From what I have found on the Net related to this device, it doesn't have any specific settings for configuring the minimum and the maximum brightness.
You can try this custom driver, first enable the 'Advanced Options' and click on Save, then select 'Öther OEM Dimmer" as Device Profile and click Save in the Preferences section again.
There are Minimum and Maximum Level settings in the preferences. Let me know if these work for your device (If I understand your needs correctly).
