JPH07105471B2 - Method for testing semiconductor integrated circuit device - Google Patents

Description

The present invention relates to a semiconductor integrated circuit device (IC) suitable for application to electronic equipment such as a VTR that requires a large number of mode selections.

[Conventional technology]

There is a semiconductor integrated circuit in which an electronic circuit having functions such as logic operation, amplification operation, control operation, and oscillation operation is formed on the same semiconductor substrate.

In this case, a digital signal is supplied as a switching signal for mode selection, and control of a motor that is a load, switching control of a tape running direction, and the like are performed via a logic circuit.

In addition, "Basics of Digital IC" (September 20, 1982, 1st
Edition 5th edition, Publisher Tokyo Denki University Press, p150-15
An example of the interface circuit is described in 1).

The outline is that a transistor is provided as an interface between a logic output and a relay switch which is a load, or a lamp.

The inventors of the present invention studied to simplify the testing of an IC including the logic circuit and the interface circuit, that is, an electronic device. The following is a technology that has not been publicly known but has been studied by the present inventors, and the outline thereof is as follows.

That is, when testing the IC, it is necessary to supply a digital signal suitable for the selected mode and display or read the test result.

For this purpose, it is necessary to provide the IC with a large number of terminals for supplying a digital signal for each mode and a large number of output terminals.

[Problems to be solved by the invention]

According to the study of the present inventors, it has been clarified that providing a large number of terminals on the IC as described above is one of the causes of a decrease in the integration degree of the IC and an increase in cost, which is not preferable.

In addition, electronic devices are required to have more and more functions, which makes the circuit configuration inside the IC more complicated. Therefore, since many terminals are required for the IC, it is preferable that the number of terminals for testing is small, and it is preferable that one terminal can be used as a multiple signal transmission terminal in view of the above technical trend.

An object of the present invention is to provide an interface circuit capable of bidirectional signal transmission via one signal transmission path and reducing the number of terminals for signal transmission.

The above and other objects and novel features of the present invention will be apparent from the description of this specification and the accompanying drawings.

[Means for solving problems]

The outline of the representative one of the inventions disclosed in the present application will be briefly described as follows.

A semiconductor integrated circuit is provided with a bidirectional signal transmission terminal capable of inputting a test signal and outputting a signal indicating a test result, and a signal corresponding to the input test signal connected to the bidirectional signal transmission terminal. Two or more logic gate circuits having mutually different input threshold voltages supplied to the circuit under test, and a resistance element and a switch element connected in series between the bidirectional signal transmission terminal and the power supply voltage terminal are provided. , The bidirectional signal transmission terminal is connected to the test signal transmission terminal of the tester that supplies the test signal by one signal transmission path, and the test signal is output as a voltage from the tester to the bidirectional signal transmission terminal. On the other hand, the signal indicating the test result is transmitted from the bidirectional signal transmission terminal to the tester as a current according to ON / OFF of the switch element, Is obtained to carry out the judgment is converted into a voltage in the tester.

[Action]

According to the above-mentioned means, it is possible to achieve the object of the present invention that the signal signal is bidirectionally transmitted and received through one signal transmission path to reduce the number of IC terminals.

〔Example〕

An embodiment of an IC to which the present invention is applied will be described below with reference to FIG.

The tester 1 corresponds to the first control circuit, and the portion surrounded by the broken line 10 provided in the IC 2 corresponds to the second control circuit.
The two are connected by _one signal transmission path l ₁ .

In the first control circuit 1, Vcc ₁ is a power source with a voltage of 5V,
Vcc ₂ is a power supply with a voltage of about 3.7V.

The voltage level of the control signal supplied to the terminal T ₃ is Vc <VbeQ
_If it is ₂ , (in this case, the switch SW1 is on the W side, so Vc = 0V in this case). The transistor Q ₂ is turned off. In this state, a pulse is supplied to the terminal T ₁ (SW2 is W
Be on the side. ), The transistor Q ₁ is turned on and off, and the first voltage output (pulse) Vo is obtained from its emitter.

The voltage output Vo is the second voltage output via the second terminal and the line l ₁ .
Is supplied to the control circuit 2.

Inverter 1 as a logic gate circuit provided in IC2
The threshold voltages of 1 and 12 are different, for example, as shown in the figure, and depending on the potential level of the pulse signal applied to the signal line l ₁ , the signal is selectively or simultaneously supplied to the circuit blocks E and F in the IC2. Can be entered. The circuit blocks E and F are counters composed of, for example, D-type flip-flops, and a pulse can be input as a clock signal from a test pin to determine whether or not the counter operates normally with an output signal from the number pin.

