LT8647

• 5.6V–65V Operating Input Voltage
  • Reduced EMI emissions for CISPR 32 Class B
• Delivers up to 7A (Maximum Continuous) and 8A (Peak Transient) Output Current
• Configurable SYNC pin for Pulse-skipping Mode, Burst Mode, Spread Spectrum, and external Frequency Synchronization
• Optional Transient Response Circuit
• Optimized PCB Layout

Demonstration circuit EVAL-LT8647-AZ is a 65V, 7A micropower synchronous step-down Silent Switcher^® with spread spectrum frequency modulation featuring the LT8647. The demo board is designed for a 5V output from a 5.6V to 65V input. The wide input range allows a variety of input sources, such as industrial supplies. The LT8647 is a compact, ultralow-emission, high-efficiency, and high-speed synchronous monolithic step-down switching regulator.- The integrated power switches and inclusion of all necessary circuitry reduce the component count and solution size. Special Silent Switcher architecture minimizes Electromagnetic interference (EMI) /Electromagnetic compatibility (EMC) emissions. Selectable spread spectrum mode can further improve EMI/EMC performance. Ultralow 2.5μA quiescent current in Burst Mode® operation achieves high efficiency at very light loads. A fast minimum on-time of 40ns enables high V_IN to low V_OUT conversion at high frequency.

The LT8647 switching frequency can be programmed via an oscillator resistor or external clock over a 200kHz to 2.2MHz range. The default frequency of the demo circuit EVAL-LT8647-AZ is 2MHz. The SYNC pin on the demo board is grounded (JP1 at BURST position) by default for low ripple Burst Mode operation. Spread spectrum mode and pulse-skipping mode can be selected, respectively, by moving the JP1 shunt. To synchronize to an external clock, move JP1 to SYNC and apply the external clock to the SYNC terminal.

The LT8647 data sheet gives a complete description of the part, operation, and application information. The data sheet must be read in conjunction with this demo manual for the demo circuit EVAL-LT8647-AZ. The LT8647 is assembled in a 3mm × 6mm, Flip chip 2 quad flat no-lead (FC2QFN) package with exposed pads for low thermal resistance. The layout recommendations for low EMI operation and maximum thermal performance are available in the data sheet section Low EMI Printed circuit board (PCB) Layout and Thermal Considerations.

Design files for this circuit board are available at Product Evaluation Boards and Kits | Design Center | Analog Devices.