JPH0712942Y2 - IC test equipment - Google Patents

Description

[Detailed Description of Device] [Industrial Application Field] The present invention relates to an IC tester.

"Prior Art" In an IC test apparatus, as shown in FIG. 3, a timing signal TM forms a test signal of a logic level according to an applied pattern IP which is a kind of test pattern in a signal forming circuit 11, and ECL in test signal and driver 12
A relay switch that is converted to a signal voltage such as level or TTL level and turned on during testing by the control register 44
IC1 is supplied to the terminal (pin) 1c of IC1 through 13 and the test signal is supplied in this way.
The IC output voltage Vo obtained at the terminal 1c is supplied to the comparator 15 through the relay switch 13 and compared with the reference voltage Vr to obtain a signal of a logic level from the comparator 15, and the signal is strobed in the latch circuit 16. After being latched by the signal ST, it is supplied to the logical comparison circuit 17 and logically compared with an expected value pattern EP which is a kind of test pattern, and the output of the logical comparison circuit 17 determines the quality of IC1. The terminal 1c is a generic term for terminals excluding the power supply terminal 1a and the ground terminal 1e of the IC1.

In such an IC test apparatus, the current flowing between the power supply terminal 1a and the ground terminal 1e of IC1 in IC1, that is, IC
To measure the power supply current Id of 1, power supply 2 as shown
The current Ia flowing through the resistor 21 connected between the power supply terminal 1a of the IC1 and the power supply terminal 1a of the IC1 is measured. In this case, if the current Ib flowing from the terminal 1c of the IC1 through the relay switch 13 to the comparator 15 is small enough to be ignored compared to the power supply current Id, the current Ia
Is substantially equal to the power supply current Id, and the power supply current Id can be accurately measured. However, if the current Ib is large enough to be ignored with respect to the power supply current Id, the power supply current Id cannot be accurately measured.

Therefore, in the prior art, as shown in FIG. 4, the comparator 15 is composed of a bipolar transistor, and the bipolar transistor has a low input impedance of about 10 kΩ. Change it to turn off the relay switch 13, or, as shown in FIG.
Power supply current Id
It is conceivable that the relay switch 13 is turned on without changing the contents of the control register 44 at the time of measurement of, and an amplifier circuit 14 composed of a FET (field effect transistor) is provided on the input side of the comparator 15. .

In the device of FIG. 4, when the power supply current Id is measured, the relay switch 13 is turned off, so the above current Ib becomes zero, the current Ia becomes equal to the power supply current Id, and the power supply current Id
Can be measured accurately. Also, in the apparatus of FIG.
Since the input impedance of FET is as high as about 10 MΩ,
At the time of measuring the power supply current Id, the current Ib becomes negligibly smaller than the power supply current Id, and the current Ia becomes substantially equal to the power supply current Id, so that the power supply current Id can be accurately measured.

[Problems to be Solved by the Invention] However, in the conventional IC test apparatus shown in FIG. 4, since the input side of the comparator 15 configured by the bipolar transistor is not provided with the amplification circuit configured by the FET, High-speed operation can be adjusted during normal testing, but when measuring the power supply current Id, the relay switch 13 must be switched from on to off, and after measurement, it must be switched from off to on. Since milliseconds to several tens of milliseconds are required, it takes a long time to measure the power supply current Id as a whole, and there is a disadvantage that a normal test cannot be performed for the long time.

Further, in the conventional IC test apparatus shown in FIG. 5, since the relay switch 13 is not switched when measuring the power supply current Id, the time required to measure the power supply current Id is shortened as a whole. However, since the amplifier circuit 14 composed of the FET is provided on the input side of the comparator 15 composed of the bipolar transistor, it is possible to perform a high-speed operation during the normal test. In addition to this, there is a problem that the scale of the test circuit section becomes large and the cost becomes high.

Therefore, this invention is an IC that has the function of measuring the IC power supply current.
The test equipment can be operated at high speed during normal testing, the time required to measure the IC power supply current can be shortened, and the size of the test circuit section can be reduced, resulting in lower prices. It is the one.

"Means for Solving the Problem" In the present invention, as a plurality of comparators for respectively comparing the IC output voltage obtained at the terminal of the IC with a reference voltage, a power down function constituted by bipolar transistors is provided. When the IC power supply current is measured, the same power-down control signal from the common power-down control unit sets each of the plurality of comparators to the power-down mode at least during the IC power supply current measurement period.

"Operation" In the IC test apparatus of the present invention configured as described above, since the comparator is configured by the bipolar transistor, and the amplifier configured by the FET is not provided on the input side of the comparator, In addition to being able to perform high-speed operation during testing, the comparator is placed in power-down mode to increase the input impedance of the comparator when measuring the IC power supply current, and the relay connected between the IC pin and the comparator. Even if the switch is not switched from ON to OFF, the current flowing from the IC pin to the comparator becomes negligibly smaller than the IC power supply current, and the IC power supply current can be measured accurately, so it is necessary to measure the IC power supply current. The time can be shortened.

"Embodiment" FIG. 1 is an example of an IC test apparatus of the present invention.

Terminal 1c of IC1 to be tested, excluding power terminal 1a and ground terminal 1e
On the other hand, a signal forming circuit 11 that forms a test signal of a logic level according to the applied pattern IP by the timing signal TM, and a driver 12 that converts the test signal into a signal voltage of a predetermined level such as an ECL level or a TTL level. , The signal voltage is inserted in the passage to the terminal 1c of IC1, and the control register 4
4, a relay switch 13 controlled by 4, the IC output voltage Vo obtained at the terminal 1c of IC1 is compared with a reference voltage Vr to obtain a signal of a logic level, a comparator 31 having a power-down function constituted by a bipolar transistor, A test circuit unit 10 including a latch circuit 16 that latches the output signal So of the comparator 31 by a strobe signal ST, and a logical comparison circuit 17 that logically compares the latched signal with an expected value pattern EP is provided.

