JP2860794B2 - IC monitor current monitor - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an apparatus for monitoring an overcurrent of a supply current to an IC tester.

[Prior Art] The performance of an IC chip of a semiconductor product is inspected by an IC tester after production. Since the tester has a large number of IC chips mounted and tested in parallel, the current value for the whole is considerably large, for example, about 800A. However, the voltage is as low as several volts. It should be noted that, in order to test the performance of the IC, the voltage of the tester is specified to a constant value, and the fluctuation range is suppressed.

FIG. 3 shows an example of a power supply wiring system in an IC tester, in which positive and negative wirings 1a and 1b from a DC power supply 1 are shown.
Is branched into several primary branch wirings 2a and 2b in the terminal board 1c and connected to the terminal 3a of the distribution board 3. This primary branch wiring
2a and 2b are further subdivided into secondary branch wiring (three branches in the figure), and each terminal of the back board 4 of the IC tester from the terminal 3b.
Via 4a, it is connected to the platter 5 inserted into the backboard 4, and the current is supplied to the IC chip mounted thereon.
In order to prevent a voltage drop, each wire is made of an electric wire having a very small resistance and a sufficient width for current, and is wired as short as possible.

[Problem to be Solved] In the above wiring configuration, when an abnormality such as a short circuit occurs in each branch wiring or IC chip, the voltage decreases due to an overcurrent, and in some cases, there is a risk that these may burn out.
Generally, the main AC power supply is provided with a circuit breaker and can be cut off when an overcurrent occurs, but each of the above branch wirings is not provided with any protection circuit as well as an ammeter. That is the fact. Therefore, for safety of the device, it is conceivable to provide an ammeter and a safety fuse at an appropriate place at least for each primary branch wiring. However, since the current value of the primary branch wiring is about 200 A, The meter requires a shunt and may have a voltage drop due to internal resistance. Further, since the operation of the fuse requires a certain period of time, the components are often burned during that time and cannot be made in time. On the other hand, it is a good measure to insert an overcurrent detector to operate the circuit breaker. However, as described above, the IC tester is a large-current low-voltage circuit, while a normal overcurrent detector has an internal resistance, which may cause a voltage drop, and further has a problem of mounting space. in short,
The method using an ammeter and an overcurrent detector is difficult to apply to an IC tester.

The present invention has been made in view of the above, and does not require wiring change of an IC tester and does not cause any voltage drop. It is an object of the present invention to provide a current monitoring device of an IC tester capable of monitoring a value and shutting off an AC power supply for an overcurrent.

[Means for Solving the Problems] A feature of the configuration of the present invention that achieves the above object is to have a DC power supply that receives power from an AC power supply via a circuit breaker and converts the power into DC power of a predetermined voltage. In a current monitoring device of an IC tester that monitors a supply current of a DC power supply in an IC tester that supplies power to a large number of ICs to be tested from a DC power supply through wirings branched in multiple stages and tests the ICs in parallel, A current value detector consisting of a Hall element mounted on each of the positive and negative ones of the primary branch wiring, which is the first branch wiring of the multi-stage branch wiring, and the detection values of these current value detectors according to the control signal. A changeover switch for sequentially selecting and outputting, and a detection signal selected by the changeover switch, receiving the detection signal and comparing the detection signal with an allowable value for overcurrent to detect an overcurrent of each primary branch wiring. A current detection circuit, an alarm circuit that generates an alarm in response to an overcurrent signal output by the overcurrent detection circuit, outputs a cutoff signal to the circuit breaker, and a control circuit that generates a control signal. .

[Operation] In the power supply monitoring device of the IC tester having the above configuration, the current of the primary branch wiring is measured without any voltage drop due to the internal resistance because the Hall element can measure the current without contacting the wiring. You. The measurement data is sequentially switched by the changeover switch to each ammeter and input to the overcurrent detection circuit. The measured data is compared with a preset allowable value for overcurrent, and an overcurrent signal is output for an overcurrent exceeding this value. In response, an alarm is generated and the AC power is cut off at the same time. The switching control of the changeover switch is automatically performed by a control circuit (such as a microprocessor).

[Embodiments] FIGS. 1 (a) and 1 (b) are explanatory views of a Hall element ammeter applied to a current monitoring device of an IC tester according to the present invention and an embodiment of the current monitoring device of the IC tester according to the present invention. The mounting diagram of a Hall element ammeter is shown. In FIG. 1A, a Hall element ammeter 6 is a current value detector, in which a Hall element is incorporated in a housing 6a having a through hole 6b, and a DC voltage E is applied to an excitation terminal 6c to excite the excitation. Then, the wiring 2 'of the measured current is passed through the through hole. A voltage e proportional to the current i of the wiring 2 'is output from the output terminal 6d to the output terminal 6d by the action of the Hall element. The shape is small and the current measurement range is quite wide. Things are commercially available. FIG. 2B is the same as the power supply wiring system of the IC tester described with reference to FIG. 3, and the same parts are denoted by the same reference numerals. In the figure, each primary branch wiring 2a of the positive electrode from the terminal 1c of the DC power supply 1 is provided at an appropriate place of the distribution board 3.
Are provided, respectively, and the respective wires 2a are passed through the through holes 6b. The primary branch wiring 2b of the negative electrode is left irrespective of it. Hall element ammeter 6
The excitation voltage E is supplied from the DC power supply terminals 1a and 1b to the excitation terminal 6c via the wiring 6e. The output wiring of each Hall element ammeter 6 is not shown.

