Datasheet

LTC3890-1
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BG1, BG2 (Pin 23, Pin 18): High Current Gate Drives
for Bottom (Synchronous) N-Channel MOSFETs. Voltage
swing at these pins is from ground to INTV
CC
.
BOOST1, BOOST2 (Pin 24, Pin 17): Bootstrapped Supplies
to the Topside 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 BOOST pins is from INTV
CC
to (V
IN
+ INTV
CC
).
SW1, SW2 (Pin 25, Pin 16): Switch Node Connections
to Inductors.
TG1, TG2 (Pin 26, Pin 15): High Current Gate Drives for
Top N-Channel MOSFETs. These are the outputs of float-
ing drivers with a voltage swing equal to INTV
CC
– 0.5V
superimposed on the switch node voltage SW.
PIN FUNCTIONS
PGOOD1 (Pin 27): Open-Drain Logic Output. PGOOD1 is
pulled to ground when the voltage on the V
FB1
pin is not
within ±10% of its set point.
TRACK/SS1, TRACK/SS2 (Pin 28, Pin 14): External Track-
ing and Soft-Start Input. The LTC3890-1 regulates the
V
FB1,2
voltage to the smaller of 0.8V or the voltage on the
TRACK/SS1,2 pin. An internal 1µA pull-up current source
is connected to this pin. A capacitor to ground at this
pin sets the ramp time to final regulated output voltage.
Alternatively, a resistor divider on another voltage supply
connected to this pin allows the LTC3890-1 output to track
the other supply during start-up.