JP2702820B2 - IC memory card and card holder - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an IC memory card equipped with a static RAM, and more particularly to an IC memory card and a card holder in which a connector is shared with an IC memory card equipped with another semiconductor memory.

[0002]

2. Description of the Related Art In recent years, IC memory cards have become widespread as external memories of personal computers and digital still cameras. For this IC memory card, a static RAM (hereinafter referred to as SRAM), which has a faster access time than other semiconductor memories, is often used. Recently, an EEPROM (electrically erasable and erasable ROM) that does not require a back-amplifier battery has been used. Various proposals have been made to make these IC memory cards compatible.

[0003] For example, the Japan Electronic Industry Development Association (JEIDA)
The third edition of the "IC Memory Card Guidelines" proposes a 20-pin connector for an IC memory card. This connector is supplied with a power supply voltage terminal for receiving a 5 V power supply voltage Vcc from an external host processing device such as a personal computer, and a 12 V voltage Vpp for programming for writing and erasing when EEPROM is used. Program terminal. Therefore, in this case, the SRAM
Even an IC memory card using the same has a program terminal.

By the way, conventionally, SRAM (static RAM)
An IC memory card equipped with a, for example, has a built-in 3V battery such as a lithium battery for retaining data. The life of this battery is about one year when the SRAM has a capacity of 8 Mbits, for example. Using SRAM
In order to hold data for a longer time in an IC memory card, it is set in a card holder having a dry battery of, for example, about 5 V when not in use.

In this case, an IC memory card using a connector conforming to JEIDA guidelines and its card holder are configured to be connected via a power supply voltage terminal.
The program terminal for PROM was not used. In addition, this type of IC memory card is provided with a power supply circuit for switching power supply from a built-in battery to SRAM and power supply from a card holder.

[0006]

However, in the above-mentioned conventional technology, when an IC memory card using an SRAM is set in a card holder and supplied with power through a power supply voltage terminal, an extra current is generated in the power supply circuit itself. And the consumption of the dry battery in the card holder becomes faster.

In this case, it is conceivable to provide a backup terminal by providing a dedicated terminal for the holder without using a power supply circuit by using a connector that does not comply with the JEIDA guidelines. However, an EEPROM is used to make the connector common. When such a connector is applied to an IC memory card, a dedicated terminal for the holder is not required, and therefore, there is a problem that the terminal is wasted.

The present invention solves such disadvantages of the prior art, and can reduce the consumption of dry batteries in a card holder for supplying a data holding voltage when an SRAM is used as a semiconductor memory. An object of the present invention is to provide an IC memory card and a card holder which can share a connector for an EEPROM without waste.

[0009]

In order to solve the above problems, an IC memory card according to the present invention uses a static RAM as a semiconductor memory for storing data.
In the IC memory card, a connector including a first power supply terminal for supplying a power supply voltage and a second power supply terminal for common use with another semiconductor memory, and a first power supply terminal from an external host processing device. When a connector is connected to a power supply circuit for applying a power supply voltage supplied via the power supply to the static RAM and a card holder for applying a data holding voltage when not in use, a second connection is made from this card holder. The holding voltage supplied via the power supply terminal is supplied to the static RAM, and the program voltage supplied from the second power supply terminal is reduced to a predetermined voltage when connected to an external host processing device. static
IC having a protection circuit applied to RAM
Memory card.

The present invention also provides a card holder for backing up an IC memory card using a static RAM as a semiconductor memory for storing data when not in use, wherein the IC memory card supplies a power supply voltage. And a connector provided with a second power terminal for common use with the first power terminal and another semiconductor memory, wherein the card holder supplies a data holding voltage to the second power terminal of the connector. It is characterized by having a voltage terminal.

[0011]

According to the IC memory card and the card holder of the present invention, the power supply voltage supplied from the external host processing device is statically supplied via the first power supply terminal of the connector.
Supplied to RAM. When the card is not used, when the connector is connected to the card holder for applying the data holding voltage of the static RAM, the voltage is supplied to the static RAM via the second terminal of the connector.
When a program voltage is erroneously supplied to the second power supply terminal of the connector from the external host processor, the static RAM is protected by the protection circuit.

[0012]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing an embodiment of an IC memory card and a card holder according to the present invention. As shown in FIG. 1, the IC memory card 20 in this embodiment has a connector 22 having a power supply terminal # 10 to which a power supply voltage is supplied and a backup terminal # 11 supplied from the card holder 10 when not in use. Having. Card holder
10 has a connector 12 corresponding to the connector 22 of the IC memory card 20, and a terminal for backup of the connector 22.
The data holding voltage is supplied to the static RAM 28 via # 11.

The connectors 12 and 22 of the card holder 10 and the IC memory card 20 in this embodiment are, for example,
This connector conforms to JEIDA guidelines. That is, the connector 22 of the IC memory card 20
Are common to both, and as shown in FIG.
ND) Terminals # 1 and # 20, data terminals # 2 to # 9 for inputting / outputting 8-bit data D0 to D7 and addresses, and a relatively low power supply of, for example, 5 V from an external host processing device (not shown). A power supply terminal # 10 to which the voltage Vcc is supplied, and a relatively high programming voltage of, for example, 12 V from an external host processing unit.
Vpp supply terminal # 11 for program and ready signal
Terminal # 12 for (RDY) and busy signal (BSY), terminal # 13 for chip enable signal (CE), and data terminals # 2 to # 9
To selectively use for data or address
State signal (A0, A1) terminals # 14 and # 15 for bits, read clock (RD) terminal # 16, and write clock (WR)
A terminal # 17, a write inhibit (WP) terminal # 18, and a VBAT terminal # 19 for notifying the host of the consumption state of the internal battery (VBAT) are provided. In this embodiment, the program terminal # 11 is used for backup as described above.

