11 Power Supply Recommendations

To help make sure that operation is reliable at data rates and supply voltages, adequate decoupling capacitors must be located as close to supply pins as possible. V_ISOOUT needs to be connected to V_ISOIN to ensure the feedback channel is properly powered to regulate the DC-DC converter. If V_ISOOUT and V_ISOIN are not connected, the DC-DC converter will run open loop and the V_ISOOUT voltage will drift until the over-voltage clamp clamps at 6 V. There are two ways to connect V_ISOOUTand V_ISOIN:

1) connect V_ISOOUT and V_ISOIN directly with a ferrite bead. A ferrite bead is recommended between V_ISOOUTand V_ISOIN to further reduce emissions.

2) connect V_ISOOUT and V_ISOIN with a ferrite bead through an LDO that remains powered up at all times. If the LDO has an EN pin then keep the EN high at all times.

The input supply (V_IO and V_DD) must have an appropriate current rating to support output load and switching at the maximum data rate required by the end application. For more information, refer to the Section 10.2 section.

For an output load current of 110 mA, it is recommended to have >600 mA of input current limit and for lower output load currents, the input current limit can be proportionally lower.