JPH02205066A - Semiconductor device - Google Patents

Abstract

PURPOSE:To avoid the fluctuation of a composite output voltage by a method wherein comparators which judges whether fuses are cut off or not are provided. CONSTITUTION:A comparator group 9 composed of the same number of comparators as the number of fuses in a fuse group 8 is provided between a switch group 4 and respective points A. The (+) input terminals of the respective comparators in the comparator group 9 are connected to the respective points A. One of resistors in a resistor group 7 is connected to a reference resistor 10 whose one end is grounded and is used as the (-) input terminal of the comparator. The resistance of the fuse before cutting-off in the fuse group 8 is denoted by (r) and the resistance of the fuse after cutting-off is denoted by (r'). Further, the resistance of the reference resistor 10 is denoted by R. R is a little larger than (r) and large enough for the respective comparators in the comparator group 9 to judge IR>Ir for a current I. After the fuse is cut off, as r'>>R, the potential of the point A becomes higher than the potential of the point B, so that the output of the comparator is turned to 'H'.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a semiconductor device, and in particular, in order to generate a highly accurate output voltage, trimming is performed by cutting an arbitrary fuse out of a plurality of fuses. The present invention relates to a semiconductor device having a circuit that performs the following steps.

[Conventional technology]

Conventionally, in this type of semiconductor device, as shown in FIG. 3, when an arbitrary fuse is cut out of a plurality of (three in this case) fuse group 8, an A connected to the cut fuse is connected to the cut fuse.
The potential at the point becomes higher than the threshold voltage of the corresponding transistor constituting the switch group 4 (hereinafter, a potential higher than this threshold voltage will be referred to as "H" and a potential lower than this threshold voltage will be referred to as "L"). The desired output voltage 3 was generated by directly switching the switch group 4. In other words, whether the fuse is blown or not is determined by whether the potential at point A is on the L'' side or not.
The decision was made depending on whether it was on the "H" side.

Now, if one fuse in fuse group 8 is cut, the other end of the corresponding resistor in current limiting resistor group 7 is connected to power supply voltage 6, so the potential at point A will rise to the voltage level of power supply voltage 6. Rise. Each point A is guided to a switch group 4, and a resistor group 5 controlled by the switch group 4 determines the voltage at the output terminal 3.

The switch group 4 is connected to the - (minus) input terminal of the operational amplifier 2, and the output of the operational amplifier 2 is
It is connected to the output terminal 3 and one end of a resistor group 5 consisting of nine resistors connected in series. An input voltage is applied to the + (plus) input terminal 1 of the operational amplifier 2 .

Here, the switch group 4 includes inverters 20.21.22 corresponding to each point A, and these inverters 20.21.2.
MOS transistors 24, 2 each receiving the output of MOS transistor 2 as an input.
5, 28, 30, 32゜34.36 and MOS) transistors 23, 26.27 led directly from each point A to the gate.
．． 29°31.33.35.

[Problem to be solved by the invention]

In the conventional semiconductor device described above, since the switch group 4 is directly switched by the potential at point A, even if the - carrying fuse is cut and the desired output voltage 3 is obtained, the fuse is still not completely cut. There are accidents where they are physically reconnected due to heat or other stress. In this case, the resistance becomes high and continuity is restored, and depending on the resistance value, the potential at point A becomes “
Despite changing to "L" and cutting the fuse,
There is a drawback that it is determined that the disconnection is not performed, the switch group 4 switches, and the output voltage 3 fluctuates.

It is an object of the present invention to solve the above-mentioned drawbacks, and even when the fuse is incompletely cut and is physically connected again due to heat or other stress after cutting, the resistance becomes high and continuity is restored. It is an object of the present invention to provide a semiconductor device in which erroneous determination as to whether a fuse is blown or not is unlikely to occur and the adjusted output voltage does not fluctuate.

