| 摘要 |
PURPOSE:To prevent an IC card from being damaged due to an electrostatic charge given carelessly by connecting a depression-type FET element across the electrode and the earth of an IC chip and then connecting the gate of the FET to a DC current power source connecting electrode. CONSTITUTION:The depression-type FET elements 11, 12 and 13 are connected across the power source terminal 1 of the IC chip, terminals 2 and 3 and the earth terminal 8, and a bias available from dividing a voltage by resistances 9 and 10 is impressed on the gate of each FET element from the power source terminal 1. In the disuse of the card, an impedance between the drain and source of the FET elements 11-13 comes to a low value because a voltage between the gate and source is low. When data is written and read from the card, a bias of about 1V is given to the gate from the power source terminal 1 to raise the impedance between the drain and the source. Thus even if the electrostatic charge is carelessly given to the electrode in the disuse of the card, a sharp rise in a potential can be prevented, and the card can be protected from the damage.
|
