AM2434: SPI Flash Layout Guideline

Hi Lawrence,

Lawrence Wong said:

Customer asking which design guide they should follow in the datasheet. 

This depends on what their usecase is going to be. If they are planning to run QSPI over 50MHz then they should consider using the External Board Loopback design implementation

QSPI does not use the DQS signal from the Flash device, it will instead use the DQS pin on SoC as an external loopback input. Its function is to facilitates easier timing closure at higher speeds.

Lawrence Wong said:

Do we need to control LBCLK and DQS length for QSPI?

There is a consideration to keep in mind for LBCLK and DQS propagation:

"The signal propagation delay of the OSPI[x]_LBCLKO pin to the OSPI[x]_DQS pin (C to D) must be approximately twice the propagation delay of the OSPI[x]_CLK pin to the attached OSPI/QSPI/SPI device CLK pin (A to B)"

Please refer to section 9.2.3.2 External Board Loopback under 9.2.3 OSPI/QSPI/SPI Board Design and Layout Guidelines of the device's datasheet for more information on design and implementation

Best,

Daniel

Link to DS: AM243x Sitara Microcontrollers datasheet (Rev. E) (ti.com)