ltc3853euj Linear Technology Corporation, ltc3853euj Datasheet - Page 9

• Manufacturer Part Number: ltc3853euj
• Description: Triple Output, Multiphase Synchronous Step-down Controller
• Manufacturer: Linear Technology Corporation

TG1, TG2, TG3 (Pins 32, 26, 19): Top Gate Driver Outputs.
These are the outputs of fl oating drivers with a voltage
swing equal to INTV
voltages.
BOOST1, BOOST2, BOOST3 (Pins 33, 25, 18): Boosted
Floating Driver Supplies. The (+) terminal of the booststrap
capacitors connect to these pins. These pins swing from a
diode voltage drop below INTV
RUN1, RUN2, RUN3 (Pins 36, 35, 34): Run Control In-
puts. A voltage above 1.2V on any RUN pin turns on the
IC. However, forcing any of these pins below 1.2V causes
the IC to shut down the circuitry required for that particular
channel. There are 0.5μA pull-up currents for these pins.
Once the RUN pin rises above 1.2V, an additional 4.5μA
pull-up current is added to the pin.
MODE/PLLIN (Pin 37): Force Continuous Mode, Burst
Mode, or Pulse Skip Mode Selection Pin and External
Synchronization Input to Phase Detector Pin. Connect
this pin to SGND to force all channels into the continuous
mode of operation. Connect to INTV
skip mode of operation. Leaving the pin fl oating will en-
able Burst Mode operation. A clock on the pin will force
the controller into continuous mode of operation and
synchronize the internal oscillator.
PIN FUNCTIONS
CC
superimposed on the switch nodes
CC
up to V
CC
to enable pulse
IN
+ INTV
CC
.
FREQ/PLLFLTR (Pin 38): The phase-locked loop’s low-
pass fi lter is tied to this pin. Alternatively, this pin can
be driven with a DC voltage to vary the frequency of the
internal oscillator.
I
Inputs. This pin is to be programmed to SGND, FLOAT or
INTV
three different levels.
TK/SS1, TK/SS2, TK/SS3 (Pins 40, 1, 2): Output Voltage
Tracking and Soft-Start Inputs. When one particular channel
is confi gured to be the master, a capacitor to ground at
this pin sets the ramp rate for the master channel’s output
voltage. When the channel is confi gured to be the slave,
the V
resistor divider and applied to this pin. Internal soft-start
currents of 1.3μA are charging the soft-start capacitors.
In dual output (2 + 1) mode, TK/SS1 and TK/SS2 need to
be shorted externally.
Exposed Pad (Pin 41): Power Ground. Connect these pins
closely to the sources of the bottom N-channel MOSFETs,
the (–) terminal of C
LIM
(Pin 39): Current Comparator Sense Voltage Range
CC
FB
voltage of the master channel is reproduced by a
to set the maximum current sense threshold to
VCC
and the (–) terminal of C
LTC3853
IN
.
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