Hysteretic switching regulator

• US 20070145965A1
• Filed: 12/05/2006
• Published: 06/28/2007
• Est. Priority Date: 12/05/2005
• Status: Active Grant

• Current Assignee: Panasonic Semiconductor Solutions Co., Ltd. (Winbond Electronics Corporation)
• Original Assignee: Panasonic Corporation (Panasonic Holdings Corporation)
• Inventors: Ryu, Takashi, Yamamoto, Tamotsu, Koto, Masaaki, Oswald, Richard, Tanabe, Hirohisa
• Granted Patent: US 7,714,562 B2
• Time in Patent Office: Days
• US Class Current: 323/286
• CPC Class Codes: H02M 3/1563 without using an external clock H02M3/158 takes precedence

Abstract

A switching regulator circuit including a high-side switch and a low-side switch; an inductor having a first terminal coupled to a common terminal between the high-side switch and the low-side switch, and a second terminal coupled to an output terminal of the switching regulator circuit; a low-pass filter coupled to the first terminal of the inductor, where the low-pass filter is operative for generating a ramp signal based on the voltage signal present at the first terminal of the inductor; and a hysteretic comparator coupled to the low pass filter, where the hysteretic comparator receives the ramp signal as an input signal, and generates an output signal which is operative for controlling the operation of the high-side switch and the low-side switch.

Claims

1. A switching regulator circuit comprising:

a high-side switch and a low-side switch coupled in a series configuration;

an inductor having a first terminal coupled to a common terminal between said high-side switch and said low-side switch; and

a second terminal coupled to an output terminal of said switching regulator circuit;

a low-pass filter coupled to said first terminal of said inductor, said low-pass filter operative for generating a ramp signal based on the voltage signal present at said first terminal of said inductor;

a buffer circuit having an input terminal coupled to an output terminal of said low-pass filter; and

a hysteretic comparator coupled to said low pass filter via said buffer circuit, said hysteretic comparator receiving said ramp signal as an input signal, and generating an output signal which is operative for controlling the operation of said high-side switch and said low-side switch.

2. The switching regulator circuit of claim 1, wherein an amplitude of said ramp signal does not directly fluctuate with variations in the amount of current drawn by a load coupled to the switching regulator circuit.

3. The switching regulator circuit of claim 1, wherein said buffer circuit is operative for isolating said low-pass filter from said output terminal of said switching regulator circuit.

4. The switching regulator circuit of claim 3, further comprising a damping circuit having an input terminal coupled to an output terminal of said buffer circuit and an output terminal coupled to an input terminal of said hysteretic comparator, said damping circuit operative for sampling an output voltage at said output terminal of the switching regulator circuit and adjusting the level of said ramp signal input into said hysteretic comparator.

5. The switching regulator circuit of claim 1, wherein said low pass filter comprises a first resistor and a second resistor coupled in a series configuration and a capacitor coupled in parallel with said second resistor, said first resistor being coupled to said first terminal of said inductor and a first terminal of said second resistor.

6. The switching regulator circuit of claim 4, wherein said damping circuit further comprises a resistor network coupled to said output terminal of switching regulator circuit, said resistor network configured as a voltage divider so as to feedback a reduced value of the output voltage to the input of said hysteretic comparator.

7. The switching regulator circuit of claim 1, wherein said ramp signal is a triangular wave.

8. The switching regulator circuit of claim 1, wherein said low-side switch comprises an active diode.

9. A switching regulator circuit comprising:

a high-side switch and a low-side switch coupled in a series configuration;

an inductor having a first terminal coupled to a common terminal between said high-side switch and said low-side switch; and

a second terminal coupled to an output terminal of said switching regulator circuit;

a low-pass filter coupled to said first terminal of said inductor, said low-pass filter operative for generating a ramp signal based on the voltage signal present at said first terminal of said inductor;

a first buffer circuit having an input terminal coupled to an output terminal of said low-pass filter;

a damping circuit having a first input terminal coupled to an output terminal of said first buffer circuit, a second input terminal coupled to said output terminal of said switching regulator, and an output terminal;

a hysteretic comparator coupled to said output terminal of said damping circuit, said hysteretic comparator receiving said ramp signal as an input signal, and generating an output signal which is operative for controlling the operation of said high-side switch and said low-side switch;

a second buffer circuit which receives a reference voltage signal and the output signal generated by said hysteretic comparator as an input signal, and

a switching network coupled to an output of said second buffer, said switching network operative for coupling said output of said second buffer to said input of said first buffer if there is a change in the reference voltage signal.

10. The switching regulator circuit of claim 9, wherein said switching network comprises a first diode and a second diode coupled in parallel with one another, said first diode and said second diode capable of conducting current in opposite directions within the switching network.

11. The switching regulator circuit of claim 10, wherein each of said first diode and said second diode are formed utilizing active diodes.

12. The switching regulator circuit of claim 9, wherein an amplitude of said ramp signal does not directly fluctuate with variations in the amount of current drawn by a load coupled to the switching regulator circuit.

13. The switching regulator circuit of claim 9, wherein said buffer circuit is operative for isolating said low-pass filter from said output terminal of said switching regulator circuit.

14. The switching regulator circuit of claim 9, wherein said damping circuit is operative for sampling an output voltage at said output terminal of said switching regulator circuit and adjusting the level of said ramp signal input into said hysteretic comparator.

15. The switching regulator circuit of claim 9, wherein said low pass filter comprises a first resistor and a second resistor coupled in a series configuration and a capacitor coupled in parallel with said second resistor, said first resistor being coupled to said first terminal of said inductor and a first terminal of said second resistor.

16. The switching regulator circuit of claim 9, wherein said damping circuit further comprises a resistor network coupled to the output terminal of switching regulator circuit, said resistor network configured as a voltage divider so as to feedback a reduced value of the output voltage to the input of said hysteretic comparator.

17. The switching regulator circuit of claim 9, wherein said ramp signal is a triangular wave.

18. The switching regulator circuit of claim 9, wherein said low-side switch comprises an active diode.