Hitachi hard disk 0J11285 500 GB 2.5 " 8 MB 0J11285 Ficha De Dados

Z5K500 OEM Specifications 

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6.3.6 

Load/unload 

The product supports a minimum of 600,000 normal load/unloads. 

Load/unload is a functional mechanism of the hard disk drive. It is controlled by the hard disk drive micro 
code. Specifically, unloading of the heads is invoked by the following commands: 

Standby 
Standby immediate 
Sleep 

Load/unload is also invoked as one of the idle modes of the hard disk drive. 

The specified start/stop life of the product assumes that load/unload is operated normally, not in 
emergency mode. 

6.3.6.1 

Emergency unload 

When a power is interrupted while the heads are still loaded, the micro code cannot operate and the 
normal 5-volt power is unavailable to unload the heads. In this case, normal unload is not possible. 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 controllable without a normal 
seek current profile. 

Emergency unload is intended to be invoked in rare situations. Because this operation is inherently 
uncontrolled, it is more mechanically stressful than a normal unload. 

The hard disk drive supports a minimum of 20,000 emergency unloads. 

6.3.6.2 

Required Power-Off Sequence 

The required host system sequence for removing power from the hard disk drive is as follows: 

Step 1: Issue one of the following commands. 

Standby  
Standby immediate 
Sleep 

Step 2: Wait until the Command Complete status is returned. 

The host system time out value needs to be 30 seconds considering error recovery time. 

Step 3: Terminate power to hard disk drives. 

This power-down sequence should be followed for entry into any system power-down state, system 
suspend state, or system hibernation state.    In a robustly designed system, emergency unload is limited 
to rare scenarios, such as battery removal during operation. 

6.3.6.3 

Power switch design considerations 

In systems that use the Travelstar Z5K500 consideration should be given to the design of the system 
power switch. 

HGST recommends that the switch operate under control of the host system, as opposed to being 
hardwired. The same recommendation is made for cover-close switches. When a hardwired switch is 
turned off, emergency unload occurs, as well as the problems cited in section 5.1, "Data loss by power 
off" and section 5.2, “Write Cache”.