JPH0574133A - Memory card - Google Patents

Abstract

PURPOSE:To prevent occurrence of a false operation of RAM inside a memory card by selecting a high-potential power source to be connected to a control signal line of the memory card through a pull-up resistor, from a plurality of power source systems inside the memory card of which power source lines can be connected and interrupted, and also to reduce consumption of current by connection and interruption of the power source lines. CONSTITUTION:A power source switching element 102 switches an external source voltage 100 and a battery voltage 101. An internal power source 103 is impressed on an element 106 controlling RAM and on the RAM 107. A card control signal line 104 of a memory card is connected, through a pull-up resistor 105, to a high potential power source switching element 108 which switches the external power source 100 and the internal power source 103. Besides, a three-state buffer 109 is connected to a route of input to the high potential power source switching element 108 from the internal power source 103, and a control signal is sent to a control signal line so as to connect and interrupt the power source line of the internal power source 103.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for connecting a control signal line in a memory card to a high potential power source via a pull-up resistor.

[0002]

2. Description of the Related Art A block of a memory card which is composed of at least a RAM, a battery, a power source switching element, an element for controlling the RAM, and a pull-up resistor for connecting a control signal line of the memory card to a high potential power source. The figure is FIG.

In a conventional memory card, as shown in FIG. 2, a control signal line 204 of the memory card (hereinafter,
It is abbreviated as the card control signal line 204. ) Is a power supply 200 supplied from outside the memory card (hereinafter, the external power supply 200
Abbreviated. ) Is connected via a pull-up resistor 205.

As a result, the voltage of the card control signal line 204 of the conventional memory card becomes the same voltage as the voltage of the external power supply 200 when the control signal is not directly input from the outside of the memory card.

[0005]

However, in the above-mentioned conventional technique, when no signal is input to the card control signal line 204 from the outside of the memory card, the card control signal line 20 is used.
Since the same voltage as that of the external power supply 200 is applied to 4, the voltage of the card control signal line 204 follows the fluctuation of the external power supply 200.

Therefore, there is a problem that the RAM in the memory card malfunctions and the data is rewritten.

Therefore, the present invention is made to solve such a problem, and when the control signal line of the memory card is connected to the high potential power source through the pull-up resistor, the high potential power source to be connected is It is an object of the present invention to provide a method for connecting a control signal line and a high-potential power supply for preventing a RAM inside a memory card from malfunctioning under the influence of the influence.

[0008]

In the memory card of the present invention, the high-potential power supply connected to the control signal line of the card through the pull-up resistor can be selected from a plurality of power supply systems capable of connecting / disconnecting the power supply line. Is characterized by.

[0009]

EXAMPLES The present invention will be described in detail below based on examples.

FIG. 1 is a block diagram of a memory card showing an embodiment of the present invention.

In FIG. 1, a power source 100 supplied from outside the memory card (hereinafter, abbreviated as an external power source 100).
The battery 101 is input to an external power supply 100 and an element 102 for switching the battery voltage (hereinafter, abbreviated as the power supply switching element 102).

The output of the power supply switching element 102 (hereinafter referred to as the internal power supply 103) is the element 10 for controlling the RAM.
6 and RAM 107.

The power source switching element 102 is an external power source 10.
When 0 is applied, the external power supply voltage is set to the internal power supply 1
When the external power supply 100 is not applied, the battery voltage is set to the internal power supply 103.

A control signal line 104 of the memory card (hereinafter abbreviated as a card control signal line 104) is an element 108 (hereinafter, a high-potential power source switching element) that switches between the external power source 100 and the internal power source 103 via a pull-up resistor 105. 108).

The high-potential power supply switching element 108 supplies the external power supply voltage to the card control signal line 104 through the pull-up resistor when the external power supply 100 is applied, and when the external power supply 100 is not applied, the internal power supply is provided. 1
The voltage 03 is applied to the card control signal line 104 via a pull-up resistor.

Therefore, when the external power supply 100 is applied, the voltage of the control signal 104 becomes the external power supply voltage,
Control signal 10 when the external power supply 100 is not applied
The voltage of 4 becomes the internal power supply voltage.

Further, by connecting the 3-state buffer 109 in the path for inputting from the internal power source 103 to the high potential power source switching element 108 and sending a control signal to the control signal line 110 of the 3-state buffer 109, the internal power source 103 Power line can be connected or disconnected.

As described above, when the signal is not directly input to the card control signal 104 of the memory card from the outside of the memory card, the voltage of the card control signal 104 can be selected from the external power supply or a plurality of internal power supply systems. , The voltage of the card control signal 104 following the fluctuation of the external power supply is reduced, and the R
It is possible to prevent the AM from malfunctioning.

Further, even if a plurality of power supply systems are used as described above, the power supply line of the internal power supply 103 can be connected and disconnected, so that the power supply line is cut off when it is not necessary to reduce current consumption. Can be planned.

The embodiment described here is merely one embodiment.

[0021]

As described above, in the memory card of the present invention, the high potential power source connected to the control signal line of the memory card through the pull-up resistor can be connected to or disconnected from the power source line. Since it is possible to select from multiple power supply systems, it is possible to reduce the RA of the memory card by reducing the tracking of the control signal to the fluctuation of the external power supply.
It is effective in preventing M from malfunctioning.

Further, since the power line can be connected / cut off,
This has the effect of reducing the current consumption.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of an internal circuit configuration of a memory card of the present invention.

FIG. 2 is a block diagram showing an internal circuit configuration of a conventional memory card.

[Explanation of reference numerals] 100 power source supplied from outside the memory card 101 battery 102 element for switching between external power source and battery voltage 103 internal power source 104 control signal line of memory card 105 pull-up resistor 106 element for controlling RAM 107 RAM 108 external power source And an element for switching the internal power source 109 3-state buffer 110 Control signal line for 3-state buffer 200 Power source externally supplied from the memory card 201 Battery 202 Element for switching between external power source and battery voltage 203 Internal power source 204 Control signal line for memory card 205 Pull Up resistor 206 Element for controlling RAM 207 RAM

Claims (1)

[Claims] 1. A RAM, a battery, an element for switching between a battery voltage and a power source supplied from outside the memory card (hereinafter referred to as a power source switching element), an element for controlling the RAM, and a control signal for the memory card. In a memory card composed of a pull-up resistor that connects a wire to a high-potential power supply, select the high-potential power supply that connects the pull-up resistor from multiple power supply systems inside the memory card that can connect and disconnect the power supply line. A memory card that can be used.