low power clock configuration register
| BT_LPCK_DIV_B | This field is lower power clock frequent division factor b |
| BT_LPCK_DIV_A | This field is lower power clock frequent division factor a |
| LPCLK_SEL_RTC_SLOW | Set 1 to select rtc-slow clock as rtc low power clock |
| LPCLK_SEL_8M | Set 1 to select 8m clock as rtc low power clock |
| LPCLK_SEL_XTAL | Set 1 to select xtal clock as rtc low power clock |
| LPCLK_SEL_XTAL32K | Set 1 to select xtal32k clock as low power clock |
| LPCLK_RTC_EN | Set 1 to enable RTC low power clock |