topic Re: Deinitializing FS85 driver in Power Management

Deinitializing FS85 driver

haby_a — Mon, 05 Aug 2019 05:44:13 GMT

Hello NXP team,

I have a query regarding the De-initialization of FS85 driver (for watchdog). De-initialization is usually done during under/over voltage conditions to disable the functionality of external devices. Usually a system basis chip shall move to sleep mode on calling DeInit API. I would like to know how this can be done for FS85 chip ( I am only using the watchdog functionality of FS85, no power management functionality is used). Hoping for an early response.

Thanks in advance

Haby Ashraf

Re: Deinitializing FS85 driver

TomasVaverka — Tue, 13 Aug 2019 09:39:26 GMT

Hello Haby,

As far as I know there is no DeInit or similar function in the current version of FS8x driver. You can find there functions for refreshing the watchdog, changing the seed of the LFSR, releasing the FS0B pin, selecting the voltage channel to AMUX pin etc. There is also a general FS8x_ReadRegister function that can be used to read regulator registers and the one with a fault can than be disabled using the FS8x_SetRegulatorState function. Or you can use the FS8x_WriteRegister function and set the GOTOSTBY bit in the M_MODE register to turn all regulators off.

Best regards,

Tomas

Re: Deinitializing FS85 driver

haby_a — Wed, 14 Aug 2019 06:51:48 GMT

Hi Tomas,

Thank you for the information. This really is helpful.

I would like to know how the SBC will come back to normal operation after switching it to standby mode. Will the SBC move to power down sequence and turn OFF completely after GOTOSTANBY is issued?

Regards

Haby Ashraf

Re: Deinitializing FS85 driver

TomasVaverka — Thu, 15 Aug 2019 11:01:17 GMT

Hi Haby,

Please take a closer look at the simplified functional state diagram shown in Figure 5 of the datasheet and below.

As you can notice, the FS8x goes back to Normal_M mode when WAKE1 = 1 or WAKE2 = 1.

If WAKE1 = 1 all the time, with WAKE1 wake up enable (W1DIS = 0), setting the GOTOSTBY bit in the M_MODE register will cause getting back to normal operation immediately.

If you want to use WAKE2 to wake up the device when WAKE1 = 1, then set W1DIS = 1 to disable WAKE1 wake up before going to Standby mode.

When the device is in Standby mode and both WAKE1 = WAKE2 = 0, the device will go to Power Down mode.

Best regards,

Tomas