JP2508085B2 - IC card - Google Patents
IC cardInfo
- Publication number
- JP2508085B2 JP2508085B2 JP62122023A JP12202387A JP2508085B2 JP 2508085 B2 JP2508085 B2 JP 2508085B2 JP 62122023 A JP62122023 A JP 62122023A JP 12202387 A JP12202387 A JP 12202387A JP 2508085 B2 JP2508085 B2 JP 2508085B2
- Authority
- JP
- Japan
- Prior art keywords
- power supply
- signal
- terminal
- card
- signal terminal
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
Links
- 238000001514 detection method Methods 0.000 claims description 48
- 239000004065 semiconductor Substances 0.000 claims description 27
- 230000005611 electricity Effects 0.000 claims 1
- 238000010586 diagram Methods 0.000 description 4
- 230000000694 effects Effects 0.000 description 2
- 230000003068 static effect Effects 0.000 description 2
Landscapes
- Techniques For Improving Reliability Of Storages (AREA)
- Credit Cards Or The Like (AREA)
Description
【発明の詳細な説明】 〔産業上の利用分野〕 この発明は、電池によりバックアップされる半導体素
子をもつICカードの入力回路の改良に関する。Description: TECHNICAL FIELD The present invention relates to improvement of an input circuit of an IC card having a semiconductor element backed up by a battery.
第２図は従来のICカードの入力回路のブロック図で、
Ａは外部電源に接続される電源端子、Ｄは外部からチッ
プイネーブル信号やアドレス信号などが与えられる信号
端子であり、信号端子Ｄは複数のうちの１つを代表的に
図示している。また１は電源端子Ａに接続され該電源端
子Ａの電圧値が一定値以上であると検出信号を出力する
電源電圧検出回路、２は電源電圧検出回路１からの信号
により電源の切り換えを行なう電源切り換え回路、３は
半導体素子をバックアップするため電源切り換え回路２
を介して半導体素子に接続された電池、４は電源切り換
え回路２を介して電源電圧を供給されまた信号端子Ｄか
ら信号を受けて作動する半導体素子、５は信号端子Ｄと
接地との間に接続されたプルダウン抵抗である。Figure 2 is a block diagram of a conventional IC card input circuit.
A is a power supply terminal connected to an external power supply, D is a signal terminal to which a chip enable signal, an address signal, and the like are externally applied, and the signal terminal D representatively shows one of the plurality. Reference numeral 1 is a power supply voltage detection circuit which is connected to the power supply terminal A and outputs a detection signal when the voltage value of the power supply terminal A is a certain value or more. Reference numeral 2 is a power supply for switching the power supply according to a signal from the power supply voltage detection circuit 1. The switching circuit 3 is a power supply switching circuit 2 for backing up semiconductor elements.
A battery 4 connected to a semiconductor element via a semiconductor element which is supplied with a power source voltage via a power source switching circuit 2 and which operates by receiving a signal from a signal terminal D, and 5 between a signal terminal D and ground. This is the connected pull-down resistor.
従来のICカードの入力回路は上記のように構成されて
いる。そして一般にICカードが使用される場合、外部機
器と接続される。以下、ICカードを外部機器に接続した
場合と外部機器に接続しない場合について説明する。The input circuit of the conventional IC card is configured as described above. In general, when an IC card is used, it is connected to an external device. Hereinafter, the case where the IC card is connected to the external device and the case where the IC card is not connected to the external device will be described.
