JPH1098156A - Semiconductor device and method of resetting semiconductor device - Google Patents

Abstract

(57) [Problem] To provide a problem that a semiconductor device cannot be protected from an excessive current without replacing the semiconductor device itself. SOLUTION: Floating gate type transistor 8
The connected drain-source V _CC 6 and the internal circuit 5, respectively, a positive voltage is applied from V _CG 9 to the control gate of a floating gate transistor 8, V _CC
6 and the internal circuit 5, and electrically connected, the threshold of the floating gate transistor 8 is increased if flows through excessive current between V _CC 6 and the internal circuit 5, the floating gate transistor 8 is turned OFF By doing so, it is used as a circuit breaker.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device capable of protecting a semiconductor device from an excessive current and a method for resetting the semiconductor device.

[0002]

2. Description of the Related Art In order to protect a semiconductor device from excessive current, a method of protecting a semiconductor device by providing a circuit breaker or the like outside the semiconductor device has been used. However, this method requires a device other than the semiconductor device, and has a problem that the electric device itself becomes large. Therefore, a circuit for protecting the semiconductor device from excessive current has been newly conceived, and is configured as described below.

FIG. 5 is a diagram showing a configuration of a conventional semiconductor device. In the figure, 1 is an internal circuit, 2 is a power supply pin for connecting a semiconductor device and a power supply, 3 is a power supply input pin for connecting the internal circuit 1 and a power supply pin 2, and 4 is a power supply pin 2 and a power supply input. This is a fuse made of, for example, a resistor connected to the pin 3. The internal circuit 1 is connected to various parts other than the power supply pin 1 as shown in FIG.

Next, the operation of the conventional semiconductor device configured as described above will be described. First, power is supplied to the internal circuit 1 via the power supply pin 2, the fuse 4, and the power supply input pin 3 in a normal state. When an excessive current flows through the semiconductor device for some reason, if no processing is performed, the amount of the excessive current follows a temporal change as indicated by X in FIG. Then, there is a possibility that the semiconductor device may be broken or burnt. However, here, if an excessive current flows, the fuse 4 is blown and the internal circuit 1 is connected to the power supply pin 2.
, Power is not supplied, and protection from excessive current can be achieved. As described above, by providing the fuse 4 in the semiconductor device, the size of the electric device can be reduced.

[0005]

Since the conventional semiconductor device is constructed as described above, if the fuse 4 is blown, the semiconductor device itself is not destroyed or burned, but the semiconductor device itself must be replaced. There was a problem.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and provides a semiconductor device and a method of resetting a semiconductor device capable of protecting the semiconductor device from an excessive current without replacing the semiconductor device. The purpose is to provide.

[0007]

Means for Solving the Problems Claim 1 according to the present invention.
In the semiconductor device, the input portion and the semiconductor circuit are connected to the drain / source of the floating gate transistor, respectively, and the input portion and the semiconductor circuit are electrically connected via the floating gate transistor. If a positive voltage is applied to the control gate of the transistor and an excessive current flows between the input portion and the semiconductor circuit, the threshold value of the floating gate transistor increases, and the floating gate transistor is turned off. It is used as a circuit breaker for interrupting the connection between the circuit and the semiconductor circuit.

According to a second aspect of the present invention, there is provided the semiconductor device according to the first aspect, wherein the input section is a power supply pin.

According to a third aspect of the present invention, in the semiconductor device according to the first aspect, the input section is an information input pin.

According to a fourth aspect of the present invention, there is provided the semiconductor device according to any one of the first to third aspects, wherein the semiconductor circuit of the semiconductor device is formed with an ultraviolet erasing structure.

According to a fifth aspect of the present invention, there is provided a method of resetting a semiconductor device according to any one of the first to third aspects, wherein the control gate of the floating gate type transistor is connected to the drain. The input section and the semiconductor circuit are electrically connected with the threshold value of the floating gate type transistor being set to an initial state by making it negative.

According to a sixth aspect of the present invention, there is provided a method of resetting a semiconductor device according to any one of the first to third aspects, wherein the resetting of the semiconductor device is performed by irradiating a floating gate of a floating gate type transistor with ultraviolet rays. , With the threshold value of the floating gate type transistor as an initial state, the input section and the semiconductor circuit are electrically connected.

