KR20050044254A - Semiconductor device and testing method thereof - Google Patents

Abstract

The semiconductor device according to the present invention has a liquid crystal driving circuit, and at the time of the gray scale voltage test, the gray scale voltage Vx generated by the gray scale voltage generation circuit provided therein and the comparison voltage generated to test the gray scale voltage (e.g., For example, Vx + ΔV) is compared, and the test results are output from the external terminal of the semiconductor device as a binary voltage. This speeds up the gray scale voltage test even for the high gray scale of the liquid crystal drive circuit and the increase in the number of output terminals of the semiconductor device, so that the time required for this is shortened and the cost is reduced.

Description

Semiconductor device and test method of semiconductor device {SEMICONDUCTOR DEVICE AND TESTING METHOD THEREOF}

This application claims the priority of patent application No. 2003-378595 for which it applied to Japan on November 7, 2003, The content is taken in here.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device having a drive circuit for a liquid crystal display and a test method thereof, and more particularly, to a semiconductor device having a plurality of external terminals (output terminals) and a test method for testing the output voltage thereof.

A semiconductor device having a driving circuit (also referred to as a liquid crystal driving circuit or an LCD driver) of a liquid crystal display outputs a multilevel (multi-gradation) voltage from a plurality of external terminals (output pins) to form a liquid crystal display (liquid crystal panel). Drive.

Conventionally, the gradation voltage test of the semiconductor device provided with the liquid crystal drive circuit was performed by the voltage measurement (analog voltage measurement) using a tester.

However, with the increase of the output terminal of the semiconductor device accompanying the recent high precision of the liquid crystal display, and the high gradation of the liquid crystal display, the time required for the gradation voltage test increases, and the semiconductor device (liquid crystal drive circuit) There has been a problem that the costs associated with the testing and manufacturing of the components increase.

Japanese Unexamined Patent Application Publication No. 2002-156412 discloses a differential voltage between the output terminal voltage of the liquid crystal drive circuit and the reference voltage of the tester as a means for speeding up the gray scale voltage test, and the gray level at each output terminal of the liquid crystal drive circuit is detected. Techniques for testing the terminal-to-terminal variations in voltage are described.

However, the technique described in the patent document 1 has the following problem.

(1) Since the output voltage is measured (analog voltage measurement) by the tester, it takes time for the output voltage to stabilize and the test time increases.

(2) When the determination range of the output voltage becomes very narrow with the miniaturization of the gradation voltage step due to the high gradation of the liquid crystal display, it is necessary to subdivide the difference voltage between the output terminal voltage of the liquid crystal drive circuit and the reference voltage of the tester. And that increases the test time.

(3) In order to realize the measurement circuit described in Patent Literature 1, it is necessary to add a gradation voltage measurement circuit to a tester newly, and an existing tester cannot be used.

An object of the present invention is to solve the above problems and to provide a technique for shortening the time required for the gradation voltage test of a semiconductor device provided with a driving circuit of a liquid crystal display. Moreover, it is providing the technique which can reduce the test and manufacturing cost of the semiconductor device provided with the drive circuit of a liquid crystal display.

Among the inventions disclosed in the present application, an outline of representative ones will be briefly described as follows.

In order to achieve the above object, a semiconductor device having a liquid crystal drive circuit according to the present invention is characterized in that for outputting a gray level voltage test signal binarized during a gray voltage test.

For example, a semiconductor device having a liquid crystal drive circuit, wherein a gray voltage generated in a gray voltage generator circuit of the semiconductor device is compared with a comparison voltage generated to test the gray voltage at a gray voltage test of the semiconductor device. The test result is output as a binary voltage from an external terminal of the semiconductor device.

Further, a semiconductor device having a liquid crystal driving circuit, the liquid crystal driving circuit having a gradation voltage generating circuit and a gradation voltage selecting circuit for receiving a gradation voltage generated by the gradation voltage generating circuit and selecting a gradation voltage corresponding to the gradation. And, in the gray voltage test of the semiconductor device, in the gray voltage selection circuit, compare the gray voltage generated in the gray voltage generation circuit with a comparison voltage generated to test the gray voltage, and compare the test result with 2. A semiconductor device characterized by outputting from an external terminal of the semiconductor device as a value voltage.

