JPH0537354A - Semiconductor integrated circuit - Google Patents

Abstract

PURPOSE:To reduce the current consumption of a logic circuit of an IIL type, and to use it even in the case a battery is used. CONSTITUTION:Turn-on and turn-off of a transistor Q3 of a constant-current source circuit 3 for supplying a current to a logic circuit 2 are controlled by a control signal CNT. A terminal Tc of a control signal supply means for supplying the control signal CNT to the transistor Q3 is provided. The control signal CNT becomes a power supply voltage Vcc, when the logic circuit 2 does not execute a logical processing, turns off the transistor Q3 and stops supply of a current to the logical circuit 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor integrated circuit,
In particular, the present invention relates to a semiconductor integrated circuit including an IIL type logic circuit.

[0002]

2. Description of the Related Art Conventionally, a semiconductor integrated circuit of this type has an input signal DI from an external circuit as shown in FIG.
a to DIn are IIL (Integrated Inje)
interface circuit 1 for converting to a logic level of an action logic type and for outputting an IIL type logic level signal from the inside in conformity with a logic level of an external circuit.
And an IIL type logic circuit 2 including a plurality of unit gates 21a to 21n and performing a predetermined logic process on an input signal from the interface circuit 1 and outputting it to the interface circuit 1.
And a transistor Q that receives a bias voltage Vb at its base
3, each unit circuit 21 of this logic circuit 2 is provided with 3 and a resistor R1.
It has a configuration including a constant current source circuit 3c for supplying a constant current to a to 21n.

Since the bias voltage Vb is always applied to the base of the transistor Q3 of the constant current source circuit 3c,
A constant current is always supplied to the logic circuit 2. This current is determined based on the characteristics of each of the unit gates 21a to 21n and the required operation speed, and is normally set to about several 10 μA per unit gate.

[0004]

In this conventional semiconductor integrated circuit, a constant current is always supplied to the logic circuit 2. Therefore, even if the logic circuit 2 does not perform the logic processing operation, this current component is not supplied. However, there is a problem in that it is difficult to use in applications requiring low power consumption such as using a battery as a power source.

An object of the present invention is to provide a semiconductor integrated circuit which consumes less power and can be used even when a battery is used as a power source.

[0006]

SUMMARY OF THE INVENTION A semiconductor integrated circuit according to the present invention includes an IIL type logic circuit which is activated when a current is supplied to a current input terminal and performs a predetermined logic process on an input signal and outputs the same. A current source circuit that supplies a current to the logic circuit when the transistor is on, and a control signal supply unit that supplies the control signal to the current source circuit. ing.

[0007]

Embodiments of the present invention will now be described with reference to the drawings.

FIG. 1 is a circuit diagram showing a first embodiment of the present invention.

In this embodiment, an input signal D from an external circuit is used.
An interface circuit 1 for converting Ia to DIn to an IIL type logic level, and for outputting an IIL type logic level signal from the inside in conformity with the logic level of an external circuit,
A current input terminal II including a plurality of unit gates 21a to 21n
An IIL type logic circuit 2 which is activated when a current is supplied to N and performs a predetermined logic process on an input signal from the interface circuit 1 and outputs it to the interface circuit 1, and a control signal CNT is input to the base to turn it on, A low current source circuit 3 that includes a transistor Q3 that turns off and a resistor R1 and that supplies a current to the logic circuit 2 when the transistor Q3 is in an on state, and a terminal of a control signal supply unit that supplies a control signal CNT to the current source circuit 3. It has a structure including Tc.

Control signal CNT attains power supply voltage Vcc level when logic circuit 2 does not perform logic processing, and turns off transistor Q3. Therefore, in this state, since no current flows through the logic circuit 2, it is possible to reduce current consumption as compared with the case where a constant current constantly flows as in the conventional example.

FIG. 2 is a circuit diagram showing a second embodiment of the present invention.

In this embodiment, two logic circuits 2a and db are provided.
Are provided, and constant current source circuits 3a and 3b are provided corresponding to these logic circuits 2a and 2b, respectively, and the ON / OFF of the transistor Q3 of these constant current source circuits 3a and 3b is controlled by control signals CNTa and CNTb. It was done like this.

The levels of the control signals CNTa and CNTb are determined by the interface circuit 1a according to the contents of the input signal DI. That is, if the content of the input signal DI does not need to be processed by the logic circuits 2a and 2b, the control signals CNTa and CNTb become the power supply voltage Vcc level and the constant current source circuits 3a and 3b.
Of the logic circuit 2a (or 2
If logical processing according to b) is required, the control signal CNTa
(Or CNTb) to a low level to make the constant current source circuit 3a
The transistor Q3 (or 3b) is turned on to supply a current to the logic circuit 2a (or 2b).

In this way, only the necessary logic circuits are activated according to the contents of the input signal DI, and the other logic circuits are inactivated so that no current flows. Therefore, the current consumption is suppressed to the minimum necessary. be able to.

[0015]

As described above, according to the present invention, by providing the control signal supply means for controlling the current supplied from the constant current source circuit to the logic circuit by the control signal, the logic processing is performed in the logic circuit. Current is supplied only when performing a logic operation, and current supply is stopped when no logic processing is performed, so that useless current consumption is eliminated and consumption current can be reduced. Therefore, even when a battery is used as a power source, this There is an effect that a semiconductor integrated circuit can be used.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing a first embodiment of the present invention.

FIG. 2 is a circuit diagram showing a second embodiment of the present invention.

FIG. 3 is a circuit diagram showing an example of a conventional semiconductor integrated circuit.

[Explanation of symbols]

1,1a interface circuit 2, 2a, 2b logic circuit 3, 3a to 3c constant current source circuit 21a-21n unit gate Q1 to Q3 transistors R1 resistance

Claims (2)

[Claims] 1. A device which is activated when a current is supplied to a current input terminal and performs a predetermined logical processing on an input signal and outputs the signal II
A current source circuit that includes an L-type logic circuit and a transistor that is turned on and off by a control signal and supplies a current to the logic circuit when the transistor is on, and the control signal is supplied to the current source circuit. And a control signal supply means for controlling the semiconductor integrated circuit. 2. The first and second currents, wherein the logic circuit comprises first and second logic circuits, and the current source circuit supplies and controls currents corresponding to the first and second logic circuits, respectively. And a control signal supply means for generating the first and second control signals for controlling ON / OFF of the transistors of the first and second current source circuits according to the contents of the input signal. The semiconductor integrated circuit according to claim 1.