JP2002218739A - Power supply circuit and semiconductor card using the same - Google Patents

Abstract

(57) [Summary] [Problem] If the voltage drops even during standby,
The booster circuit is activated, and the current consumption increases. When the supply voltage is equal to or higher than a prescribed level, a switch means for outputting the supply voltage as an output voltage;
When the supply voltage is lower than a specified level, in a semiconductor card provided with a power supply circuit having means for turning on a booster circuit, when the memory in the semiconductor card is not accessed, both the switch means and the booster circuit are turned off. State.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power supply circuit used for a semiconductor card or the like.

[0002]

2. Description of the Related Art With the spread of mobile terminals such as portable information terminals, semiconductor cards used for their data storage and the like require lower operating voltage and wider operating voltage (for example,
2.5V to 3.6V) and operation guarantee in a wide temperature range (-40 to 85 ° C) is required. In response to these demands, for example, it is conceivable that a failure occurs in the mounted memory in low-voltage operation.

In such a case, as shown in FIG. 1, a power supply circuit for boosting is mounted on the semiconductor card 2 mounted on the system 1 so as to operate under a required condition. A possible semiconductor card was realized.

The internal structure of the semiconductor card 2 includes a memory 3, a controller 4 for writing to the memory 3, an oscillator 5 for oscillating a clock in the controller 4, and a reset circuit for resetting the controller 4 when the power is turned on. 6 and a power supply circuit section 7 for supplying power to the memory 3 and the controller 4. The power supply circuit section 7 includes a booster circuit section 8, a PMOS Tr 9, a comparator 10, and an input / output capacitor 11.

Further, although only the main elements are described here in the booster circuit section 8 (further tuning is required in an actual circuit), the booster DC / DC converter 12 and the booster DC / D
It includes a diode 13 for absorbing a back electromotive force, which is connected between an input section and an output section of the C converter 12, and an inductor 14 inserted in series with the input section. The step-up DC / DC converter 12 has an “L” active control terminal CE (overline omitted in the text).

The operation of the power supply circuit section 7 will be described. Here, the following conditions are set in order to understand the explanation. Memory 3 mounted on semiconductor card 2
Requires 2.7 V or more for wide temperature and wide voltage operation, and the output voltage of the step-up DC / DC converter 12 is 3.5 V and the release voltage of the comparator 10 is 2.8 V.

First, the system 1 has a normal voltage.
When operating at 3V, 3.3V from this system 1
Is supplied to the power supply circuit section 7. Since this voltage exceeds the release voltage of the comparator 10, the comparator 10 outputs "H". Since the “H” level is the CE terminal of the step-up DC / DC converter 12, the step-up DC / DC converter 12 (step-up circuit unit 8) is stopped and the PMOS Tr
9 turns on. Therefore, 3.
The power supply voltage of 3 V passes through the PMOS Tr 9 and the power supply circuit section 7.
Is output as it is as 3.3V.

On the other hand, when the system 1 is operating at a low voltage of 2.5 V, this voltage is lower than the release voltage of the comparator 10, so that the comparator 10 outputs "L". As a result, the PMOS Tr 9 is turned off,
The booster circuit section 8 is activated, boosts the input voltage of 2.5 V, and outputs 3.5 V as the output voltage of the power supply circuit section 7.

As described above, when the power supply voltage of the system 1 is lower than the predetermined voltage, the power supply voltage is boosted by the boost DC / DC converter 12 to a specified voltage and supplied to the memory 3 and the controller 4. .

[0010]

However, in the semiconductor card 2 provided with such a power supply circuit section 7, the standby current increases due to the switching of the booster circuit section 8 from off to on, and the rise at power-on. During execution of the card initialization with the gentle power supply voltage waveform, the voltage waveform is disturbed due to the switching of the step-up circuit unit 8 on and off, so that the card initialization may fail.
In addition, there is a problem that an operation failure occurs due to a change in output voltage due to switching of the booster circuit section 8 during card operation due to noise generated on the power supply voltage side.

An object of the present invention is to provide a power supply circuit capable of solving the above-mentioned problem and a semiconductor card using the same.

[0012]

According to the first aspect of the present invention, there is provided voltage determining means for detecting whether a supply voltage is at a prescribed level, and outputting the supply voltage when the supply voltage is at or above the prescribed level. A power supply circuit having switch means for outputting a voltage and means for turning on the booster circuit when the supply voltage is lower than a specified level, comprising: means for turning off both the switch means and the booster circuit. Features.

