63.5.1 First Value Read after Power-up

After a power-up and the first configuration to enable the TRNG, the first data can be read as soon as the flag DATRDY is set in the Interrupt Status register (TRNG_ISR). However, randomness (entropy) of a sequence of first value read after a power-up sequence is correct only if the TRNG has been enabled for a significant period of time.

When the first value after power-up is a key factor for the application, it is recommended to wait for 5 ms before reading the first value and after the power-up followed by the initial enable of the TRNG.