JP4967762B2 - Short detection circuit, short / open detection circuit, and detection methods thereof - Google Patents

Description

  The present invention relates to a short detection circuit, a short / open detection circuit, and detection methods thereof. Specifically, when a potential is supplied from the outside to an internal circuit such as an LSI, the potential of the power supply is directly supplied. Detection circuit and short / open detection circuit effective for detecting whether or not the internal circuit and the power supply are short-circuited, and detecting the open circuit between the internal circuit and the power supply, and methods for detecting these About.

2. Description of the Related Art In semiconductor integrated circuits, applications requiring an analog potential are increasing due to high speed and high functionality of the interface. Therefore, there are many cases where the potential is applied by a resistance element that is applied from outside the LSI.
As the number of parts to be assembled on the board increases, the number of defects also increases, and the detection method becomes a problem for creating a good product.
The conventional assembly inspection method (hereinafter referred to as a known method) creates a test device (jig) that can supply power in assy units (board substrate), directly observes the potential of the suspicious object and opens it. / Short check (assy defect) was performed.

Patent Document 1 discloses a disconnection / short circuit inspection circuit of a catalytic combustion type gas sensor. This inspection circuit is a circuit that detects disconnection / short circuit of a reference element and a detection element connected in series. In order to detect this disconnection / short circuit, the voltages at both ends of the reference element and the detection element are detected by the corresponding voltage detection means. The larger voltage and the smaller voltage of the two voltage detection means are output from separate OR circuits. A configuration is adopted in which the voltage output from each OR circuit is compared with the corresponding upper limit reference voltage and lower limit reference voltage by a separate comparison circuit to detect disconnection / short circuit of the reference element and the detection element.
JP 11-271256 A

In the above-described known method, a test device must be prepared separately from the assembly unit, and the assembly inspection must be performed using the device. Therefore, the creation of the individual test device and the inspection work are indispensable.
Further, although Patent Document 1 can detect the disconnection and short circuit of the reference element and the detection element, the detection output of the voltage across the reference element and the detection element is indispensable for the detection. However, there is still room for improvement in order to develop the detection of other disconnections and short circuits.

  The present invention has been made in view of the above-described circumstances, and in the electric potential supply from the outside to an internal circuit such as an LSI, the electric potential of the electric power supply is directly supplied (the internal circuit and the electric power supply) A short detection circuit and a short / open detection circuit capable of detecting whether or not the internal circuit and the power supply are open (open), and a detection method thereof. It is aimed.

  In order to solve the above-mentioned problem, the invention described in claim 1 provides a single potential output of a potential output circuit that outputs a predetermined potential intermediate between the potential of the first potential source and the potential of the second potential source. The present invention relates to a circuit that detects a short circuit between a power supply line and one of the two potential sources via a connected power supply line, and a first value that is higher than the potential of the potential output by a first value set in advance. From a first reference potential source that outputs a reference potential, a first comparison circuit that compares the potential of the potential output with the first reference potential of the first reference potential source, and a potential of the potential output A second reference potential source that outputs a second reference potential that is lower by a preset second value is compared with the potential of the potential output and the second reference potential of the second reference potential source. Comparison output of the second comparison circuit and the first comparison circuit and the second comparison circuit On the basis it is characterized by comprising a determination circuit for determining whether the short-circuit.

  The invention according to claim 2 relates to the short inspection circuit according to claim 1, wherein the first value and the second value are determined by the accuracy of the potential of the potential output and the range of the potential. It is a feature.

  A third aspect of the present invention relates to the short inspection circuit according to the first or second aspect, wherein the first value and the second value are the same value.

  A fourth aspect of the invention relates to the short detection circuit according to the first, second, or third aspect, wherein the first potential is a potential supplied from an external potential source, and the second potential is a ground potential. In addition, the first and second reference potential sources, the first and second comparison circuits, and the determination circuit are formed in a semiconductor integrated circuit.

