The evaluation circuit EVAL-LT8390A-AZ is a synchronous 4-switch buck-boost controller featuring the LT8390A and 4 EPC GaN FETs. This circuit outputs 24V and maintains tight regulation with up to 5A load current and over an input voltage from 8V to 60V. 2MHz switching frequency provides a small footprint using a single 6mm x 6mm x 6mm inductor while maintaining high efficiency.
The LT8390A features a 5V gate driver that is used to safely drive GaNFETs. Additionally, the EVAL-LT8390A-AZ board features external clamping circuitry around the bootstrap capacitors to guarantee that the gate drive of the top FETs is driven under the absolute maximum gate-to-source voltage of the GaNFET. Additionally, Schottky diodes are placed anti-parallel to the synchronous GaNFETs to help with reverse conduction during the LT8390A’s 25ns dead time.
The LT8390A has a wide input voltage range from 4V to 60V. It can regulate an output as a boost, a buck, or a 4-switch boost-buck controller. It has an adjustableswitching frequency between 600kHz and 2MHz. It has anoption for external frequency synchronization or spreadspectrum frequency modulation. Its high switchingfrequency is unique to buck-boost controller ICs. Becauseof this, it can be used for high power when the input maybe above, below, or equal to the output.
The LT8390A data sheet gives a complete description of the part, operation, and applications information. The data sheet must be read in conjunction with this user guide. The LT8390AJUFD is assembled in a 28-lead 4mm x 5mm plastic QFN package with a thermally enhanced ground pad. LT8390A is also available in a 28-Lead plastic TSSOP (FE) package. Proper board layout is essential for maximum thermal performance. Refer to the data sheet PC Board Layout Checklist section for more details.
Design files for this circuit board are available at Product Evaluation Boards and Kits | Design Center | Analog Devices.