A semiconductor device having a liquid crystal driving circuit, wherein the liquid crystal driving circuit includes a gray voltage generating circuit, a gray voltage selecting circuit for receiving a gray voltage generated by the gray voltage generating circuit and selecting a gray voltage corresponding to the gray, And a buffer for temporarily storing information about the gray voltage selected by the gray voltage selection circuit, and supplying the stored information to the gray voltage selection circuit, wherein the gray voltage selection circuit is based on the output of the buffer. The selector circuit for selecting the gray scale voltage generated in the voltage generating circuit and the comparison voltage generated for testing the gray scale voltage selected in the selector circuit and the gray scale voltage during the gray voltage test of the semiconductor device are compared with each other. Amplify the differential voltage and output the result of comparison as external voltage from the external terminal Is a semiconductor device, characterized in that the amplifier circuit, having as input information to said amplifier circuit, further selecting means for selecting whether or which of the comparison voltage, or the output of the amplifier circuit.

A test method for a semiconductor device having a liquid crystal drive circuit, wherein the gray voltage generated in the gray voltage generation circuit of the semiconductor device and the comparison voltage generated to test the gray voltage are used during the gray voltage test of the semiconductor device. It compares and uses the binary voltage output from the external terminal of the said semiconductor device as a test result, and the gray voltage of the said semiconductor device is tested, The test method of the semiconductor device characterized by the above-mentioned.

Further, as a test method of a semiconductor device having a liquid crystal driving circuit, the liquid crystal driving circuit has a gray voltage generating circuit and a gray voltage selection circuit for receiving a gray voltage generated in the gray voltage generating circuit, and in the gray voltage generating circuit The generated gradation voltage and the comparison voltage generated to test the gradation voltage are compared in the gradation voltage selection circuit, and the gradation voltage of the semiconductor device is tested using the binary voltage output from the semiconductor device as the test result. It is a test method of the semiconductor device characterized by the above-mentioned.

In the test of the gradation voltage, the external terminal of the semiconductor device and the comparator of the tester are electrically connected, and the gradation test is collectively performed by the comparator of the tester using the binary voltage output from the external terminal. It is a test method of the semiconductor device characterized by the above-mentioned.

According to the present invention, the gray scale voltage test time of the semiconductor device including the driving circuit (liquid crystal driving circuit) of the liquid crystal display can be shortened.

Moreover, the test and manufacturing cost of the semiconductor device provided with the drive circuit of a liquid crystal display can be reduced.

<Example>

EMBODIMENT OF THE INVENTION Hereinafter, the Example of this invention is described in detail based on drawing. In addition, in the whole figure for demonstrating an Example, the same code | symbol is attached | subjected to the member which has the same function, and the repeated description is abbreviate | omitted.

BRIEF DESCRIPTION OF THE DRAWINGS It is a figure which shows an example of the structure of the semiconductor device which has a liquid crystal drive circuit in the Example of this invention. In the structural example of this semiconductor device, a gate driver 1, a source driver 2, a liquid crystal drive voltage generation circuit 3, a liquid crystal panel 5, an MPU 6, and the like are provided.

The gate driver 1 applies a gate signal to the liquid crystal panel 5. The source driver 2 applies the gray scale output voltage to the liquid crystal panel 5. The liquid crystal drive generation circuit 3 generates a drive voltage of the liquid crystal panel 5. The liquid crystal panel 5 has a structure in which TFTs are arranged in a matrix shape, for example, and luminance is controlled by charging of the storage capacitance of each pixel. The MPU 6 controls the operation and processing of the operations of the gate driver 1 and the source driver 2.

Hereinafter, the "semiconductor device provided with the drive circuit (liquid crystal drive circuit) of the liquid crystal display" demonstrated in the Example of this invention is a case comprised with the (1) source driver 2, (2) the gate driver 1 And the source driver 2 and the liquid crystal drive voltage generation circuit 3 in some cases.