  According to a fifth aspect of the present invention, there is provided a power supply line connected to a single potential output of a potential output circuit that outputs a predetermined potential intermediate between the potential of the first potential source and the potential of the second potential source. The circuit detects a short circuit between the power supply line and one of the two potential sources or an open circuit between the potential output and the power supply line, and is higher than the potential of the potential output by a preset first value. A first reference potential source for outputting a first reference potential; a first comparison circuit for comparing the potential of the potential output with the first reference potential of the first reference potential source; and the potential output. A second reference potential source that outputs a second reference potential that is lower than the potential by a second value preset in advance, the potential of the potential output, and the second reference potential of the second reference potential source And a second comparison circuit for comparing the power supply line and the power supply line. A potential changing circuit for changing the potential of the power supply line when the output and the power supply line are opened to a potential different from the potential of the potential output by a predetermined value; and when the potential output and the power supply line are opened. A third reference potential source that outputs a third reference potential that is set in advance between the potential of the power supply line and the potential of the potential output; the potential of the power supply line at the time of opening; and the third reference The presence or absence of the short circuit based on the comparison output of the third comparison circuit for comparing the third reference potential of the potential source with the first comparison circuit, the second comparison circuit, and the third comparison circuit Or a determination circuit for determining whether the power supply line is open or not.

According to a sixth aspect of the present invention, there is provided the short / open detection circuit according to the fifth aspect, wherein the potential output circuit is a first connected in series between the first potential source and the second potential source. And the second resistance element, the connection point between the first resistance element and the second resistance element is used as the potential output, and the potential changing circuit includes a third potential source , 4 potential source , a third resistance element connected between the third potential source and the feed line, and a fourth resistor connected between the fourth potential source and the feed line. The resistance values of the third resistance element and the fourth resistance element are different from each other by a predetermined value from the potential of the potential output when the open-circuit occurs. The resistance of the first resistance element and the second resistance element is a value necessary for changing the resistance. It is characterized by being selected greater.

  According to a seventh aspect of the present invention, in the short / open detection circuit according to the sixth aspect, the different potential is a potential that is higher than the potential of the potential output by the predetermined value.

  According to an eighth aspect of the present invention, in the short / open detection circuit according to the sixth aspect, the different potential is a potential lower than the potential of the potential output by the predetermined value.

  A ninth aspect of the present invention relates to the short / open inspection circuit according to the fifth, sixth, seventh, or eighth aspect, wherein the first value and the second value are the accuracy of the potential of the potential output, the potential. It is characterized by being determined by the range of.

  A tenth aspect of the present invention relates to the short / open inspection circuit according to any one of the fifth to ninth aspects, wherein the first value and the second value are the same value. .

  An eleventh aspect of the present invention relates to the short / open detection circuit according to any one of the fifth to tenth aspects, wherein the first potential is a potential supplied from an external potential source, and the second potential is The potential is a ground potential, and the first and second reference potential sources, the first and second comparison circuits, and the determination circuit are formed in a semiconductor integrated circuit.

  According to a twelfth aspect of the present invention, the power supply line is connected via a power supply line connected to a potential output of a potential output circuit that outputs a predetermined potential intermediate between the potential of the first potential source and the potential of the second potential source. And a potential of the potential output and a first reference potential higher than a potential of the previous potential output by a first value set in advance. Compare the potential output potential with a second reference potential that is lower than the potential output potential by a preset second value, and determine the presence or absence of the short circuit based on the results of the two comparisons. It is characterized by doing.

  The invention described in claim 13 relates to the short detection method according to claim 12, wherein the first value and the second value are determined by the accuracy of the potential of the potential output and the range of the potential. It is a feature.

  According to a fourteenth aspect of the present invention, in the short detection method according to the twelfth or thirteenth aspect, the first value and the second value are the same value.

  A fifteenth aspect of the present invention relates to the short detection method according to the twelfth, thirteenth or fourteenth aspect, wherein the first potential is a potential supplied from an external potential source, and the second potential is a ground potential. It is characterized by being.

