EXTON signal When Power On Reset

In order to improve the ranging accuracy, I used TCXO and separately supplied TCXO and VBat through a LDO. To further reduce power consumption , the LDO enable pin is controlled by EXTON. At present, the DW1000 is capable of ranging, but the strange thing is that the exton signal will wait for the DW1000 to power up for a few hundred milliseconds before it changes from low to high.

Can the LDO that powers the TCXO be enabled with the EXTON signal?

Why does ExtOn go high after a few hundred milliseconds after the DW1000 is powered up?