Notification 700 – Switched Feedback Network Incompatible with Output

CATEGORY

ISSUE / RESULT

FIX / REFERENCE(S)

Error

The Switched Feedback network type is not compatible with a programmable output voltage range. This is because by nature the switched feedback network requires as many resistors as the number of voltage levels -1. Moreover for small voltage steps, the voltage error caused by the resistor tolerance might be bigger than the step itself.

When a programmable range is required, other feedback network types are more suitable for the task, like, current source sink or an Operational amplifier based feedback circuit, with a PNP transistor whose base voltage is controlled by an error amplifier.  PI Expert gives the user both options.