JPH1010199A - Ic tester - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an IC tester in which highly accurate voltage test and function test are performed for a gradation voltage by storing the upper and lower limit voltages and an expected value for gradation voltage test in a shared memory circuit and switching the output from the shared memory circuit between a D/A converter and a digital comparator depending on the purpose of test. SOLUTION: A shared memory circuit 10 is preset with a multiple gradation upper limit voltage corresponding to an IC to be tested. Address of the circuit 10 is incremented according to the variation in the gradation of a voltage 100 to be tested. Upper limit voltages being outputted sequentially from the circuit 10 are set in a D/A converter 3 and the voltage 100 is compared with the upper limit voltage by means of a comparator 1. A decision is made quickly whether an object to be tested is acceptable or not by incrementing the address of the circuit 10 according to the variation in the gradation of the voltage 100 thereby setting an upper limit voltage in real time. The process is applicable similarly to the lower limit voltage. At the time of function test, an expected value of IC is preset in the circuit 10 and a digital comparator 18 compares the expected value with an output from the comparator 1 and decides whether they match each other or not.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an IC test apparatus such as an LCD driver IC for generating a multi-gradation voltage, and more particularly to an IC test capable of performing a high-precision voltage test and a function test of a generated gradation voltage. Related to the device.

[0002]

2. Description of the Related Art An LCD driver IC generates a multi-gradation voltage for each pin in order to display multi-gradation on an LCD.
For this reason, when testing the LCD driver IC, it is necessary to individually test (hereinafter, referred to as a high-accuracy voltage test) whether or not each multi-tone voltage is within the upper and lower limit voltage.

FIG. 2 is a block diagram showing an example of such a conventional IC test apparatus. In FIG. 2, 1 and 2
Is a comparator, 3 and 4 are D / A converters, 5 and 6 are comparison voltage value storage circuits, 7 is a storage circuit, 100 is a test voltage, 1
01 and 102 are address control signals.

The voltage under test 100 is input to the non-inverting input terminal of the comparator 1 and the inverting input terminal of the comparator 2. The address control signals 101 and 102 are input to comparison voltage value storage circuits 5 and 6, respectively.

The outputs of the comparison voltage value storage circuits 5 and 6 are D /
The outputs of the D / A converters 3 and 4 are connected to the inverting input terminal of the comparator 1 and the non-inverting input terminal of the comparator 2, respectively. The outputs of the comparators 1 and 2 are connected to the storage circuit 7, respectively.

The operation of the conventional example shown in FIG. 2 will be described with reference to FIG. FIG. 3 is a timing chart for explaining the change of the voltage under test 100 and the upper and lower limit voltage which is the output signal of the D / A converters 3 and 4. In FIG.
00, “b” and “c” in FIG. 3 indicate an upper limit voltage and a lower limit voltage, respectively.

The comparison voltage value storage circuits 5 and 6 store the upper and lower limit voltage values of the multi-gradation corresponding to the IC that generates the multi-gradation voltage, such as the LCD driver IC to be tested, in advance. (Not shown).

The address control signals 101 and 102 increment the addresses of the comparison voltage value storage circuits 5 and 6 in accordance with the change in the gradation of the voltage under test 100, and are output from the D / A converters 3 and 4. Change the lower limit voltage.

That is, the upper limit voltage and the lower limit voltage indicated by "b" and "c" in FIG. 3 are changed at the timing indicated by "d", "e" and "f" in FIG. It changes in conjunction with the key change.

Here, a voltage under test 100, such as an output of an LCD driver IC, is input to comparators 1 and 2, and D / D
The voltage is compared with the upper and lower limit voltage output from the A converters 3 and 4 as shown in FIG.

For example, "0" is stored in the memory circuit 7 if the voltage signal is output from the D / A converters 3 and 4, and if it is within the range of the upper and lower limit voltage, it is "1". It is memorized. Therefore, if all the data stored in the storage circuit 7 is “0”, it is a non-defective product, and if at least one is “1”, it is a defective product.

As a result, the upper and lower limit voltage values are set in real time by incrementing the addresses of the comparison voltage value storage circuits 5 and 6 in accordance with the change in the gradation of the voltage under test 100. Can be determined. Therefore, a high-speed test can be performed.

[0013]

However, in the conventional example as shown in FIG. 2, the quality of the generated gradation voltage can be determined, but the function test using the expected value cannot be performed. Had a problem that another IC test apparatus had to be used. Accordingly, an object of the present invention is to realize an IC test apparatus capable of performing a high-precision voltage test and a function test of a generated gray scale voltage.

