LTC3543_15 Datasheet, PDF (7/20 Pages) Linear Technology – 600mA Synchronous Step Down Buck Regulator with PLL, Soft-Start and Spread Spectrum

LTC3543
PIN FUNCTIONS
SW (Pin 1): Switch Node Connector to Inductor. This pin
connects to the drains of the internal main and synchronous
power MOSFET switches.
CAP (Pin 2): Capacitor used for smoothing out spread
spectrum or for PLL response. Connect to a capacitor
whose other plate is connected to GND, or allow the pin
to float. Value = 1nF – 10nF.
MODE (Pin 3): Mode Selection Pin. Connect as follows
to invoke desired operation: MODE = GND → Burst Mode
operation, MODE = V_FB → Pulse skip with spread spec-
trum, MODE = V_IN → Pulse skip, MODE = External clock
→ PLL mode.
V_FB (Pin 4): Feedback sensing pin for the external feedback
resistors.
RUN (Pin 5): Run Control Input. Forcing pin above 1.5V
enables the part. Forcing the pin below 0.3V shuts down
the device. In shutdown, all functions are disabled,
drawing <1μA of supply current. Do not leave the RUN
pin floating.
V_IN (Pin 6): Main Supply Pin.
Exposed Pad (Pin 7): Exposed Pad connected to
ground.
FUNCTIONAL DIAGRAM
V_OUT
R2
V_FB
4
R1
CAP
2
C1
MODE ₃
RUN 5
EA
PEAK CURRENT LEVEL REF
0.6V
RS
V_IN
6
V_IN
C_IN
OSC
SQ
R QB
I_COMP
LOGIC
PLL
SPREAD
SPECTRUM
MODE SELECT
BURST
I_RCMP
BP
MAIN
L
L
SYNCHRONOUS
SW _L
1
7
GND
3543 FD
V_OUT
C_OUT
3543fa
7