Parallel RC current detection circuit and DC/DC converter with a parallel RC current detection circuit

• US 6,469,481 B1
• Filed: 12/09/1999
• Issued: 10/22/2002
• Est. Priority Date: 12/25/1998
• Status: Expired due to Fees

• Current Assignee: Kabushiki Kaisha Toyoda Jidoshokki Seisakusho
• Original Assignee: Kabushiki Kaisha Toyoda Jidoshokki Seisakusho
• Inventors: Tateishi, Tetsuo
• Primary Examiner(s): BERHANE, ADOLF D
• Application Number:
  US09/457,540
• Time in Patent Office: 1,048 Days
• Field of Search: 323/282, 323/285, 323/287, 323/351
• US Class Current: 323/282
• CPC Class Codes: H02M 1/0009 Devices or circuits for detecting current in a converter
• CPC Class Codes: H02M 3/1588 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

An RC series circuit is provided in parallel with an inductor. The RC series circuit is comprised of a resistor and a capacitor which are connected with each other in series. A voltage across the capacitor is applied to a detection circuit. The detection circuit detects inductor current flowing through the inductor based on the applied voltage. If the inductance of the inductor, the parasitic resistance value of the inductor, the capacitance of the capacitor and the resistance value of the resistor are L, RL, C_a and R_a, respectively, the RC series circuit is designed so as to satisfy L/RL=C_a*R_a.

Claims

1. A circuit for detecting current flowing through an inductor, comprising:

a first resistor which is connected in series with the inductor;

a first circuit comprising a second resistor and a capacitor connected with each other in series and in parallel with the inductor and the first resistor; and

a second circuit detecting current flowing through the inductor based on a voltage across the capacitor.

2. A DC/DC converter, comprising:

a switch, to which DC input is applied, and which is turned on/off according to a control signal;

an inductor connected to said switch;

a circuit comprising a resistor and a first capacitor connected with each other in series with the resistor in parallel with a second capacitor and the resistor and first capacitor in parallel with the inductor; and

a control unit generating a control signal to be provided to said switch based on a voltage across the first capacitor.

3. A switching voltage regulator comprising:

an output terminal connected to a load;

an output circuit including an inductor for storing energy and an output capacitor coupled to said output terminal which supplies a regulated voltage to said output terminal;

a switching element coupled to said inductor so as to supply a current to said inductor in response to a switching control signal;

a switching control circuit providing said switching control signal so as to maintain said regulated voltage to said output terminal;

a first circuit monitoring an output voltage and generating a voltage feedback signal which indicates a target inductor current for regulating the output voltage;

a second circuit comprising a series circuit of a resistor and a capacitor connected between both ends of said inductor, such that a voltage across said capacitor as a current feedback is generated, the second circuit further comprising an auxiliary resistor connected in series with the capacitor and generates voltage across the capacitor and the auxiliary resistor as a current feedback signal; and

a third circuit providing said switching control signal in response to said voltage and current feedback signals.

4. A switching voltage regulator comprising:

an output terminal connected to a load;

an output circuit including an inductor for storing energy and an output capacitor coupled to said output terminal which supplies a regulated voltage to said output terminal;

a switching element coupled to said inductor so as to supply a current to said inductor in response to a switching control signal;

a switching control circuit providing said switching control signal so as to maintain said regulated voltage to said output terminal;

a first circuit monitoring an output voltage and generating a voltage feedback signal which indicates a target inductor current for regulating the output voltage;

a second circuit comprising a series circuit of a resistor and a capacitor connected between both ends of said inductor, such that a voltage across said capacitor as a current feedback is generated, the second circuit further comprising an auxiliary capacitor connected in parallel with the resistor and generates voltage across the capacitor as a current feedback signal; and

a third circuit providing said switching control signal in response to said voltage and current feedback signals.

5. A switching voltage regulator comprising:

an output terminal connected to a load;

an output circuit including an inductor for storing energy and an auxiliary resistor connected in series with said inductor and an output capacitor coupled to said output terminal which supplies a regulated voltage to said output terminal;

a switching element coupled to said inductor so as to supply a current to said inductor in response to a switching control signal;

a switching control circuit providing said switching control signal so as to maintain said regulated voltage to said output terminal;

a first circuit monitoring an output voltage and generating a voltage feedback signal which indicates a target inductor current for regulating the output voltage;

a second circuit comprising a series circuit of a resistor and a capacitor connected in parallel with said inductor and the auxiliary resistor, such that a voltage across said capacitor as a current feedback is generated; and

a third circuit providing said switching control signal in response to said voltage and current feedback signals.