Cypress Semiconductor CY7C68301C Manual de usuario descargar pdf (Pagina 41)

CY7C68300C, CY7C68301C

CY7C68320C, CY7C68321C

Document Number: 001-05809 Rev. *K Page 41 of 44

Figure 16. Plot of the Solder Mask (White Area)

Figure 17. X-Ray Image of the Assembly

Other Design Considerations

Certain design considerations must be followed to ensure proper

operation of the CY7C68300C/CY7C68301C. The following

items must be taken into account when designing a USB device

with the CY7C68300C/CY7C68301C.

Proper Power Up Sequence

Power must be applied to the CY7C68300C/CY7C68301C

before, or at the same time as the ATA/ATAPI device. If power is

supplied to the drive first, the CY7C68300C/CY7C68301C

startup in an undefined state. Designs that use separate power

supplies for the CY7C68300C/CY7C68301C and the ATA/ATAPI

device are not recommended.

IDE Removable Media Devices

The AT2LP does not fully support IDE removable media devices.

Changes in media state are not reported to the operating system

so users are unable to eject or reinsert media properly. This may

result in lost or corrupted data. Note that standard ATAPI optical

drives and ATA CompactFlash-type devices are not part of this

group.

Devices With Small Buffers

The size of the drive’s buffer can greatly affect the overall data

transfer performance. Ensure that drives have large enough

buffers to handle the flow of data to and from it. The exact buffer

size needed depends on a number of variables, but a good rule

of thumb to follow is:

(approx min buffer) = (data rate) * (seek time + rotation time + other)

where ‘other’ may include things such as the time required to

switch heads and power up a laser. Drives with buffers that are

too small to handle the extra data may perform considerably

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Cypress Semiconductor CY7C68301C Manual de usuario Pagina 41