JPS63277422A - Integrated circuit - Google Patents

Abstract

PURPOSE:To improve power-noise-proofness, by setting a limiter circuit for limiting line voltage with the specified voltage of the range of working voltage or higher or withstand voltage or lower. CONSTITUTION:A widely used linear IC is composed of transistors 1-10 and the circuit elements of a resistor and the like as an integrated circuit. In order to feed current to these elements, a limiter circuit consisting of a transistor 11, a Zener diode 12, and a resistor 13 is combined with the integrated circuit. The Zener voltage of the Zener diode 12 is set to be the range of working voltage or higher of the integrated circuit and withstand voltage or lower. When line voltage Vcc comes to specified voltage or lower, then the Zener diode 12 turns conductive, and the transistor 11 works, and the line voltage Vcc is limited to approx. specified voltage.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to the characteristics of the power supply voltage and power supply current of a four-circuit fA circuit.

[Conventional technology]

Figure 5 shows, for example, "Mitsubishi General-Purpose Linear IC User's Manico, Al (P2-45) J.
FIG. 2 is a main circuit diagram showing a conventional integrated circuit shown in FIG.

In the figure, (1) is a high resistance called a collector pinch resistance, which has a constant current characteristic as shown in FIG. 6, but because its value varies widely, it is used to drive the circuit. (2) β) (4) +9) Ql is NPN
Transistor (2) L3) (
91 is used as a diode by shorting its base and collector. (61 (7) (81 is a PNP type transistor, and the transistor (6) is used as a diode by shorting its base and collector. (9
is a resistance called the base resistance, which is made by the same diffusion as the base of an NPN transistor.

A conventional integrated circuit is constructed as described above, with the positive power supply line V
When cc rises, resistor (1), transistor a (3)
A current flows through the transistor (2), and the base potential of the transistor (2) becomes approximately 1.2V with respect to the negative power supply line GND (=OV).

This is connected to the base of the transistor (A), and a resistor (5) is connected between the emitter of the transistor (A) and GND.
is connected, current flows through the resistor (5) so that a voltage drop of approximately 0.16 V occurs, and this flows through the transistor (4).
) and further flows to the transistor (6). Since the transistor (7) and the transistor (6) are connected in a power current mirror, a collector current of almost the same magnitude as the transistor (6) flows through the transistor (71), which serves as a source of constant current. 8) is also connected in a current mirror with 1 to transistor (6), and its collector current becomes a constant current and flows into the transistor (9).Transistor QOI is connected in a current mirror with 1 to transistor (9), and the A collector current that is almost the same as that of the transistor QOI flows through (9), and this becomes a sinking constant current source.The integrated circuit operates with this constant current source.The power supply current/voltage characteristics at this time are as shown in Figure 7. Almost constant current characteristics.

[Problem that the invention seeks to solve]

In conventional integrated circuits such as those mentioned above, if noise with a voltage exceeding the withstand voltage jumps into Vcc, that voltage may be applied as is and the circuit may be destroyed. There was a problem in that it was necessary to take measures such as inserting a capacitor or Zener diode between Vcc and GND to protect the circuit.

This invention was made in order to solve this problem, and when it comes to noise that exceeds the withstand voltage of the integrated circuit, it absorbs the energy of the noise and suppresses the rise in Vcc due to the noise to below the withstand voltage. By doing so, it is an object of the present invention to obtain an integrated circuit that will not be destroyed even if no measures are taken to suppress noise or the like outside of the integrated circuit.

[Means for solving problems]

The integrated circuit according to the present invention is provided with a limiter circuit that limits the power supply voltage to a predetermined voltage that is above the operating voltage range and below the withstand voltage.

[Effect]

In the present invention, by suppressing energy such as noise to a predetermined voltage and passing it as a current, the rise in Vcc is kept below the withstand voltage of the integrated circuit, thereby preventing damage to the integrated circuit.