まずICカードを外部機器に接続した場合について説明
する。この場合、電源端子Ａに外部機器から電圧が供給
されるため、電源端子Ａの電圧が電源電圧検出回路１の
検出電圧以上となる。そのため電源電圧検出回路１から
検出信号が出力される。そしてその検出信号が電源切り
換え回路２に入力され電源の切り換えが行なわれ、半導
体素子４の電源は電源端子Ａから供給される。またこの
場合、半導体素子４の信号端子Ｄにも外部機器からチッ
プイネーブル信号やアドレス信号などが与えられる。そ
して、半導体素子４（例えばスタティックRAM）は作動
し、データの書込みや読出しが行なわれる。このときプ
ルダウン抵抗５は、信号端子Ｄに接続されたままであ
る。First, a case where the IC card is connected to an external device will be described. In this case, since a voltage is supplied to the power supply terminal A from an external device, the voltage of the power supply terminal A becomes equal to or higher than the detection voltage of the power supply voltage detection circuit 1. Therefore, the detection signal is output from the power supply voltage detection circuit 1. Then, the detection signal is input to the power source switching circuit 2 to switch the power source, and the power source of the semiconductor element 4 is supplied from the power source terminal A. Further, in this case, the signal enable D of the semiconductor element 4 is also given a chip enable signal, an address signal, etc. from an external device. Then, the semiconductor element 4 (for example, static RAM) operates, and data writing and reading are performed. At this time, the pull-down resistor 5 is still connected to the signal terminal D.
次にICカードを外部機器に接続しない場合について説
明する。この場合、電源端子Ａには外部機器から電圧が
供給されないため、電源端子Ａの電圧は、電源電圧検出
回路１の検出電圧以下となる。そのため電源電圧検出回
路１からは検出信号が出力されない。従って電源切り換
え回路２に検出信号が入力されず、半導体素子４の電源
電圧は、半導体素子４をバックアップするための電池３
により供給される。またICカードが外部機器に接続され
ていない場合、半導体素子４の信号端子Ｄには外部機器
から信号は供給されない。従って、半導体素子４は作動
しない。この場合プルダウン抵抗５は、信号端子Ｄの電
位を接地レベルにプルダウンしている。Next, a case where the IC card is not connected to an external device will be described. In this case, since no voltage is supplied to the power supply terminal A from the external device, the voltage of the power supply terminal A becomes equal to or lower than the detection voltage of the power supply voltage detection circuit 1. Therefore, no detection signal is output from the power supply voltage detection circuit 1. Therefore, the detection signal is not input to the power supply switching circuit 2, and the power supply voltage of the semiconductor element 4 is the battery 3 for backing up the semiconductor element 4.
Supplied by If the IC card is not connected to an external device, no signal is supplied to the signal terminal D of the semiconductor element 4 from the external device. Therefore, the semiconductor element 4 does not operate. In this case, the pull-down resistor 5 pulls down the potential of the signal terminal D to the ground level.
従来のICカードは以上のように構成されており、ICカ
ードを外部機器に接続した場合、つまり半導体素子４の
制御端子Ｄに電圧がかかった場合、プルダウン抵抗５は
常に半導体素子４の信号端子Ｄに接続されているため、
プルダウン抵抗５が半導体素子４の信号端子Ｄからの入
力電流を必ず消費するという問題があった。一例として
プルダウン抵抗５の抵抗値が10KΩ程度のときにはプル
ダウン抵抗５には500μＡ程度の電流が流れることにな
る。特にICカード使用時に接続される外部機器の電源が
電池の場合、プルダウン抵抗５が半導体素子４の信号端
子Ｄからの入力電流を消費すると、外部機器の電源であ
る電池の寿命が短くなり不便である。The conventional IC card is configured as described above, and when the IC card is connected to an external device, that is, when a voltage is applied to the control terminal D of the semiconductor element 4, the pull-down resistor 5 always maintains the signal terminal of the semiconductor element 4. Since it is connected to D,
There is a problem that the pull-down resistor 5 always consumes the input current from the signal terminal D of the semiconductor element 4. As an example, when the resistance value of the pull-down resistor 5 is about 10 KΩ, a current of about 500 μA flows through the pull-down resistor 5. Especially when the power source of the external device connected when using the IC card is a battery, if the pull-down resistor 5 consumes the input current from the signal terminal D of the semiconductor element 4, the battery life of the power source of the external device is shortened and it is inconvenient. is there.
この発明は、従来のICカードにおける上述の問題点を
解決するためになされたもので、内蔵のスタティックRA
M等の半導体素子の信号端子に電圧がかかったときに該
信号端子からの入力電流を減少させ、外部機器の電源が
電池の場合にその電池を無用に消費することのないICカ
ードを提供することを目的とするものである。The present invention has been made to solve the above-mentioned problems in the conventional IC card, and has a built-in static RA.
