CN-122001194-A - Signal generating circuit and switching power supply

Abstract

The application discloses a signal generating circuit and a switching power supply. The signal generating circuit of the embodiment of the application is applied to a switching power supply. The signal generating circuit comprises a ramp wave generating module, a spread spectrum control module and a signal selecting module. The ramp wave generating module is connected with the signal selecting module and is used for generating source current according to the input voltage and outputting a ramp wave signal to the signal selecting module according to the source current. The spread spectrum control module is connected with the oblique wave generation module and is used for adjusting the source current so as to control the slope of the oblique wave. The signal selection module is used for determining a clock signal according to the ramp signal and the input voltage. Therefore, the intensity of electromagnetic interference can be reduced, the stability of a clock signal is improved, and the influence of the electromagnetic interference on the stability of the switching power supply is reduced.

Inventors

• LIU PENGZHI
• LI JIN

Assignees

• 深圳市智融微电子有限公司

Dates

Publication Date

20260508

Application Date

20241105

Claims (10)

1. 1. The signal generation circuit is characterized by being applied to a switching power supply, and comprises a ramp wave generation module, a spread spectrum control module and a signal selection module; the ramp wave generation module is connected with the signal selection module and is used for generating source current according to input voltage and outputting a ramp wave signal to the signal selection module according to the source current; The spread spectrum control module is connected with the oblique wave generation module and is used for adjusting the source current so as to control the slope of the oblique wave signal; The signal selection module is used for determining a clock signal according to the ramp signal and the input voltage.
2. 2. The signal generating circuit of claim 1, wherein the ramp generating module comprises a first ramp generating module and a second ramp generating module; The first ramp wave generation module is used for generating a first source current according to an input power supply voltage and outputting a first ramp wave signal to the signal selection module according to the first source current; The second ramp wave generating module is used for generating a second source current according to the input battery voltage and outputting a second ramp wave signal to the signal selecting module according to the second source current.
3. 3. The signal generation circuit of claim 1, wherein the ramp generation module comprises a ramp resistor, a first current mirror unit, a ramp capacitor, and a transistor, the ramp resistor, the first current mirror unit, and the ramp capacitor being connected in sequence, the transistor being connected between the first current mirror unit and the ramp capacitor, the signal selection module further configured to output the clock signal to the ramp generation module; the first current mirror unit is used for mirroring input current according to a preset proportion to obtain the source current, wherein the input current is generated by the input voltage through the ramp resistor; the ramp capacitor is used for charging based on the source current so as to generate the ramp signal; the transistor is used for switching on/off states according to the clock signal so that the ramp wave signal is a sawtooth wave signal.
4. 4. The signal generating circuit according to claim 1, wherein the signal selecting module is connected to the spread spectrum control module, the signal selecting module further configured to output the clock signal to the spread spectrum control module, the spread spectrum control module including a first switching unit, a switch selecting unit, a second switching unit, and a second current mirror unit; The first switch unit is used for switching on/off states according to a spread spectrum switch signal so as to control the working state of the spread spectrum control module, wherein the spread spectrum switch signal is sent to the spread spectrum control module by a main control circuit of the switch power supply; the switch selection unit is used for determining a switch selection signal of the second switch unit according to the clock signal and the spread spectrum switch signal; the second switch unit is used for switching on/off states according to the switch selection signal; The second current mirror unit is used for generating at least one spread spectrum current according to the on-off state of the second switch unit and outputting the spread spectrum current so as to regulate the source current.
5. 5. The signal generating circuit of claim 2, wherein the signal selection module comprises a first signal selection module, a second signal selection module, and a third signal selection module; The first signal selection module is used for determining a working mode signal of the switching power supply according to the power supply voltage, the battery voltage and a charging and discharging signal, wherein the charging and discharging signal is sent to the signal selection module by a main control circuit of the switching power supply; the second signal selection module is used for determining the clock signal according to the power supply voltage, the battery voltage, the first ramp wave signal, the second ramp wave signal and the charge-discharge signal; The third signal selection module is used for determining a voltage reduction ramp signal and a voltage increase ramp signal according to the first ramp signal, the second ramp signal and the charge-discharge signal.
6. 6. The signal generating circuit of claim 5, wherein the first signal selection module comprises a first comparator and a logic gate unit connected to each other; The first comparator is configured to compare the power supply voltage with the battery voltage; The logic gate unit is used for outputting a working mode signal of the switching power supply according to the comparison result of the first comparator and the charging and discharging signals.
7. 7. The signal generating circuit according to claim 5, wherein the second signal selecting module includes a second comparator, a third switching unit, and a fourth switching unit, the third switching unit and the fourth switching unit being connected to the second comparator, respectively; The third switch unit is used for connecting different input ends according to the charge-discharge signals, selecting the first ramp signal or the second ramp signal and inputting the first ramp signal or the second ramp signal into the second comparator; the fourth switch unit is used for connecting different input ends according to the charge-discharge signals, selecting the power supply voltage or the battery voltage and inputting the power supply voltage or the battery voltage into the second comparator; The second comparator is used for outputting the clock signal according to the selection results of the third switch unit and the fourth switch unit.
8. 8. The signal generating circuit according to claim 7, wherein the charge-discharge signal includes a first charge-discharge signal and a second charge-discharge signal, the third switching unit is configured to select the first ramp signal, the fourth switching unit is configured to select the power supply voltage, and the second comparator is configured to determine the clock signal based on a relationship between the first ramp signal and the power supply voltage and output the clock signal; When the charge-discharge signal is the second charge-discharge signal, the third switch unit is used for selecting the second ramp signal, the fourth switch unit is used for selecting the battery voltage, and the second comparator is used for determining the clock signal according to the relationship between the second ramp signal and the battery voltage and outputting the clock signal.
9. 9. The signal generating circuit of claim 5, wherein the third signal selecting module comprises a fifth switching unit and a sixth switching unit; The fifth switch unit is used for connecting different input ends according to the charge-discharge signals, and selecting the first oblique wave signal or the second oblique wave signal as the voltage-reduction oblique wave signal to output; The sixth switch unit is used for connecting different input ends according to the charge-discharge signals, and selecting the first ramp signal or the second ramp signal as the boost ramp signal to output.
10. 10. A switching power supply, comprising: the signal generating circuit of any one of claims 1-9; The main control circuit is used for outputting a spread spectrum switch signal and a charge-discharge signal to the signal generating circuit; the PWM control circuit is connected with the signal generation circuit; And the buck-boost circuit is connected with the PWM control circuit.

