupled to the RT pin through a 100pF capacitor C3 to ensure that the pulse width of RT is less than 60% of the clock cycle under all conditions. Outputting the clock frequency signal (PWM waveform) in the MCU usually requires several steps: configuring the relevant I / O of the MCU to the PWM output mode; configuring the clock source, frequency division coefficient, duty cycle and output enable of the PWM module; starting the PWM module. However, the driving current of the I / O port of the MCU is only 5mA, and it is necessary to cooperate with a complementary push-pull circuit to improve its driving capability. The complementary push-pull circuit composed of NPN+PNP with the same parameters is a common emitter output. At any time, only one transistor is turned on, so the conduction loss is small and the efficiency is high. When the input signal jumps from a low level to a high level, Q1 is turned on; when the input signal jumps from a high level to a low level, Q2 is turned on. The common emitter output of Q1 and Q2 can both inject current into the load end and extract current from the load end. This push-pull output not only improves the load capacity of the circuit, but also increases the switching speed.
[0012] The above are only preferred specific implementations of the utility model, but the protection scope of the utility model is not limited thereto. Any changes or substitutions that can be easily thought of by anyone familiar with the technology within the technical scope disclosed by the utility model should be included in the protection scope of the utility model. Therefore, the protection scope of the utility model should be based on the protection scope of the claims.
Claims
1. A DC / DC converter clock frequency control circuit, characterized in that: It includes a microcontroller unit, a complementary push-pull circuit and a PWM controller arranged inside a DC / DC converter. The PWM signal emitted by the microcontroller unit is connected to the input end of the complementary push-pull circuit through a current-limiting resistor. The output end of the complementary push-pull circuit is coupled to the RT pin of the PWM controller through a high-frequency capacitor. The PWM controller synchronizes with an external clock by applying a narrow pulse to its RT pin.
2. A method according to claim 1, characterized in that: The microcontroller unit includes a single-chip microcomputer N1, and the single-chip microcomputer N1 uses a single-chip microcomputer of model KF8F2020MB-S. The PWM controller includes a PWM controller N2, and the PWM controller N2 uses a PWM controller of CYT5035.
3. A method according to claim 1, characterized in that: The complementary push-pull circuit includes an NPN transistor Q1 and a PNP transistor Q2. Pin 1 of the single-chip microcomputer N1 is connected to one end of a resistor R1, one end of a capacitor C1 and a P5V1 power supply. The other end of the resistor R1 is connected to the P5V power supply. The other end of the capacitor C1 is grounded. Pin 5 of the single-chip microcomputer N1 is connected to one end of a resistor R3. The other end of the resistor R3 is connected to the base of the transistor Q1 and the base of the transistor Q2. The collector of the transistor Q1 is connected to the P5V1 power supply. The collector of the transistor Q2 is grounded. The emitter of the transistor Q1 is connected to the emitter of the transistor Q2. The first and second electrodes are connected to each other and then connected to one end of a capacitor C3. The other end of the capacitor C3 is connected to one end of a resistor R4 and pin 4 of the PWM controller N2. Pin 5 of the PWM controller N2 is connected to the other end of the resistor R4 and then grounded. Pin 15 of the PWM controller N2 is connected to one end of the capacitor C4 and grounded. Pin 19 of the PWM controller N2 is connected to the other end of the capacitor C4 and connected to a VREF power supply. Pin 16 of the PWM controller N2 is connected to one end of the capacitor C2 and one end of the resistor R2. The other end of the resistor R2 is connected to a P10V power supply, and the other end of the capacitor C2 is grounded.