[Means to solve the problem]

The structure of the semiconductor device of the present invention is such that trimming can be performed by cutting off a predetermined fuse. It is characterized by providing a comparator that determines the

〔Example〕

Next, the present invention will be explained with reference to the drawings.

FIG. 1 is a circuit diagram of a semiconductor device according to an embodiment of the present invention. In FIG. 1, the semiconductor device of this embodiment is provided with a comparator group 9 consisting of the same number of comparators as the number of foos of the seven-piece group 8 between the switch group 4 and each point A. , which is significantly different from the conventional figure 3. Each comparator of this comparator group 9 has ten input terminals connected to each point A. One resistor of the resistor group 7 and a reference resistor 10 whose one end is grounded are connected to serve as one input terminal of the comparator. switch! #: 4, etc. The other circuits are the same as in FIG.

Now, the resistance value of the fuse before cutting shown in fuse group 8 is r
Let the resistance value of the fuse after one cut be r'.

Further, the resistance value of the reference resistor 10 is assumed to be R. Here, each comparator shown in the comparator group 9 can determine that R is (In > Ir) with respect to the electric current, and is a value slightly larger than r. Before the fuse is cut, the potential at point A is lower than the potential at point B, so the output of the comparator remains "L".

After the fuse is blown, (r'>R) and the potential at point A is higher than the potential at point B, so the output of the comparator is “
In this way, the desired output voltage 3 can be obtained by cutting off any fuse and switching the switch group 4.Furthermore, if the fuse is not completely cut off, heat or other stress may occur. , the disconnected fuse is physically connected again, and its resistance value becomes (r/→r“(
If the potential changes to r'<r'', the potential at point A will be low, but if it is higher than the potential at point B, that is, (r'>
R), the output of the comparator remains at 'H@' and does not change, so the output voltage 3 does not fluctuate.

In reality, even if the fuse is physically reconnected after being cut, since rl exhibits a considerably higher resistance value than R, an erroneous determination as to whether the fuse is cut or not will not occur. □M2 is a circuit diagram of a semiconductor device according to another embodiment of the present invention. In FIG. 2, the semiconductor device of this embodiment has a reference resistor group 1 consisting of the same number of reference resistors as the number of fuses in the fuse group 8, and a resistor group 7 consisting of twice the number of resistors. It differs from FIG. 1 in that it has . Here, each comparator in the comparator group 9 is connected to the point B of the corresponding reference resistance.

This embodiment has a reference resistance group 11, and uses reference resistances corresponding to each fuse in the fuse group 8 to determine whether or not a fuse is blown by a comparator in the comparator group 9.

This formation also has the advantage of being less likely to cause an erroneous determination as to whether or not the fuse is blown, as in the first embodiment.

〔Effect of the invention〕

As explained above, the present invention uses a comparator to compare the reference potential provided by the reference resistor and the potential provided by the fuse, thereby making it difficult to misjudge whether or not the fuse is disconnected. Even if the disconnection is incomplete and the connection is physically reconnected due to heat or other stress ζ after the disconnection, resulting in high resistance and continuity is restored, the desired output voltage can be obtained.

FIG. 1 is a circuit diagram of a semiconductor device according to one embodiment of the present invention, FIG. 2 is a circuit diagram of a semiconductor device according to another embodiment of the present invention, and FIG. 3 is a circuit diagram of a conventional semiconductor device.

1... Input voltage, 2... Operational amplifier,
3. River: Output terminal, 4: Switch group, 5.
...Output voltage control resistor group, 6...Power supply voltage, 7...Current limiting resistor N, 8...
・Fuse group, 9...Comparator group, 10・
...Reference resistance, 11 ...Reference resistance group, 2
o.

21.22... Inverter, 23 to 36... MOS) transistor.

Agent Patent Attorney Oto Uchihara

[Brief explanation of the drawing]

Claims (1)

[Claims] In a semiconductor device equipped with multiple fuses, trimming can be performed by cutting a predetermined fuse.
A semiconductor device comprising a comparator for determining whether the fuse is blown.