Datasheet

LTC3789
10
3789fa
pin FuncTions
(SSOP/QFN)
INTV
CC
(Pin 21/Pin 18): Output of the Internal Linear Low
Dropout Regulator. The driver and control circuits are
powered from this voltage source. Must be bypassed to
power ground with a minimum of 4.7µF tantalum, ceramic,
or other low ESR capacitor.
V
IN
(Pin 22/Pin 19): Main Supply Pin. A bypass capa-
citor should be tied between this pin and the signal
ground pin.
BG1, BG2 (Pins 23, 19/Pins 20, 16): High Current
Gate Drives for Bottom (Synchronous) N-Channel
MOSFETs. Voltage swing at these pins is from ground to
INTV
CC
.
PGND (Pin 24/Pin 21): Driver Power Ground. Connects
to C
OUT
and R
SENSE
(–) terminal(s) of C
IN
.
BOOST1, BOOST2 (Pins 25, 18/Pins 22, 15): Bootstrapped
Supplies to the Top Side Floating Drivers. Capacitors
are connected between the BOOST and SW pins and
Schottky diodes are tied between the BOOST and INTV
CC
pins. Voltage swing at the BOOST1 pin is from INTV
CC
to (V
IN
+ INTV
CC
). Voltage swing at the BOOST2 pin is
from INTV
CC
to (V
OUT
+ INTV
CC
).
TG1, TG2 (Pins 26, 17/Pins 23, 14): High Current
Gate Drives for Top N-Channel MOSFETs. These are the
outputs of floating drivers with a voltage swing equal
to INTV
CC
– 0.5V superimposed on the switch node
voltage SW.
SW1, SW2 (Pins 27, 16/Pins 24, 13): Switch Node
Connections to Inductors. Voltage swing at the SW1
pin is from a Schottky diode (external) voltage drop
below ground to V
IN
. Voltage swing at the SW2 pin is
from a Schottky diode voltage drop below ground to
V
OUT
.
PGOOD (Pin 28/Pin 25): Open-Drain Logic Output.
PGOOD is pulled to ground when the voltage on the V
FB
pin is not within ±10% of its regulation window, after the
internal 20µs power-bad mask timer expires.