# 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>


---

# Agent Instructions: Querying This Documentation

If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter:

```
GET https://nxp.gitbook.io/mr-canhubk344/hardware/fs26-pmic.md?ask=<question>
```

The question should be specific, self-contained, and written in natural language.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.