PROGRAM_B is the Spartan UltraScale+ input to reconfigure the device. It is controlled using a push button for easy access. The pin must be held high during the configuration process.
The SCU35 board PROGRAM_B circuit is shown in the following figure. U63 allows bidirectional level shifting for the INIT_B, DONE, and SYS_PGOOD signals. The PROGRAM_B signal can be configured via the J2 jumper to be controlled by the SYS_PGOOD signal until power is valid.
Figure 1. PROGRAM_B Reset Circuit
