Datasheet

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