〔Example〕

FIG. 1 is a circuit diagram showing an embodiment of the present invention. In the figure, (1) to α indicate the same or equivalent parts as in the conventional example, (ll) is an NPN type transistor, (12)
is a Zener diode, (13) is a base resistor, and the above (11) to (13) constitute a limiter circuit.

In the integrated circuit configured as described above, the Zener diode (I2) has its Zener voltage set to a predetermined voltage that is above the working voltage range and below the withstand voltage of the integrated circuit, and when Vcc is within the working voltage range. The Zener diode (12) is not energized, and the transistor (+1) is not activated. When Vcc reaches the predetermined voltage, the Zener diode (11) is energized, the transistor <11) is activated, and Vcc is stabilized around the predetermined voltage. and is limited to a certain voltage. As shown in FIG. 2, the relationship between Vcc and 1 cc of power supply current is as follows: v8 to v2 is the operating voltage range, (2) is the integrated circuit withstand voltage, and V is the predetermined voltage, ie, the limiter voltage. Icc is almost a constant current until Vcc reaches v4, but when it reaches v4, it increases rapidly and operates so that Vcc does not exceed v4.

The current capacity of the limiter circuit is almost determined by the transistor (11), and the integrated circuit can withstand energy noise and the like that cause a current to flow below that amount without being destroyed.

In the above embodiment, the transistor (11) is a single transistor, but it may have a Darlington configuration as shown in FIG. (12) is a Zener diode, (13) and (15) are base resistances.

Also, as shown in Figure 3(b), a Zener diode (17)
The limiter circuit (11) may be configured only by the above. At this time, the Zener diode (12
), it is necessary to increase the element area and increase the current capacity.

Furthermore, in the above embodiment, the Vcc of the integrated circuit is set to the external power supply Vcc.
cc', but as shown in Figure 4, an external resistor (16) is installed between the integrated circuit's Vcc and the external power supply Vcc' to prevent noise, etc. that may come on Vcc'. By limiting the current caused by the resistor (16) with the resistor (16), it is possible to withstand larger energy noise, etc.However, regarding the voltage drop of the external resistor, the power supply current must be kept at the minimum necessary below the specified voltage at which the limiter circuit operates. When the voltage is stabilized to a certain level, the voltage drop across the external resistor is minimized, and the power supply voltage loss due to this voltage drop can be minimized.

〔Effect of the invention〕

As explained above, this invention provides a limiter circuit that limits the power supply voltage to a predetermined voltage that is above the operating voltage range and below the withstand voltage, thereby improving breakdown strength against noise, etc. that comes on the power supply line. There is no need to provide a capacitor or Zener diode outside the integrated circuit to protect the integrated circuit against noise that is less than the energy allowed by the circuit. In particular, in an integrated circuit in which the power supply current is stabilized, a high voltage such as Vcc is directly applied to Vcc, so providing a limiter circuit has a great effect. Furthermore, by inserting an external resistor between the external power source and the integrated circuit power source, it is possible to withstand noise on the external power source that exceeds the energy allowed by the limiter circuit.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing an embodiment of the present invention, FIG. 2 is a diagram showing the power supply current and constant voltage characteristics with respect to the power supply voltage in FIG. 1, and FIGS. 4 is a circuit diagram showing still another embodiment of the present invention, FIG. 5 is a circuit diagram showing a conventional integrated circuit,
6 is a diagram showing the constant current characteristics of the high resistance (1) in FIG. 5, and FIG. 7 is a diagram showing the current/voltage characteristics in FIG. 5. In addition, the same reference numerals in each figure indicate the same or equivalent parts.
11) is a transistor, (12) is a Zener diode, and (13) is a base resistor.

Claims (2)

[Claims] (1) An integrated circuit equipped with a limiter circuit that limits the power supply voltage to a predetermined voltage above the operating voltage range and below the withstand voltage. (2) The integrated circuit according to claim 1, wherein the power supply current is stabilized to a minimum necessary value within the working voltage range and a predetermined voltage.