JP2000165244A - Semiconductor integrated circuit device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a semiconductor integrated circuit device that incorporates an inspection facilitating circuit that attains measurement with high precision by using an inexpensive inspection device without increasing an inspection time. SOLUTION: The semiconductor integrated circuit device incorporates a D/A converter including a plurality of reference power supply terminals 110,... a resistance division circuit 12 that applies resistance division to a voltage among the reference power supply terminals 110,... to generate an intermediate voltage, and a gradation voltage selector switch 5 that selects any of the reference power supply voltages and intermediate voltages in response to an input digital signal and outputs an output voltage of the D/A converter from its output terminal 6. Relays 13, 14 are provided to locally short-circuit part of the resistance division circuit 12. Through the configuration above, the voltage between the output voltage being an inspection object can be extended, and digital discrimination by a comparator is attained in place of the measurement by a conventional analog voltage measurement device with high precision, the inspection time can considerably be reduced and high precision inspection is attained by using the inexpensive digital inspection device.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to at least two reference power supply voltage input terminals, a resistance dividing circuit for dividing a voltage between the reference power supply voltage input terminals to generate an intermediate voltage, and an input digital signal. And a switch circuit for selecting and outputting one of the reference power supply voltage and the intermediate voltage in accordance with the D / A converter. The output of the D / A converter A semiconductor integrated circuit device configured to output a voltage from its output terminal (for example,
Multi-gradation liquid crystal driver IC, etc.), and in particular, to an inspection method thereof.

[0002]

2. Description of the Related Art Multi-tone liquid crystal driver I with a built-in DAC
C has a DAC for each liquid crystal drive output terminal, and outputs an analog voltage from each liquid crystal drive output terminal in accordance with a multi-bit digital signal which is input multi-tone data. For this reason, the inspection of the multi-tone liquid crystal driver IC having a built-in DAC is performed by measuring and determining the analog voltages output from all the DACs.

FIG. 2 shows the configuration of the prior art.

[0004] The input gradation data is stored in an internal circuit 1 and then applied to a DAC bus line 3 via a decoder 2. According to each gradation data, one of the gradation voltage selection switches 5 for determining the output voltage from the reference power supply 4 is selected, and each of the output terminals (1-N) 6 is output via the output amplifier 6 '.
Thus, each gradation voltage is output. In the conventional inspection method, the output analog gray scale voltage is measured by an inspection device having a high-precision voltage measuring device to determine the voltage.

More specifically, as shown in FIG. 3, not only the reference power supply voltage input from the reference power supply terminal 11 but also
In order to select and output also the intermediate voltage generated by the resistance dividing circuit 12, for each reference power supply voltage and each intermediate voltage,
A gradation voltage selection switch 5 is provided, and the decoder 2
One of the switches 5 is selected according to the decoded signal, and the corresponding gray scale voltage is selected and output. In the conventional inspection method, the output analog gray scale voltage is measured by an inspection device having a high-precision analog voltmeter and is determined.

However, the inspection method based on analog voltage measurement uses a single voltage measurement device to measure and determine the voltage output from all the liquid crystal drive output terminals. The test time is greatly increased as compared with a test method in which all outputs are digitally determined at the same time using a separately prepared comparator. Therefore, the inspection items are also limited due to the inspection time. In addition, since the potential difference between the gradation voltages output from the liquid crystal drive output terminal is very small, a highly accurate measuring device is required for measuring and determining the difference.
It will be very expensive.

As a conventional technique for shortening the test time of the DAC, there is a technique disclosed in Japanese Patent Application Laid-Open No. 9-313569. In this technology, a chip (semiconductor integrated circuit device) known in advance as a non-defective product is used as a comparison reference (reference D / A converter), and this is compared with a device under test (DUT).
The pass / fail judgment is made depending on whether or not it is included. According to this technique, the test time of the DAC can be shortened. However, since the pass / fail judgment is performed based on the relative comparison with the reference chip, when the DAC output value is shifted due to the characteristic variation of the reference chip or the like, The deviation is the deviation of the test range as it is, making it impossible to accurately determine the specification range.In fact, the one outside the specification range is judged as good, and conversely, the one within the specification range is defective. There is a problem in determination accuracy, such as determining that

[0008]

As described above, the conventional inspection method has a problem that the inspection time is greatly increased because the analog voltage is measured and determined. Also,
In order to measure each gradation voltage with high accuracy, there is a problem that an extremely expensive inspection device is required.

