4.2 Pin Description
Power Supply Input Voltage Pin (VIN)
The VIN pin supplies voltage to both the buck converter power stage and the internal circuitry. It is connected to the drain terminal of the internal high-side N-Channel MOSFET. A minimum 10 µF ceramic capacitor must be placed as close as possible between VIN and GND. For optimal performance, a combination of multiple ceramic capacitors of varying sizes is recommended.
Enable Pin (EN)
The EN pin is a logic-level input used to enable or disable the device operation, reducing quiescent current when disabled. To turn off the device, pull the EN pin low. Do not leave this pin floating.
Feedback Voltage Pin (FB)
The FB pin is used to provide output voltage regulation via a resistor divider. When the output is in regulation, the typical feedback voltage (VFB) is 0.800V.
Power Good Output Pin (PG)
The PG pin is the drain connection of an internal N-channel FET. When the output voltage is within 93% of the nominal set point, this pin transitions from logic-low to logic-high (through an external pull-up resistor).
Ground Pin (GND)
The ground or return pin is used for circuit ground connection. To minimize noise, keep the trace lengths from the input capacitor return, output capacitor return, and GND pin as short as possible.
Boost Diode Pin (BD)
The BD pin is the anode of a diode, which is connected to the BOOST pin. It must be connected to a voltage source between 3V and 5.5V. If the output voltage of the converter is set between these values, connecting the BD pin to the output is recommended.
Boost Pin (BOOST)
The BOOST pin supplies voltage to the driver of the high-side N-Channel power MOSFET. Connect a bootstrap capacitor to this pin.
Switch Node Pin (SW)
The SW pin is internally connected to the source of the high-side N-channel MOSFET and externally to the switching node, which includes the inductor, Schottky diode, and bootstrap capacitor. Place these external components as close as possible to the SW pin to minimize the size of the switching node.
Exposed Pad (EP)
The exposed pad is not electrically connected to the GND pin. Connect with thermal vias to the ground plane to ensure adequate heat-sinking.