Datasheet LTC3812-5 (Analog Devices) - 9

LTC3812-5
PIN FUNCTIONS EXTVCC (Pin 10):
External Driver Supply Voltage. When
SW (Pin 14):
Switch Node Connection to Inductor and this voltage exceeds 4.2V, an internal switch connects Bootstrap Capacitor. Voltage swing at this pin is from a this pin to INTVCC through an LDO and turns off the exter- Schottky diode (external) voltage drop below ground nal MOSFET connected to NDRV, so that controller and to VIN. gate drive are drawn from EXTVCC.
TG (Pin 15):
Top Gate Drive. The TG pin drives the gate of
INTVCC (Pin 11):
Main Supply and Driver Supply Pin. All the top N-channel synchronous switch MOSFET. The TG internal circuits and bottom gate output driver are powered driver draws power from the BOOST pin and returns to the from this pin. INTVCC should be bypassed to SGND and SW pin, providing true fl oating drive to the top MOSFET. PGND with a low ESR (X5R or better) 1μF capacitor in
BOOST (Pin 16):
Top Gate Driver Supply. The BOOST pin close proximity to the LTC3812-5. supplies power to the fl oating TG driver. BOOST should
BG (Pin 12):
Bottom Gate Drive. The BG pin drives the be bypassed to SW with a low ESR (X5R or better) 0.1μF gate of the bottom N-channel synchronous switch MOSFET. capacitor. An additional fast recovery Schottky diode from This pin swings from PGND to INTVCC. INTVCC to the BOOST pin will create a complete fl oating charge-pumped supply at BOOST.
PGND (Pin 13):
Bottom Gate Return. This pin connects to the source of the pull-down MOSFET in the BG driver
GND (Exposed Pad Pin 17):
Ground. The Exposed Pad and is normally connected to ground. must be soldered to PCB ground. 38125fc 9