JPH05120861A - Memory card system - Google Patents

Abstract

PURPOSE:To prevent the malfunction and the destruction of a memory card by providing a comparing circuit which supplies a supply voltage and an input signal only in the case of coincidence between the supply voltage value and the supply voltage value from a proper voltage value output part of the memory card. CONSTITUTION:A comparing circuit 4 compares digital signals PD0 and PD1 outputted from a register 3 of a memory card 1 with digital signals PDA and PDB of the supply voltage value on the side of a device 2 to which the card should be set. Only when the combination of digital signals PD0 and PD1 and that of digital signals PDA and PDB coincide with each other, coincidence between the supply voltage on the card 1 side and that on the device 2 side is discriminated, and the supply voltage and the input signal are supplied to the card 1 through a switch circuit 4 and a driver circuit 5. Thus, the supply voltage other than a proper voltage value is not supplied to the card 1, and the malfunction and the destruction of the card 1 are prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a memory card system to which a memory card is applied.

[0002]

2. Description of the Related Art Conventionally, in a memory card, the power supply voltage supplied during operation has been a single 5V. However, in the future, the power supply voltage supplied to the LSI memory tends to be low due to miniaturization accompanying the increase in the capacity of the LSI memory. Specifically, the power supply voltage is 3.3 V in a DRAM of 16 Mbits or 64 Mbits or later.

When a memory card is manufactured by using DRAM, the power supply voltage of the memory card is 5V when the conventional 4M bit DRAM is used. Furthermore, if 64Mbit DRAM is used in the future, the power supply voltage of the memory card will be 3.3.
It becomes V system.

Considering the actual use of such a memory card, when the power supply voltage of the card-mounted device using the memory card is 5V, the power supply voltage becomes insufficient for the memory card of 3.3V power supply voltage. Will end up. Also, if the power supply voltage of the card-mounted device is 3.3 V system, the power supply voltage is 5
The power supply voltage is excessively supplied to the V type memory card.

[0005]

In such a memory card, even if the memory capacity or the power supply voltage is different, if the connectors and the pin arrangements are compatible, the memory is erroneously stored in the card-attached device having a different power supply voltage. If you connect the card, the memory card may malfunction or be damaged.

The present invention solves the above problems, and an object of the present invention is to provide a memory card system for supplying a power supply voltage suitable for a memory card.

[0007]

SUMMARY OF THE INVENTION In order to solve the above problems, the present invention provides a memory card with an appropriate voltage for outputting a signal obtained by encoding an appropriate power supply voltage value suitable for the memory card to the card mounted device side. Provided with a value output section, a switch circuit that disconnects the supply of power supply voltage to the memory card side to the card mounted device, a driver circuit that disconnects the supply of input signal to the memory card side, and an appropriate voltage value output To the memory card side through the switch circuit and driver circuit only when the power supply voltage value to be supplied to the memory card side is decoded and the appropriate power supply voltage value from the appropriate voltage value output section is decoded. And a comparison circuit for starting the supply of the power supply voltage and the input signal.

[0008]

With the above structure, when the power supply voltage value to be supplied to the memory card and the power supply voltage value from the appropriate voltage value output section are equal, the switch circuit and the driver circuit are closed and suitable for the memory card. While the power supply voltage and input signal are being supplied, if the power supply voltage value to be supplied to the memory card side and the power supply voltage value from the appropriate voltage value output section are different, the switch circuit and driver circuit are opened and the memory is opened. No power supply voltage or input signal is supplied to the card. As a result, it is possible to prevent the memory card from malfunctioning or being destroyed.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIG. FIG. 1 shows a circuit configuration in a state where the memory card 1 is connected to the card receiving device 2.

The memory card 1 includes the memory card 1
A register 3 is provided as an appropriate voltage value output unit for outputting 2-bit digital signals PD0 and PD1 obtained by binary-coding an appropriate power supply voltage value suitable for the digital signal PD0 and PD1. Is set to the ground level, and the H level is opened from the memory card 1, but is made equal to the power supply voltage on the card mounted device 2 side by the pull-up resistors R1 and R2.

The card receiving device 2 is provided with a switch circuit 4 for connecting and disconnecting the power supply voltage to the memory card 1 side.
The driver circuit 5 that disconnects the supply of the input signal to the memory card 1 side, and the digital signal P from the memory card 1
A comparison circuit 6 for comparing D0, PD1 and a digital signal PDA, PDB obtained by binary-coding the value of the power supply voltage on the card mounted device 2 side, and a switch circuit 4 and a driver for storing the signal from the comparison circuit 4. A flip-flop 7 for connecting and disconnecting the circuit 5 is provided.

