Datasheet

12.4 Power-off considerations
12.4.1 Load/Unload
The product will support a minimum of 300,000 normal load/unloads.
The Load/Unload is a functional mechanism of the drive. It is controlled by the drive microcode. Specifi-
cally, unloading of the heads is invoked by the commands:
Microcode revision: CSxICxx (where 'x' can be any character)
Command
*UL J CompleteStandby Immediate
*UL J CompleteStandby
Reset
*UL J **RdyHard Reset
*UL J **RdySoft Reset
Rdy means interface ready**
UL means unload*
Figure 65. A Device's behavior by ATA commands
The microcode revision is referred to in words 23–26 in Figure 82 on page 95. This is 8 characters in
ASCII.
Load/Unload is also invoked as one of the idle modes of the drive.
The specified start/stop life of the product assumes that Load/Unload is operated normally, NOT in emer-
gency mode.
12.4.2 Emergency unload
When the heads are still loaded, the microcode cannot operate when the drive power is interrupted. The
normal 5 V power is unavailable to unload the heads. In this case a normal unload of the heads is not
possible. However, the heads are unloaded by routing the back-EMF of the spinning motor to the voice
coil. The actuator velocity is greater than the normal case and the unload process is inherently less con-
trollable without a normal seek current profile.
An emergency unload is intended to be called for in rare situations. Because this operation is inherently
uncontrolled it is more mechanically stressful than a normal unload.
A single emergency unload operation is more stressful than 100 normal unloads. The use of an emer-
gency unload reduces the start/stop life of the drive at a rate at least 100X faster than that of normal
unload and may damage the drive.
Warranty is void on a drive that has experienced 3,000 or more emergency unloads.
Hard disk drive specification for DSCM-11000/-10512/-10340
66