LTC3549 Datasheet, PDF (7/16 Pages) Linear Technology – 250mA Low VIN Buck Regulator in 2mm × 3mm DFN

LTC3549
PI FU CTIO S
V_IN (Pin 1): Main Supply Pin. Must be closely decoupled
to GND, Pins 2 and 7, with a 4.7µF or greater ceramic
capacitor.
GND (Pin 2): N/C. Ground this pin.
SW (Pin 3): Switch Node Connection to Inductor. This pin
connects to the drains of the internal main and synchronous
power MOSFET switches.
MODE (Pin 4): Mode Select Input. To select pulse-skip-
ping mode, force this pin above 1.1V. Forcing this pin
below 0.3V selects Burst Mode operation. Do not leave
MODE floating.
RUN (Pin 5): Run Control Input. Forcing this pin above 1.1V
enables the part. Forcing this pin below 0.3V shuts down
the device. In shutdown, all functions are disabled drawing
<1µA supply current. Do not leave RUN floating.
V_FB (Pin 6): Feedback Pin. Receives the feedback voltage
from an external resistive divider across the output.
GND (Pin 7): Exposed Pad. The Exposed Pad is ground. It
must be soldered to PCB ground to provide both electrical
contact and optimum thermal performance.
W
FU CTIO AL DIAGRA
MODE
4
OSCILLATOR
SLOPE
COMP
OSC
V_FB
6
+
0.611V _–
EA
SOFT-
START
V_IN
RUN
5
REFERENCE
+
OV
OVDET
0.671 –
SHUTDOWN
0.65V
EN
–
SLEEP
0.4V
+
BURST
I_COMP
SQ
RQ
RS LATCH
SWITCHING
LOGIC
AND
BLANKING
CIRCUIT
ANTI-
SHOOT-
THRU
I_RCMP
1 V_IN
5Ω
3 SW
2 GND
7 GND
3549 FD
3549f
7