Further, the technique disclosed in Japanese Patent Application Laid-Open No. Hei 9-313569 devised for the purpose of shortening the inspection time also has a problem in determination accuracy.

The present invention has been made in view of the above-mentioned conventional circumstances, and has a built-in inspection facilitating circuit which enables high-precision measurement with an inexpensive inspection device without increasing the inspection time. It is an object of the present invention to provide a semiconductor integrated circuit device.

[0011]

According to a semiconductor integrated circuit device of the present invention, at least two reference power supply voltage input terminals and a resistor for dividing a voltage between the reference power supply voltage input terminals to generate an intermediate voltage. A D / A converter including a dividing circuit and a switch circuit for selecting and outputting one of the reference power supply voltage and the intermediate voltage in accordance with the input digital signal; The output voltage of the converter is
In the semiconductor integrated circuit device configured to output from the output terminal, switch means for partially short-circuiting a part of the resistance dividing circuit is provided.

That is, the semiconductor integrated circuit device of the present invention is characterized in that a switch means for partially short-circuiting a part of the resistance dividing circuit is incorporated as a test facilitating circuit. According to the configuration, by turning on the switch means, the potential difference between the gradation voltages generated by other parts of the resistance dividing circuit can be enlarged, and the resistance dividing circuit set as an inspection target can be enlarged. As the voltage applied to the reference power supply voltage input terminal provided at both ends of
By setting a voltage at which a larger potential difference can be obtained, for example, a power supply voltage (a power supply voltage applied to the semiconductor integrated circuit device, for example, 5 V) and a ground voltage (GND), the potential difference between the gradation voltages can be further reduced. Can be expanded. As a result, the potential difference between the output voltages to be inspected can be expanded, and instead of the conventional measurement using a high-precision analog voltage measuring instrument, digital judgment by a comparator becomes possible, thereby greatly shortening the inspection time, High-precision inspection can be performed by using an inexpensive digital inspection device.

[0013]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a configuration diagram of a main part of a multi-gradation liquid crystal driver IC with a built-in inspection facilitation circuit according to an embodiment of the present invention.

The input gradation data is stored in an internal circuit (not shown), and then supplied to a DAC bus line 3 via a decoder 2. According to each gradation data, one of the gradation voltage selection switches 5 for determining the output voltage from the reference power supply terminal 11 and the resistance dividing circuit 12 is selected, and each of the output terminals (1 to N) is output via the output amplifier 6 '. 6) output the respective gradation voltages.

In this embodiment, eleven reference power supply terminals 11 ₀ ,..., 11 ₁₀ are provided (to perform fine adjustment for each gradation area such as gamma correction) during normal use. information, the reference power supply terminal 11 _0, ..., the 11 _10, respectively, 0V (GND), 0.5V, 1V, ..., 4.5
V and 5V are applied. Also, between each reference power supply terminal,
Each of the resistance division circuits 12 is provided, and each resistance division circuit 12 is configured to generate seven intermediate voltages. The potential differences between the intermediate voltages are all set equal. Therefore, the potential difference between the intermediate grayscale voltages is a very small value of 0.5V / 8 = 0.0625V.

In the prior art, it was necessary to judge such a minute potential difference, so that an expensive inspection device having a very accurate voltage measuring device was required.

The present invention solves this problem. In the embodiment shown in FIG. 1, a series connection circuit of two relays 13 and 14 is connected between each reference power supply terminal.
The connection point of the relays 13 and 14 is connected to the middle point of the resistance dividing circuit 12. In FIG. 1,
Shows only relay connection circuit that is provided between the reference power supply terminal 11 ₁₀ and the reference power supply terminal 11 _9, even in between the other of the reference power supply terminal, in which the same relay connection circuit are connected is there.

