JPH03268013A - Ic memory card - Google Patents

Abstract

PURPOSE:To realize a long service life of the IC memory card by constituting the card so that a power is supplied to only a RAM chip in which data is stored, and the power source is not supplied to a RAM in which data is not written. CONSTITUTION:At the time of write and at the time of read-out of data, a software of an external device 2 discriminates a use state of a file, and writes switch data in a register 40 so that a power is supplied to only an effective RAM chip in RAMs 11 - 14. A switch signal is supplied to only a switch circuit being the corresponding bit '1' of the switch data held in this register, and the power source is supplied to the connected RAM. In such a way, in an IC memory card 1 of a large capacity constituted of plural RAM-ICs, the storage contents can be saved for a long period by realizing a long service life of a built-in battery 30.

Description

DETAILED DESCRIPTION OF THE INVENTION [Overview] [Field of Industrial Application] The present invention relates to an IC memory card, and particularly to a RAM card with a built-in backup power supply.

[Conventional technology]

Magnetic cards have traditionally been widely used as portable storage media, but their storage capacity is extremely limited. For this reason, in recent years, IC memory cards have begun to become popular as storage media with a relatively large storage capacity in place of magnetic cards.

Among IC memory cards, a RAM card using SRAM as a storage medium is generally composed of a plurality of SRAM-ICs and has a large capacity.

Further, the RAM card has a built-in backup battery to save data written in the SRAM.

[Problem to be solved by the invention]

Since the life of the built-in battery is determined by the sum of standby currents of the plurality of SRAMs, the battery life becomes shorter as the number of components increases.

For this reason, if an attempt is made to increase the capacity of an IC memory card, the battery life will be short and the stored contents cannot be stored for a long period of time. Furthermore, since the IC memory card is extremely thin, it is difficult to extend the battery life by increasing the capacity of the built-in battery.

Furthermore, since RAM cards can be freely rewritten, they are often used as files. And the file usage area is 10 of the memory capacity
It is extremely rare for the battery to occupy 0%, and in most cases it is only a few tens of percent at most, so supplying power to chips that do not store information among multiple SRAMs is a waste of the limited battery capacity. be.

The present invention provides a large-capacity I
The purpose of this invention is to enable long-term preservation of memory contents in a C memory card by extending the lifespan of a built-in battery.

[Means to solve problems]

In order to solve the above problems, the IC memory card of the present invention includes a readable/writable memory, a backup power source for the memory, and an input/output terminal for connecting to an external device and inputting/outputting information. The IC memory card is equipped with a register for holding switch switching information inputted from an external device through the input/output terminal, and the memory is divided into a plurality of blocks, and the backup data is stored in each block. A switch circuit is connected between the backup power supply and the backup power supply and turns on and off the supply of the backup power supply according to the value of switch switching information held by the register.

[Effect]

That is, the IC memory card of the present invention has a structure in which the RAM is divided into a plurality of blocks to which power is supplied independently, a switch circuit is inserted into each power line, and power is supplied only to the blocks in use. It is something. The state of the above-mentioned switch circuit is turned on or off by storing a switch signal inputted by an external device accessing the IC memory card in a register, and a switch signal sent from this register.

〔Example〕

The present invention will be described in detail below with reference to the drawings.

FIG. 1 is a block diagram showing the configuration of a first embodiment of the present invention.

In the figure, 1 is the IC memory card of this embodiment, and terminal 5
It is connected to a connection mechanism (not shown) of the external device 2 via terminals 1 to 57.

The information storage section of this IC memory card 1 has 4 chips.
AMII to 14 are connected to each memory, and an address bus, control signal lines such as read/write, and a data bus are commonly connected to each memory. It is interfaced with external device 2 via bus terminal 55 . Of course RAM
The number of chips is not limited to four, and the present invention can be applied to two or more chips.

30 is a backup power source for the IC memory card;
Power is supplied to switch circuits 21 to 24 and a resistor 40, which will be described later, through a diode 62 and a power supply line 31. The power line 31 is also connected to the power terminal 51 via a diode 61, and the IC memory card 1
is connected to external device 2, this power terminal 5
1 and a diode 61, and is connected to the external device 2 via a GND terminal 52.

A register 40 holds switch data sent from the external device 2 via the switch data terminal 57. This register 40 is RAMII~1
It is a 4-bit one to store information on the presence or absence of power supply for each of the 4 bits. The contents of each digit of the register are sent to switch circuits 21 to 24 as switch signals.

Note that the switch data is sent serially, so
The switch data is read using the clock sent from the external device 2 via the clock terminal 56 as a shift clock.

The switch circuits 21 to 24 are specifically MOS-FETs, and RAM II to 24 are connected to the power supply voltage from the device or the battery voltage in the IC memory card from the power supply line by applying a switch signal to their gates.
14.

In this embodiment, when writing and reading data, the software of the external device 2 determines the usage status of the file, and sets switch data to the register 40 so that power is supplied only to valid RAM chips among RAM II-14. Write. The switch held in this register
A switch signal is supplied only to the switch circuit whose data corresponds to "1", and the connected RAM
Power is supplied to the

Next, a second embodiment of the present invention will be described using FIG. 2 of the present invention. In the figure, the same parts as in FIG. 1 are indicated by the same reference numerals.

This embodiment transmits switch on/off data.
A bit switch bus and a data bus for writing to or reading from RAM II-14 are connected by a selector 41, and interfaced with the external device 2 via a shared bus terminal 58. and external device 2
A selection signal input via the selection signal terminal 59 selects between RAM data and switch on/off data.

For example, when the selection signal "0" is input, the data to be interfaced from the shared bus terminal 58 is data to be read or written to the RAM, so the selector 41 selects the data bus side and connects it to the shared bus. .

On the other hand, when the selection signal "1" is input, the selector 41 selects the switch bus and writes the switch data input from the external device 2 into the register 40 using the lower four bits of the shared bus. Further, the clock applied to the register 40 is used as a latch clock for switch on/off data.

Note that the components of this embodiment other than those described above and the power on/off control are basically the same as those of the first embodiment, so their explanations will be omitted.

〔Effect of the invention〕

As described above, according to the present invention, power is supplied only to the RAM chips that store data, and power is not supplied to the RAM chips to which no data is written. This reduces the consumption of the built-in battery, so the IC
Memory cards have a longer lifespan.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration of a first embodiment of the invention, and FIG. 2 is a block diagram showing the configuration of a second embodiment of the invention. In the figure, 1... IC memory card, 2... External device, 11-14... RAM chip, 21-24 Switch circuit, 0 Built-in battery, 0 Register, Selector, 1-59 (External connection) terminal. 1-62 Diode. Figure 1: Semi-fabricated F measurement plan for anchoring the rod of the present invention.

Claims (1)

[Claims] An IC memory card comprising a readable and writable memory, a backup power source for the memory, and an input/output terminal for connecting to an external device and inputting and outputting information, the IC memory card comprising:
A register is provided for holding switch switching information input from an external device through the input/output terminal, and the memory is divided into a plurality of blocks, each of which is connected between the block and the backup power source. An IC memory card characterized in that a switch circuit is provided for turning on and off the supply of the backup power source according to the value of switch switching information held by the register.