POWER SUPPLY DEVICE AND SWITCHING POWER SUPPLY DEVICE

• US 20090267587A1
• Filed: 06/18/2009
• Published: 10/29/2009
• Est. Priority Date: 04/14/2004
• Status: Abandoned Application

• Current Assignee: Renesas Electronics Corporation
• Original Assignee: Renesas Technology Corporation (Renesas Electronics Corporation)
• Inventors: Hosokawa, Kyoichi, Kudo, Ryotaro, Tateno, Koji, Nagasawa, Toshio, Chiba, Shin
• Application Number:
  US12/487,474
• Publication Number:
  US 20090267587A1
• Time in Patent Office: Days
• US Class Current: 323/316
• CPC Class Codes: H01L 2224/0603 Bonding areas having different sizes, e.g. different heights or widths
• CPC Class Codes: H01L 2224/48137 the bodies being arranged next to each other, e.g. on a common substrate
• CPC Class Codes: H01L 2224/48247 connecting the wire to a bond pad of the item
• CPC Class Codes: H01L 2924/00 Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/13091 Metal-Oxide-Semiconductor Field-Effect Transistor [MOSFET]
• 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

In a driver circuit constructing a switching power supply device that switches power transistors passing a current through a coil by a PWM mode, a current detection transistor, which is smaller in size than the low-potential side power transistor, and a current detection resistor are provided in parallel to the low-potential side power transistor. The same control voltage as the power transistor is applied to the control terminal of the current detection transistor. An operational amplifier is formed, that has the potential of the connection node between the current detection transistor and the current detection resistor applied to its inverse input terminal and a feedback loop, so as to make a pair of input terminals of the operational amplifier be at the same potential. A signal produced by the current detection resistor is thus outputted as a current detection signal.

Claims

1. A power supply driver circuit including a switching power supply device that switches a power transistor passing a current through an inductance by a PWM mode to convert an input voltage and outputs the converted voltage, the circuit comprising:

a current detection transistor that has a drain terminal or a collector terminal, a source terminal or an emitter terminal, and a control terminal, wherein a drain terminal or a collector terminal of the power transistor is coupled to the drain terminal or the collector terminal of the current detection transistor, and the control terminal of the current detection transistor is coupled to receive a driving voltage which is received by a control terminal of the power transistor;

a current detection resistor that is coupled to the source terminal or the emitter terminal of the current detection transistor; and

an operational amplifier circuit that has a pair of input terminals, one of the pair of input terminals being coupled to a connection node of the resistor and the current detection transistor and the other of the pair of input terminals applied to a voltage of same potential as a source voltage or an emitter voltage of the power transistor,

wherein a feedback loop is formed so as to make the pair of input terminals of the operational amplifier circuit be at a same potential, and

wherein a signal produced by the current detection resistor is outputted as a current detection signal.