  According to a sixteenth aspect of the present invention, the power supply line and the two potential sources are connected via a power supply line connected to a potential output of a potential output circuit that outputs a predetermined potential between the first potential and the second potential. A first circuit that is higher than the potential of the potential output and the potential of the potential output by a first value set in advance. A reference potential is compared, a potential of the potential output is compared with a second reference potential that is lower than a potential of the potential output by a second value set in advance, and when the potential output and the power supply line are opened A third reference potential that is preset between the potential of the power supply line that is changed from the potential of the potential output to a potential that differs by a predetermined value and the potential of the potential output, and the potential of the power supply line at the time of opening. And the above three comparisons Based on the results it is characterized by determining the presence or absence of the opening of the short circuit.

  According to a seventeenth aspect of the present invention, there is provided the short / open detection circuit according to the sixteenth aspect, wherein the different potential is a third resistance element connected between the first reference potential and the power supply line, and the third resistance element. The first potential and the second potential are only the values necessary to change the resistance value of the fourth resistance element connected between the second reference potential and the power supply line to the different potential. The resistance value of the first resistance element and the second resistance element that are connected in series to constitute the potential output circuit is selected and set.

  An eighteenth aspect of the invention relates to the short / open detection method of the sixteenth or seventeenth aspect, wherein the different potential is higher than the potential of the potential output.

  According to a nineteenth aspect of the present invention, there is provided the short / open detection method according to the sixteenth or seventeenth aspect, wherein the different potential is lower than the potential of the potential output.

  A twentieth aspect of the present invention relates to the short / open inspection method according to the sixteenth, seventeenth, eighteenth or nineteenth aspect, wherein the first value and the second value are the accuracy of the potential of the potential output, the potential. It is characterized by being determined by the range of.

  A twenty-first aspect of the invention relates to the short / open inspection method according to any one of the sixteenth to twentieth aspects, wherein the first value and the second value are the same value. .

  A twenty-second aspect of the invention relates to the short / open detection method according to any one of the sixteenth to twenty-first aspects, wherein the first potential is a potential supplied from an external potential source. The potential is a ground potential.

According to this invention, the first value preset from the potential of the single potential output of the potential output circuit that outputs a predetermined potential intermediate between the potential of the first potential source and the potential of the second potential source. The first reference potential that is higher than the potential output potential is compared, and the second reference potential that is lower than the potential output potential by a preset second value is compared with the potential output potential. Thus, it is possible to detect a short circuit between the power supply line and one of the two potential sources.
Further, in addition to the above two comparisons, a third reference potential set in advance between the potential of the power supply line and the potential of the potential output when the potential output and the power supply line are opened, and the open By considering the comparison with the potential of the power supply line at the time, it is possible to detect the opening of the potential output and the power supply line.
For both detections, there is no need to create a dedicated device as in the prior art, and no detection work is required.

The present invention is higher by a preset first value than the potential of a single potential output of a potential output circuit that outputs a predetermined potential intermediate between the potential of the first potential source and the potential of the second potential source. A comparison between the first reference potential and the potential output potential and a comparison between the second reference potential lower than the potential output potential by a preset second value and the potential output potential are used. Configured.
Further, in both of these comparisons, a third reference potential set in advance between the potential of the power supply line and the potential of the potential output when the potential output and the power supply line are opened, A comparison with the potential of the power supply line is incorporated.

FIG. 1 is a diagram showing an electrical configuration of a short detection circuit according to Embodiment 1 of the present invention, and FIG. 2 is a truth table of the short detection circuit.
In the short detection circuit 10 of this embodiment, the divided output of the voltage dividing resistance element connected between the external power supply and the ground potential swings to the voltage of the external power supply (the divided output and the external power supply are short-circuited). 1, or a circuit that can detect whether the voltage swings to the ground potential (the divided voltage output and the ground potential are short-circuited). As shown in FIG. And a second differential potential comparison circuit 14, a determination circuit 16, a first reference potential source 18, and a second reference potential source 20, and these circuits are configured in the LSI 22.
The inverting inputs of the first differential potential comparison circuit 12 and the second differential potential comparison circuit 14 are resistors connected in series between the external power supply 24 and the ground potential 26 via the external connection terminal 22P of the LSI 22. The connection point 32 between the element 28 and the resistance element 30 is connected. This connection point 32 is connected to a power supply path 34 in the LSI 22 via an external connection terminal 22P.