According to a seventh aspect of the present invention, there is provided a reset method for a semiconductor device according to the fifth aspect, further comprising: a transistor inserted between the input unit and the floating gate type transistor; A reset unit including a semiconductor circuit and a reset control circuit connected to a gate of the transistor;
The reset control circuit applies the power of the semiconductor circuit as a high voltage to the drain of the floating gate type transistor, and sets the control gate of the floating gate type transistor to 0 V by grounding to the ground.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiment 1 FIG. Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a diagram showing a configuration of a semiconductor device according to Embodiment 1 of the present invention. This is an example applied to a serial data I / O type EEPROM. In the figure, 5 is an internal circuit as a semiconductor circuit, 6 is a power supply pin (hereinafter abbreviated as V _CC ) as an input section for connecting the internal circuit 5 and a power supply, and 7 is an internal circuit 5 and V _CC 6 8 is a floating gate type transistor as a circuit breaker having a drain / source connected between _Vcc 6 and the power supply input pin 7, and 9 is a floating gate type transistor 8 a control gate pins for connecting the control gate and the external (hereinafter, abbreviated as V _CG). The internal circuit 5 is connected to various parts other than the power supply pins 6 as shown in FIG.

Next, the operation of the semiconductor device of the first embodiment configured as described above will be described. First, at normal time, a positive voltage is applied to the control gate of the floating gate type transistor 8 from V _CG 9,
The floating gate type transistor 8 keeps the ON state. Then, power is supplied to the internal circuit 5 via the _Vcc 6, the floating gate transistor 8, and the power input pin 7. Next, when an excessive current flows through the semiconductor device for some reason, the same operation as in a normal write state occurs in the floating gate transistor 8.

That is, hot electrons are generated in the channel of the floating gate type transistor 8.
Then, the hot electrons (electrons) are drawn to the potential of V _CG 9 and injected into the floating gate of the floating gate type transistor 8. The hot electrons shift the threshold value of the floating gate transistor 8 from the initial state of FIG. 3A to the state of FIG. Therefore, the floating gate transistor 8 is turned off due to the shift of the threshold value.

[0017] Thus, the internal circuit 1 is disconnected from the V _CC 6, together with the power supply is not supplied, and to be protected from excessive current. FIG. 2 shows the change with time of the current amount at this time.
As shown by Y in FIG. 2, an excessive current as shown by X in FIG. 2 can be prevented.

Next, when the excess current does not occur and returns to the normal state, the floating gate type transistor 8 is turned off.
It is necessary to perform the same operation as the state of N, that is, the state of normal erasing of the floating gate transistor.
For this purpose, the floating gate type transistor 8
May be made negative with respect to the drain. Here, V _CG 9 is grounded to ground and set to 0 V, and a high voltage higher than the voltage supplied from V _CC 6 in the normal state is applied to the drain side of floating gate type transistor 8 (the high voltage referred to here). Voltage is the internal circuit 5
Within the range of voltage that can withstand the above).

With this setting, electrons are extracted from the floating gate of the floating gate type transistor 8. Accordingly, the threshold value of the floating gate transistor 8 returns from the state of FIG. 3B to the initial state a, and the floating gate transistor 8 is reset. Then, V _CC 6 and internal circuit 5 are again electrically connected.

In the semiconductor device of the first embodiment configured as described above, since the floating gate transistor 8 is automatically turned off by an excessive current, the internal circuit 5 is broken and burnt by the excessive current. Can be prevented. Further, by electrically resetting the floating gate transistor 8, the semiconductor device itself can be reused. Further, by providing the floating gate transistor 8 inside the semiconductor device, the size and weight of the electric device can be reduced.

In the first embodiment, the input section is connected to V _CC
Although an example of connection to the floating gate type transistor 8 is shown as 6, the present invention is not limited to this, and any portion that can be an input unit may be used. For example, a clock input, a data input, a reset input, and a chip select input, which are information input pins as input units shown in FIG. Even if they are provided in the same manner, control can be performed in the same manner as in the first embodiment, and thus the same effects can be obtained.

Embodiment 2 FIG. Although the internal circuit 5 is not particularly limited in the first embodiment, for example, when the internal circuit is formed by an ultraviolet erasing type structure (for example, EPROM), the semiconductor device has a structure capable of irradiating the semiconductor device with ultraviolet light from outside. I have. Therefore, by irradiating the floating gate of the floating gate transistor with ultraviolet light, the threshold of the floating gate transistor can be reset to an initial state and the floating gate transistor can be reset. Therefore, it is possible to obtain a semiconductor device that can easily reset a floating gate transistor without having to perform electrical control.