In the case of the semiconductor device of the structure (2), the part including the gate driver 1, the source driver 2 and the liquid crystal drive voltage generation circuit 3 may be referred to as the liquid crystal display controller 4. . In addition, the MPU 6 may also be included in addition to the above-described parts to constitute one semiconductor device.

The semiconductor device in the case of (1) is mainly used when driving a large liquid crystal display, and the semiconductor device in the case of (2) is, for example, a small color TFT liquid crystal provided in a mobile phone or the like. It is used when driving a display.

In FIG. 1, the liquid crystal display controller 4 is connected to the liquid crystal panel 5 in which TFTs are arrange | positioned in matrix form. Then, the liquid crystal display controller 4 applies a gate signal for selecting an arbitrary display line to the liquid crystal panel 5 from the gate driver 1, and the source driver 2 for each pixel of the selected display line. By applying the gray scale output voltage, the storage capacitor of the target pixel is charged to control the luminance of each pixel. In addition, the liquid crystal display controller 4 is connected to the MPU 6 which controls the calculation and processing of the operations of the gate driver 1 and the source driver 2.

EMBODIMENT OF THE INVENTION The semiconductor device provided with the liquid crystal drive circuit by the Example of this invention, and its test method are demonstrated in order with reference to FIGS.

<First Embodiment>

2 shows a configuration of a semiconductor device having a liquid crystal drive circuit in the first embodiment of the present invention. Fig. 2 shows a state in which a semiconductor device having a liquid crystal drive circuit is constituted by a source driver as a first embodiment of the present invention (corresponding to the configuration of the above-mentioned (1)). That is, the liquid crystal drive circuit in the semiconductor device of the first embodiment is the source driver 2 shown in FIG.

In Fig. 2, the source driver 2 includes a display data RAM 12 for storing data written or read out via an external interface, and a line buffer 13 for holding data written to the display data RAM 12. ), The gradation voltage generation circuit 16 which generates the gradation voltage of the predetermined level, and the gradation setting data held in the line buffer 13 based on the gradation voltage generated by the gradation voltage generation circuit 16. According to the present invention, the gray voltage selection circuit 14 outputs the gray scale voltage, and the test mode switching circuit 21 switches the operation mode during normal operation and gray scale test.

S1 to Sn shown in FIG. 2 are a plurality of output terminals (output pins) included in the semiconductor device according to the first embodiment, and output gray level voltages during normal operation. In addition, VTEST shown in FIG. 2 is a terminal provided for the input (application) of the comparative voltage produced | generated for the test of the gradation voltage in the gradation test. The tester 35 is a device for performing a gradation test on the present semiconductor device, and includes a comparison voltage setting unit, a plurality of comparators CMP1 to CMPn, and the like, and can be electrically connected to an output terminal of the present semiconductor device.

The gray voltage selection circuit 14 includes a plurality of selector circuits 18, amplification circuits 20, and a switch circuit 15 composed of an operation switching switch 19. As shown in FIG.

In addition, when it is not necessary about the display data RAM 12, it can abbreviate | omit and comprise a semiconductor device.

In the normal operation, the source driver 2 connects the operation switching switch 19 to the test mode switching circuit 21 so that the output terminal of the amplifying circuit 20 is connected with an inverting input terminal indicated by a "-" symbol. To control. As a result, the amplifying circuit 20 is brought into an operation state equivalent to that of the buffer circuit, and outputs the gray scale voltage selected through the selector circuit 18 to the output terminal.

On the other hand, this source driver 2 has an external interface of a display controller (not shown), an output terminal of the gray voltage selection circuit 14 (switch circuit 15), and a VTEST terminal, respectively, to the tester 35 during the gray scale test. The gray scale test is executed by the test signal from the tester 35.

Specifically, during the gradation test (gradation test mode, test mode), the source driver 2 is connected to the VTEST terminal and the amplification circuit 20 by the test mode switching circuit 21 from the tester 35. The operation switching switch 19 is switched to connect the inverting input terminal indicated by. The amplification circuit 20 compares the gradation voltage selected through the selector circuit 18 with the comparison voltage applied through the VTEST terminal, and outputs a comparison result to the output terminal.