The first reference potential source 18 is connected to the non-inverting input of the first differential potential comparison circuit 12, and the second reference potential source 20 is connected to the non-inverting input of the second differential potential comparison circuit 14. Is connected. The first reference potential source 18 outputs a first reference potential (VR1 + α) that is higher than the potential (VR1) appearing at the connection point 32 by a value α, and the second reference potential source 20 is more than the potential (VR1). A second reference potential (VR1-β) that is lower by a value of β is output.
The values of α and β described above are determined by the accuracy of the potential (VR1) supplied from the connection point 32 to the circuit in the LSI and the range of the potential.
Based on the comparison result A of the first differential potential comparison circuit 12 and the comparison result B of the second differential potential comparison circuit 14, the determination circuit 16 determines whether the potential at the connection point 32 is a normal value (see FIG. 2 is a circuit for determining whether the potential of the external power supply 24 is (VDD short-circuited in FIG. 2 ) or ground potential (GND short-circuited in FIG. 2 ).

Next, the operation of this embodiment will be described with reference to FIGS.
A potential VR1 obtained by dividing the potential of the external power supply 24 and the ground potential by the resistance element 28 and the resistance element 30 is supplied to the internal circuit of the LSI 22 via the power supply path 34 via the external connection terminal 22P as the power supply potential VRin. Power is supplied.
If this potential VR1 is in a normal potential range, that is, a range less than (VR1 + α) and a range exceeding (VR1−β), the output level of the first differential potential comparison circuit 12 becomes a low level L ( On the other hand, the output level of the second differential potential comparison circuit 14 becomes a high level H (B in FIG. 2 is H), and the determination circuit 16 that receives these output levels has a normal potential VR1. Is output (the determination in FIG. 2 is normal).

When the potential VR1 exceeds (VR1 + α), the output level of the first differential potential comparison circuit 12 and the output level of the second differential potential comparison circuit 14 also become a high level H (see A and FIG. 2). When B is H), the determination circuit 16 that receives these output levels outputs a VDD short, that is, a determination that the power supply voltage is supplied as it is (the determination in FIG. 2 is VDD short).
When the potential VR1 becomes less than (VR1-β), the output level of the first differential potential comparison circuit 12 and the output level of the second differential potential comparison circuit 14 become low level L (FIG. 2). When A and B are L), the determination circuit 16 that receives these output levels outputs a GND short, that is, a determination that the ground potential is supplied as it is (the determination in FIG. 2 is a GND short).

As described above, according to the configuration of this embodiment, only the power supply potential supplied to the power-supplied part (the internal circuit of the LSI), the first reference potential, and the second reference potential are used in the LSI or the like. Thus, it is possible to determine whether or not a short circuit between the external power source or the ground potential and the feeding path has occurred. Reduction of circuit components required for this determination can be achieved.
Since this short inspection circuit is configured in an LSI or the like, a test device capable of supplying power in ASSY units is prepared for detecting an ASSY defect that constitutes an LSI or the like. It is no longer necessary to check the potential by observing the potential, and the work cost is also unnecessary.