Even if the internal circuit 5 is not formed with an ultraviolet erasing type structure, if the structure is such that ultraviolet light can be irradiated from the outside only on the floating gate type transistor, the same as in the second embodiment described above. It is possible to do. By resetting the floating gate transistor with ultraviolet light in this manner, the electric circuit required for resetting described in Embodiment Mode 1 becomes unnecessary, and the size and simplification of electric equipment can be reduced.

Embodiment 3 FIG. In each of the above embodiments, an example has been described in which the floating gate transistor is reset from the outside. However, the present invention is not limited to this. The semiconductor device includes a reset unit that can reset the floating gate transistor. You may do so.

FIG. 4 is a diagram showing a configuration of a semiconductor device according to a third embodiment of the present invention. In the figure, 10 is an internal circuit as a semiconductor circuit, 11 is a _Vcc as an input unit for connecting the internal circuit 10 to a power supply, and 12 is an internal circuit 5
Power input pin for connecting the V _CC 6 and, 13 V _CC
A floating gate type transistor as a circuit breaker having a drain and a source connected between the floating gate type transistor 11 and a power supply input pin 12, respectively. A V _CG for connecting a control gate of the floating gate type transistor 13 to a reset unit is provided. It is.

Reference numeral 15 denotes a transistor as a reset unit connected between the V _CC 11 and the floating gate transistor 13. The transistor 15 applies a high voltage higher than the voltage of the V _CC 11 to the drain of the floating gate transistor 13. This is provided to separate the floating gate type transistor 13 from the V _CC 11. 16
Is a reset control circuit as a reset unit, 17 is a ground line connected to the reset control circuit 16, 18 is a power supply line for supplying power to the reset control circuit 16, and 19 is the reset control circuit 16 and the floating gate type transistor 13. And a drain control line 20 for connecting a reset signal from the internal circuit 10 to the reset control circuit 16.
Signal line for transmission to the

Next, the operation of the semiconductor device of the third embodiment configured as described above will be described. First, the power supply line 1 is normally supplied to the control gate of the floating gate type transistor 13 by the reset control circuit 16.
8, a positive voltage is applied to V _CG 14, and the floating gate transistor 13 is kept ON. Further, the transistor 15 is also kept ON. Then, power is supplied to the internal circuit 10 via the V _CC 11, the transistor 15, the floating gate transistor 13, and the power input pin 12.

Next, if an excessive current flows through the semiconductor device for some reason, the floating gate transistor 13 operates in the same manner as in the first embodiment, and
FF is performed.

Next, when the excess current no longer occurs and returns to the normal state, the floating gate type transistor 13
Is turned on. First, the signal line 2 from the internal circuit 10
A reset command signal is output to the reset control circuit 16 via the signal 0. Then, the transistor 15 is turned off by the reset control circuit 16. Next, the control gate of the floating gate transistor 13 may be made negative with respect to the drain. Here, the V _CG 14 is connected to the ground line 17 via the reset control unit 16, and the V _CG 14 is grounded.

The power supplied from the power supply line 18 is converted by the reset control circuit 16 into a high voltage higher than the normal state voltage, and then applied to the drain side of the floating gate type transistor 13 via the drain control line 19. (The high voltage here is within a range of a voltage that the internal circuit 10 can withstand.) With this setting, the threshold value of the floating gate transistor 13 returns to the initial state, and the floating gate transistor 13 is reset, similarly to the first embodiment. Then, the internal circuit 11 and the internal circuit 10 are electrically connected again.

The semiconductor device according to the third embodiment configured as described above has the same effect as that of the first embodiment, and the floating gate type transistor 13 is reset as a part of the semiconductor device. Control circuit 1
6, forming a reset portion including the transistor 15 and the like,
Since the reset unit can be electrically reset, external control of V _CC 11 and V _CG 14 becomes unnecessary.

[0032]

As described above, according to the first aspect of the present invention, the input portion and the semiconductor circuit are connected to the drain and source of the floating gate type transistor, respectively, and the input portion and the semiconductor circuit are connected to the floating gate type transistor. Electrically connected through a transistor, a positive voltage is applied to the control gate of the floating gate transistor, and if an excessive current flows between the input part and the semiconductor circuit, the threshold of the floating gate transistor is Is used as a circuit breaker that cuts off the connection between the input portion and the semiconductor circuit when the floating gate transistor is turned off. Therefore, the semiconductor circuit is protected from excessive current by turning off the floating gate transistor. Semiconductor device that can It is possible.

According to the second aspect of the present invention, in the first aspect, since the input section is a power supply pin, it is possible to obtain a semiconductor device capable of cutting off the input of the power supply when an excessive current flows. is there.

