Datasheet

LTC3548A
6
3548afa
PIN FUNCTIONS
V
FB1
(Pin 1): Output Feedback. Receives the feedback volt-
age from the external resistive divider across the output.
Nominal voltage for this pin is 0.6V.
RUN/SS1 (Pin 2): Regulator 1 Enable and Soft-Start Input.
Forcing this pin to V
IN
enables regulator 1, while forcing it
to GND causes regulator 1 to shut down. Connect external
RC network with desired time-constant to enable soft-start
feature. This pin must be driven; do not float.
V
IN
(Pin 3): Main Power Supply. Must be closely decoupled
to GND.
SW1 (Pin 4): Regulator 1 Switch Node Connection to the
Inductor. This pin swings from V
IN
to GND.
NC (Pin 5): No Connect. This pin is not connected inter-
nally. Connect to ground on PCB for shielding purposes.
MODE/SYNC (Pin 6): Combination Mode Selection and
Oscillator Synchronization. This pin controls the opera-
tion of the device. When tied to V
IN
or GND, Burst Mode
operation or pulse-skipping mode is selected, respectively.
Do not float this pin. The oscillation frequency can be
synchronized to an external oscillator applied to this pin
and pulse-skipping mode is automatically selected.
SW2 (Pin 7): Regulator 2 Switch Node Connection to the
Inductor. This pin swings from V
IN
to GND.
POR (Pin 8): Power-On Reset. This common-drain logic
output is pulled to GND when the output voltage is not
within ±8.5% of regulation and goes high after 2
16
clock
cycles when both channels are within regulation.
RUN/SS2 (Pin 9): Regulator 2 Enable and Soft-Start Input.
Forcing this pin to V
IN
enables regulator 2, while forcing it
to GND causes regulator 2 to shut down. Connect external
RC network with desired time-constant to enable soft-start
feature. This pin must be driven; do not float.
V
FB2
(Pin 10): Output Feedback. Receives the feedback
voltage from the external resistive divider across the output.
Nominal voltage for this pin is 0.6V.
Exposed Pad (GND) (Pin 11): Power Ground. Connect to
the (–) terminal of C
OUT
, and (–) terminal of C
IN
. Must be
soldered to electrical ground on PCB.