DC/DC converter

• US 8,836,305 B2
• Filed: 01/28/2013
• Issued: 09/16/2014
• Est. Priority Date: 02/02/2012
• Status: Active Grant

• Current Assignee: Sony Interactive Entertainment Inc. (Sony Group Corp.)
• Original Assignee: Sony Computer Entertainment Incorporated (Sony Group Corp.), Sony Corporation (Sony Group Corp.)
• Inventors: Sasao, Kazuki, Mitsui, Kazuaki
• Primary Examiner(s): BERHANE, ADOLF D
• Application Number:
  US13/751,710
• Publication Number:
  US 20130200869A1
• Time in Patent Office: 596 Days
• Field of Search: 323282-290, 323/351
• US Class Current: 323/282
• CPC Class Codes: G05F 1/46 wherein the variable actually regulated by the final control device is dc G05F1/625 takes precedence
• 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

Based upon a detection voltage V_L that develops between ISEN+ and ISEN− terminals, a current detection circuit detects a coil current I_L that flows through an inductor. A measurement circuit is connected to an inductor, and measures an inductance value L and a DC resistance value R_DC of the inductor in a calibration operation before normal operation of a DC/DC converter. Based upon the inductance value L and the DC resistance value R_DC thus measured, the current detection circuit detects the coil current I_L using the detection voltage V_L.

Claims

1. A DC/DC converter comprising:

an input line via which a DC input voltage is to be supplied;

an output line via which a load is to be connected;

a switching transistor and a synchronous rectification transistor sequentially arranged in series between the input line and a ground line;

an inductor having its one end connected to a switching node which is a connection node that connects the switching transistor and the synchronous rectification transistor, and having its another end connected to the output line;

an output capacitor connected to the output line; and

a control circuit configured to perform switching of the switching transistor and the synchronous rectification transistor, wherein the control circuit comprises;

a pulse modulator configured to generate a pulse signal having a duty cycle adjusted such that a DC output voltage that develops at the output line matches a predetermined target voltage;

a driver circuit configured to perform switching of the switching transistor and the synchronous rectification transistor according to the pulse signal;

a first detection terminal connected to the switching node;

a second detection terminal connected to the output line;

a measurement circuit connected to the inductor via the first detection terminal and the second detection terminal, and configured to measure an inductance value and a DC resistance value of the inductor during calibration, before normal operation of the DC/DC converter; and

a current detection circuit configured to detect, in normal operation, a current that flows through the inductor based upon a detection voltage that develops between the first detection terminal and the second detection terminal, using the inductance value and the DC resistance value thus measured.

2. A DC/DC converter according to claim 1, wherein the current detection circuit comprises:

an RC low-pass filter configured to perform filtering of the detection voltage during normal operation; and

a current detection unit configured to detect a current that flows through the inductor based upon an output voltage of the RC low-pass filter and the measured DC resistance value,

wherein, during normal operation, a time constant CR of the RC low-pass filter is set to be equal to a ratio L/R_DC between the inductance value L and the DC resistance value R_DCd.

3. A DC/DC converter according to claim 2, wherein the current detection unit is configured to correct, using a predetermined correction function, a measured current that flows through the inductor.

4. A DC/DC converter according to claim 2, wherein, with the inductance value and the DC resistance value measured by the measurement circuit as L₀ and R_DC0, respectively, and with a predetermined correction function of F_CMP(x), the time constant C_F×

R_F of the RC low-pass filter is set to a value represented by C_F×

R_F=L₀/R_DC0, and wherein the current detection unit is configured to calculate a current that flows through the inductor according to I_L=V_C/{R_DC0×

(1+F_CMP(x))}.

5. A DC/DC converter according to claim 2, wherein the RC low-pass filter comprises a variable resistor, and wherein the resistance value of the variable resistor is adjusted according to the inductance value L and the DC resistance value R_DC.

6. A DC/DC converter according to claim 3, wherein the RC low-pass filter comprises a variable resistor, and and wherein the resistance value of the variable resistor is adjusted according to the inductance value L and the DC resistance value R_DC.

7. A DC/DC converter according to claim 4, wherein the RC low-pass filter comprises a variable resistor, and wherein the resistance value of the variable resistor is adjusted according to the inductance value L and the DC resistance value R_DC.

8. A DC/DC converter according to claim 1, wherein, with the inductance value and the DC resistance value measured by the measurement circuit as L₀ and R_DC0, respectively, with a predetermined function as F_CMP(x), and with s=j×

2π

F_SW (where F_SW represents a switching frequency of the DC/DC converter), the current detection unit is configured to calculate an inductor current according to I_L=V_L/{R_DC0+s×

L₀+F_CMP(x)}.

9. A DC/DC converter according to claim 1, wherein, when the DC resistance value is greater than a predetermined threshold value, the control circuit is configured to judge that a disconnection fault has occurred.

10. A DC/DC converter according to claim 1, wherein the driver circuit is arranged as an external component of the control circuit.

11. An electronic device comprising:

a processor; and

a DC/DC converter configured to supply a power supply voltage to a power supply terminal of the processor, wherein the DC/DC converter comprises;

an input line via which a DC input voltage is to be supplied;

an output line via which the processor is to be connected;

a switching transistor and a synchronous rectification transistor sequentially arranged in series between the input line and a ground line;

an inductor having its one end connected to a switching node which is a connection node that connects the switching transistor and the synchronous rectification transistor, and having its another end connected to the output line;

an output capacitor connected to the output line; and

a control circuit configured to perform switching of the switching transistor and the synchronous rectification transistor, and wherein the control circuit comprises;

a pulse modulator configured to generate a pulse signal having a duty cycle adjusted such that a DC output voltage that develops at the output line matches a predetermined target voltage;

a driver circuit configured to perform switching of the switching transistor and the synchronous rectification transistor according to the pulse signal;

a first detection terminal connected to the switching node;

a second detection terminal connected to the output line;

a measurement circuit connected to the inductor via the first detection terminal and the second detection terminal, and configured to measure an inductance value and a DC resistance value of the inductor in calibration, before normal operation of the DC/DC converter; and

a current detection circuit configured to detect, in normal operation, a current that flows through the inductor based upon a detection voltage that develops between the first detection terminal and the second detection terminal, using the inductance value and the DC resistance value thus measured.