Description

STTS424E02

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Description

The STTS424E02 is targeted for DIMM Modules in Mobile Personal Computing Platforms

(Laptops), Server Memory Modules and other industrial applications. The Thermal Sensor

(TS) in the STTS424E02 is fully compliant with the JEDEC 42.4 specification, which defines

Memory Module Thermal Sensors requirements for Mobile platforms. The 2Kbit Serial

(EEPROM) in the STTS424E02 is organized as 256 x8 bits and is functionally identical to

the industry standard M34E02.

Ambient temperature sensing range for the temperature sensor is -40°C to +125°C per

JC42.4 specifications. The operating temperature range for the SPD EEPROM is

guaranteed for -40°C to +85°C.

The TS-SPD EEPROM combination provides space as well as cost savings for Mobile and

Server Platform Dual Inline Memory Modules (DIMM) manufacturers, as it is packaged in

the compact 2mm x 3mm 8-lead DFN package which has a height that will not exceed

0.9mm. It is also available in the JEDEC compliant TSSOP8 package.

The temperature sensor includes a band gap-based temperature sensor and 10-bit Analog-

to-Digital Converter (ADC) which monitor and digitize the temperature to a resolution of up

to 0.25°C. The typical accuracies over these temperature ranges are:

●

±3°C (max) over the full temperature measurement range of –40°C to 125°C,

●

±2°C in the +40°C to +125°C temperature range, and

●

±1°C in the +75°C to +95°C temperature range.

The temperature sensor in the STTS424E02 is specified for operating at supply voltages

from 2.7V to 3.6V. Operating at 3.3V, the supply current is 100µA (typ).

The on-board sigma delta ADC converts the measured temperature to a digital value that is

calibrated in °C. For Fahrenheit applications, a lookup table or conversion routine is

required. The STTS424E02 is factory-calibrated and requires no external components to

measure temperature.

The digital temperature sensor component has user-programmable registers that provide

the capabilities for DIMM temperature-sensing applications. The open drain Event output pin

is active when the monitoring temperature exceeds a programmable limit, or it falls above or

below an alarm window. The user has the option to set the Event output as a critical

temperature output. This pin can be configured to operate in either a comparator mode for

thermostat operation or in interrupt mode.

The 2Kbit serial EEPROM memory in the STTS424E02 has the ability to permanently lock

the data in its first half (upper) 128 bytes (locations 00h to 7Fh). This facility has been

designed specifically for use in DRAM DIMMs with SPD. All of the information concerning

the DRAM module configuration (e.g. access speed, size, and organization) can be kept

write protected in the first half of the memory. The second half (lower) 128 bytes of the

memory can be write protected using two different software write protection mechanisms.

By sending the device a specific sequence, the first 128 bytes of the memory become write

protected: permanently or resettable. In the STTS424E02 the EEPROM Write Control (WC)

is always held low. Thus, the write protection of the memory array is dependent on whether

the software protection has been set.