LTC3829 Datasheet, PDF (9/40 Pages) Linear Technology – 3-Phase, Single Output Synchronous Step-Down DC/DC Controller with Diffamp

LTC3829
Pin Functions (UHF/FE)
DIFFN (Pin 1/Pin 3): Negative Input of Remote Sensing
Differential Amplifier. Connect this to the remote load
ground pin.
DIFFP (Pin 2/Pin 4): Positive Input of Remote Sensing
Differential Amplifier. Connect this to the remote load
positive terminal directly.
RUN (Pin 3/Pin 5): Run Control Input. A voltage above
1.22V on this pin turns on the IC. There is a 1.0µA pull-up
current for this pin. Once the RUN pin rises above 1.22V,
an additional 4.5µA pull-up current is added to the pin.
AVP (Pin 4/Pin 6): Active Voltage Positioning Load Slope
Programming Pin. A resistor tied between this pin and the
DIFFP pin sets the load slope.
SENSE1⁺, SENSE2⁺, SENSE3⁺ (Pins 5, 7, 11/Pins 7, 9,
13): Current Sense Comparator Inputs. The (+) inputs to
the current comparators are normally connected to DCR
sensing networks or current sensing resistors.
SENSE1^–, SENSE2^–, SENSE3^– (Pins 6, 8, 12/Pins 8, 10,
14): Current Sense Comparator Inputs. The (–) inputs to
the current comparators are connected to the output.
TK/SS (Pin 9/Pin 11): Output Voltage Tracking and Soft-
Start Input. When one particular IC is configured to be the
master of two ICs, a capacitor to ground at this pin sets
the ramp rate for the master IC’s output voltage. When the
IC is configured to be the slave of two ICs, the V_FB voltage
of the master IC is reproduced by a resistor divider and
applied to this pin. An internal soft-start current of 1.25µA
is charging this pin.
FREQ (Pin 10/Pin 12): There is a precision 10µA current
sourced out of this pin. A resistor to ground sets a voltage
which in turn programs the frequency. Alternatively, this
pin can be driven with a DC voltage to vary the frequency
of the internal oscillator.
V_FB (Pin 13/Pin 15): Error Amplifier Feedback Input. This
pin receives the remotely sensed feedback voltage from
an external resistive divider.
I_TH (Pin 14/Pin 16): Current Control Threshold and Error
Amplifier Compensation Point. Each associated channels’
current comparator tripping threshold increases with this
I_TH control voltage.
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
Internal 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): Bottom
Gate Driver Outputs. These pins drive the gates of the bot-
tom 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.
3829f