In general, since the amplifying circuit 20 has a high amplification factor, the amplifying circuit 20 amplifies the difference voltage between the gray voltage and the comparison voltage during the gray scale test, so that the positive side H or the negative side of the buffer circuit is an output terminal voltage. The voltage value near the power supply voltage of (L) is output.

Therefore, at the time of the gradation test, arbitrary gradation data is set from the tester 35 through the display data RAM 12 and the line buffer 13, and the comparison voltage is applied to the VTEST terminal in the tester 35, The output voltage of the source driver 2 becomes either of predetermined binary voltages ("H" or "L"). Since the output of the gradation test signal is a binary voltage, the gradation voltages of the plurality of output terminals (output pins) of the source driver 2 can be tested at the same time in the comparators CMP1 to CMPn arranged in plural in the tester 35. .

3 shows an example of the configuration of a plurality of switch circuits 15 provided in the above-described gradation voltage selection circuit 14. In Fig. 3, the switch circuit 15 includes an operation switching switch 19 composed of an amplifier circuit 20 having transistors 101a to 101i, transistors 102a and 102b, and a transformer parent switch having transistors 103a and 103b. ), And a selector circuit 18 for selecting the gray voltage generated by the gray voltage generator circuit 16 (not shown in FIG. 3). In addition, a bias voltage generation circuit 105 and a test mode switching circuit 21 are connected to the switch circuit 15 to generate a voltage level required for the operation of the amplifier circuit 20. The test mode switching circuit 21 controls the operation switching switch 19 having a higher operating voltage by using a logic circuit having a lower operating voltage (for example, an internal logic circuit, not shown in FIG. 3), thereby providing a level shift function. An inverted gate circuit 104a having a structure and an inverted gate circuit 104b operating at an operating voltage (high voltage) of the operation switching switch 19. The output terminal Vout of the amplifying circuit 20 is connected to the output terminal (any one of the output terminals S1 to Sn shown in Fig. 2) of the semiconductor device according to the present invention and the terminal A of the operation switching switch 19. The voltage supplied from the tester 35 through the terminal VTEST (see FIG. 2) or from the comparison voltage generation circuit 22 described later in the second embodiment with reference to FIG. 5 is converted into a comparison voltage Vcomp. Applied to terminal B of the switch 19;

Hereinafter, an outline of the operation of the switch circuit 15 shown in FIG. 3 will be described. By setting the logic state of the test mode switching circuit 21 to "0" in its normal operation, the transformer parent switch composed of the transistors 102a, 102b is turned off, and the transformer parent composed of the transistors 103a, 103b. The switch is turned ON. As a result, the output terminal Vout of the amplifier circuit 20 is connected to the transistor 101d (its gate) serving as the inverting input of the amplifier circuit 20 through the operation switching switch 19. As a result, the amplifying circuit 20 operates as a buffer circuit having a voltage amplification factor of about 1 times, and the voltage equivalent to the gradation voltage selected by the selector circuit 18 is described above through the output terminal Vout of the corresponding amplifying circuit 20. It is output from the output terminal of the semiconductor device which concerns on this invention.

On the other hand, during the gradation test of this semiconductor device, the logic state of the test mode switching circuit 21 is set to "1". As a result, the transformer parent switch composed of the transistors 102a and 102b is switched to the ON state, and the transformer parent switch composed of the transistors 103a and 103b is switched to the OFF state, respectively, so that the tester 35 or the comparison voltage generation circuit 22 are switched. The comparison voltage Vcomp supplied from the above is applied to the gate of the above-described transistor 101d via an operation switching switch 19. As a result, the voltage amplification ratio of the amplifying circuit 20 becomes higher than when the test mode switching circuit 21 is normally operated, that is, it operates as an amplifying circuit having a high amplification factor. Therefore, the amplifying circuit 20 amplifies the difference (differential voltage) between the gradation voltage selected by the selector circuit 18 and the comparison voltage Vcomp at the voltage amplification ratio described above, and when the level of the gradation voltage is higher than the comparison voltage Vcomp One Vdd of the power supply voltage of the amplifying circuit 20 or a voltage near it is output from the output terminal Vout. When the level of the gradation voltage is lower than the comparison voltage Vcomp, the other Vss of the power supply voltage of the amplifying circuit 20 or a voltage of the vicinity thereof is output from the output terminal Vout of the amplifying circuit 20.

