4.2 Pin Description
Power Supply Input Voltage Pin (VIN)
The VIN pin is the input voltage for the buck converter power stage and internal circuitry. This pin is connected to the drain terminal of the internal high-side N-Channel MOSFET. A 10 μF minimum ceramic capacitor must be connected from the VIN to the GND pin, as close as possible to the device. A combination of multiple ceramic capacitors of different sizes is recommended.
Enable Pin (EN)
The EN pin is a logic-level input used to enable or disable the device switching and lower the quiescent current while disabled. To turn off the device, the EN pin must be pulled low. Do not leave this pin floating.
Feedback Voltage Pin (FB)
The FB pin is used to provide output voltage regulation by using a resistor divider. The VFB voltage will be 0.800V typical with the output voltage in regulation.
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 will go 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. The length of the trace from the input capacitor return, output capacitor return and GND pin must be made as short as possible to minimize the noise on the GND pin.
Boost Diode Pin (BD)
The BD pin is the anode of a diode, which is connected to the BOOST pin. The BD pin must be connected to a voltage output 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 is used to supply voltage for the driver of the high-side N-Channel power MOSFET. Connect the bootstrap capacitor to this pin.
Switch Node Pin (SW)
The switch node pin is connected internally to the source of the high-side N-channel MOSFET and externally to the SW node consisting of the inductor, Schottky diode and bootstrap capacitor. The external components must be placed as close as possible to the SW pin such that the switching node is minimized as much as possible.
Exposed Pad (EP)
The exposed pad is not electrically connected to the GND pin. Connect it with thermal vias to the ground plane to ensure adequate heat-sinking.