LTC3811_15 Datasheet, PDF (13/48 Pages) Linear Technology – High Speed Dual, Multiphase Step-Down DC/DC Controller

LTC3811
PIN FUNCTIONS
SENSE1^–, SENSE2^–: Negative Inputs to the Current
Comparators and Voltage Positioning g_m Amplifier. The
common mode input voltage range for the current com-
parators is 0V to 3.5V.
SW1, SW2: Bootstrapped Supply Return Paths for the
Topside Gate Drivers, Connected to the Sources of the
Upper Power MOSFETs.
SGND: Signal Ground Pin for the IC. Common to both
controllers, this pin should be connected to the negative
terminals of the V_OUT and INTV_CC decoupling capacitors
and should be routed separately from any high current
paths on the PC board.
SS/TRACK1, SS/TRACK2: Combined Soft-Start and Track-
ing Inputs. For soft-start operation, connecting a capacitor
from this pin to ground will control the voltage ramp at
the output of the power supply. An internal 2.5μA current
source will charge the capacitor and thereby control an
extra input on the reference side of the error amplifier. For
tracking operation, this input allows the start-up of a sec-
ondary output to track a primary output according to a ratio
established by a resistor divider from the primary output
to the secondary error amplifier track pin. For coincident
tracking of both outputs at start-up, a resistor divider with
values equal to those connected to the secondary FB pin
from the secondary output should be used to connect the
secondary track input from the primary output.
TG1, TG2: High Current Gate Driver Outputs for the
N-Channel Upper Power MOSFETs.
V_IN: Main Supply Input. A low ESR ceramic bypass capacitor
should be connected between this pin and SGND.
3811f
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