Logo on microsite – link to home or brand website

We have a brand with some complex products. For these we have separated microsites, where you get some infos and where you can purchase the product. This sites have the logo from our main brand in the navigation bar. Now I'm wondering where to navigate the user when he clicks on the logo.

Regarding this the logo should be linked to the home of the website: Why is it standard for a website logo to navigate to the home page?

But what does the user expects on a microsite? To get more information about the brand (link to brand website) or get back to the home of the microsite?