Datasheet

LTC1877
6
1877fb
PIN FUNCTIONS
RUN (Pin 1): Run Control Input. Forcing this pin below
0.4V shuts down the LTC1877. In shutdown, all functions
are disabled drawing <1μA supply current. Forcing this
pin above 1.2V enables the LTC1877. Do not leave RUN
fl oating.
I
TH
(Pin 2): Error Amplifi er Compensation Point. The current
comparator threshold increases with this control voltage.
Nominal voltage range for this pin is from 0.5V to 1.9V.
V
FB
(Pin 3): Feedback Pin. Receives the feedback voltage
from an external resistive divider across the output.
GND (Pin 4): Ground Pin.
SW (Pin 5): Switch Node Connection to Inductor. This pin
connects to the drains of the internal main and synchronous
power MOSFET switches.
V
IN
(Pin 6): Main Supply Pin. Must be closely decoupled
to GND, Pin 4.
SYNC/MODE (Pin 7): External Clock Synchronization
and Mode Select Input. To synchronize with an external
clock, apply a clock with a frequency between 400kHz
and 700kHz. To select Burst Mode operation, tie to V
IN
.
Grounding this pin selects pulse-skipping mode. Do not
leave this pin fl oating.
PLL LPF (Pin 8): Output of the Phase Detector and Control
Input of Oscillator. Connect a series RC lowpass network
from this pin to ground if externally synchronized. If un-
used, this pin may be left open.