NDRV pulse magnitude can be increased by connecting an external supply at the INTVCC pin. When an external source >=8V is connected to INTVCC, internal LDO turns off and the MAX17690 will be supplied from the external voltage source. The recommended external source should be between 8V and 16V. Connecting an external source at INTVCC will improve the overall system efficiency as the Internal INTVCC LDO is turned off.
The external voltage can be supplied by using an extra auxiliary winding on the main power transformer. Ensure that the applied voltage is always within 16V.