When the switch SW1 of the in-tester control circuit 1 is set to the R side and SW2 is set to the R side, the base of the transistor Q ₁ is biased to a predetermined potential, and the DC voltage V _A appears at the emitter of the transistor Q ₁ . When the MOS transistor Q _{11 of} IC2 is turned on by the output of the output of the circuit block C, I = V _A / (R ₁₁
+ R _ONG11 ) (R _ONG11 is the ON resistance of the MOS transistor Q ₁₁ ) flows, and this current change is transmitted to the base of the transistor Q ₅ via the current mirrors Q ₃ and Q ₄ and finally. Is expressed as the collector potential change of the transistor Q ₅ and is obtained from T _{2 as} the output of the sense amplifier 11. Thus, whether the circuit block C in the IC is operating normally can be checked by checking the output from the T ₂ terminal of the in-tester control unit 1.

Further, according to the present invention, as shown in FIG. 2, bidirectional signals can be exchanged between the block A and the block B by utilizing the voltage and current changes with one signal transmission line 1.
Various uses are also possible in the internal circuit inside.

(1) The first voltage output corresponding to the input signal is derived at one end of the signal transmission path 1 and the second voltage output corresponding to the current control performed via the signal transmission path 1 is obtained. A first control circuit is provided, and an input circuit for obtaining a control signal for inspecting or controlling the load circuit from the first voltage output and a current signal corresponding to the operation of the load circuit are provided at the other end of the first signal transmission path. By providing the second control circuit including the obtained current control circuit, by the action of performing signal exchange between the first control circuit and the second control circuit via the first signal transmission path, The effect of using one signal transmission path for multiple purposes is obtained.

(2) According to the above (1), the IC provided with the above interface circuit has only one terminal for signal transmission / reception, and the effect that the number of terminals of the IC can be reduced can be obtained.

(3) By the above (2), the integration degree of IC can be improved,
The effect is obtained.

(4) According to the above (1), there is an effect that the inspection of the IC and the electronic circuit formed in the IC can be performed easily and efficiently.

Although the invention made by the present inventor has been specifically described above based on the embodiments, the present invention is not limited to the above embodiments, and various modifications can be made without departing from the scope of the invention. Needless to say. For example, the interface circuit may be used for FDD, the control signal Vc may be a write / read switching signal, the input signal Vi may be a write signal, and the voltage output Vt may be a read signal.

In the above description, the case where the invention made mainly by the present inventors is applied to the inspection of the IC which is the field of application which is the background has been described, but the present invention is not limited thereto and, for example, a memory circuit or a CPU. And a data bus can be used as an interface circuit.

〔The invention's effect〕

The following is a brief description of an effect obtained by the representative one of the inventions disclosed in the present application.

In other words, bidirectional signal transmission is possible via one signal transmission path, and since the logic gate circuits with different threshold voltages are connected to the IC test pins, the level of the test signal supplied from the tester is increased. Is changed according to the threshold voltage, it is possible to test by supplying different test signals to a plurality of circuits in the IC through one signal transmission path.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing an embodiment of the present invention, and FIG. 2 is a circuit diagram showing another embodiment of the present invention. 1 ...... first control circuit, 2 ...... second control circuit, l ₁ ......
l signal transmission path, Q _{1 to} Q ₁₁ ... Transistor, 11, 12 ...
… Inverter, 13 …… Load circuit.

Claims (1)

[Claims] 1. A bidirectional signal transmitting terminal capable of inputting a test signal and outputting a signal indicating a test result to a semiconductor integrated circuit device, and a test signal inputted to said bidirectional signal transmitting terminal. Two or more logic gate circuits having mutually different threshold voltages for supplying a signal according to the above to a predetermined internal circuit block, and a predetermined internal circuit block connected between the bidirectional signal transmission terminal and the power supply voltage terminal. ON by the output signal of
A switch element that is turned off is provided, and the bidirectional signal transmission terminal and the test signal transmission terminal of the tester that supplies the test signal are connected by a single signal transmission path, and the tester is connected to the test circuit. A signal is transmitted as a voltage output to the bidirectional signal transmission terminal, while a signal indicating a test result is transmitted from the bidirectional signal transmission terminal to the tester as a current accompanying turning on / off of the switch element, and the current is transmitted. A method for testing a semiconductor integrated circuit device, characterized in that the tester converts the voltage into a voltage for determination.