According to a third aspect of the present invention, in the first aspect, since the input section is an information input pin, it is possible to obtain a semiconductor device capable of cutting off information input when an excessive current flows. It is.

According to a fourth aspect of the present invention, the semiconductor circuit of the semiconductor device according to any one of the first to third aspects is formed with an ultraviolet erasing structure, so that the semiconductor circuit of the floating gate type transistor can emit ultraviolet light. Reset can be performed without changing the structure of the semiconductor device.

According to a fifth aspect of the present invention, in the semiconductor device reset method according to any one of the first to third aspects, the control gate of the floating gate type transistor is made negative with respect to the drain, and Since the input portion and the semiconductor circuit are electrically connected with the threshold value of the gate transistor set as an initial state, it is possible to obtain a reset method of a semiconductor device capable of electrically resetting a floating gate transistor.

According to a sixth aspect of the present invention, in the method for resetting a semiconductor device according to any one of the first to third aspects, the floating gate of the floating gate type transistor is irradiated with ultraviolet rays. Since the input portion and the semiconductor circuit are electrically connected with the threshold value of as an initial state, it is possible to obtain a method of resetting a semiconductor device capable of resetting a floating gate transistor with ultraviolet light.

According to a seventh aspect of the present invention, in the fifth aspect, a transistor inserted between the input portion and the floating gate type transistor, the input portion, the floating gate type transistor, the semiconductor circuit, and the transistor And a reset unit comprising a reset control circuit connected to the gate of the reset circuit. When the reset unit resets, the transistor is turned off, and the reset control circuit applies the power of the semiconductor circuit as a high voltage to the drain of the floating gate type transistor. Since the control gate of the floating gate transistor is grounded to 0 V and grounded to 0 V, it is possible to obtain a reset method of the semiconductor device that can easily reset the floating gate transistor in a circuit in the semiconductor device. is there

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a configuration of a semiconductor device according to a first embodiment of the present invention;

FIG. 2 is a diagram illustrating a change over time in a current amount and an excessive current of the semiconductor device illustrated in FIG. 1;

FIG. 3 is a diagram showing a change in a threshold value of the floating gate transistor shown in FIG.

FIG. 4 is a diagram illustrating a configuration of a semiconductor device according to a second embodiment of the present invention;

FIG. 5 is a diagram illustrating a configuration of a conventional semiconductor device.

FIG. 6 is a diagram showing a temporal change in the amount of excessive current.

[Explanation of symbols]

5,10 internal circuit, 6,11 V _CC , 7,12 power input pin, 8,13 floating gate transistor, 9,14 V _CG , 15 transistor, 16 reset control circuit, 17 ground line, 18 power line, 19
Drain control line, 20 signal line.

Claims (7)

[Claims] 1. An input unit and a semiconductor circuit are connected to a drain and a source of a floating gate type transistor, respectively, and the input unit and the semiconductor circuit are electrically connected via the floating gate type transistor. A positive voltage is applied to the control gate of the floating gate transistor, and if an excessive current flows between the input portion and the semiconductor circuit, the threshold value of the floating gate transistor increases,
A semiconductor device, which is used as a circuit breaker that cuts off connection between the input unit and the semiconductor circuit when a floating gate transistor is turned off. 2. The semiconductor device according to claim 1, wherein the input section is a power supply pin. 3. The semiconductor device according to claim 1, wherein the input section is an information input pin. 4. A semiconductor device according to claim 1, wherein the semiconductor circuit of the semiconductor device according to claim 1 is formed with an ultraviolet erasing structure. 5. The reset method for a semiconductor device according to claim 1, wherein the control gate of the floating gate transistor is made negative with respect to the drain, and the threshold value of the floating gate transistor is set to be negative. Resetting the input section and the semiconductor circuit as an initial state. 6. The method for resetting a semiconductor device according to claim 1, wherein the floating gate of the floating gate transistor is irradiated with ultraviolet light to reset the threshold value of the floating gate transistor to an initial state. A method of electrically connecting the input unit and the semiconductor circuit. 7. A transistor inserted between an input unit and a floating gate transistor, a reset control circuit connected to the input unit, the floating gate transistor, a semiconductor circuit, and a gate of the transistor. A reset unit, wherein the reset unit turns off the transistor when resetting;
The reset control circuit applies a power supply of the semiconductor circuit as a high voltage to a drain of the floating gate transistor, and sets a control gate of the floating gate transistor to 0 V by grounding to a ground. 6. The method for resetting a semiconductor device according to claim 5.