[0014]

According to a first aspect of the present invention, there is provided an IC test apparatus for performing a high-precision voltage test and a function test of a voltage under test from a test object. A shared memory circuit in which an upper limit voltage, a lower limit voltage or an expected value is stored, a register circuit in which a function test voltage is set, and the upper limit voltage, the lower limit voltage or A D / A converter that generates a function test voltage, a comparator that compares the voltage under test with the upper limit voltage, the lower limit voltage, or the function test voltage, and compares the output of the comparator with the expected value A digital comparator, a storage circuit in which an output of the comparator or the digital comparator is stored, and switching of outputs of the shared storage circuit and the register circuit It is characterized in that a test switching means for switching input to the memory circuit.

In order to achieve the above object, in a second aspect of the present invention, in the first aspect of the present invention, an address is incremented in synchronization with the change of the voltage to be inspected, and a plurality of the upper limit values stored in advance are stored. The shared memory circuit for outputting a value voltage or a lower limit voltage is provided.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the drawings. FIG. 1 is a block diagram showing the configuration of an embodiment of an IC test apparatus according to the present invention.

In FIG. 1, reference numerals 1 to 4 and 100 denote the same reference numerals as in FIG. 2, 8 and 9 denote register circuits, 10 and 11 denote shared storage circuits, 12, 13, 14, 15, 1
6, 17, 20 and 21 are switch circuits, 18 and 19
Is a digital comparator, and 22 is a storage circuit.
In addition, 12 to 17, 20, and 21 constitute the inspection switching means 50.

The voltage under test 100 is input to the non-inverting input terminal of the comparator 1 and the inverting input terminal of the comparator 2. Outputs of the registers 8 and 9 are connected to input terminals of switch circuits 12 and 13, respectively.

The output terminal of the switch circuit 12 is connected to the input terminal of the D / A converter 3 and one output terminal of the switch circuit 14, and the input terminal of the switch circuit 14 is connected to the output of the shared storage circuit 10. .

The other output terminal of the switch circuit 14 is connected to one input terminal of a digital comparator 18. The output of the D / A converter 3 is connected to the inverting input terminal of the comparator 1.

The output terminal of the switch circuit 13 is connected to the input terminal of the D / A converter 4 and one output terminal of the switch circuit 15, and the input terminal of the switch circuit 15 is connected to the output of the shared storage circuit 11. .

The other output terminal of the switch circuit 15 is connected to one input terminal of the digital comparator 19. The output of the D / A converter 4 is connected to the non-inverting input terminal of the comparator 2.

The outputs of the comparators 1 and 2 are connected to a switch circuit 16
17 are connected to the input terminals of switch circuits 16 and 17, respectively. One output terminal of switch circuits 16 and 17 is connected to the other input terminals of digital comparators 18 and 19, respectively.

The other output terminals of the switch circuits 16 and 17 are connected to one input terminal of the switch circuits 20 and 21, and the outputs of the digital comparators 18 and 19 are connected to the other input terminals of the switch circuits 20 and 21, respectively. Is done. The output terminals of the switch circuits 20 and 21 are connected to the storage circuit 22, respectively.

Here, the operation of the embodiment shown in FIG. 1 will be described. Also, the operations of the portions "A" and "B" in FIG. 1 are the same, so for simplicity, only the portion indicated by "A" in FIG. 1 will be described.

First, in the case of a high-precision voltage test for judging the quality of a generated gradation voltage as in the conventional example, a control circuit or the like (not shown) switches the switch circuit 14 to the "b" side in FIG. And the switch circuits 16 and 20 are connected to the "d" and "f" sides in FIG. Further, the switch circuit 12 is set to “O”
FF ”.

In the shared storage circuit 10, a multi-gray scale upper limit voltage corresponding to an IC for generating a multi-gray scale voltage such as an LCD driver IC or the like to be tested is controlled in advance by a control circuit or the like (not shown). ). Then, a control circuit or the like (not shown) increments the address of the shared storage circuit 10 in accordance with the change in the gradation of the voltage under test 100.

The upper limit voltage sequentially output from the shared storage circuit 10 is set in the D / A converter 3 via the switch circuit 14, and the upper limit voltage output from the D / A converter 3 changes sequentially. go.

Here, the voltage under test 100 such as the output of the LCD driver IC is input to the comparator 1 and compared with the upper limit voltage output from the D / A converter 3, and the result is stored in the storage circuit 22. It is memorized.

As a result, as in the conventional example shown in FIG. 2, the shared storage circuit 1
By incrementing the address of 0, the upper limit voltage is set in real time, and at the same time, the quality of the test object can be determined at high speed. The same operation can be performed for the lower limit voltage.

Second, when performing a function test, a control circuit or the like (not shown) connects the switch circuit 14 to the "A" side in FIG. 1 and connects the switch circuits 16 and 20 to "C" and "C" in FIG. Connect to "e" side. Further, the switch circuit 12 is set to “O”
N ".

An expected value of an IC such as an LCD driver IC to be tested is previously set in the shared storage circuit 10 from a control circuit or the like (not shown). The window width of the configured window comparator is set as the function test voltage.

