Switching power supply device
View Patent ↗The peak current flowing to the switching device drops in a no-load state with PWM control, but because the number of switching operations is constant regardless of the load, further reducing power consumption is difficult. The switching power supply device has a PWM signal generator for generating a PWM signal, a switching device Q 1 for switching the first supply voltage VIN based on the PWM signal, converters for outputting the difference between a second supply voltage and a reference voltage as a difference signal, and an intermittent oscillation control circuit for stopping the switching operation of the first switching device when the difference signal is less than a predetermined first threshold value (Vp 1 ). The PWM signal generator changes the pulse width based on the difference signal to generate the PWM signal.
1. A switching power supply device comprising:
a first source voltage supply arrangement operable to supply a first supply voltage;
a PWM signal generator operable to generate a PWM signal;
a first switching arrangement operable to switch the first supply voltage based on the PWM signal;
a converter operable to convert the switched first supply voltage to a second supply voltage;
a difference signal detector operable to output the difference between the second supply voltage and a predetermined reference voltage as a difference signal;
an intermittent controller operable to stop the switching operation of the first switching arrangement when the difference signal is less than or equal to a first threshold value;
a current converter operable to convert the difference signal to a current signal; and
a voltage converter operable to convert the current-converted difference signal to a voltage signal;
wherein the PWM signal generator varies the pulse width of the PWM signal based on the voltage-converted difference signal and generates the PWM signal.
2. The switching power supply device described in claim 1 , further comprising:
a first regulator operable to convert the first supply voltage to a predetermined third supply voltage, and to supply the third supply voltage to the PWM signal generator and voltage converter; and
a second regulator operable to convert the second supply voltage to a predetermined fourth supply voltage, and to supply the fourth supply voltage to the difference signal detector and current converter.
3. The switching power supply device described in claim 2 , further comprising:
a first capacitor connected to the output node of the first regulator.
4. The switching power supply device described in claim 1 , further comprising:
an inversion signal generator operable to generate an inverted signal of the PWM signal; and
a second switching arrangement connected to the first switching arrangement;
wherein the second switching arrangement switches based on the inversion signal.
5. The switching power supply device described in claim 2 , wherein the second regulator converts the first supply voltage to the fourth supply voltage.
6. The switching power supply device described in claim 1 , wherein the intermittent controller restarts the switching operation when the difference signal goes to a second threshold value or above while the switching operation is stopped.
7. The switching power supply device described in claim 2 , further comprising:
a circuit having a first diode and a zener diode connected in series;
wherein the series circuit converts the second supply voltage to the third supply voltage.
8. The switching power supply device described in claim 2 , further comprising:
a second diode connected to an input terminal of the voltage converter.
9. The switching power supply device described in claim 1 , wherein the first switching arrangement is a high voltage transistor.
10. The switching power supply device described in claim 1 , wherein the converter comprises a third diode, a coil, and an output capacitor.
11. The switching power supply device described in claim 1 , further comprising an overcurrent protection circuit.
12. The switching power supply device described in claim 1 , further comprising an overheating protection circuit.
13. The switching power supply device described in claim 1 , wherein the converter outputs a second supply voltage of the same polarity as the first supply voltage.
14. The switching power supply device described in claim 1 , wherein the converter outputs a second supply voltage of opposite polarity to the first supply voltage.
15. A switching power supply device comprising:
a first source voltage supply arrangement operable to supply a first supply voltage;
a PWM signal generator operable to generate a PWM signal;
a first switching arrangement operable to switch the first supply voltage based on the PWM signal;
a converter operable to convert the switched first supply voltage to a second supply voltage;
a difference signal detector operable to output the difference between the second supply voltage and a predetermined reference voltage as a difference signal;
a current converter operable to convert the difference signal to a current signal;
a voltage converter operable to convert the current signal to a voltage-converted difference signal;
a first regulator operable to convert the first supply voltage to a predetermined third supply voltage, and to supply the third supply voltage to the PWM signal generator and voltage converter; and
a second regulator operable to convert the second supply voltage to a predetermined fourth supply voltage, and to supply the fourth supply voltage to the difference signal detector and current converter;
wherein the PWM signal generator varies a pulse width of the PWM signal based on the voltage-converted difference signal and generates the PWM signal.
16. The switching power supply device described in claim 15 , further comprising:
a first capacitor connected to the output node of the first regulator.
17. The switching power supply device described in claim 15 , further comprising:
an inversion signal generator operable to generate an inverted signal of the PWM signal; and
a second switching arrangement connected to the first switching arrangement;
wherein the second switching arrangement switches based on the inversion signal.
18. The switching power supply device described in claim 15 , wherein the second regulator converts the first supply voltage to the fourth supply voltage.
19. The switching power supply device described in claim 15 , further comprising an intermittent controller operable to stop the switching operation of the first switching arrangement when the difference signal is less than or equal to a first threshold value.
20. The switching power supply device described in claim 19 , wherein the intermittent controller restarts the switching operation when the difference signal goes to a second threshold value or above while the switching operation is stopped.
21. The switching power supply device described in claim 15 , further comprising:
a circuit having a first diode and a zener diode connected in series;
wherein the series circuit converts the second supply voltage to the third supply voltage.
22. The switching power supply device described in claim 15 , further comprising:
a second diode connected to an input terminal of the voltage converter.
23. The switching power supply device described in claim 15 , wherein the first switching arrangement is a high voltage transistor.
24. The switching power supply device described in claim 15 , wherein the converter comprises a third diode, a coil, and an output capacitor.
25. The switching power supply device described in claim 15 , further comprising an overcurrent protection circuit.
26. The switching power supply device described in claim 15 , further comprising an overheating protection circuit.
27. The switching power supply device described in claim 15 , wherein the converter outputs a second supply voltage of the same polarity as the first supply voltage.
28. The switching power supply device described in claim 15 , wherein the converter outputs a second supply voltage of opposite polarity to the first supply voltage.