SPRUJ28E November 2021 – September 2024 AM68 , AM68A , TDA4AL-Q1 , TDA4VE-Q1 , TDA4VL-Q1
PLL configuration registers are write-protected at power-up. Software must first un-lock the PLLn_LOCKKEY0 and PLLn_LOCKKEY1 registers prior to writing to any chip-level registers.
The un-lock process shall follow the steps:
After these two steps a write access to the PLL registers is allowed. Writing any other data value to either of these two registers locks the kicker mechanism and blocks any writes to the PLL registers.
In order to ensure that all PLL registers are write protected, software must always re-lock the kicker mechanism after completing the register writes.