JPH082752Y2 - IC card - Google Patents

Description

[Detailed Description of the Invention] [Industrial field of application] The present invention relates to an IC card, and more particularly to an IC card with a built-in battery that has improved electrical characteristics such as noise margin of input terminals and memory loss during latchup. is there.

[Conventional technology]

FIG. 2 shows a schematic configuration of a conventional IC card of this type.
In the figure, 1 is a connector that serves as an input / output connection point of an IC card signal line, 2 is a battery, 3 is a charging current limiting resistor, and 4, 5
Is a diode for switching between the battery 2 and the power supplied from the connector 1, 6 is a semiconductor element backed up by the battery 2, 7 is a ground line, 8 is a primary power line, 9 is a secondary power line, and 10 is It is an input / output signal line group.

 Next, the operation of this IC card will be described.

In order to operate the IC card configured as described above, a voltage (for example, 5V) is supplied between the primary power supply line 8 and the ground line 7 of the connector 1. At this time, the voltage of the battery 2 is set lower than the voltage of the primary power supply line 8 (for example, 3V), and therefore the diode 5 is reverse biased, and the semiconductor element 6 is connected from the primary power supply line 8 via the diode 4 to the reverse bias. Voltage is being supplied. In this way, the semiconductor element 6 is released from the state of being backed up by the battery 2,
The semiconductor element 6 is put into a state in which a proper operating voltage is applied and then operated via the input / output signal line group 10.
On the other hand, in the state of being backed up by the battery 2, no voltage is applied to the primary power supply line 8 and accordingly the diode 4
Is reverse-biased and the diode 5 is forward-biased so that the voltage is supplied from the battery 2 to the semiconductor element 6. At this time, since the semiconductor element 6 is not at the proper operating voltage, it cannot be operated via the input / output signal line group 10.

[Problems to be solved by the device]

However, in the IC card configured as described above, since the semiconductor element 6 backed up by the battery 2 is supplied with the power supply voltage via the diode 4, the forward voltage of the diode 4 causes the power supply of the semiconductor element 6 to be supplied. The terminal voltage (potential of the secondary power supply line 9) is lowered, and the threshold voltage of the input / output signal line group 10 is also lowered (specifically, the semiconductor element is at the TTL interface level (power supply voltage 5V, "L"). Input voltage = 0.8V, "H" input voltage = 2.0V, input voltage threshold voltage = 1.4V, and the threshold voltage is assumed to be directly proportional to the power supply voltage.) If there is 0.6V, the semiconductor power supply voltage is 4.4V
And the threshold voltage is 1.4V / 5.0V × 4.4V = 1.232V. That is, the noise margin of "L" input is 1.4V-0.8V
= 0.632 to 1.232V-0.8V = 0.432V by 0.168V). Further, when the input / output signal line group 10 has a higher potential than the secondary power supply line 9 when the IC card is inserted / removed in / from the system, the semiconductor device 6 may be latched up and its stored contents may be lost. There was a problem.

The present invention has been made to solve the above problems, and an object thereof is to obtain an IC card which improves the noise margin of the input terminal of the IC card and prevents loss of stored contents at the time of ratcheting. There is.

[Means for solving the problem]

The IC card according to the present invention is arranged in the forward direction from the primary power line to the secondary power line between the primary power line (8) of the connector (1) and the secondary power line (9) connected to the primary power line. And a second diode connected in a forward direction from the battery to the secondary power supply line between the secondary power supply line and the backup battery (2). A diode (5) and a first power supply connected to the secondary power supply line so that power is supplied from the battery via the second diode and power is supplied from the primary power supply line via the first diode. Of the semiconductor device (6), which is connected to the primary power supply line and is supplied with power from the primary power supply line, is connected to the first semiconductor device through the first input / output signal line group (10), and is a connector. And the second input / output signal line group (10 ') The amplifying the input signal 1
And a second semiconductor element (11) for transmitting to the semiconductor element of (1).

[Action]

The second semiconductor element (11) which is not backed up by the battery (2) in this invention is the connector (1) of the IC card.
The voltage input to the amplifier is amplified and its output is transmitted to the first semiconductor element backed up by the battery.

〔Example〕

 Hereinafter, the present invention will be described in detail with reference to the drawings.

FIG. 1 is a schematic configuration diagram showing an embodiment of an IC card according to the present invention, and the same parts as those in the above-mentioned figures are designated by the same reference numerals. In FIG. 1, the input / output signal line group 10 of the semiconductor element 6 backed up by the battery 2 is connected to the connector 1 via the semiconductor element 11 not backed up by the battery 2.
It is connected to the. Reference numeral 10 'is an input / output signal line group for connecting the connector 1 and the semiconductor element 11 which is not backed up by the battery 2. The semiconductor element 11 which is not backed up by the battery 2 is electrically connected between the primary power line 8 and the ground. Connected.

 Next, the operation of this embodiment will be described.

In the IC card configured as described above, the state of back-up by the battery 2 is the same as that of the conventional example, and therefore the description thereof is omitted. In operation, the semiconductor element 6 is in the operating voltage range as in the conventional case, but the voltage input from the connector 1 is amplified by the semiconductor element 11 that is not backed up by the battery 2 (for example, if the semiconductor element 11 is CMOS, the power supply voltage is Amplification of noise) and short input / output signal line group
It is transmitted through 10 to the semiconductor element 6 backed up by the battery 2. Therefore, the input voltage input to the connector 1 is amplified and the noise margin of the input voltage is increased. Further, even if the voltage of the input terminal of the connector 1 exceeds the power supply voltage, it is the semiconductor element 11 that is not backed up by the battery 2 that causes latchup, and the semiconductor element 6 that is backed up by the battery 2 is less likely to be affected.

In addition, in the above-described embodiment, the case where the semiconductor element 6 which is backed up by the battery 2 and the semiconductor element 11 which is not the semiconductor element 11 are separate semiconductor elements are described, but the same semiconductor element may be incorporated in the same semiconductor element. Of course, the effect can be obtained.

[Effect of device]

As described above, according to the present invention, by connecting the semiconductor element which is not backed up by the battery between the input terminal of the semiconductor element which is backed up by the battery and the connector input terminal, the noise margin of the input voltage is increased and It is possible to prevent the loss of the memory content at the time of ratcheting and to improve the electrical characteristics, which is an extremely excellent effect.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of an IC card according to an embodiment of the present invention, and FIG. 2 is a schematic configuration diagram of a conventional IC card. 1 ... Connector, 2 ... Battery, 3 ... Charging current limiting resistance, 4,5 ... Diode, 6 ... Semiconductor element backed up by battery, 7 ... Ground wire, 8 ... Primary power supply wire, 9 ...... Secondary power line, 10,10 '…… I / O signal line, 1
1 …… Semiconductor element that is not backed up by a battery.

Claims (1)

[Scope of utility model registration request] 1. A first diode connected between a primary power supply line of a connector and a secondary power supply line connected to the primary power supply line in a forward direction from the primary power supply line to the secondary power supply line. A second diode connected between the secondary power source line and the backup battery in a forward direction from the battery to the secondary power source line; and a power source from the battery via the second diode. A first semiconductor element connected to the secondary power supply line so that power is supplied from the primary power supply line through the first diode; and a primary semiconductor connected to the primary power supply line. Power is supplied from a power supply line and is connected to the first semiconductor element via a first input / output signal line group and is connected to the connector via a second input / output signal line group. Amplifies the input signal and IC card comprising the second semiconductor element for transmission to the conductor element.