Renesas Electronics Corporation

Tomoki Yasukawa

Toyohiko Yoshida

Akira Oizumi

Yoshinori Tokioka

Kazuyoshi Kawai

The disclosed invention is intended to prevent malfunction of an internal circuit because of unwanted power supply switching caused by a noise during operation of a semiconductor device powered by a backup power supply, while eliminating wasteful consumption of the backup power supply. A first switching transition time after coupling the main power supply terminal to the internal power supply node until decoupling the backup power supply terminal from the internal power supply node is made longer than a second switching transition time after coupling the backup power supply terminal to the internal power supply node until decoupling the main power supply terminal from the internal power supply node.

Semiconductor device

A frequency error calculator circuit calculates the frequency error in a basic clock based on the basic clock and on a reference clock having a frequency higher than the basic clock. An operation clock generator circuit outputs an operation clock whose error has been corrected based on the frequency error calculated by the frequency error calculator circuit. An ON/OFF control circuit outputs an ON/OFF control signal that specifies the calculation timing that the frequency error calculator circuit calculates the frequency error of the basic clock based on the frequency error calculated by the frequency error calculator circuit.

Semiconductor device and clock correction method

An operation clock generation circuit performs calculation on the basis of the frequency errors of a fundamental clock and the clock pulses of the fundamental clock, and generates an operation clock obtained by correcting the frequency errors at first intervals. A correction clock generation circuit converts a lower-bit value that is a value represented by the bits lower than the predefined bit used for judging the change of the state of the operation clock into a count number of the clock pulses of a second clock whose frequency is higher than that of the operation clock, generates a correction clock obtained by correcting the operation clock on the basis of a time required for counting the count number of the clock pulses and the clock pulses of the operation clock.

Clock correction circuit and clock correction method

An operation clock generation circuit performs a calculation on the basis of the frequency errors of a fundamental clock and the clock pulses of the fundamental clock, and generates an operation clock obtained by correcting the frequency errors at first intervals. A correction clock generation circuit converts a lower-bit value that is a value represented by the bits lower than the predefined bit used for judging the change of the state of the operation clock into a count number of the clock pulses of a second clock whose frequency is higher than that of the operation clock, generates a correction clock obtained by correcting the operation clock on the basis of a time required for counting the count number of the clock pulses and the clock pulses of the operation clock.

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Tokyo, Japan

Tomoki Yasukawa