TPS548B22EVM-847: use both local sense and remote sense

Will Wang47 

The TPS548B22 only has one feedback point, the RSP - RSN remote sense differential input.

This single point feedback can be connected to multiple circuit points through resistive or capacitive sensing and the TPS548D22 will attempt to regulate the voltage at that point, as averaged by the relative impedances of the multiple connections.

For example, when there is a long power transfer path between the TPS548B22 converter and the remote load, it can be advantageous to add a resistive or capacitive feedback path from the local output and a resistive feedback path from the remote output so that the DC regulation is at the load, but the high-frequency regulation loop does not suffer from instability due to the delays introduced by the parasitic inductance in the power path and the bypass capacitors at the load input.

Alternately, if a single TPS548B22 is powering several devices, one might connect the input voltage at each device back to this single point with the same resistance, say 50-ohms, so that the TPS548D22 regulates the average voltage across all of the devices it is powering.

Another common usage is when the output of the TPS548B22 is being passed through a connector.  A local feedback path is provided to prevent disconnecting the connector from breaking the feedback loop while a lower impedance path is provided through sense pins in the corrector so that the TPS548B22 can compensate for the drop across the connector in establishing the regulation voltage.  In this case, the local sense typically has much higher sensing impedance so that the average is more heavily weighted towards the remote sense point.