JPH05135564A - Memory card - Google Patents

Abstract

PURPOSE:To easily set an invalid state of a control signal with no limitation caused by the setting of a valid state when the control signal is not directly inputted from the outside of a memory card and to prevent malfunctions of a RAM contained in the memory card by selecting a power supply system that is connected to the control signal line of the memory card via a large current preventing resistance out of those power supply systems included in the memory card which can connect and disconnect the power lines. CONSTITUTION:The card control signal line 103 of a memory card is connected to an outside power supply 100 via a pull-up resistance 104 and a pull-up switch 107. At the same time, the line 103 is grounded via a pull-down resistance 108 and a pull-down switch 109. A switch control signal line 111 is connected to each switch to apply the control signal which connects and disconnects a power line. Then the control is carried out so that the switch 107 or 109 is kept in a connection state.

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 power supply system via a large current preventing resistor.

[0002]

2. Description of the Related Art A conventional memory card including at least a RAM, a battery, a power supply switching element, an element for controlling the RAM, and a large current preventing resistor for connecting a control signal line of the memory card and a power supply system. The block diagram is shown in Figure 2.
Is.

In a conventional memory card, as shown in FIG. 2, the control signal line 203 (hereinafter,
It is abbreviated as the card control signal line 203. ) Is a power supply 200 supplied from outside the memory card (hereinafter, the external power supply 200
Abbreviated. ) Is connected via a large current prevention resistor 204. .

As a result, the voltage of the card control signal line 203 of the conventional memory card becomes the same voltage as the voltage of the external power source 200 when the control signal is not directly input from the outside of the memory card, and the control signal is disabled. The RAM 206 in the memory card is prevented from malfunctioning.

[0005]

However, since the external power supply 200 is applied to the card control signal line 203 of the above-mentioned conventional memory card through the resistor for preventing large current, the control signal is directly input from the outside of the memory card. When not set, the setting for setting the control signal to the invalid state is limited to the case where the valid state is the control signal of the low potential voltage.

Therefore, there is a problem in that the effective state of the control signal cannot be set to a high potential voltage or a low potential voltage after the memory card is manufactured.

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 power supply system via the large current preventing resistor,
It is an object of the present invention to provide a method for easily connecting a control signal line and a power supply system, which is not limited to setting the valid state of a control signal.

[0008]

In the memory card of the present invention, a power supply system connected to a control signal line of the card through a large current preventing resistor is selected from a plurality of power supply systems capable of connecting / disconnecting the power supply line. It is characterized by being able to do it.

[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 control signal line 103 of a memory card (hereinafter abbreviated as a card control signal line 103).
Is a connection between a power supply line and a large current prevention resistor 104 (hereinafter, referred to as a pull-up resistor 104) connected to a high potential power source.
It is connected to the external power supply 100 via an element 107 that can be cut off (hereinafter, referred to as a pull-up switch 107).

At the same time, the card control signal line 103 is
A large-current prevention resistor 108 (hereinafter,
This is referred to as pull-down resistor 108. ) And the power supply line can be connected / cut off by an element 109 (hereinafter referred to as a pull-down switch 10
It is called 9. ) Is grounded to the ground.

A switch control signal line 111 is connected to the pull-up switch 107 to connect / disconnect the pull-up switch 107.

Similarly, the pull-down switch 109
A control signal line 111 of the switch is connected via the inverter 110 to connect / disconnect the pull-down switch 109.

Therefore, when the control signal of the memory card is set to the valid state at a low potential voltage, the pull-up switch 107 is connected and the pull-down switch 109 is cut off by the control signal of the switch.

As a result, the card control signal line 103 is connected to the external power supply 100, which is a high potential power supply, via the pull-up resistor 104.

In this case, when the control signal is not directly input from the outside of the memory card, a high potential voltage is applied to the control signal and the control signal becomes invalid.

On the other hand, when the control signal of the memory card is activated by the high potential power source, the pull-up switch 107 is turned off and the pull-down switch 109 is turned on by the control signal of the switch.

As a result, the card control signal line 103 is connected to the ground, which is a low potential power supply, via the pull-down resistor.

In this case, when the control signal is not directly input from the outside of the memory card, a low potential voltage is applied to the control signal and the control signal becomes invalid.

From the above, the card control signal line 103 of the memory card is connected to the pull-up switch 107 and the pull-down switch 1 according to the setting of the valid state of the control signal.
It is connected to the power supply system which was connected / disconnected by 09.

Therefore, when the control signal is not directly input from the outside of the memory card, the voltage power supply for making the control signal in the invalid state can be easily selected by the internal circuit of the memory card. RAM
It is possible to prevent the 106 from malfunctioning.

The embodiment described here is merely one embodiment.

[0024]

As described above, the memory card of the present invention is a memory card capable of connecting / disconnecting the power supply line for connecting the power supply system connected to the control signal line of the memory card through the resistance for large current prevention. Since it is possible to select from multiple internal power supply systems, when the control signal is not directly input from the outside of the memory card, the setting that disables the control signal is not limited to the valid state setting, and it can be done easily. , It is effective in preventing the RAM in the memory card from malfunctioning.

[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 symbols]

 100 power supply supplied from outside of memory card 101 battery 102 element for switching between external power supply and battery voltage 103 memory card control signal line 104 pull-up resistor 105 RAM control element 106 RAM 107 pull-up switch 108 pull-down resistor 109 pull-down resistor Switch 110 Inverter 111 Switch control signal line 200 Power supply supplied from outside the memory card 201 Battery 202 Element for switching between external power supply and battery voltage 203 Memory card control signal line 204 Pull-up resistor 205 RAM control element 206 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 large current prevention resistor that connects a line and a power supply system, the power supply system that connects the large current prevention resistor is connected to a plurality of power supply systems inside the memory card A memory card that can be selected from