JP2008047152A - Memory card - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an information recording medium, such as a memory card of low power consumption, IC card, or the like, which can be used even when power supply voltage supplied by information processing equipment is different from operating voltage of a memory integrated circuit. <P>SOLUTION: The card is provided with the memory integrated circuit (14) for operating at a prescribed operating voltage. The memory card to which the power supply voltage is supplied from the information processing equipment is provided with: a power supply voltage control circuit (12) which converts the power supply voltage into a prescribed operating voltage to output it when the power supply voltage is within a prescribed voltage and outputs the power supply voltage when the power supply voltage is outside a second prescribed voltage range; and an input output buffer (13) which is placed between the information processing equipment and the memory integrated circuit to convert signal voltage of signals input and output between the information processing equipment and the memory integrated circuit. To the memory integrated circuit, the operating voltage is supplied from the supply voltage control circuit. The first and the second prescribed voltage ranges have an upper limit value and a lower limit value. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an information recording medium such as a PC card using a DRAM memory based on the PCMCIA specification, particularly a memory card that has low power consumption and can be used without depending on a power supply voltage.

  FIG. 4 shows a conventional DRAM memory card. In the figure, in a conventional DRAM memory card (hereinafter referred to as a memory card) 51, a power supply voltage is supplied to a DRAM integrated circuit 52 between a connected information processing device (hereinafter referred to as a PC). The power supply line Vcc, the data access control line 53 for exchanging signals, and the ground line GND to which a reference potential is applied are connected. Normally, a memory card is composed of a plurality of DRAM integrated circuits 52, but here, only one DRAM integrated circuit 52 is configured to simplify the description. The data access control line 53 is a collection of address, data, and control signal lines for reading and writing data with the PC, and control signals based on the PCMCIA specification are exchanged therein.

Conventionally, the DRAM integrated circuit 52 has been mainly operated with a power supply voltage and a signal voltage of 5V. However, in recent years, a DRAM which operates at 3.3V due to a problem of dielectric breakdown due to fine patterning due to high integration of LSI. An integrated circuit 52 is also used. At present, a DRAM integrated circuit having an operating voltage of 5V (hereinafter referred to as a 5V DRAM) and a DRAM integrated circuit having an operating voltage of 3.3V (hereinafter referred to as a 3.3V DRAM) Are coexisting). The PC determines the operating voltage of the memory card to be connected and supplies an appropriate voltage to the memory card. That is, a voltage of 5V is supplied to a memory card operating at 5V, and a voltage of 3.3V is supplied to a memory card operating at 3.3V. However, some PCs only support memory cards that operate at 5V, and such PCs cannot use memory cards that operate at 3.3V. As a technique related to an IC card operable with two types of power supply voltages, there is one disclosed in Patent Document 1.
Japanese Patent Laid-Open No. 06-333103

  FIG. 5 shows the current consumption of the 5V and 3.3V DRAM integrated circuits in the conventional memory card. From FIG. 5, the 3.3V DRAM is the same as the 5V DRAM in operation. It can be seen that the current consumption is about half.

  That is, if a 3.3V DRAM is used instead of a 5V DRAM in the memory card, the current consumption can be greatly reduced, and the life of the battery battery built in the PC can be extended. However, a conventional memory card equipped with a 3.3V DRAM cannot be used for a PC that supports only a 5V DRAM, and the current consumption is reduced by using a 3.3V DRAM. Was impossible.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a low-power consumption DRAM memory card that does not depend on a power supply voltage supplied from an information processing device.