The comparator 31 has a power-down function composed of bipolar transistors as described above, and specifically, has transistors 32 to 35 and constant current sources 36, which are bipolar transistors, respectively. The emitters are commonly connected, and the collector of the transistor 34 is connected to the connection point.
5 emitters are connected in common, and a constant current source 3
6 is connected, and IC output voltage Vo is applied to the base of transistor 32.
Is supplied, the reference voltage Vr is supplied to the base of the transistor 33, and the power-down control signal PDC is supplied to the base of the transistor 35 as described later. Therefore, when the power down control signal PDC becomes low level, the transistor 35 is turned off, the transistor 34 is turned on, and the comparator 31 performs a normal comparison operation, but when the power down control signal PDC becomes high level. , Transistor 3
5 turns on, transistor 34 turns off and comparator 31 goes into a power down mode. Further, although the comparator 31 is composed of a bipolar transistor, the input impedance becomes sufficiently high in the power down mode.

A resistor 21 is connected between the power source 2 and the power source terminal 1a of the IC 1, and the voltage obtained at one end and the other end of the resistor 21 is supplied to the differential amplifier circuit 22 so that the differential amplifier circuit 22 supplies the resistor 21 with the voltage. A voltage proportional to the flowing current Ia is obtained, and the voltage is supplied to the A / D converter 23, and the measurement control signal AD is supplied as described later.
A / D converted by C. The resistor 21, the differential amplifier circuit 22, and the A / D converter 23 form a power supply current measuring unit 20.

Then, the sequence controller 41 obtains the power-down control signal PDC and the measurement control signal ADC from the power-down controller 42 and the measurement controller 43, respectively, and the power-down control signal PDC is applied to the terminal 1c of the IC1 for each test. It is supplied to the base of the transistor 35 of the comparator 31 of the circuit section 10, and its measurement control signal ADC is supplied to the power supply current measuring section 2
0 is supplied to the A / D converter 23. The power down control signal PDC and the measurement control signal ADC are as shown in FIG.
Make sure that the measurement control signal ADC is at a high level within the period Tp when the power-down control signal PDC is at a high level, that is, at least during the period T when the measurement control signal ADC is at a high level.
At a, the power down control signal PDC is set to a high level. Specifically, each of the power-down control unit 42 and the measurement control unit 43 can be provided with a control register having a 1-bit configuration, and the sequence control unit 41 can write a control command of 1-bit to each of them.

Before time tx in FIG. 2, the relay switch 13 is turned on, the IC output voltage Vo obtained at the terminal 1c of IC1 is supplied to the comparator 31 through the relay switch 13, and the power-down control unit 42 performs power-down. The control signal PDC is set to the low level and the comparator 31 performs the normal comparison operation as described above, and the output signal So of the comparator 31 depends on whether the IC output voltage Vo is higher than the reference voltage Vr or lower than the reference voltage Vr. Since the comparator 31 is not in the power down mode and the input impedance of the comparator 31 is low, the current Ib flowing from the terminal 1c of IC1 to the comparator 31 through the relay switch 13 is smaller than the power supply current Id. It becomes a size that cannot be ignored.

During the period Tp from the time point tx to the time point ty, the content of the control register 44 is not changed and the relay switch 13 is kept on.
Is supplied to the comparator 31 through the power-down control unit 42, but the power-down control signal PDC from the power-down control unit 42 is set to a high level, the comparator 31 enters the power-down mode as described above, and the output signal So of the comparator 31 becomes undefined. At the same time, since the input impedance of the comparator 31 becomes high as the comparator 31 enters the power down mode as described above, the current Ib flowing from the terminal 1c of the IC1 to the comparator 31 through the relay switch 13 can be ignored compared to the power supply current Id. The current Ia flowing through the resistor 21 becomes substantially equal to the power supply current Id, and the power supply current Id can be accurately measured. In the period Ta within the period Tp, Measurement control signal AD
C is set to a high level and the output voltage of the differential amplifier circuit 22 is A / D converted in the A / D converter 23.

Therefore, the power supply current Id can be accurately measured, and
In this way, the power supply current Id can be accurately measured without switching the relay switch 13 from ON to OFF.
The time required for measuring Id, that is, the period Tp can be shortened. Moreover, since the comparator 31 is composed of bipolar transistors and the amplifier circuit composed of the FET is not provided on the input side of the comparator 31, it is possible to perform a high-speed operation during a normal test, and the test circuit section 10 will be smaller and the price will be lower.

[Advantages of Device] As described above, according to the device of the present invention, it is possible to perform a high-speed operation during a normal test, and it is possible to shorten the time required to measure the IC power supply current, and moreover, the test circuit. The size of the department becomes smaller and the price becomes cheaper.

[Brief description of drawings]

FIG. 1 is a connection diagram showing an example of the IC test device of the present invention,
FIG. 2 is a time chart used for explaining the operation, FIG. 3 is a connection diagram for explaining the case of measuring an IC power supply current in an IC test apparatus, and FIGS. 4 and 5 are conventional diagrams. It is a connection diagram showing an example of an IC test device.

Claims (1)

[Scope of utility model registration request] 1. As a plurality of comparators for respectively comparing the IC output voltage obtained at the terminal of the IC with a reference voltage, comparators each having a power down function constituted by bipolar transistors are provided, and when measuring the IC power supply current, An IC test apparatus in which the plurality of comparators are set to a power down mode at least during an IC power supply current measurement period by the same power down control signal from a common power down control unit.