FIG. 3 is a diagram showing a short / open test circuit according to a second embodiment of the present invention, and FIG. 4 is a truth table of the short / open test circuit.
The configuration of this embodiment differs greatly from that of the first embodiment in that, in addition to a short circuit between an external power source or a ground potential and a power supply path, a power supply potential output section to the LSI and an external connection terminal (power supply path) of the LSI. It is the point which can judge open | release of (open).
That is, the characteristic part of the short / open test circuit 10A of this embodiment is that, as shown in FIG. 3, in addition to the components of the first embodiment, a resistance element 44, a resistance element 48, and a third reference potential source. 50 and a third differential potential comparison circuit 52 in which the third reference potential source 50 is connected to the non-inverting input and the power supply path 34 is connected to the inverting input. The resistance element 44 and the resistance element 48 are connected in series between the external power supply 42 and the ground potential 46, and the connection point 54 is connected to the power supply path 34. The potential of the external power supply 42 may be the same as or different from the potential of the external power supply 24.

The resistance values of the resistance element 44 and the resistance element 48 are much larger than the resistance values of the resistance element 28 and the resistance element 30, for example, a value of 100 to 1000 times the resistance value of the resistance element 28 and the resistance element 30 (for example, When there is no power supply (application) to the internal circuit of the LSI 22, the potential VR2 at the connection point 54 is selected in advance as a value that is changed to a potential between VDD and VR1 (power supply potential).
The circuit portion of the above-described characteristic portion that has been selected as described above constitutes a potential changing circuit.
Further, the reference potential of the third reference potential source 50 is set in advance to a potential between VR2 and VR1.
Since the configuration of this embodiment other than this configuration is the same as that of the first embodiment, the same components are denoted by the same reference numerals, and the description thereof is omitted.

Next, the operation of this embodiment will be described with reference to FIGS.
The determination of the VDD short and the GND short in this embodiment is almost the same as that of the first embodiment. That is, in the determination, in addition to the comparison result A of the first differential potential comparison circuit 12 and the comparison result B of the second differential potential comparison circuit 14, the comparison result of the third differential potential comparison circuit 52 is used. C is used.

  Therefore, also in the determination of this embodiment, as in the first embodiment, when the potentials VR1 and VR2 at the connection point 32 and the connection point 54 are normal, the comparison result A of the first differential potential comparison circuit 12 is low. On the other hand, the comparison result B of the second differential potential comparison circuit 14 is at a high level H, and when the potentials VR1 and VR2 are VDD, the comparison result of the first differential potential comparison circuit 12 is L. A and the comparison result B of the second differential potential comparison circuit 14 are also at a high level H, and when the potentials VR1 and VR2 are at ground potential, the comparison result A of the first differential potential comparison circuit 12 In addition, although the comparison result B of the second differential potential comparison circuit 14 is also at the low level L, the comparison result C of the third differential potential comparison circuit 52 is at the low level L when the potentials VR1 and VR2 are normal. When VDD is short-circuited, it goes high. When the GND is short-circuited, the low level is L.

  When the power supply to the internal circuit of the LSI 22 is stopped, that is, when the external connection terminal is opened, the comparison result A from the first differential potential comparison circuit 12 is at the low level L. Since both the comparison result B from the differential potential comparison circuit 14 and the comparison result C from the third differential potential comparison circuit 52 are at a high level, the determination circuit 16A generates the above-mentioned open. It is possible to output a determination of whether or not

As described above, according to the configuration of this embodiment, the comparison result output from the above-described characteristic portion is incorporated into the configuration of Embodiment 1, so that in addition to the normality of power supply, VDD short-circuit, and ground potential short-circuit, Thus, it is possible to detect whether or not the external connection terminal is open.
Similarly to the first embodiment, a test apparatus capable of supplying power in ASSY units is manufactured for detecting an ASSY defect that constitutes an LSI or the like, and the potential of the location subject to suspicion is directly observed to make a short circuit. / No need to check for openness, and no work cost.