Here, the flip-flop 7 is latched by the clock signal CLK and its internal state is cleared by the clear signal CLR. This flip-flop 7
Outputs the output Q (output signal CHK) at H level only when the digital signal PD0 and the digital signal PDA are the same and the digital signal PD1 and the digital signal PDB are the same. When the H-level output signal CHK is input to the switch circuit 4 and the driver circuit 5, the switch circuit 4 and the driver circuit 5 are turned on, and the power supply voltage and the input signal are sent from the card-mounted device 2 side to the memory card. It is designed to be input to the 1st side. Where the output signal CH
K is a signal that outputs the result of matching or mismatching of the power supply voltages of the card-mounted device 2 and the memory card 1. If they match, H is output, and if they do not match, L is output. The input signal to the memory card 1 side is a plurality of signal groups in which address signals and other control signals are combined.

In this embodiment, the digital signal PD
0, PD1, PDA, PDB are output as shown in Table 1.

[0014]

[Table 1]

L in Table 1 indicates a ground level,
H indicates an open state, and the power supply voltage level is set by the pull-up resistors R1 and R2. In the above configuration, when the memory card 1 is mounted on the card mounted device 2, digital signals PD0 and PD1 which are binary codes of the appropriate power supply voltage value are output from the register 3 of the memory card 1 to the card mounted device 2 side. ..

In the comparison circuit 4, the digital signals PD0 and PD1 from the memory card 1 are compared with the digital signals PDA and PDB of the value of the power supply voltage on the card mounted device 2 side, and the digital signal (PD0 on the memory card 1 side is compared. , PD
When the combination of 1) and the combination of the digital signals (PDA, PDB) on the card mounted device 2 side are equal, it is determined that the power supply voltages on the memory card 1 side and the card mounted device 2 side are equal. The memory card 1 receives the power supply voltage and the input signal only through the switch circuit 4 and the driver circuit 5.
Supply to.

As an example, when the digital signal (PD0, PD1) = (L, L) on the memory card 1 side, the power supply voltage is 3.3 V as shown in Table 1. Then, the digital signal (PDA, PDB) of the card mounted device 2 side =
Only when the power supply voltage is (L, L) and is 3.3 V, the power supply voltage 3.3 V and the input signal are supplied from the card receiving device 2 to the memory card 1.

Since the digital signal (PD0, PD1) = (L, H) in the case of the memory card 1 whose power supply voltage is 5 V, such a memory card 1 has a digital signal (PDA, PDB) = (L, H). When connected to a device with a power supply voltage of 3.3 V in L), it is determined that the power supply voltage of the card-equipped device 2 and the power supply voltage of the memory card 1 side do not match,
The power supply voltage is not supplied to the memory card 1.

This prevents the memory card 1 from being supplied with a power supply voltage which is not an appropriate voltage value, and prevents the memory card 1 from malfunctioning or being destroyed.

[0020]

As described above, according to the present invention, the switch circuit and the driver circuit are provided only when the power supply voltage value to be supplied to the memory card side is equal to the proper power supply voltage value from the appropriate voltage value output section. A comparator circuit that starts the supply of the power supply voltage and input signal to the memory card side is provided, so that the power supply voltage that is not the proper voltage value is not supplied to the memory card, and malfunction and damage of the memory card are prevented. It

[Brief description of drawings]

FIG. 1 is a circuit diagram showing a connection between a memory card and a card mounting device according to an embodiment of the present invention.

[Explanation of symbols]

 1 Memory card 2 Card mounted device 3 Register (appropriate voltage value output section) 4 Switch circuit 5 Driver circuit 6 Comparison circuit 7 Flip-flop

Claims (1)

[Claims] 1. A memory card system comprising a memory card and a card receiving device to which the memory card is attached, wherein the memory card is provided with a signal encoded with an appropriate power supply voltage value suitable for the memory card. Providing an appropriate voltage value output section to output to the card mounted device side, connect the card mounted device to the switch circuit that disconnects the power supply voltage supply to the memory card side and the input signal supply to the memory card side. Switch circuit only when the driver circuit to be disconnected and the signal from the appropriate voltage value output section are decoded and the power supply voltage value to be supplied to the memory card side is equal to the appropriate power supply voltage value from the appropriate voltage value output section. And a comparison circuit for starting supply of a power supply voltage and an input signal to the memory card side via a driver circuit.