According to a second aspect of the present invention, there is provided a voltage determining means for detecting whether a supply voltage is at a prescribed level, and a switch means for outputting the supply voltage as an output voltage when the supply voltage is at or above the prescribed level. A power supply circuit having a means for turning on a booster circuit when the supply voltage is less than a prescribed level, a means for detecting an access state to a memory in the semiconductor card; Means for turning off both the switch means and the booster circuit.

According to a third aspect of the present invention, there is provided a voltage determining means for detecting whether or not a supply voltage is at a prescribed level, and a switch means for outputting the supply voltage as an output voltage when the supply voltage is higher than the prescribed level. A power supply circuit having means for turning on the booster circuit when the supply voltage is lower than a prescribed level, wherein the booster circuit is turned off for a predetermined period after the power switch is turned on, and the switch circuit is locked on. Means for performing the operation.

According to a fourth aspect of the present invention, there is provided a voltage determining means for detecting whether a supply voltage is at a prescribed level, and a switch means for outputting the supply voltage as an output voltage when the supply voltage is higher than the prescribed level. And a power supply circuit having means for turning on the booster circuit when the supply voltage is lower than the specified level, wherein the booster circuit is turned on during a card initialization executed by turning on a power switch. Means for turning off and locking the switch circuit on.

According to a fifth aspect of the present invention, there is provided a voltage determining means for detecting whether or not a supply voltage is at a prescribed level, and a switch means for outputting the supply voltage as an output voltage when the supply voltage is higher than the prescribed level. A power supply circuit having a means for turning on a booster circuit when the supply voltage is less than a prescribed level, a means for detecting an access state to a memory in the semiconductor card; Means for turning off both the switch means and the booster circuit, and means for turning off the booster circuit and locking the switch circuit on during a card initialization executed by turning on a power switch. It is characterized by having.

[0017]

FIG. 2 shows a semiconductor card 2A according to a first embodiment of the present invention, and the same elements as those in FIG. 1 are denoted by the same reference numerals.

In the power supply circuit section 7A, the output of the comparator 10 is supplied to an OR circuit OR and an AND circuit AND.
Are supplied to one input terminal. Then, the control signal S1 output from the controller 4A is supplied to the other input terminal of the OR circuit OR and to the other input terminal of the AND circuit AND via the inverter INV. This control signal S1 turns on the power supply circuit section 7A.
This is a control signal newly provided for turning off the memory 3 and becomes "H" level when the controller 4A does not access the memory 3.

The output terminal of the OR circuit OR is controlled by the CE terminal of the step-up DC / DC converter 12, and the AND circuit AND
Is controlled by the gate of the PMOS Tr9.

In the semiconductor card 2A, when the controller 4A is reading from or writing to the memory 3, the control signal S1 is at "L" level, so that one input terminal of the OR circuit OR is connected to L. The H level is supplied to one input terminal of the level and AND circuit AND.

Therefore, when the comparator 10 outputs the H level (when the power supply voltage is normal), the OR circuit O
Since the output terminal of R becomes H level, the booster circuit section 8 stops, and the output terminal of the AND circuit AND also becomes H level.
Since the PMOS Tr 9 is turned on, the power supply voltage from the system 1 is output as it is as the output voltage of the power supply circuit section 7A through the PMOS Tr 9.

On the other hand, when the comparator 10 outputs the L level (when the power supply voltage is low), the AND circuit AND
Is at L level and the PMOS Tr 9 is in the off state, but the output terminal of the OR circuit OR is at L level, so the booster circuit section 8 is activated and boosts the low power supply voltage to a voltage of 3.5 V. Is output.

As described above, the controller 4A stores the memory 3
On the other hand, the operation when reading and writing is the same as in the case of the conventional example of FIG. Next, a case where the controller 4A is in a non-access state to the memory 3 will be described.

At this time, since the control signal S1 is at "H" level, H level is supplied to one input terminal of the OR circuit OR and L level is supplied to one input terminal of the AND circuit AND. .

Therefore, when the comparator 10 outputs the H level (when the power supply voltage is normal), the OR circuit O
Since the output terminal of R goes to the H level, the booster circuit section 8 stops, the output terminal of the AND circuit AND goes to the L level,
Since the PMOS Tr 9 is also turned off, the power supply circuit unit 7A itself is turned off.