As mentioned above, although an example of the switch circuit 15 was demonstrated with reference to FIG. 3, in the implementation of the semiconductor device which concerns on this invention, it is clear that the switch circuit 15 or its equivalent is not limited to the structure mentioned above. Do. For example, some or all of the transistors 101a to 101i, 102a, 102b, 103a, and 103b illustrated as the field effect transistor in FIG. 3 may be replaced with a bipolar transistor (in this case, the transistor ( The gate of 101d is replaced with a base) and the logic circuit built in the test mode switching circuit 21 may be configured to operate at an operating voltage equivalent to or close to that of the operation switching switch 19. Therefore, in the implementation of the test method and the manufacturing method of the semiconductor device according to the present invention, of course, it is obvious that the configuration of the switch circuit 15 described above is not restricted.

Next, FIG. 4 is a flowchart of a process relating to the semiconductor device having the liquid crystal drive circuit and the test method thereof according to the embodiment of the present invention. First, the source driver 2 is set to the above-described gradation test mode (S2), and then the gradation setting data is set in the line buffer 13 to select the gradation voltage Vx in the selector circuit 18 (S3). . Next, a comparison voltage having a voltage value of (Vx-ΔV) is applied from the tester 35 to the VTEST terminal (S4), and the output terminal voltage of the source driver 2 is compared with the expected value in the tester 35. A determination is made (S5).

In this output voltage determination, when the source driver 2 is normal, the potential difference between the input terminals of the amplifying circuit 20 is + ΔV, and a voltage corresponding to "H" is output to the output terminal voltage of the source driver 2. This is compared with the expected value in the tester 35 (S5-output voltage " H "). If the output voltage is "L", the result for the corresponding output terminal is FAIL (bad) (S10).

Next, a comparison voltage having a voltage value of (Vx + ΔV) is applied from the tester 35 to the VTEST terminal (S6), and the output terminal voltage of the source driver 2 is compared with the expected value at the tester 35. A determination is made (S7).

In this output voltage determination, when the source driver 2 is normal, the potential difference between the input terminals of the amplifying circuit 20 is -ΔV, and a voltage corresponding to "L" is output to the output terminal voltage of the source driver 2. This is compared with the expected value in the tester 35 (S7-output voltage " L "). If the output voltage is "H", the result for the corresponding output terminal is FAIL (S10).

Through the processing steps S3 to S7, the source driver 2 makes the comparison voltage (Vx ± ΔV) with respect to the internally selected gray voltage Vx, thereby testing whether the gray voltage is in a predetermined voltage range. If normal, the result for the output terminal is PASS (good) (S9).

In the case where the test is performed on another gradation voltage value Vx ', it is obvious that the processing steps S3 to S7 can be similarly repeated using the gradation voltage value (S8). In addition, although the comparison voltage was made into (Vx + (DELTA) V) for the description here, of course, it can be tested by setting arbitrary voltage ranges.

In addition, the liquid crystal display has a characteristic in which the display luminance rises curvedly with respect to the increase in the input voltage. In contrast, in the liquid crystal driving circuit, the relationship between the gray scale voltage Vx and the gray scale setting value is shown in FIG. In this embodiment, the magnitude of ΔV with respect to the selected gradation voltage Vx can be changed in accordance with the gradation setting value in accordance with the relationship between the gradation voltage Vx and the gradation setting value. That is, since the change (tilt) of the gray voltage Vx with respect to the gray scale setting value is large in the region indicated by A or C in FIG. 7, ΔV is also set approximately. In the region indicated by B, the change of the gray voltage Vx with respect to the gray scale set value ( ΔV is also finely set because the slope is small. Thereby, the gradation voltage test which matches the characteristic of a liquid crystal display becomes possible, and the precision of a gradation voltage test can be improved.

