Microcomputer

Abstract

A microcomputer includes an oscillator for generating a clock signal having a frequency by using a CR circuit, a multiplier for outputting the clock signal having a multiplied frequency relative to the frequency generated by the oscillator based on data from an external source, a temperature detection unit for detecting temperature at a proximity of the CR circuit, a storage unit for storing data that enables the multiplied frequency of the clock signal in an output from the multiplier to have a constant value based on a temperature-dependent oscillation characteristic of the oscillator, and a control unit for setting a multiplication value for generating the multiplied frequency of the clock signal to the multiplier based on the data in the storage unit that is correlated to the temperature detected by the temperature detection unit.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

Other objects, features and advantages of the present invention will become more apparent from the following detailed description made with reference to the accompanying drawings, in which:

FIG. 1 shows a flow chart of a clock signal compensation process in a CPU of a microcomputer in an embodiment of the present disclosure;

FIG. 2 shows a sequence diagram of compensation timing;

FIG. 3 shows a diagram of approximation of relationship between temperature and compensation error;

FIG. 4 shows a flow chart of an EEPROM writing process;

FIG. 5 shows a diagram of approximation of detection voltage and oscillation output cycle;

FIG. 6 shows a block diagram of a microcomputer; and

FIG. 7 shows a block diagram of DPLL circuit that is coupled with a regulator and a CR oscillation circuit.

Claims

1. A microcomputer comprising: an oscillator for generating a clock signal having a frequency by using a CR circuit;a multiplier for outputting the clock signal having a multiplied frequency relative to the frequency generated by the oscillator based on data from an external source;a temperature detection unit for detecting temperature at a proximity of the CR circuit;a storage unit for storing data that enables the multiplied frequency of the clock signal in an output from the multiplier to have a constant value based on a temperature-dependent oscillation characteristic of the oscillator; anda control unit for setting a multiplication value for generating the multiplied frequency of the clock signal to the multiplier based on the data in the storage unit that is correlated to the temperature detected by the temperature detection unit.

2. The microcomputer as in claim 1, wherein the data in the storage unit is an approximation of an output of the temperature-dependent oscillation characteristic of the oscillator represented by a quadratic curve.