FIG. 2 shows a block diagram of the current monitoring device of the IC tester according to the present invention. The output lines from the Hall elements 61, 62, 63... Provided in FIG. Connect to The output side is collectively connected to an overcurrent detection circuit 9 via an A / D converter 8, and a control circuit 10 is connected to the changeover switch 7 and the A / D converter 8. The overcurrent detection circuit 9, the control circuit 10, the memory 13, and the alarm circuit are provided on the bus 11 of the microprocessor (MPC) 12.
14 is connected and the AC circuit part 15 circuit breaker
Wired to 15a.

The operation of the device will be described. The current value of each primary branch wiring 2a is measured by the Hall elements 61, 62, 63,..., And the measurement data is switched by the control circuit 10 by the control circuit 10 according to the instruction of the microprocessor 12. The changeover switch 7 is constituted by an electronic circuit to minimize the cyclic cycle and detect the current value of each wiring without delay. The measurement data is manually digitized by the A / D converter 8 sequentially, and an overcurrent detection circuit 9 detects an overcurrent. The overcurrent detection circuit 9 is constituted by a comparator and can detect a minute voltage change. The microprocessor 12 sets an allowable value for the overcurrent stored in the memory 13 in advance. At the moment an overcurrent occurs, the overcurrent signal is transferred to the alarm circuit 14 to turn on the alarm lamp or activate the alarm buzzer, and at the same time, the shutoff signal is
Transferred to a, AC power is cut off. Here, the allowable value for the overcurrent is set to two levels, and only an alarm is given to an overcurrent in a range that does not matter, and an AC power supply is shut off together with an alarm for an overcurrent larger than that. be able to.

[Effects of the Invention] As is clear from the above description, the IC according to the present invention
In the current monitoring device of the tester, we focused on the non-contact type Hall element ammeter and provided it in each primary branch wiring of the power supply system of the IC tester to monitor the current without causing a voltage drop due to internal resistance. Measures and switches the measurement data cyclically and monitors it.If an overcurrent occurs, an alarm is issued instantaneously, and at the same time, the AC power supply can be shut off to prevent burnout accidents, contributing to the safe operation of the IC tester. There are big things to do.

[Brief description of the drawings]

FIG. 1 (a) is an external view of a Hall element ammeter applied to a current monitoring device of an IC tester according to the present invention, and FIG. 1 (b).
FIG. 2 is a wiring mounting diagram of the Hall element ammeter in the embodiment of the current monitor of the IC tester according to the present invention. FIG. 2 is a block diagram of the embodiment of the current monitor of the IC tester according to the present invention. FIG. 1 DC power supply, 1a, 1b positive and negative wiring, 1c terminal board, 2a, 2b primary branch wiring, 3 distribution board, 3a, 3b terminal, 4 back board 4a Terminal 5 Platter 6 Hall element ammeter 6a Housing 6b Through hole 6c Exciting terminal 6e Exciting wiring 6d Output terminal 7 ... Changeover switch, 8 ... A / D converter, 9 ... Overcurrent detection circuit, 10 ... Control circuit, 11 ... Bus, 12 ... Microprocessor, 13 ... Memory, 14 ... Alarm circuit, 15 ... AC power supply, 15a ... Circuit breaker.

Claims (1)

(57) [Claims] A DC power supply which receives power from an AC power supply via a circuit breaker and converts the power into DC power of a predetermined voltage, and has wirings branched from the DC power supply in multiple stages to a number of ICs to be tested. IC that supplies power through the IC and tests the ICs in parallel
IC for monitoring the supply current of the DC power supply in a tester
In a current monitoring device of a tester, a current value detector including a Hall element mounted on each of one of the positive and negative wirings of the primary branch wiring, which is the first branch wiring of the multi-tiered wiring, A changeover switch for sequentially selecting and outputting the detection value of the current value detector, receiving a detection signal selected by the changeover switch, comparing the detection signal with an allowable value for overcurrent, and comparing each of the primary branch wiring An overcurrent detection circuit that detects a current, an alarm circuit that generates an alarm in response to an overcurrent signal output by the overcurrent detection circuit, and outputs a cutoff signal to the circuit breaker; and generates the control signal. A current monitoring device for an IC tester, comprising: a control circuit.