JPH05143806A - Memory card - Google Patents

Abstract

PURPOSE:To reduce the malfunction of a RAM in a memory card against the fluctuation of an external power source by selecting high potential connected to the control signal line of a memory card via a pull-up resistor from plural power source systems in the memory card. CONSTITUTION:The control signal line 7 of the memory card is connected to an element 9 which switches the external power source 1 and an internal power source 6 via the pull-up resistor 8. The power source 9 for pull-up outputs an external source voltage as the voltage for control signal pull-up when the external power source 1 is applied. Also, when no external power source 1 is applied, the power source 9 outputs an internal source voltage as the voltage for control signal pull-up. Thereby, it is possible to reduce the follow-up of potential when no card control signal is directly added on the outside of the memory card, and to reduce the malfunction of the RAM in the memory card.

Description

Detailed Description of the Invention

[0001]

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

[0002]

2. Description of the Related Art A conventional pull-up for connecting at least a RAM and a battery, an element for switching a battery voltage and a power supplied from the outside of a memory card, an element for controlling a memory and a control signal line of the memory card to a high voltage. FIG. 2 is a block diagram of a memory card composed of resistors.

In a conventional memory card, as shown in FIG. 2, a power source 21 (hereinafter referred to as an external power source 21) supplied from the outside of the memory card is a control signal line of the memory card.
27 (hereinafter, abbreviated as card control signal line 27) was connected to a pull-up resistor 28 for connecting a high voltage. The voltage of the control signal line 27 of the conventional memory card is the same as the external power supply voltage 21 when the control signal is not directly applied from the outside of the memory card.

[0004]

In the above-mentioned prior art, as shown in FIG. 2, the potential of the control signal line when the control signal is not applied from the outside of the memory card is the same as that of the external power source 21. ..

Therefore, there is a problem that the potential of the control signal line follows the fluctuation of the external power source 21, the RAM inside the memory card is likely to malfunction, and the data of the RAM is rewritten.

The present invention is made to solve the above problems, and an object of the present invention is to provide a high potential, which is connected to a control signal line of a memory card via a pull-up resistor, inside the memory card. By selecting from a plurality of power supply systems, it is intended to reduce the follow-up of the potential of the control signal line with respect to the fluctuation of the external power supply and to reduce the malfunction of the RAM inside the memory card.

[0007]

In the memory card according to the present invention, the high potential connected to the control signal line of the memory card via the pull-up resistor can be selected from a plurality of power supply systems, so that the external power supply The fluctuation of the potential of the control signal line to the fluctuation is reduced, and the RA inside the memory card is reduced.
It is intended to reduce the malfunction of M.

[0008]

1 is a block diagram of a memory card showing an embodiment of the present invention. In FIG. 1, a power source 1 supplied from outside the memory card (hereinafter abbreviated as an external power source 1) and a battery 2 are an element 3 (hereinafter referred to as a power source switching element 3) that switches between a battery voltage and a voltage supplied from outside the memory card.
Is abbreviated).

The internal power source 6 is an element 4 for controlling the memory.
(Hereinafter, memory control element 4) and power source for RAM 5.

The power supply switching element 3 outputs the external power supply voltage as the internal power supply voltage when the external power supply 1 is applied, and outputs the battery voltage as the internal power supply voltage when the external power supply 1 is not applied.

A control signal line 7 of the memory card (hereinafter abbreviated as a card control signal line 7) is an element 9 for switching between an external power source 1 and an internal power source 6 via a pull-up resistor 8 (hereinafter, pull-up power source 9). Abbreviated) and is connected.

The pull-up power supply 9 outputs the external power supply voltage as the control signal pull-up voltage when the external power supply 1 is applied. When the external power supply 1 is not applied, the internal power supply voltage is output as the control signal pull-up voltage.

Therefore, the voltage applied to the card control signal line is the voltage applied to the pull-up resistor connected to the card control signal line when the card control signal is not directly applied from outside the memory card. Becomes

In this case, the potential of the card control signal line when the external power supply 1 is applied becomes the external power supply voltage.

The potential of the card control signal line when the external power supply 1 is not applied is the internal power supply voltage.

As a result, when the card control signal is not directly applied from the outside of the memory card, the follow-up of the potential of the card control signal line to the fluctuation of the external power source is reduced, and the RAM of the RAM inside the memory card is reduced. Malfunctions can be reduced.

[0017]

As is apparent from the above description, according to the present invention, at least the RAM, the battery, the element for switching the battery voltage and the power supplied from the outside of the memory card, the element for controlling the memory, and the memory card. In a memory card composed of a pull-up resistor that connects the control signal line to a high potential, the high potential to which the pull-up resistor is connected can be selected from multiple power supply systems inside the memory card, and To reduce the tracking of the potential of the control signal line,
There is an effect that it is possible to reduce the malfunctions of.

[Brief description of drawings]

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

FIG. 2 is a block diagram of a conventional memory card.

[Explanation of symbols]

1 power supply supplied from outside the memory card 2 battery 3 device that switches between battery voltage and voltage supplied from outside the memory card 4 device that controls memory 5 RAM 6 internal power supply 7 memory card control signal line 8 pull-up resistor 9 external Element that switches between power supply 1 and internal power supply 21 Power supply supplied from outside the memory card 22 Battery 23 Element that switches between battery voltage and voltage supplied from outside the memory card 24 Memory control element 25 RAM 26 Internal power supply 27 Memory card Control signal line 28 Pull-up resistor

Claims (1)

[Claims] 1. A RAM, a battery, an element for switching a battery voltage and a power source supplied from outside the memory card, an element for controlling the memory, and a pull-up resistor for connecting a control signal line of the memory card to a high potential. The high-potential to which the pull-up resistor is connected can be selected from a plurality of power supply systems inside the memory card.