Transmission voltage loss compensation circuit, compensation method, controlling chip and switching power supply

Patent metadata

Field	Value
Publication number	US-9413252-B2
Application number	US-201414246065-A
Country	US
Kind code	B2
Filing date	Apr 5, 2014
Priority date	Apr 15, 2013
Publication date	Aug 9, 2016
Grant date	Aug 9, 2016

Abstract

In one embodiment, a method of compensating for transmission voltage loss from a switching power supply, can include: (i) receiving a sampling signal that represents an output current of the switching power supply; (ii) delaying the sampling signal to generate a delayed sampling signal; (iii) converting the delayed sampling signal to generate a compensation signal; and (iv) regulating an output voltage of the switching power supply based on the compensation signal to compensate for the transmission voltage loss from the output voltage transmission to a load such that a voltage at the load is maintained as substantially consistent with an expected voltage at the load.

First claim

What is claimed is:

1. A method of compensating for transmission voltage loss from a switching power supply, the method comprising:
a) receiving, in a current feedback circuit, a feedback signal from a feedback terminal that is coupled to an auxiliary winding of said switching power supply, and a signal from a common node of a sampling resistor and a main switch of said switching power supply;
b) generating, by said current feedback circuit, a sampling signal that represents an output current of said switching power supply, wherein said sampling signal is generated from said feedback signal and said common node signal;
c) delaying, by a delay circuit, said sampling signal to generate a delayed sampling signal;
d) converting said delayed sampling signal to generate a compensation signal; and
e) regulating an output voltage of said switching power supply based on said compensation signal to compensate for said transmission voltage loss from said output voltage transmission to a load such that a voltage at said load is maintained as substantially consistent with an expected voltage at said load;
wherein said delay circuit comprises:
a) first and second switches coupled in series between said sampling signal and said delayed sampling signal, wherein said second switch is controllable by a clock signal, and said first switch is controllable by an inverted version of said clock signal;
b) a first capacitor coupled between a common node of said first and second switches and ground; and
c) a second capacitor a coupled between said delayed sampling signal and ground.

2. The method of claim 1 , wherein said compensation signal generation comprises:
a) converting said delay signal to a first current signal by a voltage-current conversion circuit;
b) generating an output voltage feedback signal by a resistor divider and said first current signal; and
c) using a voltage drop generated on said resistor divider as said compensation signal.

3. The method of claim 1 , wherein a signal other than said clock signal is connected to a gate of said main switch.

4. The method of claim 1 , wherein a capacitance of said second capacitor is far greater than a capacitance of said first capacitor.

5. The method of claim 4 , wherein said capacitance of said second capacitor is about 20 times greater than said capacitance of said first capacitor.

6. A transmission voltage loss compensation circuit configured for a switching power supply, the transmission voltage loss compensation circuit comprising:
a) a current feedback circuit configured to receive a feedback signal from a feedback terminal coupled to an auxiliary winding of said switching power supply, and a signal from a common node of a sampling resistor and a main switch of said switching power supply, and to generate a sampling signal that represents an output current of said switching power supply therefrom:
b) a delay circuit configured to delay said sampling signal to generate a delayed sampling signal;
c) a voltage-current conversion circuit configured to convert said delayed sampling signal to a first current signal, wherein said first current signal is coupled to said feedback terminal to generate a compensation signal; and
d) a controlling circuit having said current feedback circuit and said feedback terminal: and being configured to regulate an output voltage of said switching power supply based on said compensation signal to compensate for transmission voltage loss from said output voltage transmission to a load such that a voltage at said load is maintained as substantially consistent with an expected voltage at said load;
wherein said delay circuit comprises:
a) first and second switches coupled in series between said sampling signal and said delayed sampling signal, wherein said second switch is controllable by a clock signal, and said first switch is controllable by an inverted version of said clock signal;
b) a first capacitor coupled between a common node of said first and second switches and ground; and
c) a second capacitor a coupled between said delayed sampling signal and ground.

7. The transmission voltage loss compensation circuit of claim 6 , wherein said voltage-current conversion circuit comprises:
a) a first comparator configured to compare said delay signal against a first voltage signal, and to generate a first comparison signal; and
b) a third switch being controllable by said first comparison signal, and having a first power terminal coupled to said feedback terminal, and a second power terminal coupled to ground through a resistor, wherein a voltage at a common node of said third switch and said resistor is configured as said first voltage signal.

8. A switching power supply, comprising:
a) a power stage configured as a flyback converter; and
b) the transmission voltage loss compensation circuit of claim 6 .

9. The switching power supply of claim 8 , wherein said power stage comprises said auxiliary winding and a resistor divider coupled in parallel, and wherein an output terminal of said resistor divider is configured as said feedback terminal.

10. The transmission voltage loss compensation circuit of claim 6 , wherein said controlling circuit further comprises a voltage feedback circuit coupled to said feedback terminal.

11. The transmission voltage loss compensation circuit of claim 6 , wherein a signal other than said clock signal is connected to a gate of said main switch.

12. The transmission voltage loss compensation circuit of claim 6 , wherein an equivalent time constant of said delay circuit is related to a period of said clock signal.

13. The transmission voltage loss compensation circuit of claim 6 , wherein a capacitance of said second capacitor is far greater than a capacitance of said first capacitor.

14. The transmission voltage loss compensation circuit of claim 13 , wherein said capacitance of said second capacitor is about 20 times greater than said capacitance of said first capacitor.

15. The transmission voltage loss compensation circuit of claim 6 , further comprising a resistor divider coupled in parallel with said auxiliary winding, wherein said resistor divider comprises first and second resistors coupled in series between a first terminal of said auxiliary winding and ground, wherein a common node between said first and second resistors is configured as said feedback terminal, and wherein a resistance of said first resistor is predetermined in accordance with said transmission voltage loss.

16. The transmission voltage loss compensation circuit of claim 6 , wherein a time constant of said delay circuit is determined to decrease a bandwidth of said transmission voltage loss compensation circuit.

Assignees

• Silergy Semiconductor Technology Hangzhou Ltd

Inventors

• Xu Xiaoru
• Han Yunlong

Classifications

• H02M3/33507

  with automatic control of the output voltage or current, e.g. flyback converters (H02M3/33561, H02M3/33569 take precedence) · CPC title

• H02M3/33523 Primary

  with galvanic isolation between input and output of both the power stage and the feedback loop · CPC title

• H02M3/335

  using semiconductor devices only · CPC title

• H02M2001/0025

  Electricity · mapped topic

• H02M1/08

  Circuits specially adapted for the generation of control voltages for semiconductor devices incorporated in static converters · CPC title