LTC3547 Datasheet, PDF (6/16 Pages) Linear Technology – Dual Monolithic 300mA Synchronous Step-Down Regulator

LTC3547
PI FU CTIO S
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.
FUNCTIONAL DIAGRAM
REGULATOR 1
V_{FB1 1}
–
I_TH
EA
+
0.6V
SOFT-START
BURST
CLAMP
SLOPE
COMP
–
SLEEP
V_SLEEP +
BURST
S
Q
RS
LATCH
R
Q
SWITCHING
LOGIC
AND
BLANKING
CIRCUIT
–+
I_COMP
ANTI
SHOOT-
THRU
3 V_IN
5Ω
4 SW1
SHUTDOWN
RUN1 2
RUN2 7
V_FB2 8
0.6V REF
OSC
OSC
REGULATOR 2 (IDENTICAL TO REGULATOR 1)
6
I_RCMP
SLEEP2
SLEEP1
5 GND
3547 FD
6 SW2
3547fa