When the comparator 10 outputs L level (when the power supply voltage is low), the AND circuit AND
Becomes low, the PMOS Tr9 is turned off, and the output terminal of the OR circuit OR is turned high, so that the booster circuit 8 is also stopped and the power supply circuit 7A itself is turned off.

As described above, when the controller 4 is in the non-access state to the memory 3, the power supply circuit section 7A is in the sleep state irrespective of the state of the power supply voltage, so that power is consumed in the power supply circuit section 7A. Power consumption during standby can be reduced.

The power supply circuit section 7A described in the first embodiment
Can be applied to other than the semiconductor card 2A. Even in this case, by turning off both the booster circuit section 8 and the PMOS Tr 9 during a desired period such as during standby, the power supply circuit section 7A Power consumption.

FIG. 3 shows a semiconductor card 2B according to a second embodiment of the present invention. The difference from FIG. 1 is that a power supply control circuit 16 is provided in a controller 4B, and a reset circuit 6 and a comparator 10 are provided. The output is supplied to the power supply control circuit 16, and the booster circuit section 8 and the PMOS
A control signal S2 output from the power supply control circuit 16 is supplied as a control signal to the Tr9.

The operation of the semiconductor card 2B will be described with reference to the time chart of FIG. When the power switch is turned on at time T1, a reset signal is supplied from the reset circuit 6 to the controller 4B. As a result, the card initialization is immediately performed, and the control signal S2 output from the power supply control circuit 16 becomes H level.

As a result, the step-up DC / DC converter 12 is turned off, while the PMOS Tr 9 is turned on, so that the power supply voltage supplied to the power supply circuit section 7B is output through the PMOS Tr 9 as it is. Then, at time T2, the card initialization ends, but at time T3, which is a predetermined time after this time T2, the control signal S2 stops outputting H, and instead, the output of the comparator 10 is used as the control signal S2 as it is. Output. The time (T3-T2) is a time lag set to ensure that the card initialization is completed.

As described above, after the time T3, the booster circuit section 8
Since the output of the comparator 10 is supplied as a control signal for the PMOS Tr 9, when the power supply voltage is 2.8 V or more, the PMOS Tr 9 is turned on, the power supply voltage is output as it is, and the power supply voltage is less than 2.8 V. , The boost DC / D
The C converter 12 is turned on, and the low power supply voltage is boosted by the booster circuit section 8 before being output.

As described above, when the power supply voltage is lower than the prescribed value, the booster circuit section 8 is started, but at least during the time points T1 to T3 when card initialization is performed, the booster circuit section 8 is forcibly turned off. Since the PMOS Tr 9 is turned on, even if the power supply voltage falls below the specified voltage during this period, the booster circuit 8 does not turn on, and therefore, the card initialization is stable. It is done.

The power supply circuit section 7B described in the second embodiment
Is applicable to other than the semiconductor card 2B. Even in such a case, the booster circuit section 8 is not activated during a desired period such as a transitional period when the power is turned on, so that the operation accompanying the circuit change can be performed. Instability can be avoided.

FIG. 5 shows a semiconductor card 2C according to a third embodiment of the present invention, which is obtained by adding the power supply control circuit section 16 of FIG. 3 to the circuit configuration of FIG. That is, the outputs of the reset circuit 6 and the comparator 10 are taken into the power supply control circuit 16, and the control signal S2 output from the power supply control circuit 16 is used instead of the output of the comparator 10.
Is supplied to one input terminal of the OR circuit OR and the AND circuit AND. The control signal S1 output from the controller 16 is, as in the case of FIG.
And the other input terminal of the AND circuit AND via the inverter INV.

The operation shown in FIG. 2 (both the booster circuit section 8 and the PMOS Tr 9 are turned off when the memory is not accessed) is changed to the function shown in FIG. 3 (at least during the card initialization period, the booster circuit section 8 is turned on). No), the booster circuit section 8 is not turned on regardless of the value of the power supply voltage during the card initialization period immediately after the power is turned on. At the time of access, both the booster circuit section 8 and the PMOS Tr 9 are turned off. The operation at the time of accessing the memory is the same as that of the conventional example of FIG.

[0037]

According to the first aspect of the present invention, a switch means for outputting the supply voltage as an output voltage when the supply voltage is equal to or higher than a specified level, and a booster circuit when the supply voltage is lower than the specified level. A power supply circuit having means for turning off both the switch means and the booster circuit, so that the switch means and the booster circuit are both turned off during a desired period such as during standby. Power consumption in this power supply circuit can be eliminated.

