JPH04282904A - oscillation circuit - Google Patents

Abstract

PURPOSE:To slow down the operating clock speed and to reduce a voltage amplitude in the low power consumption mode of a microcomputer. CONSTITUTION:An operating power supply voltage of an inverting amplifier 6 oscillating a clock signal is applied to the amplifier 6 by selecting a voltage from a normal operating mode voltage application path 3 or a voltage from a low power consumption operating mode voltage application path 4 by using a switch circuit 5. The clock signal oscillating circuit for a microcomputer with less power consumption is realized.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an oscillation circuit that can be used in microcomputers that are required to operate under low power consumption conditions.

0002

2. Description of the Related Art In recent years, microcomputers have been increasingly incorporated into various electronic devices. In particular, it is required to reduce the power consumption of these microcomputers.

Conventionally, when a microcomputer is required to operate in a low power consumption state, the power consumption can be reduced simply by selecting a clock signal operating at a low frequency as the clock signal oscillation circuit used in the microcomputer circuit. It was common to try to reduce the amount.

0004

SUMMARY OF THE INVENTION Generally speaking, there is a need to further reduce power consumption in order to improve the functionality of microcomputers.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a circuit that reduces power consumption in a clock signal oscillation circuit used in a microcomputer circuit.

[0006]

[Means for Solving the Problems] In order to achieve the above objects, the present invention provides voltage dividing means for dividing an input power supply voltage, and selecting the voltage divided by the voltage dividing means and the input power supply voltage. a selection means, an amplification means for inverting and amplifying the voltage selected by the selection means as an operating power supply voltage and outputting it, a feedback resistor for feeding back the output voltage of the amplification means to the input, and a feedback resistor connected between both ends of the feedback resistor. This constitutes a clock signal oscillation circuit that is equipped with an oscillator and a capacitor that connects both ends of the feedback resistor and ground to AC ground.

[0007]

According to the present invention, in the above structure, during normal operation, a voltage equal to the oscillation circuit input voltage is supplied as the operating voltage of the inverting amplifier circuit through the normal operation mode voltage supply path. When low power consumption operation is required, the analog switch is switched by the operating voltage variable signal, and the voltage obtained by dividing the oscillation circuit input voltage by the voltage dividing resistor from the low power consumption operation mode voltage supply path is supplied as the operating voltage of the inverting amplifier circuit. do. By the above operation, a function for selecting the operating voltage to be supplied to the inverting amplifier circuit of the oscillation circuit is provided, and a lower voltage can be supplied as the operating voltage of the inverting amplifier circuit of the oscillating circuit than during normal operation when using low power consumption.

[0008]

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

As shown in FIG. 1, the input power supply voltage is divided into two using a voltage dividing resistor 1, and the input power supply voltage itself is passed through a voltage supply path 3, and a low voltage taken out from the intermediate terminal of the voltage dividing resistor 1 is are respectively applied to the switch circuit 5 through a low voltage supply path 4. Further, the operation of the switch circuit 5 is performed without changing the switch by applying an operating voltage selection signal to the terminal 2 from the outside. Next, the external power supply voltage applied from the switch circuit 5 is applied to the inverting amplifier circuit 6. The output voltage of the inverting amplifier circuit 6 is generated by a feedback resistor 8 that is fed back to the input, an oscillator 7 connected between both ends of the feedback resistor 8, and an AC voltage that is connected between both ends of the feedback resistor 8 and the ground.
The grounded capacitors 9 and 10 constitute an oscillation circuit that generates a clock signal.

The operation of the oscillation circuit configured as described above will be explained with reference to FIG. First, when the oscillation circuit operates normally, a voltage equal to the oscillation circuit input power supply voltage is supplied through the normal operation mode voltage supply path 3 as the operating power supply voltage of the inverting amplifier circuit 6 that oscillates a clock signal. Next, when low power consumption operation is required,
An operating voltage selection signal is externally applied to the input terminal 2, switches the switch circuit 5, and transfers the voltage obtained by dividing the input power supply voltage by the voltage dividing resistor 1 from the low power consumption operating mode voltage supply path 4 to the inverting amplifier circuit 6. Supplied as the operating power supply voltage.

Through the operations described above, a selection function for selecting the operating power supply voltage to be supplied to the inverting amplifier circuit 6 constituting the clock signal oscillation circuit is provided, and when using low power consumption, a lower voltage than during normal operation is provided. It is possible to realize an oscillation circuit in which the power supply voltage can be supplied as the operating power supply voltage of the inverting amplifier circuit 6 of the oscillation circuit.

0012

[Effects of the Invention] As is clear from the above embodiments, the oscillation circuit of the present invention selectively supplies a low voltage by dividing the input power supply voltage of the oscillation circuit as the operating power supply voltage of the oscillation circuit. By lowering the operating voltage of the oscillator circuit,
This makes it possible to further reduce power consumption. Since the power consumed to generate the oscillation clock signal is proportional to the square of the operating power supply voltage supplied to the inverting amplifier circuit of the oscillation circuit, when the oscillation circuit is required to operate under a low power consumption state by the above means, the oscillation circuit This makes it possible to realize an excellent oscillation circuit for a microcomputer that can reduce power consumption by lowering the operating power supply voltage of the microcomputer.

[Brief explanation of the drawing]

[Fig. 1] Circuit diagram of one embodiment of the present invention

[Explanation of symbols]

1 Voltage dividing resistor 2 Operating power supply voltage selection signal input terminal 5 Switch circuit 6 Inverting amplifier circuit 7 Oscillator 8 Feedback resistor 9 Capacitor 10 Capacitor

Claims (1)

[Claims] [Claim 1] Voltage dividing means for dividing an input power supply voltage;
a selection means for selecting the voltage divided by the voltage dividing means and the input power supply voltage; an amplification means for inverting and amplifying the voltage selected by the selection means as an operating power supply voltage; and an output of the amplification means. An oscillation circuit equipped with a feedback resistor that feeds back a voltage to an input, an oscillator connected between both ends of the feedback resistor, and a capacitor that connects both ends of the feedback resistor and ground to AC ground.