ZHCSLW2C September 2021 – April 2022 ISOW7740 , ISOW7741 , ISOW7742 , ISOW7743 , ISOW7744
PRODUCTION DATA
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. VISOOUT needs to be connected to VISOIN to ensure the feedback channel is properly powered to regulate the DC-DC converter. If VISOOUT and VISOIN are not connected, the DC-DC converter will run open loop and the VISOOUT voltage will drift until the over-voltage clamp clamps at 6 V. There are two ways to connect VISOOUTand VISOIN:
1) connect VISOOUT and VISOIN directly with a ferrite bead. A ferrite bead is recommended between VISOOUTand VISOIN to further reduce emissions.
2) connect VISOOUT and VISOIN 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 (VIO and VDD) 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.