ST Debuts Application Specific Temperature Sensors for JEDEC JC42

STMicroelectronics (NYSE: STM), an industry leader in high-performance analog and mixed-signal products, announced two high-accuracy application specific digital temperature-sensor chips, fully compliant with the JEDEC JC42.4 specification, which are intended for monitoring the temperature of the DIMMs (dual in-line memory modules) used in personal computers.

The faster DDR2 and DDR3 (double-data-rate) DRAM memories installed in computers and other systems increase the risk of memory overheating, so temperature sensing, which allows the CPU to regulate the speed of the memory traffic or take further action to prevent overheating, has become more important in system design.

The new STTS424 is a standalone digital temperature sensor, while the STTS424E02 integrates the temperature sensor with a 2 Kbit Serial Presence Detect (SPD) EEPROM that is used on DIMMs to store timing parameters and other information about the module, in accordance with JEDEC requirements. Both devices communicate with the CPU chipset through an I2C/SMBus-compatible serial bus, and are available in 2 x 3mm DFN8 and 4.4 x 3mm TSSOP8 packages.

The STTS424 sensor has a 50% lower operating current than competitive devices and the JEDEC JC42.4 standard. The integrated STTS424E02 can replace the 2 Kbit SPD EEPROM of existing memory module implementations, thereby adding temperature sensing capability with minimum board redesign cost, and with no increase in the number of components. For programming ease, the temperature sensor and the EEPROM in the STTS424E02 each have their own unique I2C/SMBus address.

The new sensor chips – application-specific members of ST’s temperature-sensor family – integrate an analog-to-digital converter (ADC) which monitors and digitizes the temperature with a resolution down to 0.25 degrees C, and an accuracy of +/–1 degree C, over the +75 to +95 degrees C temperature range. The devices are factory calibrated and require no external components for temperature measurement. They can operate on a supply voltage from 2.7V to 3.6V, and over a -40 to +125 degrees C temperature range. The typical supply current at 3.3V is 100 microamps.

An open-drain EVENT output pin is active either if the monitored temperature exceeds a programmed limit or if it strays outside the upper or lower limit of a customer-programmed Alarm window. The pin can be configured to operate either in a comparator mode for thermostat operation, or in the interrupt mode. The 2-Kbit serial EEPROM in the STTS424E02 has the ability to permanently lock the data in the first 128bytes, for use in DDR DIMMs with SPD.

Available now for production orders, the STTS424 is priced at $0.70, and the STTS424E02 at $0.85, in high volume quantities.

About STMicroelectronics
STMicroelectronics is a global leader in developing and delivering semiconductor solutions across the spectrum of microelectronics applications. An unrivalled combination of silicon and system expertise, manufacturing strength, Intellectual Property (IP) portfolio and strategic partners positions the Company at the forefront of System-on-Chip (SoC) technology and its products play a key role in enabling today’s convergence markets. The Company’s shares are traded on the New York Stock Exchange, on Euronext Paris and on the Milan Stock Exchange. In 2006, the Company’s net revenues were $9.85 billion and net earnings were $782 million.