Multi-mode DC-DC power converters

• US 8,698,467 B2
• Filed: 02/23/2010
• Issued: 04/15/2014
• Est. Priority Date: 02/24/2009
• Status: Expired due to Fees

• Current Assignee: Socionext Inc.
• Original Assignee: Fujitsu Semiconductor Limited (Fujitsu Limited)
• Inventors: Oki, Hideta
• Primary Examiner(s): Berhane, Adolf
• Assistant Examiner(s): ROSARIO BENITEZ, GUSTAVO A
• Application Number:
  US12/710,873
• Publication Number:
  US 20100213911A1
• Time in Patent Office: 1,512 Days
• Field of Search: 323/223, 323/224, 323/271, 323280-285, 323/351, 323/259, 323/344
• US Class Current: 323/282
• CPC Class Codes: H02M 1/0009 Devices or circuits for detecting current in a converter
• CPC Class Codes: H02M 3/156 with automatic control of output voltage or current, e.g. switching regulators

Abstract

A semiconductor integrated circuit includes: a first switching element and a second switching element that are provided in series between a first power line and a second power line; a power supply circuit that outputs a given output voltage by on/off controlling the first switching element and the second switch element; a current detection circuit that detects a current corresponding to an output load current of the power supply circuit; a switching time control circuit that controls a switching time defined by a power supply voltage and the output voltage based on a current value detected by the current detection circuit; and a switching element control circuit that controls the first switching element and the second switching element based on an output signal of the switching time control circuit.

Claims

1. A semiconductor integrated circuit, comprising:

a first switching element that is controlled based on a first control signal and a second switching element that is controlled based on a second control signal, the first switching element and the second switching element being provided in series between a high-voltage power line and a low-voltage power line, the first switching element being provided on one side of the high-voltage power line and the second switching element being provided on one side of the low-voltage power line;

a power supply circuit that outputs an output voltage by on/off controlling the first switching element and the second switching element;

a current detection circuit, coupled to the first switching element and the second switching element, that detects a current corresponding to an output load current of the power supply circuit;

a switching time control circuit that controls a switching time defined by a power supply voltage and the output voltage based on a current value detected by the current detection circuit;

a switching element control circuit that controls the first switching element and the second switching element based on an output signal of the switching time control circuit; and

a flip flop circuit, provided between the switching time control circuit and the switching element control circuit, including a reset terminal receiving an output of the switching time control circuit,

wherein the switching time control circuit includes;

a capacitor that is charged when the first switching element is turned on;

a third switching element, coupled to one end of the capacitor, that is controlled based on the second control signal;

a first comparator, coupled to the one end of the capacitor, which compares a voltage of the capacitor with a result obtained by adding a divided voltage of the output voltage and an output of the current detection circuit, and outputs an comparison result to the reset terminal of the flip flop circuit.

2. The semiconductor integrated circuit according to claim 1, wherein the power supply circuit comprises:

a coil that applies a current from the first switching element and the second switching element to an output terminal via a connection node; and

a smoothing capacitor that is provided between the output terminal and the low-voltage power line.

3. The semiconductor integrated circuit according to claim 2, wherein the current detection circuit is provided between the first switching element and the connection node.

4. The semiconductor integrated circuit according to claim 2, wherein the current detection circuit is provided between the high-voltage power line and the first switching element.

5. The semiconductor integrated circuit according to claim 2, wherein the current detection circuit is provided between the coil and the output terminal.

6. The semiconductor integrated circuit according to claim 2, wherein the current detection circuit is provided between the connection node and the coil.

7. The semiconductor integrated circuit according to claim 1, wherein the switching time control circuit controls an on time of the first switching element.

8. The semiconductor integrated circuit according to claim 1, further comprising:

a reference voltage generator that generates the reference voltage.

9. The semiconductor integrated circuit according to claim 8, wherein the power supply circuit controls the output voltage by using a ripple superimposed onto the output voltage by a parasitic resistance of the smoothing capacitor or by a resistor that is provided in series with the smoothing capacitor between the output terminal and the low-voltage power line;

and the reference voltage generator generates the reference voltage in a fixed manner.