Output data from the register circuit 8 is set to the D / A converter 3 via the switch circuit 12.

Here, the voltage under test 100, such as the output of the LCD driver IC, is input to the comparator 1 and compared with the function test voltage output from the D / A converter 3, and the result is further compared with a digital comparator. 18 is input.

The digital comparator 18 compares the expected value supplied from the shared storage circuit 10 via the switch circuit 14 with the output of the comparator 1 supplied via the switch circuit 16 and determines whether the output value matches the expected value. Determine whether or not. This determination result is input to the storage circuit 22 via the switch circuit 20 and stored.

That is, by using the expected value stored in the shared storage circuit 10 to determine whether the output value of the comparator 1 matches or not, a function test can be performed.

For example, consider a case in which it is checked whether the voltage under test 100, which is the output of the IC under test (not shown), normally outputs a high level or a low level.

In this case, "2.4 V" corresponding to the high level is set in the register 8 and the register circuit 9 is set to "0.8 V" corresponding to the low level. Since the switch circuits 12 and 13 are "ON", the D / A converters 3 and 4 output "2.4 V" and "0.8 V".
V "is output.

The IC under test (not shown) is set so that the voltage under test 100 becomes a high level, and the expected values of “1” and “0” are set in the shared storage circuits 10 and 11. deep.

If the voltage to be inspected 100 is at a high level, the voltage value is "2.4 V" or more.
Is "1". Similarly, the output of the comparator 2 is "0".
become.

When the voltage under test 100 is not normal, for example, if it is "1.5 V", the outputs of the comparators 1 and 2 become "0" and "0".

Accordingly, the digital comparators 18 and 19 compare the output values of the comparators 1 and 2 with the expected values supplied from the shared storage circuits 10 and 11, and if they match, it is a good product, and if they do not match, If it is defective, the information is stored in the storage circuit 22.

As a result, the upper limit voltage and the expected value for the gradation voltage test are stored in the shared memory circuit 10 and the output of the shared memory circuit 10 is output to the D / A converter 3 or the digital By switching to the comparator 18, it is possible to perform both a high-precision voltage test and a function test.

It should be noted that even if the contents of the shared storage circuits 10 and 11 are completely rewritten by a control circuit or the like (not shown) when switching from the high-precision voltage test to the function test or from the function test to the high-precision voltage test, May be stored in the shared storage circuits 10 and 11 in either case.

In addition, during the function test, the outputs of the D / A converters 3 and 4 do not need to be changed in real time and the accuracy of the output voltage is not required. Therefore, a register is provided by software from a control circuit or the like (not shown). A configuration in which the contents of the circuits 8 and 9 are rewritten may be used.

[0046]

As is apparent from the above description,
According to the present invention, the following effects can be obtained. By storing the upper and lower limit voltage and the expected value for the gradation voltage test in the shared memory circuit and switching the output of the shared memory circuit to a D / A converter or a digital comparator according to the purpose of the test, the generation is performed. An IC test apparatus capable of performing a high-precision voltage test and a function test of a gray scale voltage to be performed can be realized.

[Brief description of the drawings]

FIG. 1 is a configuration block diagram showing one embodiment of an IC test apparatus according to the present invention.

FIG. 2 is a configuration block diagram illustrating an example of a conventional IC test apparatus.

FIG. 3 is a timing chart for explaining changes in a voltage under test and upper and lower limit voltages.

[Explanation of symbols]

1, 2 comparator 3, 4 D / A converter 5, 6 comparison voltage value storage circuit 7, 22 storage circuit 8, 9 register circuit 10, 11 shared storage circuit 12, 13, 14, 15, 16, 17, 20 , 21 switch circuit 18, 19 digital comparator 50 test switching means 100 voltage under test 101, 102 address control signal

Claims (2)

[Claims] 1. An IC test apparatus for performing a high-precision voltage test and a function test of a voltage under test from a test object, a shared memory circuit storing the upper limit voltage, the lower limit voltage or an expected value, and a function test A register circuit for setting a voltage, a D / A converter for generating the upper limit voltage, the lower limit voltage or the function test voltage based on the output of the shared storage circuit or the register circuit; the voltage under test and the upper limit value A comparator for comparing a voltage, a lower limit voltage or a function test voltage; and a digital comparator for comparing the output of the comparator with the expected value.
A comparator; a storage circuit in which an output of the comparator or the digital comparator is stored; and a test switching means for switching output of the shared storage circuit and the register circuit and switching input to the storage circuit. An IC test apparatus characterized by the above-mentioned. 2. A shared memory circuit, wherein an address is incremented in synchronization with a change in the voltage to be inspected, and the shared memory circuit outputs a plurality of upper limit voltage or lower limit voltage stored in advance. Claim 1
The described IC test apparatus.