  A memory card according to the present invention is a memory card that includes a memory integrated circuit that operates at a predetermined operating voltage, and is supplied with a power supply voltage from the information processing device when mounted on the information processing device. The power supply voltage control circuit converts the power supply voltage to a predetermined operating voltage and outputs it when the power supply voltage supplied from the information processing device is within the first predetermined voltage range, while the power supply voltage is the operating voltage of the memory integrated circuit. When the voltage is within the second predetermined voltage range including, the power supply voltage is output. The input / output buffer is disposed between the information processing device and the memory integrated circuit, and converts a signal voltage of a signal input / output between the information processing device and the memory integrated circuit. The memory integrated circuit is supplied with an operating voltage from a power supply voltage control circuit. The first predetermined voltage range has an upper limit value and a lower limit value, and the second predetermined voltage range has an upper limit value and a lower limit value. The power supply voltage control circuit has an input terminal for inputting a power supply voltage supplied from an information device, an output terminal for outputting an operating voltage of the memory integrated circuit, and an input connected to the input terminal. A first voltage detection circuit that detects whether the voltage is within a predetermined voltage range and outputs a first control signal; and a power supply voltage that is input when the power supply voltage is within the first predetermined voltage range in response to the first control signal. A voltage conversion circuit for converting to a predetermined operating voltage and outputting it, and an input connected to the input terminal, detecting whether or not the input power supply voltage is within a second predetermined voltage range and outputting a second control signal A second voltage detection circuit; and a voltage output circuit that receives the second control signal and outputs the power supply voltage to the output terminal when the power supply voltage is within the second predetermined voltage range.

  According to the present invention, even if the supply voltage from the information processing device is higher than the operating voltage of the memory integrated circuit, it is converted into an appropriate voltage by the power supply voltage control circuit. Accordingly, a memory integrated circuit that operates at a low voltage can be used in the memory card or the IC card regardless of the supply voltage of the information processing device. Therefore, a memory card or an IC card with low current consumption can be realized. In addition, a usable memory card can be realized without depending on the supply voltage from the information processing device.

  Embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

  FIG. 1 shows a memory card according to an embodiment of the present invention. The memory card 11 of this embodiment is connected to the power supply voltage control circuit 12 whose input is connected to the power supply line Vcc and the output of the power supply voltage control circuit 12, and converts the voltage of data and various control signals to and from the PC. Therefore, the input / output buffer 13 connected to the data access control line 15 is connected to the input / output buffer 13 in order to exchange data and various control signals from the PC via the input / output buffer 13, and the power supply voltage control circuit And a DRAM integrated circuit 14 operating at 3.3V. The power supply voltage control circuit 12, the input / output buffer 13, and the DRAM integrated circuit 14 are connected to a ground line GND that supplies a reference potential.

  A DC voltage of 3.3V or 5V from the PC is supplied to the power line Vcc. The power supply voltage control circuit 12 (details will be described later) converts the voltage supplied via the power supply line Vcc into a predetermined voltage (3.3 V), and the input / output buffer 13 and the DRAM integrated circuit 14. To supply. The input / output buffer 13 is interposed between the PC and the DRAM integrated circuit 14 and mutually converts the voltages of signals exchanged between the PC and the DRAM integrated circuit 14. That is, the voltage of the signal from the PC side is 3.3V or 5V, and the voltage of the signal that can be processed by the DRAM integrated circuit 14 is 3.3V. For this reason, when the signal is exchanged between the PC and the DRAM integrated circuit 14 by the input / output buffer 13, the signal voltage is converted into a voltage that can be processed by each. The input / output buffer 13 has “tolerance-free” performance in which the input / output voltage is not limited within a predetermined range, and the signal voltage input / output to / from the PC is within a predetermined range from 3V to 5.5V. Any voltage within the range can be converted. Accordingly, when a signal flows from the PC to the DRAM integrated circuit 14, the input / output buffer 13 converts this signal voltage (3.3V or 5V) into a voltage (3.3V) that can be processed by the DRAM integrated circuit 14, and also the DRAM. When a signal flows from the integrated circuit 14 to the PC, the signal voltage (3.3 V) is converted into a voltage (3.3 V or 5 V) that can be processed by the PC. The input / output buffer 13 having such a function is commercially available as an IC, for example, National Semiconductor, Texas Instruments 74LVC245, or the like.

