JPS6314445A - Integrated circuit - Google Patents

Abstract

PURPOSE:To reduce the number of applicable terminal members for testing inside an integrated circuit by a method wherein a parallel/serial conversion circuit and a serial/parallel conversion circuit are inserted into an input output or both of them of a tested circuit. CONSTITUTION:A serial parallel conversion circuit 5 or a circuit outputting test signal through a parallel/serial conversion circuit 6 is contained in an input part of test signal inside an integrated circuit 1 to perform the functional test of specific part 3 inside the integrated circuit 1. For example, control signal is inputted from a control signal input terminal 13 to switch off a test signal input and output terminal 17, a test result output and input terminal 18 and a selector 4 for turning off the tested circuit 3 from an inner circuit 2 as well as for inputting the test signal from the test signal input and output terminal 17 to the parallel through the serial/parallel conversion circuit 5. Finally, a result signal outputted to the parallel is converted into serial by the parallel/ serial conversion circuit 6 to be outputted from the test result output and input terminal 18.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an integrated circuit, and more particularly to a functional test mechanism for a specific portion inside an integrated circuit and a configuration of the test circuit.

[Conventional technology]

Conventionally, in this type of integrated circuit, in order to perform a functional test of only the circuit under test 3 of the internal circuit 2 of the integrated circuit 1 as shown in FIG. 11,
The configuration is such that the output-only terminal 10 is a bidirectional terminal, one or more control signal input terminals 13 are installed, and the selector 4 is installed at the input section and output section of the circuit under test 2. At this time, inputting a control signal from the control signal input terminal 13, controlling the input/output direction of the bidirectional terminal from K, and realizing a bidirectional terminal 15 which is an input terminal and a bidirectional terminal 16 which is a single output terminal. At the same time, the circuit under test 3 is disconnected from the internal circuit 2 by switching the selector 4, the test signal is input from 15, a functional test is performed on the circuit under test 3, and the results are transmitted externally from 16. The circuit operated as if it were being taken out.

[Problem that the invention seeks to solve]

The above-mentioned conventional integrated circuit is configured to input test signals and output signals from the circuit under test by converting input-only or output-only terminals into bidirectional terminals. Depending on the package used, there is a drawback that the number of usable terminals may be insufficient compared to the number of terminals required to test the circuit under test inside the integrated circuit.

[Means for solving problems]

The integrated circuit of the present invention can be used in parallel for internal testing of the integrated circuit.
Serial conversion circuit or serial-parallel conversion circuit,
Or have both.

〔Example〕

Next, the present invention will be explained with reference to one drawing.

FIG. 1 is a block diagram of an embodiment of the present invention.

1 is the entire integrated circuit, 2 is the internal circuit, 3 is the circuit under test, 4
is a selector, 5 is a serial/parallel conversion circuit, 6 is a parallel/serial conversion circuit, 10 is an output-only terminal, 11
is an input-only terminal, 13 is a control signal input terminal, 17 is a test signal input/output terminal, 18 is a test result output/input terminal, and by inputting a control signal from the control signal input terminal 13, the test signal can be input/output. By switching the terminal 17, the test result output/input terminal 18, and the selector 4, the circuit under test 3 is disconnected from the internal circuit 2, the circuit under test 3 is directly connected to the outside, and then the test signal input/output terminal 17 is connected to the test signal input/output terminal 17. The signal is inputted to the serial/parallel conversion circuit 5 through the selector 4, and the test signal is inputted to the circuit under test 3 in parallel. Here, the result signal output in parallel from the circuit under test 3 is converted into serial data by a parallel-to-serial conversion circuit via the selector 4, and is output from the test result output/input terminal 18.

〔Effect of the invention〕

As explained above, the present invention provides a parallel-to-serial conversion circuit at the input section, output section, or both of the circuit under test.
Inserting a serial-parallel conversion circuit has the effect of reducing the number of terminals used for testing inside the integrated circuit. ! The octopus effect has the advantage that a plurality of circuits under test within an integrated circuit can be simultaneously and independently tested.

[Brief explanation of drawings]

Fig. 1 is a block diagram of an integrated circuit having a specific internal part testing mechanism according to the present invention, Fig. 2 is an integrated circuit having a conventional internal specific part testing mechanism, and Fig. 3 is an integrated circuit without a specific internal part testing mechanism. FIG. 1...Integrated circuit, 2...Internal circuit, 3
...Circuit under test, 4...Selector, 5
・・・・・・Serial-to-parallel conversion circuit, 6...
...Parallel-serial conversion circuit, 10...Output-only terminal, 11...Input-only terminal, 13...
... Control signal input terminal, 15.16 ... Bidirectional terminal, 17 ... Test signal input and output terminal,
18...Test result output and input terminal. Information Figure 2 f A Figure 3

Claims (1)

[Claims] A serial-to-parallel conversion circuit is included at the input section of the test signal inside the integrated circuit for the purpose of functional testing of a specific part inside the integrated circuit. Or an integrated circuit characterized by including a circuit that outputs a test signal through an output parallel-to-serial conversion circuit.