In the case where FPWM mode is desired, the conversion from LM61440AFS-Q1 to LM62440APP-Q1 will require a layout change. This is because the change from the LM614xx to the LM624xx requires the resistor (RT resistor for LM614xx and MODE resistor for LM624xx) on Pin 6 to be connected to VIN or an external high voltage for the FPWM mode feature. To have a future-proof PCB layout that enables easy interchange between LM614xx to LM624xx, a top RT resistor between Pin 6 to VIN can be left DNP on the board.

If the FPWM variant of the LM614xx is used then that top RT resistor will be DNP. Alternatively if the LM624xx is used and FPWM mode is required then the bottom MODE resistor to GND is left DNP and the top MODE resistor to VIN is populated. For the case of Auto mode, the Auto mode variant of the LM614xx is used and the bottom RT resistor is populated to set the output voltage. Alternatively if the LM624xx is used and Auto mode is required then the top MODE resistor is left DNP and the bottom MODE resistor is populated.