Title: Transistor drive circuit, constant voltage circuit, and method thereof using a plurality of error amplifying circuits to effectively drive a power transistor
Application Number: 200610164108 Application Date: 2006.09.21
Publication Number: 1968011 Publication Date: 2007.05.23
Approval Pub. Date: Granted Pub. Date:
International Classifi-cation: H03G3/20;H03G3/30;G05F1/648;G05F1/46
Applicant(s) Name: Ricoh KK Address:
Inventor(s) Name: Hayashi Katsuhiro;Yoshii Kohji
Attorney & Agent: luxiao zhang shaoya li
Abstract:
    A transistor drive circuit, a constant voltage circuit, and a method thereof provided with a reference voltage generator, a power voltage detector, and a plurality of error amplifying circuits. The plurality of error amplifying circuits have different operational characteristics. One of the error amplifying circuits is selectively activated in response to a control signal in accordance with an operational mode selected. A reference voltage produced by the reference voltage generator or a divided voltage produced by the power voltage detector is also changed in response to the control signal suitably for each one of the plurality of error amplifying circuits which is selectively activated so as to control the power voltage generated by a power transistor to output a constant power voltage.
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