CY7C68300 CYPRESS [Cypress Semiconductor], CY7C68300 Datasheet - Page 25

• Manufacturer Part Number: CY7C68300
• Manufacturer: CYPRESS [Cypress Semiconductor]

14.0
Certain design considerations must be followed to ensure proper operation of the EZ-USB AT2. The following items should be
taken into account when designing a USB device with the EZ-USB AT2.
14.1
Power must be applied to the EZ-USB AT2 before, or at the same time as the ATA/ATAPI device. If power is supplied to the drive
first, the EZ-USB AT2 will start up in an undefined state. Designs that utilize separate power supplies for the EZ-USB AT2 and
the ATA/ATAPI device are not recommended.
14.2
The EZ-USB AT2 does not fully support IDE removable media devices. Changes in media state are not reported to the operating
system so users will be unable to eject/reinsert media properly. This may result in lost or corrupted data.
14.3
The size of the ATA/ATAPI device’s buffer can greatly affect the overall data transfer performance. Care should be taken to ensure
that devices have large enough buffers to handle the flow of data to/from the drive. The exact buffer size needed depends on a
number of variables, but a good rule of thumb is:
(aprox min buffer size) = (data rate) * (seek time + rotation time + other)
where (other) may include things like time to switch heads, power-up a laser, etc. Devices with buffers that are too small to handle
the extra data may perform considerably slower than expected.
14.4
When the AT2 detects a lack of USB activity from the host, it enters an idle mode and waits for USB host activity to resume. While
in this idle mode, the core logic is still functioning and power consumption remains at its active level. Because of this, the AT2 is
not intended for use in battery or bus powered designs. Also, care should be taken to ensure that the AT2 does not draw power
from VBUS, since such a design will not meet USB specifications for standby current.
15.0
Purchase of I
I
as defined by Philips. EZ-USB AT2 is a trademark, and EZ-USB is a registered trademark, of Cypress Semiconductor. All product
and company names mentioned in this document are the trademarks of their respective holders.
Document #: 38-08011 Rev. *B
© Cypress Semiconductor Corporation, 2002. The information contained herein is subject to change without notice. Cypress Semiconductor Corporation assumes no responsibility for the use
of any circuitry other than circuitry embodied in a Cypress Semiconductor product. Nor does it convey or imply any license under patent or other rights. Cypress Semiconductor does not authorize
its products for use as critical components in life-support systems where a malfunction or failure may reasonably be expected to result in significant injury to the user. The inclusion of Cypress
Semiconductor products in life-support systems application implies that the manufacturer assumes all risk of such use and in doing so indemnifies Cypress Semiconductor against all charges.
2
C Patent Rights to use these components in an I
Proper Power-up Sequence
IDE Removable Media Devices
Devices With Small Buffers
USB Idle Mode
Other Design Considerations
Disclaimers, Trademarks, and Copyrights
2
C components from Cypress, or one of its sublicensed Associated Companies, conveys a license under the Philips
Figure 13-2. Plot of the Solder Mask (White Area)
Figure 13-3. X-ray Image of the Assembly
2
C system, provided that the system conforms to the I
2
C Standard Specification
CY7C68300
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