To provide an IC card that reduces the input current from a signal terminal of a semiconductor element such as M when a voltage is applied to the signal terminal and does not consume the battery unnecessarily when the external device is powered by a battery. That is the purpose.
本発明に係るICカードは、外部電源に接続されると電
源端子と、前記電源供給端子に接続され、この電源端子
の電圧値が一定値以上であると検出信号を出力する電源
電圧検出回路と、バックアップ用電源としての電池と、
前記電源電圧検出回路からの検出信号の有無に応じ前記
外部電源／前記電池の切り換えを行なう電源切り換え回
路と、外部と所定の信号の授受を行なう信号端子と、前
記電源切り換え回路を介して電源電圧を供給されまた前
記信号端子から信号を受けて作動する半導体素子と、前
記信号端子と所定電位との間に接続され、前記電源電圧
検出回路からの検出信号に応答して非導通する電気的ス
イッチと設けている。The IC card according to the present invention is connected to an external power supply, a power supply terminal, and a power supply voltage detection circuit which is connected to the power supply terminal and outputs a detection signal when the voltage value of the power supply terminal is a certain value or more. , A battery as a backup power source,
A power supply switching circuit that switches between the external power supply and the battery depending on the presence or absence of a detection signal from the power supply voltage detection circuit, a signal terminal that exchanges a predetermined signal with the outside, and a power supply voltage through the power supply switching circuit. And an electrical switch connected between the signal terminal and a predetermined potential and electrically non-conductive in response to a detection signal from the power supply voltage detection circuit. Is provided.
この発明における電気的スイッチは、電源電圧検出回
路の検出信号に応答して非導通する。従って、ICカード
使用時にICカードを外部機器に接続した場合、つまり半
導体素子の信号端子に電圧がかかった場合、該信号端子
を所定電位から電気的に切り離すことができ、所定電位
の側へは電流は流れない。また電源電圧検出回路が検出
信号を出力しないときは電気的スイッチは導通し、信号
端子は所定電位にプルダウンまたはプルアップされる。The electrical switch according to the present invention becomes non-conductive in response to the detection signal of the power supply voltage detection circuit. Therefore, when the IC card is connected to an external device when the IC card is used, that is, when a voltage is applied to the signal terminal of the semiconductor element, the signal terminal can be electrically disconnected from the predetermined potential, and the signal terminal of the predetermined potential is not supplied. No current flows. When the power supply voltage detection circuit does not output a detection signal, the electric switch is turned on and the signal terminal is pulled down or pulled up to a predetermined potential.
第１図は、この発明によるICカードの一実施例におけ
る入力回路を示すブロック図である。FIG. 1 is a block diagram showing an input circuit in an embodiment of an IC card according to the present invention.
同図において、６はプルダウン抵抗５と接地との間に
接続され、電源電圧検出回路１からの検出信号が入力さ
れることにより非導通し、プルダウン抵抗５をICカード
の信号端子から電気的に切り離す電気的スイッチであ
る。その他の構成は前記した従来のICカードの入力回路
と全く同一であるので説明を省略する。In the figure, 6 is connected between the pull-down resistor 5 and the ground, and becomes non-conductive when the detection signal from the power supply voltage detection circuit 1 is input, and the pull-down resistor 5 is electrically connected to the signal terminal of the IC card. It is an electrical switch to disconnect. The rest of the configuration is exactly the same as the input circuit of the above-mentioned conventional IC card, and therefore its explanation is omitted.
次に動作について、ICカードを外部機器に接続した場
合と外部機器に接続しない場合について説明する。Next, the operation will be described when the IC card is connected to an external device and when it is not connected to the external device.