Returning to FIG. 1, the connector 12 of the card holder 10
The connector of the external host processor corresponds to the connector 22 of the IC memory card 20. Card holder 10
Has a dry battery 14 of, for example, 6V.
The + terminal is connected to the program terminal Vpp of the connector 12, and the-terminal is connected to the ground terminal GND. Therefore, the programming terminal Vp of the connector 12 of the card holder 10
p can be connected to the program terminal # 11 of the connector 22 of the IC memory card 20.

Power supply terminal of connector 22 of IC memory card 20
# 10 is one end of a switch 24 for turning on / off the power supply voltage Vcc supplied from the host processing device, and a switch 24.
Are connected to a switch drive circuit 26 that drives the. The power supply voltage Vcc supplied from the host processing device is supplied to the SRAM 28 via the switch 24, and is supplied to the control circuit 30 via the switch drive circuit 26.

The IC memory card 20 has a built-in 3 V battery 32 such as a lithium battery. The power supply voltage of the battery 32 is supplied to the SRAM 28 via a diode 34. Note that the diode 34 is for preventing the current from the dry battery 14 of the holder 10 from flowing to the battery 32 when the card is stored in the card holder 10. Also, a terminal for supplying the program voltage of the connector 22
# 11 is connected to the power supply terminal of the SRAM 28, and a Zener diode 36 for protecting the SRAM 28 is connected here.
This Zener diode 36 constitutes protection means for lowering the input voltage to 3V.

When such an IC memory card 20 is used, the connector 22 is connected to a host processing device compatible with the SRAM 28 and the card holder 10, but the connector 22 is connected to the SRAM and the EEPROM.
Therefore, there is a possibility of connection to a host processing device compatible with EEPROM. Next, the operation of the above embodiment will be described.

First, when the IC memory card 20 is connected to the host processor corresponding to the SRAM 28, all the terminals # 1 to # 10, # 12 except for the program voltage supply terminal # 11 of the connector 22.
# 20 are used for the signal and the power supply voltage Vcc. In this case, the switch drive circuit 26 turns on the switch 24 by the power supply voltage Vcc from the external host processing device, and supplies the control circuit 30 with the external power supply voltage Vcc. Therefore, data writing and reading of the SRAM 28 are performed via the control circuit 30.

On the other hand, the IC memory card 20 is
In this case, the program voltage supply terminal # 11 of the connector 22 and, for example, the ground terminal # 20 are connected to the connector 12 of the holder 10. Therefore, the power supply voltage of the dry battery 14 of the card holder 10 is connected to the SRAM 28 via the zener diode 36.
And the data in the SRAM 28 is retained even when the battery 32 is exhausted. In this case, the switch drive circuit 26 turns off the switch 24 because the power supply voltage Vcc is not supplied from the external host processing device, and does not supply the external power supply voltage Vcc to the control circuit 30.

Finally, if the IC memory card 20 is erroneously connected to a host processing device that supports EEPROM,
A high program voltage is applied to 22 program voltage supply terminals # 11. In this case, since the high-voltage program voltage is dropped by the zener diode 36, the SRAM 28 and its retained data are protected.

[0021]

As described above, according to the IC memory card of the present invention, when the connector is connected to an external host processing device compatible with static RAM, the power supplied from the external host processing device is When a voltage is supplied to the static RAM via the first terminal of the connector and the connector is connected to a card holder for applying a data holding voltage of the static RAM, the voltage is supplied to the second terminal of the connector. It is supplied to the static RAM via the terminal. Therefore, since the backup voltage is supplied to the static RAM without passing through the power supply circuit, the consumption of the dry battery of the card holder for supplying the data holding voltage can be reduced. Also other programmable ICs
In the event that the memory card is erroneously connected to an external host processing device, even if a program voltage is applied to the second terminal of the connector, the voltage drops by the protection circuit to protect the static RAM. . Therefore, SR
A connector common to AM and EEPROM can be used.

[Brief description of the drawings]

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

FIG. 2 is an explanatory view showing the connector of FIG. 1;

[Explanation of symbols]

 10 Card holder 12, 22 Connector 14 Dry cell 24 Switch 26 Switch drive circuit 28 Static RAM 36 Zener diode # 10 Power supply voltage terminal # 11 Program terminal (backup terminal)

Claims (2)

(57) [Claims] 1. An IC memory card using a static RAM as a semiconductor memory for storing data, a first power supply terminal for supplying a power supply voltage and a second power supply terminal for sharing with another semiconductor memory. A power supply circuit for applying a power supply voltage supplied from an external host processing device via the first power supply terminal to the static RAM, and applying a data holding voltage when not in use. When the connector is connected to the card holder for the static power supply, the holding voltage supplied from the card holder via the second power supply terminal is changed to the static voltage.
Supply to the RAM, and when connected to an external host processing device, reduce the program voltage supplied from the second power supply terminal to a predetermined voltage to reduce the static voltage.
IC having a protection circuit applied to RAM
Memory card. 2. A card holder for backing up an IC memory card using a static RAM as a semiconductor memory for storing data when not in use, wherein the IC memory card is used to supply a power supply voltage. A connector provided with a first power supply terminal and a second power supply terminal for sharing with another semiconductor memory, wherein the card holder supplies a data holding voltage to a second power supply terminal of the connector; A card holder comprising a power supply voltage terminal.