In addition, FIG. 2 illustrates the principle of the gradation test according to the present invention, and for the purpose of explanation, the configuration in which the VTEST terminal for comparison voltage input is provided is described. It is also possible to change the configuration.

Further, by setting a plurality of comparison voltage setting units in the tester 35 or by arranging a plurality of comparison voltage input terminals corresponding to the VTEST terminals, different comparison voltages are applied to the plurality of switch circuits 15. In this way, different gradation voltage tests are possible for each switch circuit (for each output terminal).

For example, when (Vx + ΔV) is applied to a group of arbitrary output terminals and (Vx-ΔV) is applied to a group of other output terminals, the output from the source driver 2 is " H " L "is mixed. If this is applied, when (Vx + ΔV) is applied to odd-numbered output terminals and (Vx-ΔV) is applied to even-numbered output terminals, "H" and "L" (if normal) are output from the output terminals. This will be output alternately. As a result, the short detection between the output terminals becomes possible, and the reliability of the gradation test can be improved.

Also, (Vx + ΔV1) is applied to a group of arbitrary output terminals, (Vx + ΔV2) is applied to a group of other output terminals, or (Vx1 + ΔV) is applied to a group of arbitrary output terminals. Test methods and configurations for applying comparative voltages of different voltage values, such as applying (Vx2 + ΔV) to groups of different output terminals, are also possible.

In addition, this invention is not limited only to the above-mentioned gradation test, It is apparent that a combination of gradation setting data and a comparison voltage can be used for the functional test of a liquid crystal display controller, for example.

<2nd Example>

Subsequently, an example of the configuration and operation in the case where the comparison voltage generation circuit is disposed inside the display controller as the semiconductor device having the liquid crystal drive circuit in the second embodiment of the present invention will be described. FIG. 5 is a diagram showing the configuration of a semiconductor device in which a comparison voltage generating circuit (comparison voltage generating circuit 22 in the drawing) is disposed in a source driver as a second embodiment of the present invention.

The liquid crystal drive circuit in the semiconductor device of the second embodiment is applied to the source driver 2 shown in FIG. 1, for example.

The liquid crystal display controller 4 including the source driver 2 holds a display data RAM 12 that stores writing or reading data of data through an external interface, and data written in the display data RAM 12. The line buffer 13 to the line buffer 13 on the basis of the line buffer 13 to be generated, the gray level voltage generating circuit 16 to generate a gray level voltage of a predetermined level, and the predetermined gray level voltage generated by the gray level voltage generating circuit 16. A gradation voltage selection circuit 14 for outputting a gradation voltage in accordance with the retained gradation setting data, a test mode switching circuit 21 for switching an operation mode during normal operation and a gradation test, and a gradation voltage generation circuit 16 And a comparison voltage generation circuit 22 for generating a comparison voltage based on the gray voltage generated in the above.

The gray voltage selection circuit 14 includes a selector circuit 18, an amplifying circuit 20, and a plurality of switch circuits 15 constituted by the operation switching switch 19.

In the normal operation, this source driver 2 performs the same operation as that of the source driver of the first embodiment described with reference to FIG. On the other hand, the source driver 2 inverts the input terminal in which the comparison voltage generated by the comparison voltage generation circuit 22 by switching the operation switching switch 19 during the gradation test is indicated by a "-" symbol of the amplification circuit 20. Is applied to the amplification circuit 20, and the gray scale voltage selected by the selector circuit 18 is compared with the comparison voltage, and the comparison result is output to the output terminal.

Usually, since the amplification circuit 20 has a high amplification factor, during the gradation test, the amplification circuit 20 amplifies the difference voltage between the gradation voltage and the comparison voltage, and the output terminal voltage is the positive side (H) or the negative side of the buffer circuit. The voltage value near the power supply voltage of (L) is output.

In the second embodiment, since the comparison voltage in the gradation test is generated inside the circuit of the source driver 2, the gradation test can be performed relatively in the circuit, and the test time can be further shortened. That is, in the second embodiment, since the increase of the comparison voltage generated when the comparison voltage is applied from the outside of the semiconductor device having the configuration as shown in FIG. 1 is not a problem, the test time can be further shortened.

