Adaptive Thermal Monitoring
The device features adaptive thermal monitoring. While most host computers exhibit
operating environments that keep an SSD running in the range of 40°C to 45°C, adap-
tive thermal monitoring enables the SSD device to operate in a wide variety of environ-
ments by helping to prevent the host computer from running at excessive temperatures.
Adaptive thermal monitoring reduces total SSD power consumption by the device con-
troller, as well as the NAND media, by injecting time-based delays between internal
processing of media commands when the device temperature reaches 85 °C. The delay
times used are bound to the microsecond range, and are based on a proportional and
differential control equation of the general form shown here.
Figure 5: Adaptive Thermal Monitoring Control Equation
u(t) = Kp × T
p
(t) + Kd ×
dT
d
dt
The delay-control equation is tuned for a steady-state temperature target, which has
been designed as an optimum balance of hardware temperature tolerances and drive
performance. Steady-state temperature targets are hardware-configuration dependant,
and may range from 85 °C to 90 °C. Temperatures below the intended steady-state target
will not produce a proportional component to delay, but may produce a differential
component based on the current rate of temperature change according to the control
equation. When the feature is active, DRAM refresh rates are also adjusted to improve
data integrity and stability while operating outside of temperature specifications.
When the device temperature falls below 85 °C, normal operation will continue without
induced delays. If temperature continues to rise above the temperature target and ex-
ceeds a hardware-dependant critical threshold, the device will abort host commands to
prevent component damage. The critical threshold values have a 6 °C margin on top of
target threshold, and range between 95 °C and 101 °C.
Device temperature values used by the adaptive thermal monitoring feature are based
on an internal temperature sensor located on the device PCB, and may differ from case
or package temperatures as measured by thermocouple. Device temperature is accessi-
ble through SMART attribute 194, though usage of the SMART feature is not necessary
for adaptive thermal monitoring functionality.
Adaptive thermal monitoring does not change the current negotiated speed of the SATA
bus, nor require or cause any new commands to be issued on the SATA bus. Rated-
throughput performance is not guaranteed at any point above the maximum specified
operating temperature.
This feature is still under definition, and further details on exact behavior will be provi-
ded later.
M500IT mSATA NAND Flash SSD
Adaptive Thermal Monitoring
09005aef865b1bc7
m500it_mSATA_industrial_ssd.pdf - Rev. E 6/16 EN
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