  The power supply voltage control circuit 12 will be described in detail below with reference to FIG. The power supply voltage control circuit 12 includes a first window comparator 21 whose input is connected to the input terminal 28, a first switch 22 whose one end is connected to the input terminal 28 and is opened and closed by a control signal from the first window comparator 21, A DC-DC converter 23 having an input connected to the other end of the first switch 22 and an output connected to the output terminal 29, a second window comparator 24 having an input connected to the input terminal 28, and one end connected to the input terminal 28 The other end is connected to the output terminal 29, and the second switch 25 is opened and closed by a control signal from the second window comparator 24. The first and second window comparators 21 and 24 output a “High” level signal (hereinafter referred to as “H”) as a control signal only when a voltage within a predetermined range is input. In the present embodiment, the first window comparator 21 outputs “H” with respect to the input voltage of 5 V ± 10% (4.5 to 5.5 V), and the second window comparator 24 is 3.3 V ± 10. "H" is output for an input voltage of% (3.0 to 3.6 V). FIG. 3A shows a circuit diagram of the first window comparator 21. In FIG. 3A, a first window comparator 21 applies a reference voltage of 5.5V to the positive terminal, a first comparator 31 having a negative terminal connected to the input 33, and a reference voltage of 4.5V to the negative terminal. , And a second terminal 32 having a positive terminal coupled to the negative terminal of the first comparator 31 and an output coupled to the output 34 of the first comparator 31. The output Vout of the first window comparator 21 configured as described above is “H” only when the input Vin is 5 V ± 10% (4.5 to 5.5 V) as shown in FIG. . Similarly, by applying a reference voltage of 3.6 V to the positive terminal of the first comparator 31 and 3.0 V to the negative terminal of the second comparator 32, 3.3 V ± 10% (3.0 to 3.6 V). ), The second window comparator 24 that outputs “H” can be configured. Here, the window comparators 21 and 24 have a 10% margin in consideration of the fluctuation of the voltage from the PC. The first and second switches 22 and 25 are constituted by, for example, a field-effect transistor switch with little loss, and turn on when the control signal is “H” and turn off when the control signal is “L”. The DC-DC converter 23 outputs a voltage of 3.3V with respect to an input voltage of 4.5 to 5.5V.

  Next, the operation of the power supply voltage control circuit 12 will be described. In FIG. 2, the input terminal 28 is supplied with a voltage of 3.3 V or 5 V (having a fluctuation within 10%) from the PC. Now, when a voltage of 5 V is supplied to the input terminal 28, the output of the second window comparator 24 is “L” and the second switch 25 is “off”, so the path 27 is not established. At this time, the output of the first window comparator 21 becomes “H”, the first switch 22 is turned “ON”, and the input voltage is supplied to the DC-DC converter 23 through the path 26. Thereby, the DC-DC converter 23 converts the supply voltage from the PC into 3.3 V and outputs it. As the DC-DC converter 23 at this time, a high-efficiency converter whose conversion loss is smaller than the power consumption of the 5V DRAM integrated circuit is used. Next, consider a case where a voltage of 3.3 V is supplied to the input terminal 28. When a voltage of 3.3 V is input, the output of the first window comparator 21 is “L” and the first switch 22 is “off”, so the path 26 is not established. At this time, the output of the second window comparator 24 becomes “H”, the second switch 25 is turned “ON”, and the input voltage is output as it is via the path 27. In other words, when the input voltage is 5V, the power supply voltage control circuit 12 of the present embodiment converts the voltage to a voltage of 3.3V via the high-efficiency DC-DC converter 23, and the input voltage is 3.V. At 3V, the voltage is output as it is, so that a predetermined voltage is efficiently supplied regardless of the input voltage.

  In the memory card 11 of the present embodiment, when the power supply voltage supplied from the PC is 5V, the voltage is converted to 3.3V by the power supply voltage control circuit 12 and driven to the input / output buffer 13 and the 3.3V DRAM integrated circuit 14. Voltage is supplied. When the supply voltage from the PC is 3.3V, the power supply voltage control circuit 12 does not convert the voltage and supplies it as it is to the input / output buffer 13 and the 3.3V DRAM integrated circuit 14 as a drive voltage. Further, the signal voltage of the signal from the PC or DRAM integrated circuit 14 is mutually converted by the input / output buffer 13 and is output to the DRAM integrated circuit 14 or PC, so that the DRAM integrated circuit 14 can be used even when the signal voltage is different. And exchange of signals between PCs. In this manner, the memory card according to the present embodiment operates regardless of the supplied power supply voltage and signal voltage because the power supply voltage and the signal voltage are converted as necessary inside the memory card.