In addition, in order to improve the accuracy of the gradation voltage test of the source driver 2, although not shown in FIG. 5, the voltage measured by the tester 35 can be measured by the tester 35 through the VTEST terminal. You may comprise.

Next, an example of the circuit configuration and operation of the comparison voltage generation circuit 22 of the semiconductor device in the second embodiment will be described with reference to FIG. 6. 6 shows a detailed configuration of the comparison voltage generation circuit 22. As shown in FIG.

The comparison voltage generating circuit 22 according to the second embodiment includes a comparison voltage resistor 23 for generating a comparison voltage for each gray voltage based on the gray voltage generated by the gray voltage generating circuit 16, and a comparison voltage. A plurality of buffer circuits 24 for amplifying each divided voltage by the resistor 23 at an amplification factor and a plurality of buffer circuits 24 for switching the output of the buffer circuit 24 and connecting them to the gradation voltage selection circuit 14 as comparison voltages. The switch 25 and the decoder circuit 26 which perform ON / OFF control of the some switch 25 based on gradation setting data and a comparison voltage switching signal.

In the gray level setting data which is a control input of the decoder circuit 26, the same data as the gray level setting data set in the gray voltage selection circuit 14 is set, and as shown in Fig. 6, when the gray level voltage is V (x). Any one of V (x) ± ΔV is output as the comparison voltage based on the comparison voltage switching signal. The operation of the comparison voltage generation circuit 22 is summarized in the table below in FIG. 6. Here, 1/0 switching of the comparison voltage switching signal corresponds to the step of setting the comparison voltage of S4 or S6 in the processing flow of the gradation test shown in FIG.

As described above, the present invention can shorten the time required for the gradation voltage test of the semiconductor device including the driving circuit of the liquid crystal display, and further reduce the test and manufacturing cost of the semiconductor device including the driving circuit of the liquid crystal display. have.

BRIEF DESCRIPTION OF THE DRAWINGS The figure which shows an example of the semiconductor device which has a liquid crystal drive circuit in the Example of this invention.

Fig. 2 is a diagram showing the configuration of a semiconductor device having a liquid crystal drive circuit in the first embodiment of the present invention.

Fig. 3 is a diagram showing an example of the configuration of a switch circuit provided in the semiconductor device according to the first embodiment of the present invention.

4 is a diagram showing a processing flow of a test method for a semiconductor device having a liquid crystal drive circuit in an embodiment of the present invention.

Fig. 5 is a diagram showing the configuration of a semiconductor device having a liquid crystal drive circuit in the second embodiment of the present invention.

FIG. 6 is a diagram showing an example of a circuit configuration and an operation of a comparison voltage generation circuit of a semiconductor device according to a second embodiment of the present invention. FIG.

Fig. 7 is a diagram showing an example of the relationship between the gradation voltage and the gradation in the embodiment of the present invention.

<Explanation of symbols for main parts of drawing>

1: gate driver

2: source driver

3: liquid crystal drive voltage generation circuit

4: liquid crystal display controller

5: liquid crystal panel

6: MPU

Claims (21)

