JPS62156849A - Protecting circuit for integrated circuit - Google Patents

Abstract

PURPOSE:To enable a replacement/repair work to be completed by replacing or repairing only the malfunctioning circuit when one is damaged in a wafer by a method wherein a semiconductor element is inserted in the forward direction in parallel with the lowest-tension power source of an IC using two ore more power sources. CONSTITUTION:A driver circuit 1 generally includes 6-7 circuits in its 16-pin dual line IC and, therein, 5V low-voltage terminals and driver output terminals are positioned at many places. Accordingly, a short circuit is easily to occur between a load and a 5V low-voltage line in the event one of such circuits is broken down due for example to heat generated under an excess load. When a diode 3 is added to the driver circuit 1 as a load, there will be no +24V flowing into a 5V line and elements other than the one broken down will be protected from breakdown even if an element breaks down in the driver circuit 1 creating a short circuit between a +24V line and a +5V line, because such a flow is opposite in direction to be one in the diode 3.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a low-voltage power supply for logic circuits and a protection circuit when using an integrated circuit having a high-voltage power component drive circuit.

[Conventional technology]

Conventionally, when using this type of integrated circuit (hereinafter abbreviated as IC) to operate a logic circuit using a low-voltage power supply and using this theoretical output to drive high-voltage power components such as solenoids and relays, The IC was used without any protection circuit. This is because the logic circuit portion and the drive circuit portion are often manufactured using separate ICs.

However, recently, as the popularity of ICs has improved, and due to user demands and the desire for smaller devices, there has been an increasing trend to configure both of these circuits on the same wafer. .

[Problem that the invention seeks to solve]

However, when a logic circuit and a drive circuit (driver circuit) are integrated on the same wafer, if the circuit inside the wafer burns out due to a failure of the driver circuit or a short circuit in the circuit on the power load side, for example, dissimilar parts inside the wafer may be damaged.゛The power supply is short-circuited, and the high voltage on the driver side goes around to the low voltage section on the logic circuit side.
A low-voltage power source may be elevated to a high-voltage power source. In such a case, if high-voltage power flows in, expensive parts (such as CPU, ROM, RA
This not only damages the M, timer, A/D converter, D/A converter, etc.), but also destroys the general gate, resulting in a large amount of time and cost for repair and replacement.

The present invention has been made in view of the above-mentioned problems, and allows only the failed circuit to be replaced/repaired without causing damage to low-voltage components even when a circuit within the same wafer is damaged as described above. The purpose is to provide a protection circuit that only requires

[Means for solving problems]

Therefore, the present invention attempts to achieve the above object by inserting semiconductor elements in series in the forward direction on the lower voltage power supply side of an IC that uses two or more types of power supplies. .

[Effect]

With the above configuration, if any of the circuits of this type of IC are damaged due to overload, etc., the load and low voltage line will easily short-circuit, preventing the high voltage on the load side from flowing into the low voltage side. to protect low-voltage components from damage.

〔Example〕

The present invention will be explained below based on the drawings of the embodiments. FIG. 1 shows an embodiment of a protection circuit according to the present invention. 1 shown surrounded by a dotted line is an equivalent circuit of a driver circuit including a logic circuit, and 2 is a high power load such as a solenoid,
Further, 3 is a diode inserted according to the present invention. These driver circuits generally include 6 to 7 circuits in a 16-pin dual-line IC, and the chip has a 5V low voltage terminal and a driver output terminal.
It is strung out everywhere. Therefore, if any of the circuits generates heat and is destroyed due to overload or the like, the load and the low voltage 5V line will easily be short-circuited.

If there is no diode inserted according to the present invention, as in the conventional example, the voltage on the load side flows into the low voltage 5V line, and this 5V line becomes high voltage, such as 24V, and is originally connected to the 5V line. A high voltage of 24V was applied to all the parts that were connected, and there was a possibility that many of the element parts would be destroyed.

However, according to the present invention, by loading the diode 3, even if it causes the destruction of the driver circuit l,
Even if the 4V line is shorted to the +5V line, diode 3
Since it is in the opposite direction to , there is actually +2 to the 5v line.
4V will not flow in, and other elements can avoid destruction.

〔Effect of the invention〕

As explained above, according to the present invention, the driving IC
This type of I
If any of the circuits in C are damaged due to overload, etc.
It protects low-voltage components from damage, making it possible to replace/repair only the failed circuit.

[Brief explanation of drawings]

FIG. 1 is a diagram showing an embodiment of an IC protection circuit according to the present invention. l・・・・・・Dry eight equivalent circuit 2・・・・・・
・・・High power cylinder 3・・・・・・Diode (semiconductor element) 1 circuit diagram Figure 1

Claims (1)

[Claims] A protection circuit for an integrated circuit, characterized in that it is formed by inserting a semiconductor element in series in the forward direction on the lower voltage power supply side of an integrated circuit that uses two or more types of power supplies.