Renesas Electronics Corporation

Yosuke Tanno

Kazuki Watanabe

Takashi Endo

Yoshiyuki Amanuma

Makoto Toyoshima

Yuichiro Nariyoshi

Akihiro Toriyama

Makoto Shindo

To enhance the security of a semiconductor device, the semiconductor device has a regulator unit for generating an internal power supply voltage based on a power supply voltage supplied from outside, an internal circuit which operates on the internal power supply voltage, a current detection unit for monitoring a power supply current supplied to the internal circuit, and a control unit for controlling operation of the internal circuit. In the semiconductor device, when the current detection unit detects that the power supply current exceeds a predetermined threshold value, the control unit restricts the operation of the internal circuit.

Semiconductor device and control system

A semiconductor device includes a CPU, an EEPROM, and a ROM. The ROM includes an encryption area and a non-encryption area and the encrypted firmware is stored in the encryption area. The semiconductor device includes a decrypter which holds the encryption key, decrypts the encrypted firmware, and supplies the decrypted firmware to the CPU. The EEPROM includes a system area to which an access from the CPU is forbidden in a user mode. The encryption key is divided into split keys of plural bit strings, and stored in the distributed address areas in the system area. An encryption key reading program which is not encrypted is stored in the non-encryption area of the ROM. Executing the encryption key reading program, the CPU reads and reconfigures plural split keys stored in the EEPROM in a distributed manner to restore the encryption key and supplies the restored encryption key to the decrypter.

Semiconductor device and encryption key writing method

There is included a detection unit for detecting a magnitude of a surplus of a direct current to a source voltage generated by a voltage generation unit generating the source voltage from the direct current obtained by rectifying a signal inputted from an antenna terminal. A data processing unit operating at the source voltage and performing data processing on a transmission/reception signal includes a clock control unit for determining a frequency of a clock signal for the data processing based on the magnitude of the surplus current detected by the detection unit in a state where a frequency of the clock signal is set to a predetermined reference frequency. Since the power consumed by the data processing unit at the time of detecting the surplus of the direct current is determined by the specific reference frequency, the surplus of the direct current can be detected as an absolute surplus.

Contactless communication device, contactless IC card, and mobile information terminal

Growing community of inventors

Kanagawa, Japan

Yosuke Tanno