  That is, the memory card of the present embodiment can operate with a power supply voltage supplied from a PC of 5V or 3.3V, and uses a DRAM integrated circuit 14 that operates at a low voltage in the DRAM integrated circuit. The power consumption can be reduced, and the life of the battery in the PC can be extended.

  In the power supply control circuit of this embodiment, an additional DC-DC converter is appropriately provided by changing the setting of the reference voltage applied to the first and second window comparators and the conversion voltage of the DC-DC converter. Thus, it is clear that a memory card that operates even when the power supply voltage from the information processing device and the operating voltage of the memory card are predetermined voltages other than the voltages described above can be configured.

  In the memory card according to the present embodiment, the DRAM is used as the memory. However, the same effect can be expected with a memory card using a flash memory or the like instead of the DRAM.

The block diagram of the memory card of embodiment of this invention. The block block diagram of a power supply control circuit. (A) The circuit diagram of a 1st window comparator, (b) The figure showing the input / output relationship of a 1st window comparator. The block diagram of the conventional memory card. The figure showing the consumption current of DRAM memory integrated circuit.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 ... Memory card of embodiment of this invention, 12 ... Power supply voltage control circuit, 13 ... Input / output buffer, 14, 52 ... DRAM integrated circuit, 15, 53 ... Data access control line, 21 ... First window comparator, 22 ... 1st switch, 23 ... DC-DC converter, 24 ... 2nd window comparator, 25 ... 2nd switch, 26, 27 ... path, 28 ... Input terminal of power supply voltage control circuit, 29 ... Output terminal of power supply voltage control circuit, DESCRIPTION OF SYMBOLS 31 ... 1st comparator, 32 ... 2nd comparator, 33 ... Input terminal of 1st window comparator, 34 ... Output terminal of 1st window comparator, 51 ... Conventional memory card, Vcc ... Power supply line, Vin ... 1st window comparator , Vout: output of the first window comparator, GND: ground line.

Claims (1)

In a memory card that includes a memory integrated circuit that operates at a predetermined operating voltage, and is supplied to the information processing device in a state where it is mounted on the information processing device,
a) When the power supply voltage supplied from the information processing device is within a first predetermined voltage range, the power supply voltage is converted into the predetermined operating voltage and output, while the power supply voltage is operated by the memory integrated circuit. A power supply voltage control circuit for outputting the power supply voltage when within a second predetermined voltage range including a voltage;
An input / output buffer that is disposed between the information processing device and the memory integrated circuit and converts a signal voltage of a signal input / output between the information processing device and the memory integrated circuit;
b) The memory integrated circuit is supplied with an operating voltage from the power supply voltage control circuit;
c) the first predetermined voltage range has an upper limit value and a lower limit value, and the second predetermined voltage range has an upper limit value and a lower limit value;
d) The power supply voltage control circuit
An input terminal that inputs a power supply voltage supplied from the information device, an output terminal that outputs an operating voltage of the memory integrated circuit, an input is connected to the input terminal, and the input power supply voltage is the first terminal A first voltage detection circuit for detecting whether the voltage is within a predetermined voltage range and outputting a first control signal;
A voltage conversion circuit that receives the first control signal, converts the input power supply voltage to the predetermined operating voltage when the power supply voltage is within the first predetermined voltage range, and outputs the predetermined operating voltage;
A second voltage detection circuit that connects an input to the input terminal, detects whether the input power supply voltage is within the second predetermined voltage range, and outputs a second control signal;
And a voltage output circuit that receives the second control signal and outputs the power supply voltage to an output terminal when the power supply voltage is within the second predetermined voltage range.

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