FIG. 5 is a diagram showing a short / open test circuit according to a third embodiment of the present invention, and FIG. 6 is a truth table of the short / open test circuit.
The configuration of this embodiment differs greatly from that of the second embodiment in that the configuration of the potential changing circuit that performs open determination between the power supply potential output unit to the LSI and the external connection terminal (power supply path) of the LSI is changed. This is the point.
That is, as shown in FIG. 5, the characteristic part of the short / open test circuit 10B of this embodiment is that the resistance element 44, the resistance element 48, and the third reference potential source among the components of the second embodiment. 50, the differential potential comparison circuit 52 is modified as described later, and is configured as a resistance element 44B, a resistance element 48B, a third reference potential source 50B, and a differential potential comparison circuit 52B. As a result of this change, the determination circuit 16A according to the second embodiment causes the potentials VR1 and VR2 to be set when the potentials VR1 and VR2 between the connection point 32 and the connection point 54 are normal, and when the potentials VR1 and VR2 are VDD. When the ground potential is reached, and when the external connection terminal is opened, the differential potential comparison circuits 12, 14, and 52B are changed so that the corresponding determination can be performed.

The resistance values of the resistance element 44B and the resistance element 48B are much larger than the resistance values of the resistance element 28 and the resistance element 30, for example, 100 to 1000 times the resistance values of the resistance element 28 and the resistance element 30 (for example, When there is no power supply (application) to the internal circuit of the LSI 22, the potential VR2 at the connection point 54 is selected in advance to a value that causes the potential between the ground potential GND and VR1 (power supply potential). .
The circuit portion of the above-described characteristic portion that has been selected as described above constitutes a potential changing circuit.
Accordingly, the reference potential of the third reference potential source 50B is set in advance to a potential between VR2 and VR1 after the change from the second embodiment.
Since the configuration of this embodiment other than this configuration is the same as that of the second embodiment, the same components are denoted by the same reference numerals, and the description thereof is omitted.

Next, the operation of this embodiment will be described with reference to FIGS.
In this embodiment, the comparison result A obtained by the first differential potential comparison circuit 12 and the comparison result B obtained by the second differential potential comparison circuit 14 in the determination of the VDD short and the GND short are the same as those of the second embodiment. The same. In this embodiment, the determination of the VDD short and the GND short is made in addition to the comparison result A of the first differential potential comparison circuit 12 and the comparison result B of the second differential potential comparison circuit 14, and the third differential. The comparison result D of the potential comparison circuit 52B is used (FIG. 6).

  Therefore, also in the determination of this embodiment, as in the second embodiment, when the potentials VR1 and VR2 at the connection point 32 and the connection point 54 are normal, the comparison result A of the first differential potential comparison circuit 12 is low. On the other hand, the comparison result B of the second differential potential comparison circuit 14 is at a high level H, and when the potentials VR1 and VR2 are VDD, the comparison result of the first differential potential comparison circuit 12 is L. A and the comparison result B of the second differential potential comparison circuit 14 are also at a high level H, and when the potentials VR1 and VR2 are at ground potential, the comparison result A of the first differential potential comparison circuit 12 In addition, although the comparison result B of the second differential potential comparison circuit 14 is also at the low level L, the comparison result D of the third differential potential comparison circuit 52B is at the high level H when the potentials VR1 and VR2 are normal. High level when VDD is shorted And it becomes a low level L when the GND short.

  When the power supply to the internal circuit of the LSI 22 is stopped, that is, when the external connection terminal is open, the comparison result A from the first differential potential comparison circuit 12 is at a low level as in the second embodiment. The comparison result B from the second differential potential comparison circuit 14 is at the high level H, but the comparison result D from the third differential potential comparison circuit 52B is at the low level L. The circuit 16B can output the determination of the occurrence of the above-mentioned open.

As described above, according to the configuration of this embodiment, in addition to the normality of power supply, VDD short-circuit, and ground potential short-circuit due to the change of the comparison mode in the above-described characteristic portion and the change of the determination in the determination circuit, the external It is possible to detect whether or not the connection terminal is open.
Similarly to the second embodiment, a test apparatus capable of supplying power in ASSY units is manufactured for detecting an ASSY defect that constitutes an LSI or the like, and the potential of the part to be suspected is directly observed to make a short circuit. / No need to check for openness, and no work cost.

