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Hi, my name's Rami Sethi from IDT. I'll be talking today about IDT's new family of ultra
low power thermal sensors, primarily optimized for memory module applications.
Thermal sensors have become used quite commonly in memory applications, primarily because
both volatile and non-volatile memory can have data integrity sensitivity at high temperature.
Thermal management is critical in a lot of enterprise and storage applications nowadays.
And some key areas where thermal sensors are used are register DIMM, ECCU DIMMs, and small
outline DIMMs and DDR3 and DDR2 applications, as well as solid state disks.
There are several usage models and methods that thermal sensors are used to control DRAM
temperature. Primarily, they're used to provide a closed loop thermal algorithm for controlling
temperature and maintaining data integrity, one example of which is closed-loop thermal
throttling, or CLTT.
Typically the temperature is read over an interface, either I2C or SM-Bus, or it can
be read through an event-driven pin. And at high temperatures, that temperature reading
is then used to perform one of several actions. One may be throttling the bandwidth between
the memory control with the DRAM. To reduce temperature, that’s called closed-loop thermal
throttling. Another would be adjusting the DRAM refresh rate to maintain data integrity.
And a third may be increasing or decreasing fan speed in the system. Finally, at critical
temperatures, there may be a shutdown or data backup function that would be triggered.
Some of the key benefits in the system of CLTT are enhanced reliability, basically enhanced
data integrity, improved bandwidth performance and efficiency, because the DRAMs will operate
in a very optimal temperature range, lower overall system power, as opposed to open-loop
type of configurations, and better acoustics by having better fan control.
There's an optional feature on some of the devices, which is a serial presence detect,
or SPD. The SPD is basically 256 bytes of EEPROM, the lower 176 of which are used to
configure DIMM information and configuration, information for the system. The upper 80 bytes
are used for user-configurable information, and so that can be used for anything such
as statistical storage, event logging, or any other function.
There are several modes of operation for the thermal sensor in terms of how the event pin
behaves.
The first is interrupt mode. In interrupt mode, basically every time a temperature threshold
is crossed, the event pin will assert and needs to be de-asserted, essentially through
software. Essentially generating an interrupt to the system.
The second mode is comparator mode. In comparator mode, the even pin will assert every time
a temperature threshold is crossed and will automatically clear on the subsequent crossing.
And the finally is T-critical mode. T-crit mode essentially only observes the TCRIT temperature
setting which would be the highest level temperature typically used to trigger an emergency event
like system shutdown.
Each of the limits has programmable hysteresis to avoid metastability problems with the thermal
sensor if you're hovering around a given temperature.
If you look at the block diagrams for each part, they look very similar. The real difference
between the TSE2002 and the TSE3000 is the fact that the 2002 has an additional 256 bytes
of EEPROM, which is called the serial presence detect. Other than that, all other blocks
are common between the two. You have an analog temperature sensor that basically actually
senses the local air temperature around the device. You have a sigma-delta converter,
which basically converts the analog signal to a digital signal, which is 12 bits resolution.
You have your register space, which is actually a register space that's industry standard
and defined by JEDEC JC 42 and you have your SM-Bus and I2C interface.
Some of the key features and benefits of the family are industry leading temperature accuracy
of plus or minus one degree Celsius over the full -20 to 125 degree range, compliance to
the full standard set forth by JEDEC 42.4 for these devices on DIMM modules. SM-Bus
and I2C compatibility for maximum system flexibility, 3.3 and 2.5 volt capability for backwards
compatibility to previous and forward compatibility to next generation SM-Bus and I2C controllers,
ultra low standby current, which saves power in both mobile and battery backed applications
such as storage, very fast EPROM write time, less than three milliseconds, which is less
than half of the required specification and increases ATE and system efficiency. High
resolution, all the way down to 1/16 of a degree Celsius, is available for very fine
loop control of thermal throttling algorithms. And input glitch filtering and power on hysteresis
is also available to maximize system availability and robustness.
So that covers most of the major features and benefits of the family. I want to thank
you for watching and we'll see you next time.