In a semiconductor device having a liquid crystal drive circuit, During the gradation voltage test of the semiconductor device, the gradation voltage generated in the gradation voltage generation circuit of the semiconductor device is compared with the comparison voltage generated to test the gradation voltage, and the test result is a binary voltage. The semiconductor device outputs from the external terminal of the. The method of claim 1, And a test voltage of the gray voltage is a voltage set outside of the semiconductor device. The method of claim 2, And a terminal for inputting a voltage set outside the semiconductor device. The method of claim 2, A semiconductor device using any one of output terminals of the semiconductor device as a terminal for inputting a voltage set outside the semiconductor device. The method of claim 1, And a test voltage of the gray voltage is a voltage generated by a comparison voltage generation circuit formed inside the semiconductor device. The method of claim 5, And the comparison voltage generating circuit includes voltage dividing means, and divides the gray voltage generated in the gray voltage generating circuit through the voltage dividing means to generate the test voltage. The method of claim 1, The test of the gray voltage is performed using both the result of comparing the gray voltage Vx and the first comparison voltage Vx + ΔV and the result of comparing the gray voltage Vx and the second comparison voltage Vx-ΔV. Semiconductor device. The method of claim 1, And the semiconductor device is a source driver. The method of claim 8, The semiconductor device has a gate driver and a liquid crystal drive voltage generation circuit. In a semiconductor device having a liquid crystal drive circuit, The liquid crystal driving circuit has a gradation voltage generating circuit and a gradation voltage selecting circuit for receiving a gradation voltage generated by the gradation voltage generating circuit and selecting a gradation voltage corresponding to the gradation, In the gradation voltage test of the semiconductor device, the gradation voltage selection circuit compares the gradation voltage generated in the gradation voltage generation circuit with a comparison voltage generated to test the gradation voltage, and compares the test result with a binary voltage. And a semiconductor device outputted from an external terminal of the semiconductor device. The method of claim 2, The gray voltage selection circuit has a plurality of switch circuits, and a comparison voltage of different voltage values is applied to the first switch circuit and the second switch circuit during the gray voltage test. The method of claim 10, And a test voltage of the gray voltage is a voltage set outside of the semiconductor device. The method of claim 10, And a test voltage of the gray voltage is a voltage generated by a comparison voltage generation circuit formed inside the semiconductor device. In a semiconductor device having a liquid crystal drive circuit, The liquid crystal driving circuit includes a gray voltage generator circuit, a gray voltage selection circuit that receives a gray voltage generated by the gray voltage generator circuit, and selects a gray voltage corresponding to the gray scale, and a gray voltage selected from the gray voltage select circuit. A buffer for temporarily storing information related to the information and supplying the stored information to the gray voltage selection circuit; The gray voltage selection circuit, A selector circuit which selects a gray voltage generated in the gray voltage generation circuit based on an output of the buffer; In the gray voltage test of the semiconductor device, a voltage difference between these voltages is amplified by comparing the gray voltage selected by the selector circuit with a comparison voltage generated to test the gray voltage, and the external result is a binary voltage. An amplifying circuit output from the terminal, And a selection means for selecting either the comparison voltage or the output of the amplifier circuit as information input to the amplifier circuit. The method of claim 14, And a storage means connected to said buffer, for storing and holding information supplied to said buffer through an external interface of said semiconductor device. The method of claim 14, And a test voltage of the gray voltage is a voltage set outside of the semiconductor device. The method of claim 14, And a test voltage of the gray voltage is a voltage generated in an internal circuit of the semiconductor device. In the test method of a semiconductor device having a liquid crystal drive circuit, During the gradation voltage test of the semiconductor device, the gradation voltage generated in the gradation voltage generation circuit of the semiconductor device is compared with the gradation voltage for testing, and the binary voltage output from the external terminal of the semiconductor device as the test result. A test method of a semiconductor device which performs a test of a gradation voltage of the semiconductor device by using a. The method of claim 18, In the test of the gradation voltage, the external terminal of the semiconductor device and the comparator of the tester are electrically connected, and the semiconductor device performs the gradation test collectively in the comparator of the tester using the binary voltage output from the external terminal. Test method. In the test method of a semiconductor device having a liquid crystal drive circuit, The liquid crystal drive circuit has a gradation voltage generation circuit and a gradation voltage selection circuit that receives a gradation voltage generated by the gradation voltage generation circuit, The gradation voltage generated by the gradation voltage generation circuit and the comparison voltage generated to test the gradation voltage are compared in the gradation voltage selection circuit, and the semiconductor using the binary voltage output from the semiconductor device as the test result. A test method of a semiconductor device for testing a gray voltage of a device. The method of claim 20, In the test of the gradation voltage, the external terminal of the semiconductor device and the comparator of the tester are electrically connected, and the semiconductor device performs the gradation test collectively in the comparator of the tester using the binary voltage output from the external terminal. Test method.