Although the embodiments of the present invention have been described in detail with reference to the drawings, the specific configuration of the present invention is not limited to these embodiments, and the design does not depart from the gist of the present invention. These changes are included in the present invention.
For example, the external power source and the ground potential may be constituted by other potential sources.
Further, the values of α and β described above may be the same.

  The short detection circuit, the short / open detection circuit, and the detection methods disclosed herein can be used in any circuit configuration in which the power-supplied portion receives power supply of a necessary potential from an external power source or the like.

It is a figure which shows the electrical constitution of the short detection circuit which is Example 1 of this invention. It is a truth table of the short detection circuit. It is a figure which shows the electrical constitution of the short / open detection circuit which is Example 2 of this invention. It is a truth table of the same short / open detection circuit. It is a figure which shows the electrical constitution of the short / open detection circuit which is Example 3 of this invention. It is a truth table of the same short / open detection circuit.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Short detection circuit 10A, 10B Short / open detection circuit 12 1st differential potential comparison circuit (1st comparison circuit)
14 Second differential potential comparison circuit (second comparison circuit)
16, 16A, 16B Determination circuit 18 First reference potential source 20 Second reference potential source 24 External power source (first potential source)
26 Ground potential (second potential source)
28 Resistive element (part of potential output circuit)
30 resistance element (the remainder of the potential output circuit)
42 External power supply (part of potential change circuit)
46 Ground potential (part of potential changing circuit)
44, 44B Resistance element (part of potential changing circuit)
48, 48B Resistive element (remainder of potential change circuit)

Claims (22)

