JPH0519889A - Stand-by device - Google Patents

Abstract

PURPOSE:To provide an integrated circuit which selects the range of a stand-by function and effectively reduces current consumption. CONSTITUTION:A register 11 indicating a stand-by function level and control circuits 12-14 which are supplied with a system clock are arranged and the supply of the system clock to a CPU 8, a peripheral circuit A9, and a peripheral circuit B10 is selectively stopped to stop the operation of an optional circuit, thereby efficiently reducing the current consumption.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a circuit which effectively controls a standby function in an integrated circuit.

[0002]

2. Description of the Related Art A standby function for reducing power consumption is generally provided in an integrated circuit. Figure 2 below
Will be described with reference to.

In general, the standby function is a method of stopping the operation of other circuit parts [CPU 3 and peripheral circuit 4] except the clock generator 2 of the integrated circuit 1 as shown in the figure, and the clock generator 2 and peripheral circuit 4 There is a method of stopping the operation of the other circuit part [CPU 3] except for.

[0004]

In such a conventional standby function, the system clock 5 from the clock generator 2 is commonly used by the CPU 3 and the peripheral circuit 4. Therefore, when putting the CPU 3 and the peripheral circuit 4 into the standby mode, the system clock 5 must be stopped, and a part of the peripheral circuit 4 cannot be operated in the standby mode.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object thereof is to provide a control circuit for a standby function.

[0006]

In order to achieve the above-mentioned object, the present invention provides a circuit for controlling a clock to each functional block in an integrated circuit containing a CPU and a plurality of peripheral circuits, and executes an instruction. By operating the flags, only the necessary circuits are operated, and the rest are stopped to reduce the current consumption.

[0007]

According to the present invention, since the standby function control of the CPU and each peripheral circuit is separated by the above-mentioned configuration, the peripheral circuit can partially operate in the standby mode.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIG.

As shown in the figure, the integrated circuit 6 comprises a clock generator 7 and a CPU 8, a peripheral circuit A9 and a peripheral circuit B10 as in the conventional circuit, and a register 11 indicating the standby function level and a clock generator 7.
And control circuits 12 to 14 for supplying a system clock to each functional block.

In the above configuration, the operation of only the CPU 8 in the standby mode will be described.
By setting the flag for setting U8 to the standby mode, the system clock from the clock generator 7 is not supplied to the CPU 8 by the control circuit 12, and only the CPU 8 enters the standby mode. The return from the standby mode at this time is executed by resetting a flag for setting the CPU 8 of the register 11 to the standby mode.

Next, the operation of the CPU 8 and the peripheral circuit A9 in the standby mode will be described. In addition to the operation of the CPU 8 alone in the standby mode, a flag for setting the peripheral circuit A9 of the register 11 to the standby mode is set. The system clock from the clock generator 7 is not supplied to the peripheral circuit A9 by the control circuit 13 and the CPU
8 and the peripheral circuit A9 enter the standby mode. At this time, the return from the standby mode is performed by the CPU of the register 11.
Flag for setting 8 to standby mode and peripheral circuit A9
Is set to the standby mode by resetting the flag.

As described above, according to the circuit for controlling the standby function of the embodiment of the present invention, the CPU 8 and the peripheral circuit A9,
In the integrated circuit 6 including the peripheral circuit B10, by independently controlling the system clock, the range of the standby function can be selected and the consumption current can be effectively reduced.

[0013]

As is apparent from the above embodiments, according to the present invention, the system clock is independently controlled in an integrated circuit having a CPU and a plurality of peripheral circuits.
The range of the standby function can be selected and the current consumption can be effectively reduced.

[Brief description of drawings]

FIG. 1 is a block diagram of essential parts of an integrated circuit according to an embodiment of the present invention.

FIG. 2 is a block diagram of a main part of an integrated circuit showing a conventional standby function.

[Explanation of symbols]

 6 integrated circuit 7 clock generator 8 CPU 9 peripheral circuit A 10 peripheral circuit B 11 register 12 system clock control circuit for CPU 8 13 system clock control circuit for peripheral circuit A 9 14 system clock control circuit for peripheral circuit B 10

Claims (1)

Claim: What is claimed is: 1. An integrated circuit comprising a CPU and a plurality of peripheral circuits, comprising a circuit for independently controlling clock supply to the CPU and a plurality of peripheral circuits, and executing an instruction to flag the flag. Is set to selectively stop the clock supply to the CPU and a plurality of peripheral circuits, thereby stopping the operation of any circuit to reduce the current consumption. ..