LTC3829_15 Datasheet, PDF (9/40 Pages) Linear Technology – 3-Phase, Single Output Synchronous Step-Down DC/DC Controller with Diffamp

LTC3829
PIN FUNCTIONS (UHF/FE)
ISET (Pin 15/Pin 17): Stage Shedding Comparator and
Burst Mode Comparator Programming Pin. A resistor to
ground programs the stage shedding comparator threshold
or Burst Mode comparator threshold and its current limit
depending on MODE pin setting.
I_LIM (Pin 16/Pin 18): Current Comparator Sense Voltage
Range Pin. This pin is to be programmed to SGND, FLOAT
or INTV_CC to set the maximum current sense threshold to
one of three different levels for each comparator.
PGOOD (Pin 17/Pin 19): Power Good Indicator Output.
Open-drain logic out that is pulled to ground when the
output exceeds ±10% regulation window after the internal
100µs power bad mask timer expires.
PLLIN (Pin 18/Pin 20): External Synchronization Pin. A
clock on the pin synchronizes the internal oscillator with
the clock on this pin.
EXTV_CC (Pin 23/Pin 25): External Power Input to an Inter-
nal Switch Connected to INTV_CC. This switch closes and
supplies the IC power, bypassing the internal low dropout
regulator, whenever EXTV_CC is higher than 4.7V. Do not
exceed 6V on this pin and ensure V_IN > V_EXTVCC at all times.
INTV_CC (Pin 24/Pin 26): Internal 5V Regulator Output. The
control circuits are powered from this voltage. Decouple
this pin to PGND with a minimum of 4.7µF low ESR tan-
talum or ceramic capacitor.
V_IN (Pin 25/Pin 27): Main Input Supply. Decouple this pin
to PGND with a capacitor (0.1µF to 1µF).
BG1, BG2, BG3 (Pins 30, 29, 22/Pins 32, 31, 24): Bot-
tom Gate Driver Outputs. These pins drive the gates of the
bottom N-channel MOSFETs between PGND and INTV_CC.
SW1, SW2, SW3 (Pins 31, 28, 21/Pins 33, 30, 23):
Switch Node Connections to Inductors. Voltage swing
at these pins is from a Schottky diode (external) voltage
drop below ground to V_IN.
TG1, TG2, TG3 (Pins 32, 27, 20/Pins 34, 29, 22): Top Gate
Driver Outputs. These are the outputs of floating drivers
with a voltage swing equal to INTV_CC superimposed on
the switch nodes voltages.
BOOST1, BOOST2, BOOST3 (Pins 33, 26, 19/Pins 35,
28, 21): Boosted Floating Driver Supplies. The (+) terminal
of the bootstrap capacitors connect to these pins. These
pins swing from a diode voltage drop below INTV_CC up
to V_IN + INTV_CC.
CLKOUT (Pin 34/Pin 36): Clock Output Pin. CLKOUT is
60° out of phase relative to channel 1 in non-shedding
mode. During stage shedding, CLKOUT is 180° out of
phase with channel 1.
MODE (Pin 35/Pin 37): Forced Continuous Mode, Burst
Mode or Shed Mode Selection Pin. Connect this pin to
SGND to force IC in continuous mode of operation. Con-
nect to INTV_CC to enable shed mode operation. Leave the
pin floating to enable Burst Mode operation.
IFAST (Pin 36/Pin 38): Programmable Pin for Nonlinear
Control Trip Threshold. A resistor to ground programs the
tripping threshold for nonlinear control circuit. Connect
this pin to INTV_CC to disable this feature. See Applications
Information section for details. Leave this pin floating
when it is not used.
ITEMP (Pin 37/Pin 1): Input of the Temperature Sensing
Comparator. Connect this pin to external NTC resistors
placed near inductors.
DIFFOUT (Pin 38/Pin 2): Output of Remote Sensing
Differential Amplifier. Connect this pin to V_FB through a
resistive divider.
SGND/PGND (Exposed Pad Pin 39/Exposed Pad Pin 39):
Combined Signal and Power Ground Pad. Connect this pad
closely to the sources of the bottom N-channel MOSFETs,
the (–) terminal of C_VCC and the (–) terminal of C_IN. All
small-signal components and compensation components
should also Kelvin-connect to this pad.
For more information www.linear.com/LTC3829
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