The HDD Thermal Test Vehicle (TTV) is a representation of a “typical” HDD/SSD to be used for evaluating thermal, airflow and mechanical designs of a server.

Thermal Details:

The TTV is adjustable from 2.5W to 25W total power via jumpers located at the front of the TTV.  Details on the jumper configuration for desired powers are printed directly on the TTV case.  Note other jumper configurations can achieve target powers; however the specified configurations have been tested in the lab.  The board of the TTV consists of 50 x 1W resistors, each of which has a maximum draw of 0.5W when in use.  The resistors are thermally coupled to a lower exposed copper plane and there is a thermal pad to couple the top and bottom sides of the board to the case.  The case itself has a large thermal mass and is constructed of Aluminum, this results in a device with good heat spreading across the case.  It is recommended that thermocouples should be applied to the middle of the downstream area of the TTV when evaluating in a system.  Note that some HDDs will have local thermal hot spots due to the motor that spins the drive; the TTV is more accurate to model SSDs with its distributed heat load.

Airflow Details:

The TTV is constructed such that the airflow impedance in the working range is within limits defined by testing performed in the lab in a wind tunnel.  Multiple samples of various vendor’s HDDs and SSDs were tested then the TTV size was tuned to be in the middle of that range.  There was a surprisingly wide variance in the values obtained from different manufacturers and capacity drives.  Therefore this TTV should only be used as a first order approximation for early testing when evaluating a specific drive, or as a standard when comparing HDD mounting methods, fillers, backplanes, etc.

Mechanical Details:

The HDD TTV has mounting holes consistent with industry standards.  The connector is also compliant in location and type to that of an industry standard HDD (see standard SFF-8201 located at http://www.sffcommittee.com/ie/Specifications.html ).  The form factor chosen is that of a maximum height drive (approx 15mm).  Note that there was no consideration given to weight in constructing this TTV as the main purpose is for thermal testing, not shock/vibe, shipping, etc.

Power Details:

The power for the TTV is drawn through a standard SATA connector.  Only the +5V pins are used for power (pins 7-9).  Ground pins are pins 4-6.  The precise location of these pins is printed directly on the case of the TTV.

If you need additional information or assistance, please feel free to contact me at your convenience.