公开(公告)号：US06262903B1

公开(公告)日：2001-07-17

申请号：US09471231

申请日：1999-12-23

Applicant: Yoshinori Fujihashi ,  Tetsuyasu Kitamura ,  Takuya Harada

Inventor： Yoshinori Fujihashi ,  Tetsuyasu Kitamura ,  Takuya Harada

IPC: H02M7217

CPC classification number: H02M3/33576 ,  H02M7/1557

Abstract: A direct-current power supply circuit, incorporated in an IC card, includes a coil for receiving an amplitude-modulated signal from an external device through electromagnetic induction. A full-wave rectifying circuit rectifies the amplitude-modulated signal received by the coil. The rectified output signal is used to charge a smoothing capacitor. A clamp circuit controls the terminal voltage of the smoothing capacitor to a predetermined level so as to produce a power supply voltage. The clamp circuit controls an output transistor to stabilize the power supply voltage to a constant level. Furthermore, the direct-current power supply circuit includes a short-circuit preventing circuit to forcibly turn off the output transistor when the electric potential difference between both ends of the coil is smaller than a predetermined value, thereby preventing the power supply voltage from suddenly decreasing due to delay of operation of the circuit elements when the coil output becomes zero due to amplitude modulation.

Abstract translation: 并入IC卡中的直流电源电路包括用于通过电磁感应从外部装置接收幅度调制信号的线圈。 全波整流电路对由线圈接收的幅度调制信号进行整流。 整流输出信号用于对平滑电容器充电。 钳位电路将平滑电容器的端子电压控制到预定电平，以产生电源电压。 钳位电路控制输出晶体管，以将电源电压稳定在一定水平。 此外，直流电源电路包括短路防止电路，当线圈两端的电位差小于预定值时强制关断输出晶体管，从而防止电源电压突然下降 由于振幅调制时线圈输出变为零时由于电路元件的工作延迟。