All trademarks are the property of their respective owners.
The LM2727 evaluation board has been designed for a wide variety of components in order to show the flexibility of the LM2727 chips. The input voltage limitations are the same as the chip: 2.2 VDC to 16 VDC. The regulated output voltage range is from 0.6 V up to 85% of the input voltage. Output current is limited by the components chosen, however, the size of this board and the limitation to SOIC-8 MOSFETs means a realistic limit of about 10 A.
The example design steps 12 V down to 3.3 V at 4 A, with a switching frequency of 800 kHz. This design can be modified by following the Design Considerations section of the LM2727/LM2737 N-Channel FET Synchronous Buck Regulator Controller for Low Output Voltages data sheet.
The board is four layers, consisting of signal/power traces on top and bottom, with one internal ground plane and an internal split power plane. All planes are 1-oz. copper, and the board is 62-mil FR4 laminate.
The default circuit that comes with the LM2727 demo board uses a bootstrap diode and small capacitor (D1 and CBOOT) to provide enough gate-to-source voltage on the high-side MOSFET to drive the FET. If a separate rail is available that is more than twice the value of VIN, this higher voltage can be connected directly to the BOOT pin, through the BOOT connector, with a 0.1-µF bypass capacitor, CC. In this case, D1 and CBOOT should be removed from the board. Do not connect both CC and CBOOT/D1 at the same time.