SNAS698C May 2020 – November 2022 LMK04832-SP
PRODUCTION DATA
To ensure proper JESD204B operation, the timing relationship between the SYSREF and the Device clock must be adjusted for optimum setup and hold time as shown in Figure 8-6. The global SYSREF digital delay (SYSREF_DDLY), local SYSREF digital delay (SCLKX_Y_DDLY), local SYSREF half step (SCLKX_Y_HS), and local SYSREF analog delay (SCLKX_Y_ADLY, SCLK2_3_ADLY_EN) can be adjusted to provide the required setup and hold time between SYSREF and Device Clock. It is also possible to adjust the device clock digital delay (DCLKX_Y_DDLY) and half step (DCLK0_1_HS, DCLK0_1_DCC) to adjust phase with respect to SYSREF.
Depending on the DCLKout_X path settings, local SCLK_X_Y_DDLY might need adjustment factor. Following equation can be used to calculate the required Digital Delay Values to align SYSREF to the corresponding DCLKout:
SYSREF_DDLY > 7; SCLK_X_Y_DDLY > 1.
DCLK & HS | DCLK_HS_ADJUST |
---|---|
0 | 0 |
1 | 1 |
For example: DCLKX_Y_DIV = 32, DCLKX_Y_DDLY = 10, DCC&HS = 1;
SYSREF_DDLY=10 – 1 + 0 + 1 – 2 = 8