Power supply apparatus

• US 20070257647A1
• Filed: 05/31/2006
• Published: 11/08/2007
• Est. Priority Date: 04/24/2006
• Status: Active Grant

• Current Assignee: Industrial Technology Research Institute
• Original Assignee: Industrial Technology Research Institute
• Inventors: Kuo, Sy-Yen, Chen, Ke-Horng, Huang, Li-Ren, Huang, Hong-Wei
• Granted Patent: US 7,408,333 B2
• Time in Patent Office: Days
• US Class Current: 323/282
• CPC Class Codes: H02M 3/157 with digital control
• CPC Class Codes: H02M 3/1588 comprising at least one synchronous rectifier element H02M3/1582, H02M3/1584 take precedence
• CPC Class Codes: Y02B 70/10 Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes

Abstract

A power supply apparatus for supplying an output voltage to a load is provided, which comprises a power output unit, a feedback unit and a control unit. The power output unit adjusts and supplies the output voltage to the load in accordance with at least one driving signal. The feedback unit dynamically detects output condition of the power output unit and outputs the corresponding detection result. The control unit determines a skipping ratio for an internal clock in accordance with the detection result output from the feedback unit, and outputs the internal clock with a part of the pulses being skipped to act as the driving signal.

Claims

1. A power supply apparatus for supplying an output voltage to a load, comprising:

a power output unit, electrically connected to the load and used to adjust and supply the output voltage to the load according to at least one driving signal;

a feedback unit, electrically connected to the power output unit and used to detect the output state of the power output unit and output a corresponding detection result; and

a control unit, electrically connected to the feedback unit and the power output unit and used to skip a part of the pulse for an internal clock and select to output the skipped internal clock signal as the driving signal, wherein the control unit determines the skipping ratio for the internal clock according to the detection result output by the feedback unit, and the skipping ration is dynamically adjusted as the load is changed.

2. The power supply apparatus as claimed in claim 1, wherein the control unit further selects to output the un-skipped internal clock signal as the driving signal according to the detection result output by the feedback unit, wherein the control unit generates the internal clock signal through pulse-width modulation according to the detection result output by the feedback unit.

3. The power supply apparatus as claimed in claim 1, wherein the control unit further selects to output a second internal clock signal as the driving signal according to the detection result output by the feedback unit, wherein the control unit generates the second internal clock signal through pulse-frequency modulation according to the detection result output by the feedback unit.

4. The power supply apparatus as claimed in claim 1, wherein the control unit comprises:

a pulse-width modulator, being electrically connected to the feedback unit and used to generate and modulate the internal clock signal through the pulse-width modulation according to the detection result output by the feedback unit;

a pulse-frequency modulator, used to generate and modulate a second internal clock signal through the pulse-frequency modulation;

a load sensing circuit, being electrically connected to the feedback unit and used to sample the detection result output by the feedback unit for each preset time period, determine the output state of the power supply apparatus according to each sampling result, and then output a mode selection signal according to the output state of the power supply apparatus, wherein the load sensing circuit determines the skipping ratio for the internal clock signal according to the detection result output by the feedback unit, so as to output a skipping signal; and

a select logic, being electrically connected to the load sensing circuit, the pulse-frequency modulator, the pulse-width modulator and the power output unit, wherein according to the mode selection signal output by the load sensing circuit, the select logic selects to;

output the driving signal according to the internal clock signal provided by the pulse-width modulator;

output the driving signal according to the internal clock signal with a part of pulse having been skipped, wherein the part of pulse for the internal clock signal is skipped according to the skipping signal;

or

output the driving signal according to the second internal clock signal provided by the pulse-frequency modulator.

5. The power supply apparatus as claimed in claim 4, wherein the load sensing circuit comprises:

a sampling unit, being electrically connected to the feedback unit and used to sample the detection result output by the feedback unit for each preset time period;

a voltage-to-current converter, being electrically connected to the sampling unit and used to convert a sampling result of the sampling unit and output a conversion result;

a delay line, being electrically connected to the voltage-to-current converter, and comprising n stages of serial-connected delay cells DCELL_x used to transfer a first level among the delay cells DCELL₁-DCELL_n stage by stage according to the conversion result of the voltage-to-current during a delay period, and used to reset the output of the delay cells to be a second level during a reset period, wherein DCELL_x means the x^th delay cell, wherein 0<

x≦

n; and

a decode unit, being electrically connected to the delay line and used to sample at least one of the outputs of the delay cells DCELL₁-DCELL_n and decode the output to generate the mode selection signal;

wherein the load sensing circuit further takes the output of one of the delay cells DCELL_x as the skipping signal.

6. The power supply apparatus as claimed in claim 5, wherein the sampling unit comprises:

a sampling switch, with a first end being electrically connected to the feedback unit and with a second end being electrically connected to the voltage-to-current converter, wherein the sampling switch is turned on during a first period and turned off during a second period; and

a sampling capacitor, with a first end being electrically connected to the second end of the sampling switch and with a second end being grounded.

7. The power supply apparatus as claimed in claim 5, wherein the voltage-to-current converter comprises:

a first voltage-to-current conversion cell, with an input end being electrically connected to the sampling unit to determine the current value of an output end according to the voltage at the input end;

a second voltage-to-current conversion cell, with an input end being electrically connected to a preset voltage to determine the current value of an output end according to the voltage at the input end;

a current mirror, with the master current end being electrically connected to the output end of the second voltage-to-current converter and with the slave current end being electrically connected to the output end of the first voltage-to-current conversion cell; and

a first transistor, with the source being electrically connected to a voltage source and with the gate and the drain both being electrically to the output end of the first voltage-to-current conversion cell, wherein the current of the first transistor acts as the conversion result for the voltage-to-current converter.

