> For the complete documentation index, see [llms.txt](https://nxp.gitbook.io/mr-canhubk344/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://nxp.gitbook.io/mr-canhubk344/hardware/fs26-pmic.md).

# FS26 PMIC

The FS26 is the ‘Safety System Basis Chip with Low Power Fit for ASIL D’ of NXP Semiconductors. Figure 3 gives the block diagram of this power supply chip. This part is sophisticated and is capable of additional complex configurations than implemented here, however in this design it primarily allows for a compact power supply design and high input voltage.

Normally the FS26 is connected through SPI to the S32K344 and implements a challenger window watchdog. Sending challenges to the through SPI S32K344 as the window watchdog when the response is invalid or not during the timing window the FS26 will reset the S32K344 MCU. In included sample code, the challenge watchdog functionality has not been implemented. Instead during startup of the S32K344 the sample application sends a request to the FS26 to disable the watchdog functionality thus avoiding resetting the S32K344 while running sample applications.

<figure><img src="/files/4IyAMLd5O4bylbQtBKuR" alt=""><figcaption><p>FS26 PMIC block diagram</p></figcaption></figure>


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