AM68AX datasheet(235/251 Pages) TI

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9.2.2.1 No Loopback and Internal Pad Loopback

• The MCU_OSPI[x]_CLK output signal must be connected to the CLK pin of the flash device

• The signal propagation delay from the MCU_OSPI[x]_CLK signal to the flash device must be < 450 ps (~7cm

as stripline or ~8cm as microstrip)

• 50 Ω PCB routing is recommended along with series terminations, as shown in Figure 9-1

• Propagation delays and matching:

– A to B < 450 ps

– Matching skew: < 60 ps

MCU_OSPI[x]_CLK

OSPI/QSPI/SPI

Device Clock Input

OSPI/QSPI/SPI

Device IO[y], CS#

MCU_OSPI[x]_D[y],

MCU_OSPI[x]_CSn[z]

MCU_OSPI_Board_01

MCU_OSPI[x]_LBCLKO

MCU_OSPI[x]_DQS

OSPI Device DQS

* 0 Ω resistor (R1), located as close as possible to the MCU_OSPI[x]_CLK pin, is placeholder for fine tuning, if needed.

Figure 9-1. OSPI Interface High Level Schematic

9.2.2.2 External Board Loopback

• The MCU_OSPI[x]_CLK output signal must be connected to the CLK pin of the flash device

• The MCU_OSPI[x]_LBCLKO output signal must be looped back into the MCU_OSPI[x]_DQS input

• The signal propagation delay from the MCU_OSPI[x]_CLK pin to the flash device CLK input pin (A to B)

should be approximately equal to half of the signal propagation delay from the MCU_OPSI[x]_LBCLKO pin to

the MCU_OSPI[x]_DQS pin ((C to D)/2). See the note below.

• The signal propagation delay from the MCU_OSPI[x]_CLK pin to the flash device CLK input pin (A to B) must

be approximately equal to the signal propagation delay of the control and data signals between the flash

device and the SoC device (E to F, or F to E)

• 50 Ω PCB routing is recommended along with series terminations, as shown in Figure 9-2

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AM68A

SPRSP91 – FEBRUARY 2023

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AM68AX Datasheet(PDF) 235 Page - Texas Instruments