8. The power supply apparatus as claimed in claim 7, wherein the first voltage-to-current conversion cell and the second voltage-to-current conversion cell both have the same circuit architecture.

9. The power supply apparatus as claimed in claim 7, wherein the first voltage-to-current conversion cell comprises:

a current source;

a first converting transistor, with the gate as the input end of the first voltage-to-current conversion cell, with the first source/drain being electrically connected to the current source, and with the second source/drain being grounded;

a second converting transistor, with the gate being electrically connected to the first source/drain of the first converting transistor and with the first source/drain as the output end of the first voltage-to-current conversion cell; and

a converting resistor, with the first end being connected to the second source/drain of the second converting transistor and with the second end being grounded.

10. The power supply apparatus as claimed in claim 5, wherein the delay line further comprises:

a second transistor, with the gate receiving the conversion result of the voltage-to-current converter and with the source being electrically connected to a voltage source; and

a third transistor, with the gate and the drain being both electrically connected to the drain of the second transistor and with the source being grounded;

wherein the delay cells DCELL₁-DCELL_n are further electrically connected to the gates of the second transistor and the third transistor, so as to determine the delay time of the delay cells according to the gate level of the second transistor and the third transistor.

11. The power supply apparatus as claimed in claim 10, wherein the delay cell DCELL_x comprises:

a fourth transistor, with the source being electrically connected to the voltage source and with the gate being electrically connected to the gate of the second transistor;

a fifth transistor, with the source being electrically connected to the drain of the fourth transistor and with the gate receiving a reset signal;

a sixth transistor, with the drain being electrically connected to the drain of the fifth transistor and with the gate being electrically connected to the output of the previous stage of the delay cell DCELL_x-1;

a seventh transistor, with the drain being electrically connected to the source of the sixth transistor and with the gate receiving the reset signal;

an eighth transistor, with the drain being electrically connected to the source of the seventh transistor, with the gate being electrically connected to the gate of the third transistor, and with the source being grounded;

a ninth transistor, with the source being electrically connected to the voltage source and with the gate being electrically connected to the gate of the second transistor;

a tenth transistor, with the source being electrically connected to the drain of the ninth transistor and with the gate being electrically connected to the drain of the fifth transistor, wherein the drain of the tenth transistor is the output of the delay cell DCELL_x;

an eleventh transistor, with the drain being electrically connected to the drain of the tenth transistor and with the gate being electrically connected to the drain of the fifth transistor; and

a twelfth transistor, with the drain being electrically connected to the source of the eleventh transistor, with the gate being electrically connected to the gate of the third transistor and with the source being grounded;

wherein the fifth transistor and the seventh transistor are under the control of the reset signal, and during the delay period, the fifth transistor is turned off and the seventh transistor is turned on, and during the reset period, the fifth transistor is turned on and the seventh transistor is turned off.

12. The power supply apparatus as claimed in claim 5, wherein the decode unit comprises:

at least one latch, being electrically connected to a corresponding delay cell DCELL_y in the delay line and used to latch the output of the delay cell DCELL_y, wherein 0<

y≦

n; and

a decoder, being electrically connected to the latch and used to decode the latched content of the latch, thereby generating the mode selection signal.

13. The power supply apparatus as claimed in claim 1, wherein the power output unit comprises a buck converter.

14. The power supply apparatus as claimed in claim 13, wherein the buck converter comprises:

a first switch, with the control end being controlled by the control unit and with the first end being electrically connected to a voltage source;

a second switch, with the control end being controlled by the control unit, with the first end being electrically connected to the second end of the first switch, and with the second end being grounded;

an induction coil, with the first end being electrically connected to the second end of the first switch and with the second end used for outputting the output voltage; and

a load capacitor, with the first end being electrically connected to the second end of the induction coil and with the second end being grounded.

15. The power supply apparatus as claimed in claim 14, wherein the induction coil is an inductor.

16. The power supply apparatus as claimed in claim 1, wherein the feedback unit comprises:

an operational amplifier, having a first input end, a second input end, and an output end;

an NOT gate, with the input end being electrically connected to the control end of the first switch;

a thirteenth transistor, with the gate being electrically connected to the control end of the first switch, with the first source/drain being electrically connected to the second end of the first switch and with the second source/drain being electrically connected to the first input end of the operational amplifier;

a fourteenth transistor, with the gate being electrically connected to the output end of the NOT gate, with the first source/drain being electrically connected to the voltage source and with the second source/drain being electrically connected to the second source/drain of the thirteenth transistor;

a fifteenth transistor, with the first source/drain being electrically connected to the voltage source, with the gate being grounded and with the second source/drain being electrically connected to the second input end of the operational amplifier;

a sixteenth transistor, with the first source/drain being electrically connected to the second source/drain of the fifteenth transistor, with the gate being electrically connected to the output end of the operational amplifier, wherein the level of the second source/drain of the sixteenth transistor is the corresponding detection result output by the feedback unit; and

a first resistor, with the first end being electrically connected to the second source/drain of the sixteenth transistor and with the second end being grounded.

17. The power supply apparatus as claimed in claim 1, wherein the feedback unit comprises:

a second resistor, with the first end being electrically connected to the output of the power output unit, wherein the level of the second end of the second resistor is the corresponding detection result output by the feedback unit; and

a third resistor, with the first end being electrically connected to the second end of the second resistor and with the second end being grounded.