まずICカードを外部機器に接続した場合について説明
する。この場合、電源端子Ａに外部機器から電圧が供給
されるため、電源端子Ａの電圧が電源電圧検出回路１の
検出電圧以上となる。そのため、電源電圧検出回路１か
ら検出信号が出力される。そして、その信号が電気的ス
イッチ６に入力され、この電気的スイッチ６は非導通と
なる。従って、半導体素子４の信号端子Ｄと電気的スイ
ッチ６との間に接続されたプルダウン抵抗５は、ICカー
ドの入力回路から電気的に切り離された状態になる。そ
のためICカードが外部機器に接続された状態で、半導体
素子４の信号端子Ｄにチップセレクト信号やアドレス信
号などが与えられ、信号端子Ｄに電圧が印加されてもプ
ルダウン抵抗５が当該入力電流を無用に消費することは
ない。First, a case where the IC card is connected to an external device will be described. In this case, since a voltage is supplied to the power supply terminal A from an external device, the voltage of the power supply terminal A becomes equal to or higher than the detection voltage of the power supply voltage detection circuit 1. Therefore, the detection signal is output from the power supply voltage detection circuit 1. Then, the signal is input to the electrical switch 6, and the electrical switch 6 becomes non-conductive. Therefore, the pull-down resistor 5 connected between the signal terminal D of the semiconductor element 4 and the electric switch 6 is electrically disconnected from the input circuit of the IC card. Therefore, when the IC card is connected to an external device, a chip select signal, an address signal, or the like is given to the signal terminal D of the semiconductor element 4, and even if a voltage is applied to the signal terminal D, the pull-down resistor 5 keeps the input current concerned. It is never consumed unnecessarily.
次にICカードを外部機器に接続しない場合について説
明する。この場合、電源端子Ａには外部機器から電圧が
供給されないため、電源端子Ａの電圧は、電源電圧検出
回路１の検出電圧以下となる。そのため、電源電圧検出
回路１からは検出信号が出力されない。従って電気的ス
イッチ６には電源電圧検出回路１からの検出信号は入力
されず、電気的スイッチ６は導通する。そして、半導体
素子４の信号端子Ｄはプルダウン抵抗５を介して接地レ
ベルにプルダウンされる。ICカードが外部機器に接続さ
れていないため、半導体素子４の信号端子Ｄには信号が
与えられることはなく、プルダウン抵抗５による電流消
費の問題は生じない。Next, a case where the IC card is not connected to an external device will be described. In this case, since no voltage is supplied to the power supply terminal A from the external device, the voltage of the power supply terminal A becomes equal to or lower than the detection voltage of the power supply voltage detection circuit 1. Therefore, no detection signal is output from the power supply voltage detection circuit 1. Therefore, the detection signal from the power supply voltage detection circuit 1 is not input to the electrical switch 6, and the electrical switch 6 is conductive. Then, the signal terminal D of the semiconductor element 4 is pulled down to the ground level via the pull-down resistor 5. Since the IC card is not connected to an external device, no signal is given to the signal terminal D of the semiconductor element 4, and the problem of current consumption by the pull-down resistor 5 does not occur.
なお、上記実施例においては、プルダウン抵抗５を用
いた場合について説明したが、プルアップ抵抗でもよ
く、また抵抗を用いずに電気的スイッチ６を介して直接
に所定電位に接続する場合でも同様の動作が実現でき
る。In the above embodiment, the case where the pull-down resistor 5 is used has been described, but a pull-up resistor may be used, and the same applies when directly connecting to a predetermined potential through the electric switch 6 without using a resistor. Operation can be realized.
また、上記実施例では、電気的スイッチ６が、電池３
によりバックアップされている半導体素子４とは別々に
記載されているが、これらは１つの半導体素子内で実現
することも可能である。この場合においては、ICカード
の入力回路の小型化も期待できる。In addition, in the above embodiment, the electric switch 6 is the battery 3
Although they are described separately from the semiconductor device 4 backed up by, they can also be realized in one semiconductor device. In this case, miniaturization of the input circuit of the IC card can be expected.
