JAJSV88 June 2024 LMX1860-SEP
PRODUCTION DATA
SYSREF repeater mode with delay enabled is possible with LMX to LMX fanout devices by retiming the SYSREFout at different edge of IQ generation. This retiming can have the delay margin between CLKIN and SYSREFREQ inputs based on SYSREF_DLY_DIV value.
Table 6-16 shows how the total delay margin for the SYSREF windowing relates the various SYSREF settings.
SYSREF_DLY_DIV | POSITION CODE SELECTED DURING SYNC | EDGE FOR MAX MARGIN | TOTAL MARGIN IN CLKIN CYCLE | SYSREFx_DLY_PHASE | SYSREFx_DLY_Q | SYSREFx_DLY_I |
---|---|---|---|---|---|---|
/2 |
Before 1st edge |
I |
-1, +1 |
"11" |
0 |
127 |
After 1st edge |
Qz |
-1, +1 |
"01" |
127 |
0 |
|
After 2nd edge |
Iz |
-1, +1 |
"00" |
0 |
127 |
|
/4 |
Before 1st edge |
Qz |
-2, +2 |
"01" |
127 |
0 |
After 1st edge |
Iz |
-2, +2 |
"00" |
0 |
127 |
|
After 2nd edge |
Q |
-2, +2 |
"10" |
127 |
0 |
|
/8 |
Before 1st edge |
Qz |
-5, +3 |
"01" |
127 |
0 |
After 1st edge |
Qz |
-4, +4 |
"01" |
127 |
0 |
|
After 2nd edge |
Qz |
-3, +5 |
"01" |
127 |
0 |
|
/16 |
Before 1st edge |
I |
-9, +7 |
"11" |
0 |
127 |
After 1st edge |
I |
-8, +8 |
"11" |
0 |
127 |
|
After 2nd edge |
I |
-7, +9 |
"11" |
0 |
127 |
Repeater retime mode is required to perform the SYSREF windowing in the initial phase to synchronize the SYSREF_DLY_DIV in multiple devices. The user can later choose the SYSREFx_DLY_PHASE, SYSREF_DLY_Q and SYSREFx_DLY_I settings for the selected edge for the SYNC.
This configuration must set the device in SYSREF_MODE R17[1:0] value "2" (Repeater mode) and SYSREF_DLY_BPY R72[1:0] value "2" (Delay gen engaged in all modes).