CC2640R2F: RAM retention during reset

Part Number: CC2640R2F

I am testing the behavior of the _bim_var variable in bim_main.c:

// BIM variable
#ifdef __TI_COMPILER_VERSION__
  #pragma location = BIM_VAR_ADDR
  #pragma NOINIT(_bim_var)
  uint32_t _bim_var;
#elif __IAR_SYSTEMS_ICC__
  __no_init uint32_t _bim_var @ BIM_VAR_ADDR;
#endif

void main(void)
{
    setSearchVar(_bim_var, &FN, &IT);
    ......
}

The variable is supposed to be random every time the board is re-powered, however, I found out it's value is unchanged if I power down and power up the board again within a few seconds. So I would like to confirm under what circumstances will the RAM be re-initialized?

I found several reset source described in CC2640R2F's TRM:

0h = Power on reset
1h = Reset pin
2h = Brown out detect on VDDS
3h = Brown out detect on VDD
4h = Brown out detect on VDDR
5h = Clock loss detect
6h = Software reset via SYSRESET register
7h = Software reset via PRCM warm reset request

Is the RAM retention has something to do with the reset sources?

Best regards,

Shuyang