以上説明したように、この発明によれば、電源電圧検
出回路からの検出信号の入力により非導通する電気的ス
イッチを信号端子と所定電位との間に接続しているた
め、ICカードが外部機器に接続され、電源端子に電源電
圧検出回路の検出電圧以上の電圧が供給される通常の動
作電源電圧範囲では、電源電圧検出回路からの検出信号
が電気的スイッチに入力されて電気的スイッチは非導通
となり、信号端子は所定電位から電気的に切り離され
る。このため半導体素子の信号端子に電圧がかかってい
るICカードの通常動作範囲では、半導体素子の信号端子
から所定電位の側に無用の電流が流れることがなく、外
部機器からの入力電流を減少させることができるという
効果がある。As described above, according to the present invention, since the electrical switch that is non-conducted by the input of the detection signal from the power supply voltage detection circuit is connected between the signal terminal and the predetermined potential, the IC card can be used as an external device. In the normal operating power supply voltage range where the power supply terminal is supplied with a voltage equal to or higher than the detection voltage of the power supply voltage detection circuit, the detection signal from the power supply voltage detection circuit is input to the electrical switch and the electrical switch is turned off. It becomes conductive, and the signal terminal is electrically disconnected from the predetermined potential. Therefore, in the normal operation range of the IC card where the voltage is applied to the signal terminal of the semiconductor element, unnecessary current does not flow from the signal terminal of the semiconductor element to the side of the predetermined potential, and the input current from the external device is reduced. The effect is that you can.
第１図はこの発明の一実施例を示すブロック図、第２図
は従来のICカードの入力回路を示すブロック図である。 図において、Ａは電源端子、Ｄは信号端子、１は電源電
圧検出回路、２は電源切り換え回路、３は電池、４は半
導体素子、５はプルダウン抵抗、６は電気的スイッチで
ある。 なお、各図中同一符号は同一または相当部分を示す。FIG. 1 is a block diagram showing an embodiment of the present invention, and FIG. 2 is a block diagram showing an input circuit of a conventional IC card. In the figure, A is a power supply terminal, D is a signal terminal, 1 is a power supply voltage detection circuit, 2 is a power supply switching circuit, 3 is a battery, 4 is a semiconductor element, 5 is a pull-down resistor, and 6 is an electrical switch. In the drawings, the same reference numerals indicate the same or corresponding parts.
Claims (2)
一定値以上であると検出信号を出力する電源電圧検出回
路と、 バックアップ用電源としての電池と、 前記電源電圧検出回路からの検出信号の有無に応じ前記
外部電源／前記電池の切り換えを行なう電源切り換え回
路と、 外部と所定の信号の授受を行なう信号端子と、 前記電源切り換え回路を介して電源電圧を供給されまた
前記信号端子から信号を受けて作動する半導体素子と、 前記信号端子と所定電位との間に接続され、前記電源電
圧検出回路からの検出信号を応答して非導通する電気的
スイッチとを備えたICカード。1. A power supply terminal connected to an external power supply, a power supply voltage detection circuit connected to the power supply terminal, which outputs a detection signal when the voltage value of the power supply terminal is a certain value or more, and a backup power supply. As a battery, a power supply switching circuit for switching the external power supply / battery according to the presence or absence of a detection signal from the power supply voltage detection circuit, a signal terminal for exchanging a predetermined signal with the outside, and the power supply switching circuit. A semiconductor element that is supplied with a power supply voltage via the signal terminal and operates by receiving a signal from the signal terminal, and is connected between the signal terminal and a predetermined potential, and responds to a detection signal from the power supply voltage detection circuit to generate a non-responsive signal. An IC card with an electrical switch that conducts electricity.
的スイッチと直列に抵抗を接続した、特許請求の範囲第
１項記載のICカード。2. The IC card according to claim 1, further comprising a resistor connected in series with the electric switch between the signal terminal and a predetermined potential.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP62122023A JP2508085B2 (en) | 1987-05-19 | 1987-05-19 | IC card |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP62122023A JP2508085B2 (en) | 1987-05-19 | 1987-05-19 | IC card |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS63285692A JPS63285692A (en) | 1988-11-22 |
| JP2508085B2 true JP2508085B2 (en) | 1996-06-19 |
Family
ID=14825674
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP62122023A Expired - Lifetime JP2508085B2 (en) | 1987-05-19 | 1987-05-19 | IC card |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2508085B2 (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS647186A (en) * | 1987-06-29 | 1989-01-11 | Nec Corp | Ic card |
-
1987
- 1987-05-19 JP JP62122023A patent/JP2508085B2/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| JPS63285692A (en) | 1988-11-22 |
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