First, when inspecting the resistance dividing circuit between the reference power supply terminals 11 ₁₀ and 11 ₉ , a power supply voltage (5 V) is applied to the reference power supply terminal 11 ₁₀ and the reference power supply terminal 11 ₉
Is supplied with a ground voltage (0 V). Next, when performing the inspection of the upper part, the first relay 13 is turned off and the second relay 14 is turned on. Thereby, the reference power supply terminal 11 ₁₀
5V across the upper portion of the resistive divider circuit between the 11 ₉
Is applied. In this state, predetermined grayscale data is applied to the decoder 2 to output an analog voltage. At this time, the potential difference between the output voltages is 5V / 4 = 1.25.
V and a very large value. That is, the first gradation voltage is 5V, the second gradation voltage is 3.75V, the third gradation voltage is 2.50V, the fourth gradation voltage is 1.25V, and the fifth gradation voltage is 0V. Thus, for example, a comparator having an accuracy of 0.5 V or less can recognize the voltage of each gradation, and can perform digital determination using the comparator.

In the same manner, when inspecting the lower portion, the first relay 13 is turned on and the second relay 14 is turned on.
Is turned off. Furthermore, when performing the test of the resistance division circuit between the following reference power supply terminal, given a power supply voltage (5V) to the reference power supply terminal 11 _9, the reference power supply terminal 11 ₈ ground voltage (0
V), and the inspection is performed in the same manner.

FIG. 4 shows an example of the configuration of the gradation voltage selection switch 5 shown in FIG.

In the above embodiment, a relay is used, but other switch means may be used. Further, it is needless to say that the number of connected switch means is not limited to two and can be set as appropriate.

Further, in the above embodiment, the present invention is embodied in a multi-tone liquid crystal driver IC. However, the present invention is not limited to this, and includes a D / A converter. It goes without saying that the semiconductor integrated circuit device described above can also be effectively implemented.

[0024]

As described above in detail, the semiconductor integrated circuit device of the present invention divides the voltage between at least two reference power supply voltage input terminals and the voltage between the reference power supply voltage input terminals by resistance division, and A D / A converter including a resistor dividing circuit for generating a voltage and a switch circuit for selecting and outputting one of the reference power supply voltage and the intermediate voltage in accordance with an input digital signal. A semiconductor integrated circuit device configured to output an output voltage of the D / A converter from an output terminal thereof, wherein a switch means for partially short-circuiting a part of the resistance dividing circuit is provided. According to the semiconductor integrated circuit device of the present invention, it is possible to increase the potential difference between the output voltages to be inspected, and to replace the measurement with the conventional high-precision analog voltmeter. Digital determination by the comparator can and will, in which reduction of the significant test time, and a highly accurate inspection by the use of an inexpensive digital inspection apparatus becomes possible.

[Brief description of the drawings]

FIG. 1 is a main part configuration diagram of a multi-tone liquid crystal driver IC according to an embodiment of the present invention.

FIG. 2 is a configuration diagram of a conventional technique.

FIG. 3 is a detailed configuration diagram of a conventional technique.

FIG. 4 is a diagram illustrating a configuration example of a gray scale voltage selection switch illustrated in FIG. 1;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Internal circuit 2 Decoder 3 DAC bus line 4 Reference power supply 5 Grayscale voltage selection switch 6 Output terminal 6 'Output amplifier 11 Reference power supply terminal 12 Resistance division circuit 13 First relay 14 Second relay

Claims (1)

[Claims] 1. A method comprising: dividing at least two reference power supply voltage input terminals and a voltage between the reference power supply voltage input terminals by resistance division;
A built-in D / A converter including a resistance dividing circuit for generating an intermediate voltage and a switch circuit for selecting and outputting one of the reference power supply voltage and the intermediate voltage according to an input digital signal. In the semiconductor integrated circuit device configured to output the output voltage of the D / A converter from its output terminal, a switch means for partially short-circuiting a part of the resistance dividing circuit is provided. A semiconductor integrated circuit device characterized by the above-mentioned.