The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jun. 23, 2009
Filed:
Jan. 22, 2008
Koji Tateno, Takasaki, JP;
Ryotaro Kudo, Takasaki, JP;
Shin Chiba, Takasaki, JP;
Kyoichi Hosokawa, Takasaki, JP;
Toshio Nagasawa, Takasaki, JP;
Koji Tateno, Takasaki, JP;
Ryotaro Kudo, Takasaki, JP;
Shin Chiba, Takasaki, JP;
Kyoichi Hosokawa, Takasaki, JP;
Toshio Nagasawa, Takasaki, JP;
Renesas Technology Corp., Tokyo, JP;
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.