LTC3622-2_15 Datasheet, PDF (8/24 Pages) Linear Technology – 17V, Dual 1A Synchronous Step-Down Regulator with Ultralow Quiescent Current

LTC3622/
LTC3622-2/LTC3622-23/5
Pin Functions (DFN/MSOP)
VIN1 (Pin 1/Pin 1): Input Voltage of Channel 1 Step-Down
Regulator. This input also powers the INTV_CC LDO.
PGOOD1 (Pin 2/Pin 3): Open Drain Power Good Indicator
for Channel 1.
MODE/SYNC (Pin 3/Pin 4): Burst Mode Select and External
Clock Synchronization of the Step-Down Regulator. Tie
MODE/SYNC to INTV_CC for Burst Mode operation with a
400mA peak current clamp. Tie MODE/SYNC to GND for
pulse-skipping operation. Furthermore, connecting this pin
to an external clock will synchronize the switch clock to
the external clock and put the part in pulse-skipping mode.
PHASE (Pin 4/Pin 5): Phase Select Pin. Tie this pin to
ground to run the regulators in phase (0° phase shift)
between SW rising edge of channel 1 and channel 2. Tie
this pin to INTV_CC to set 180° phase shift between chan-
nels. When this pin is high, the phase shift may also be
set by modulating the duty cycle of external clock on the
MODE/SYNC pin (channel 1 edge synced to rising edge
of external clock, channel 2 edge synced to falling edge of
external clock). See Applications Section for more details.
PGOOD2 (Pin 5/Pin 6): Open Drain Power Good Indicator
for Channel 2.
ILIM (Pin 6/Pin 7): Current Limit Select Pin. Tying this pin
to ground sets the full current limit for both channels. Tying
this pin to INTV_CC drops the current limit by a factor of 2
for both channels. Biasing this pin to 1V sets the current
on channel 1 to be the full amount, and the current on
channel 2 to be dropped by a factor of 2.
VIN2 (Pin 7/Pin 8): Input Voltage of Channel 2 Step-Down
Regulator. May be a different voltage than V_IN1.
SW2 (Pin 8/Pin 9): Switch Node Connection to the Induc-
tor of Channel 2 Step-Down Regulator.
RUN2 (Pin 9/Pin 10): Logic Controlled RUN Input to Chan-
nel 2. Do not leave this pin floating. Logic high activates
the step-down regulator.
FB2 (Pin 10/Pin 11): Feedback Input to the Error Amplifier
of Channel 2 Step-Down Regulator. Connect resistor divider
tap to this pin. The output voltage can be adjusted from
0.6V to V_IN by: V_OUT = 0.6V • [1 + (R2/R1)]. (Figure 2) For
fixed V_OUT options, connect the FB pin directly to V_OUT.
INTV_CC (Pin 11/Pin 12): Low Dropout Regulator. Bypass
with a low ESR capacitor of at least 1µF to ground.
FB1 (Pin 12/Pin 13): Feedback Input to the Error Amplifier
of Channel 1 Step-Down Regulator. Connect resistor divider
tap to this pin. The output voltage can be adjusted from
0.6V to V_IN by: V_OUT = 0.6V • [1 + (R2/R1)]. (Figure 2) For
fixed V_OUT options, connect the FB pin directly to V_OUT.
RUN1 (Pin 13/Pin 14): Logic Controlled RUN Input to
Channel 1. Do not leave this pin floating. Logic high acti-
vates the step-down regulator.
SW1 (Pin 14/Pin 16): Switch Node Connection to the
Inductor of Channel 1 Step-Down Regulator.
GND (Pin 15/Pin 17): Ground for Power and Signal Ground.
The exposed pad must be connected to PCB ground for
rated electrical and rated thermal performance.
SV_IN (NA/Pin 2): Signal V_IN Pin. This input powers the
INTV_CC. May be a different voltage than either V_IN1 or
V_IN2. Connect SV_IN to either V_IN1 or V_IN2 , whichever one
is higher. For applications where it is not known which
V_IN is higher, connect external diode between SV_IN to both
V_IN1 and V_IN2 to ensure that SV_IN is less than a diode drop
from the higher of V_IN1 or V_IN2.
3622fa
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