10. The semiconductor integrated circuit according to claim 8, wherein the output voltage is superimposed with a ripple by a high-pass filter that includes the coil and is supplied to the error comparator;

and the reference voltage generator generates the reference voltage in a fixed manner.

11. The semiconductor integrated circuit according to claim 8, wherein the reference voltage generator generates the reference voltage onto which a ripple is superimposed.

12. The semiconductor integrated circuit according to claim 8, further comprising:

a ripple current detection circuit that is provided between the low-voltage power line and the second switching element.

13. The semiconductor integrated circuit according to claim 12, wherein the reference voltage generator generates the reference voltage to which a ripple is superimposed by adding a fixed voltage and an output voltage of the ripple current detection circuit.

14. The semiconductor integrated circuit according to claim 1 further comprising;

a ripple current detection circuit that is provided between the low-voltage power line and the second switching element;

an error amplifier that compares the output voltage with a reference voltage; and

a second comparator that compares an output signal of the error amplifier with an output signal of the ripple current detection circuit.

15. The semiconductor integrated circuit according to claim 14, wherein an operation of the current detection circuit is stopped if the output load current is small compared to an output of the ripple current detection circuit.

16. The semiconductor integrated circuit according to claim 1, wherein the power supply circuit includes a plurality of modes;

and

the semiconductor integrated circuit further comprising;

a fourth switching element and a fifth switching element that are provided in series between an output terminal and the low-voltage power line; and

a mode control circuit that sets at least one of the plurality of modes; and

wherein the output terminal is coupled to the connection node through the third switching element and the coil.

17. The semiconductor integrated circuit according to claim 16, wherein the plurality of modes includes a buck mode, a boost mode, and a buck-boost.

19. The semiconductor integrated circuit according to claim 1, wherein the switching time control circuit controls the switching time by a bottom detection comparator method for a fixed on-time DC-DC converter.

21. The semiconductor integrated circuit according to claim 1, wherein the switching element control circuit outputs a control signal for turning the first switching element off when the voltage of the capacitor exceeds the additional result.

18. A power supply device, comprising:

a semiconductor integrated circuit that includes;

a first switching element and a second switching element that are provided in series between a high-voltage power line and a low-voltage power line, the first switching element being provided on one side of the high-voltage power line and the second switching element being provided on one side of the low-voltage power line;

a power supply circuit that outputs an output voltage by on/off controlling the first switching element and the second switching element;

a current detection circuit that detects a current corresponding to an output load current of the power supply circuit;

a switching time control circuit that controls a switching time defined by a power supply voltage and the output voltage based on a current value detected by the current detection circuit;

a switching element control circuit that controls the first switching element based on a first control signal and the second switching element based on a second control signal, the first control signal and the second control signal being generated based on an output signal of the switching time control circuit;

a flip flop circuit, provided between the switching time control circuit and the switching element control circuit, including a reset terminal receiving an output of the switching time control circuit;

a coil that applies a current from the first switching element and the second switching element to an output terminal through a connection node; and

a smoothing capacitor that is provided between the output terminal and the low-voltage power line,

wherein the switching time control circuit includes;

a capacitor that is charged when the first switching element is turned on;

a third switching element, coupled to one end of the capacitor, that is controlled based on the second control signal; and

a comparator, coupled to the end of the capacitor, which compares a

voltage of the capacitor with a result obtained by adding a divided voltage of the output voltage and an output of the current detection circuit, and outputs an comparison result to the reset terminal of the flip flop circuit.

20. The semiconductor integrated circuit according to claim 18, wherein the switching time control circuit controls the switching time by a bottom detection comparator method for a fixed on-time DC-DC converter.

22. The power supply device according to claim 18, wherein the switching element control circuit outputs a control signal for turning the first switching element off when the voltage of the capacitor exceeds the additional result.