Description

Signal generating circuit and switching power supply Technical Field The present application relates to the field of integrated circuits, and in particular, to a signal generating circuit and a switching power supply. Background A switching power supply is a power supply apparatus that performs electric power conversion by a high-frequency switching device. In a switching power supply, a large amount of electromagnetic interference (Electromagnetic Interference, electromagnetic interference (EMI)) can be generated in the switching process of a switching tube, the electromagnetic interference can cause clock signals to fluctuate, the work of surrounding electronic circuits can be influenced, and the stability of the circuits is obviously influenced. Disclosure of Invention The embodiment of the application provides a signal generating circuit and a switching power supply, which aim to solve at least one technical problem. The signal generation circuit of the embodiment of the application is applied to a switching power supply and comprises a ramp wave generation module, a spread spectrum control module and a signal selection module; the ramp wave generation module is connected with the signal selection module and is used for generating source current according to input voltage and outputting a ramp wave signal to the signal selection module according to the source current; The spread spectrum control module is connected with the oblique wave generation module and is used for adjusting the source current so as to control the slope of the oblique wave signal; The signal selection module is used for determining a clock signal according to the ramp signal and the input voltage. In certain embodiments, the ramp generating module comprises a first ramp generating module and a second ramp generating module; The first ramp wave generation module is used for generating a first source current according to an input power supply voltage and outputting a first ramp wave signal to the signal selection module according to the first source current; The second ramp wave generating module is used for generating a second source current according to the input battery voltage and outputting a second ramp wave signal to the signal selecting module according to the second source current. In some embodiments, the ramp generating module includes a ramp resistor, a first current mirror unit, a ramp capacitor, and a transistor, where the ramp resistor, the first current mirror unit, and the ramp capacitor are sequentially connected, and the transistor is connected between the first current mirror unit and the ramp capacitor, and the signal selecting module is further configured to output the clock signal to the ramp generating module; the first current mirror unit is used for mirroring input current according to a preset proportion to obtain the source current, wherein the input current is generated by the input voltage through the ramp resistor; the ramp capacitor is used for charging based on the source current so as to generate the ramp signal; The transistor is used for switching on/off state according to the clock signal so as to enable the ramp wave signal to be a sawtooth wave signal In some embodiments, the signal selection module is connected to the spread spectrum control module, and the signal selection module is further configured to output the clock signal to the spread spectrum control module, where the spread spectrum control module includes a first switch unit, a switch selection unit, a second switch unit, and a second current mirror unit; The first switch unit is used for switching on/off states according to a spread spectrum switch signal so as to control the working state of the spread spectrum control module, wherein the spread spectrum switch signal is sent to the spread spectrum control module by a main control circuit of the switch power supply; the switch selection unit is used for determining a switch selection signal of the second switch unit according to the clock signal and the spread spectrum switch signal; the second switch unit is used for switching on/off states according to the switch selection signal; The second current mirror unit is used for generating at least one spread spectrum current according to the on-off state of the second switch unit and outputting the spread spectrum current so as to regulate the source current. In certain embodiments, the signal selection module comprises a first signal selection module, a second signal selection module, and a third signal selection module; The first signal selection module is used for determining a working mode signal of the switching power supply according to the power supply voltage, the battery voltage and a charging and discharging signal, wherein the charging and discharging signal is sent to the signal selection module by a main control circuit of the switching power supply; the second signal selection module is used for determining the clock sig