According to a second aspect of the present invention, when the supply voltage is equal to or higher than a prescribed level, the switch means for outputting the supply voltage as an output voltage, and when the supply voltage is less than the prescribed level, the booster circuit is turned on. And a means for turning off both the switch means and the booster circuit, wherein the switch means and the booster circuit are both turned off when the memory in the semiconductor card is not accessed. Therefore, power consumption during standby can be reduced.

According to a third aspect of the present invention, when the supply voltage is equal to or higher than a specified level, the switch means for outputting the supply voltage as an output voltage, and when the supply voltage is lower than the specified level, the booster circuit is turned on. Means for turning off the booster circuit and locking the switch circuit on during a predetermined period after the power switch is turned on, so that instability of the operation due to the circuit change can be avoided. .

According to a fourth aspect of the present invention, when the supply voltage is equal to or higher than a specified level, the switch means for outputting the supply voltage as an output voltage, and when the supply voltage is lower than the specified level, the booster circuit is turned on. Means for turning on the booster circuit and locking the switch circuit on during the card initialization executed by turning on the power switch in the semiconductor card provided with the power supply circuit having the above means. Instability can be avoided.

According to a fifth aspect of the present invention, when the supply voltage is equal to or higher than the specified level, the switch means for outputting the supply voltage as an output voltage, and when the supply voltage is lower than the specified level, the booster circuit is turned on. Means for turning off both the switch means and the booster circuit when the memory is not accessed, and during the card initialization executed by turning on the power switch. Since the booster circuit is provided with means for turning off the booster circuit and locking the switch circuit on, power consumption during standby can be reduced, and instability due to circuit change during card initialization can be avoided.

[Brief description of the drawings]

FIG. 1 is a control block diagram of a conventional semiconductor card.

FIG. 2 is a control block diagram of the semiconductor card according to the first embodiment of the present invention;

FIG. 3 is a control block diagram of a semiconductor card according to a second embodiment of the present invention;

FIG. 4 is a time chart showing the operation of the semiconductor card of FIG. 3;

FIG. 5 is a control block diagram of a semiconductor card according to a third embodiment of the present invention.

[Explanation of symbols]

2A, 2B, 2C Semiconductor card, 3 memories, 4A, 4
B, 4C controller, 6 reset circuit, 7A, 7
B, 7C power supply circuit section, 8 step-up circuit section, 10 comparator, 9 PMOS Tr, 12 step-up DC / DC converter, 1
6. Power control circuit, OR OR circuit, AND AND circuit, INV inverter

Claims (5)

[Claims] 1. A voltage judging means for detecting whether or not a supply voltage is at a specified level, a switch means for outputting the supply voltage as an output voltage when the supply voltage is equal to or higher than a specified level; A power supply circuit having means for turning on a booster circuit when the level is lower than a level, further comprising means for turning off both the switch means and the booster circuit. 2. A voltage judging means for detecting whether or not a supply voltage is at a specified level, a switch means for outputting the supply voltage as an output voltage when the supply voltage is equal to or higher than a specified level; A semiconductor card provided with a power supply circuit having a means for turning on a booster circuit when the level is lower than a level; a means for detecting an access state to a memory in the semiconductor card; Means for turning off both circuits. 3. A voltage determining means for detecting whether a supply voltage is at a specified level, a switch means for outputting the supply voltage as an output voltage when the supply voltage is equal to or higher than a specified level, and Means for turning on the booster circuit when the level is lower than the level, comprising means for turning off the booster circuit and locking the switch circuit on for a predetermined period after turning on the power switch. A power supply circuit characterized by the following. 4. A voltage determining means for detecting whether a supply voltage is at a specified level, a switch means for outputting the supply voltage as an output voltage when the supply voltage is equal to or higher than a specified level, A power supply circuit having means for turning on the booster circuit when the level is lower than the level, wherein the booster circuit is turned off during a card initialization executed by turning on a power switch; A means for locking on a semiconductor card. 5. A voltage determining means for detecting whether a supply voltage is at a prescribed level, a switch means for outputting the supply voltage as an output voltage when the supply voltage is higher than a prescribed level, and A semiconductor card provided with a power supply circuit having a means for turning on a booster circuit when the level is lower than a level; a means for detecting an access state to a memory in the semiconductor card; Means for turning off the circuits together,
A semiconductor card, comprising: means for turning off the booster circuit and locking the switch circuit on during a card initialization executed by turning on a power switch.