LTC3547B
6
3547bfb
PI FU CTIO S
UUU
V
FB1
(Pin 1): Regulator 1 Output Feedback. Receives
the feedback voltage from the external resistor divider
across the regulator 1 output. Nominal voltage for this
pin is 0.6V.
RUN1 (Pin 2): Regulator 1 Enable. Forcing this pin to
V
IN
enables regulator 1, while forcing it to GND causes
regulator 1 to shut down.
V
IN
(Pin 3): Main Power Supply. Must be closely decou-
pled to GND.
SW1 (Pin 4): Regulator 1 Switch Node Connection to the
Inductor. This pin swings from V
IN
to GND.
GND (Pin 5): Ground. Connect to the (–) terminal of C
OUT
,
and the (–) terminal of C
IN
.
SW2 (Pin 6): Regulator 2 Switch Node Connection to
the Inductor. This pin swings from V
IN
to GND.
RUN2 (Pin 7): Regulator 2 Enable. Forcing this pin to
V
IN
enables regulator 2, while forcing it to GND causes
regulator 2 to shut down.
V
FB2
(Pin 8): Regulator 2 Output Feedback. Receives
the feedback voltage from the external resistor divider
across the regulator 2 output. Nominal voltage for this
pin is 0.6V.
Exposed Pad (Pin 9): Electrically Connected to GND.
Must be soldered to the PCB for optimum thermal
performance.
–
+
–
+
EA
–
+
V
SLEEP
I
TH
SWITCHING
LOGIC
AND
BLANKING
CIRCUIT
S
R
Q
Q
RS
LATCH
PULSE SKIP
–
+
I
COMP
I
RCMP
ANTI
SHOOT-
THRU
SLOPE
COMP
SLEEP
0.6V REF OSC
OSC
REGULATOR 2 (IDENTICAL TO REGULATOR 1)
SHUTDOWN
REGULATOR 1
SW1
SW2
5Ω
3547 FD
1
2
7
8
RUN1
RUN2
V
FB2
V
FB1
4
V
IN
3
GND
5
6
0.6V
SOFT-START
FUNCTIONAL DIAGRAM