STTS424 and STTS424E02 Temperature Sensors for Monitoring PC’s Memory - STMicroelectronics

STMicroelectronics announced the STTS424 and STTS424E02, two high-accuracy application specific digital temperature-sensor chips. The new sensor chips is suitable for monitoring the temperature of the PC’s DIMMs (dual in-line memory modules), and it is fully compliant with the JEDEC JC42.4 spec. STTS424 is a standalone digital temperature sensor, while the STTS424E02 has a 2 Kbit SPD EEPROM (SPD = Serial Presence Detect) that is used on DIMMs to store information about the module. Both temperature-sensor chips communicate with the CPU chipset through an I2C/SMBus-compatible bus.

The faster memories installed in PCs increase the risk of memory overheating. Temperature monitoring mechanism is important, because it allows the CPU to regulate the speed of the memory traffic or take required action to prevent overheating.

The integrated SPD EEPROM in STTS424E02 temperature sensor IC can replace the SPD EEPROM of existing memory module implementations. Additionally, the temperature sensor and the EEPROM in the STTS424E02 each have their own unique I2C/SMBus address.

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.

The new sensor chips integrate an ADC which 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 chips operate on 2.7V to 3.6V, -40 to +125 degrees C. The typical supply current at 3.3V is 100 microamps. The sensor chips require no external components and they are factory calibrated.

STTS424 and STTS424E02 temperature sensor ICs are available in 2 x 3mm DFN8 and 4.4 x 3mm TSSOP8 packages. STTS424 is priced at US$0.70, and the STTS424E02 at US$0.85, both in high volume quantities.

More info: http:/www.st.com/sensors