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:
Sep. 21, 2010
Filed:
Dec. 23, 2008
Kiyoshi Yoshikawa, Chiba, JP;
Fumiyasu Utsunomiya, Chiba, JP;
Toshiyuki Tsuzaki, Chiba, JP;
Hiroyuki Masuko, Chiba, JP;
Osamu Uehara, Chiba, JP;
Hiroki Wake, Chiba, JP;
Michiyasu Deguchi, Chiba, JP;
Kiyoshi Yoshikawa, Chiba, JP;
Fumiyasu Utsunomiya, Chiba, JP;
Toshiyuki Tsuzaki, Chiba, JP;
Hiroyuki Masuko, Chiba, JP;
Osamu Uehara, Chiba, JP;
Hiroki Wake, Chiba, JP;
Michiyasu Deguchi, Chiba, JP;
Seiko Instruments Inc., Chiba, JP;
Abstract
Provided is a power supply switching circuit capable of efficiently supplying a desired voltage among a plurality of voltages to a load. In the case of a P-type semiconductor substrate, N-type MOS transistors are provided between a load and an AC adapter and between the load and a battery, and hence no parasitic diode exists between the load and the AC adapter or the battery, resulting in no current path due to the parasitic diode. Thus, when the AC adapter and the battery are connected to the power supply switching circuit, the N-type MOS transistor is turned off, whereby the current path between the battery and the load is cut off completely and the N-type MOS transistor is turned on. Accordingly, the battery cannot supply a voltage to the load while only the AC adapter can supply a voltage to the load.