LTC3813 Datasheet, PDF (9/32 Pages) Linear Technology – 100V Current Mode Synchronous Step-Up Controller

LTC3813
PIN FUNCTIONS
BG (Pin 19): Bottom Gate Drive. The BG pin drives the
gate of the bottom N-channel main switch MOSFET. This
pin swings from BGRTN to DRV_CC.
BGRTN (Pin 20): Bottom Gate Return. This pin connects to
the source of the pulldown MOSFET in the BG driver and
is normally connected to ground. Connecting a negative
supply to this pin allows the main MOSFET’s gate to be
pulled below ground to help prevent false turn-on during
high dV/dt transitions on the SW node. See the Applica-
tions Information section for more details.
SENSE⁺, SENSE^– (Pin 25, Pin 21): Current Sense Com-
parator Input. The (+) input to the current comparator is
normally connected to SW unless using a sense resistor.
The (–) input is used to accurately kelvin sense the bottom
side of the sense resistor or MOSFET.
SW (Pin 26): Switch Node Connection to Inductor and
Bootstrap Capacitor. Voltage swing at this pin is from a
Schottky diode (external) voltage drop below ground
to V_OUT.
TG (Pin 27): Top Gate Drive. The TG pin drives the gate of
the top N-channel synchronous switch MOSFET. The TG
driver draws power from the BOOST pin and returns to the
SW pin, providing true floating drive to the top MOSFET.
BOOST (Pin 28): Top Gate Driver Supply. The BOOST pin
supplies power to the floating TG driver. BOOST should
be bypassed to SW with a low ESR (X5R or better) 0.1μF
capacitor. An additional fast recovery Schottky diode from
DRV_CC to the BOOST pin will create a complete floating
charge-pumped supply at BOOST.
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