The power supply line and the two potentials via a power supply line connected to a single potential output of a potential output circuit that outputs a predetermined potential intermediate between the potential of the first potential source and the potential of the second potential source. A circuit for detecting a short circuit with one of the sources,
A first reference potential source that outputs a first reference potential that is higher than a potential of the potential output by a preset first value;
A first comparison circuit for comparing the potential of the potential output with the first reference potential of the first reference potential source;
A second reference potential source that outputs a second reference potential that is lower than a potential of the potential output by a preset second value;
A second comparison circuit that compares the potential of the potential output with the second reference potential of the second reference potential source;
A short-circuit detection circuit comprising: a determination circuit that determines the presence or absence of the short circuit based on comparison outputs of the first comparison circuit and the second comparison circuit.   2. The short inspection circuit according to claim 1, wherein the first value and the second value are determined by the accuracy of the potential of the potential output and the range of the potential.   The short test circuit according to claim 1, wherein the first value and the second value are the same value.   The first potential is a potential supplied from an external potential source, the second potential is a ground potential, the first and second reference potential sources, the first and second comparison circuits, and the determination 4. The short detection circuit according to claim 1, wherein the circuit is formed in a semiconductor integrated circuit. The power supply line and the two potentials via a power supply line connected to a single potential output of a potential output circuit that outputs a predetermined potential intermediate between the potential of the first potential source and the potential of the second potential source. A circuit for detecting a short circuit with any one of the sources or opening of the potential output and the power supply line,
A first reference potential source that outputs a first reference potential that is higher than a potential of the potential output by a preset first value;
A first comparison circuit for comparing the potential of the potential output with the first reference potential of the first reference potential source;
A second reference potential source that outputs a second reference potential that is lower than a potential of the potential output by a preset second value;
A second comparison circuit that compares the potential of the potential output with the second reference potential of the second reference potential source;
A potential change circuit that is connected to the power supply line and changes the potential of the power supply line when the potential output and the power supply line are opened to a potential different from the potential of the potential output by a predetermined value;
A third reference potential source that outputs a third reference potential set in advance between the potential of the power supply line and the potential of the potential output when the potential output and the power supply line are opened;
A third comparison circuit for comparing the potential of the power supply line at the time of opening with the third reference potential of the third reference potential source;
And a determination circuit for determining whether or not the short circuit is present or whether or not the power supply line is open based on comparison outputs of the first comparison circuit, the second comparison circuit, and the third comparison circuit. Short / open detection circuit. The potential output circuit includes a first resistance element and a second resistance element connected in series between the first potential source and the second potential source, and the first resistance element and the second resistance element The connection point with the second resistance element is the potential output,
The potential changing circuit includes a third potential source , a fourth potential source , a third resistance element connected between the third potential source and the power supply line, and the fourth potential source. And a fourth resistance element connected between the power supply line and the resistance values of the third resistance element and the fourth resistance element are the potentials of the power supply line when the opening occurs. The resistance value of the first resistance element and the second resistance element is selected to be larger than the resistance value of the first resistance element by a value necessary for changing to a potential different from the potential of the potential output by a predetermined value. 5. The short / open detection circuit according to 5.   7. The short / open detection circuit according to claim 6, wherein the different potential is a potential that is higher than the potential of the potential output by the predetermined value.   The short / open detection circuit according to claim 6, wherein the different potential is a potential lower than the potential of the potential output by the predetermined value.   9. The short / open test circuit according to claim 5, wherein the first value and the second value are determined by an accuracy of a potential of the potential output and a range of the potential. .   10. The short / open inspection circuit according to claim 5, wherein the first value and the second value are the same value.   The first potential is a potential supplied from an external potential source, the second potential is a ground potential, the first and second reference potential sources, the first and second comparison circuits, and the determination 11. The short / open detection circuit according to claim 5, wherein the circuit is formed in a semiconductor integrated circuit. Any one of the power supply line and the two potential sources via a power supply line connected to a potential output of a potential output circuit that outputs a predetermined potential intermediate between the potential of the first potential source and the potential of the second potential source. A method of detecting a short circuit with either one of
Comparing the potential of the potential output with a first reference potential that is higher than the potential of the previous potential output by a preset first value;
Comparing the potential of the potential output with a second reference potential that is lower than the potential of the potential output by a preset second value;
A short detection method, wherein the presence or absence of the short circuit is determined based on a result of the two comparisons.   13. The short detection method according to claim 12, wherein the first value and the second value are determined by the accuracy of the potential of the potential output and the range of the potential.   14. The short detection method according to claim 12, wherein the first value and the second value are the same value.   15. The short detection method according to claim 12, 13, or 14, wherein the first potential is a potential supplied from an external potential source, and the second potential is a ground potential. A short circuit between the power supply line and one of the two potential sources via a power supply line connected to a potential output of a potential output circuit that outputs a predetermined potential between the first potential and the second potential; A method of detecting opening of the potential output and the power supply line,
Comparing the potential of the potential output with a first reference potential that is higher than the potential of the potential output by a preset first value;
Comparing the potential of the potential output with a second reference potential that is lower than the potential of the potential output by a preset second value;
A third reference preset between the potential of the power supply line and the potential of the potential output, which is changed to a potential different from the potential of the potential output by a predetermined value when the potential output and the power supply line are opened. Comparing the potential with the potential of the feeder line at the time of opening,
A short / open detection method, wherein the presence / absence of the short circuit or the presence / absence of the open circuit is determined based on the results of the three comparisons.   The different potentials include a third resistance element connected between the first reference potential and the power supply line, and a fourth resistance element connected between the second reference potential and the power supply line. The first resistance element constituting the potential output circuit is connected in series between the first potential and the second potential by a value necessary to change the resistance value to the different potential. 17. The short / open detection circuit according to claim 16, wherein the short / open detection circuit is selected and set to be larger than a resistance value of the second resistance element.   18. The short / open detection method according to claim 16, wherein the different potential is higher than the potential output potential.   18. The short / open detection method according to claim 16, wherein the different potential is a potential lower than the potential output potential.   20. The short / open inspection method according to claim 16, 17, 18 or 19, wherein the first value and the second value are determined by an accuracy of a potential of the potential output and a range of the potential. .   21. The short / open inspection method according to claim 16, wherein the first value and the second value are the same value.   The short / open detection method according to any one of claims 16 to 21, wherein the first potential is a potential supplied from an external potential source, and the second potential is a ground potential. .

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