LTC1871 Linear Technology, LTC1871 Datasheet - Page 6

• Manufacturer Part Number: LTC1871
• Description: Wide Input Range/ No RSENSE Current Mode Boost/ Flyback and SEPIC Controller
• Manufacturer: Linear Technology

RUN (Pin 1): The RUN pin provides the user with an
accurate means for sensing the input voltage and pro-
gramming the start-up threshold for the converter. The
falling RUN pin threshold is nominally 1.248V and the
comparator has 100mV of hysteresis for noise immunity.
When the RUN pin is below this input threshold, the IC is
shut down and the V
value (typ 10 A). The Absolute Maximum Rating for the
voltage on this pin is 7V.
I
rent comparator input threshold increases with this
control voltage. Nominal voltage range for this pin is 0V
to 1.40V.
FB (Pin 3): Receives the feedback voltage from the
external resistor divider across the output. Nominal
voltage for this pin in regulaton is 1.230V.
FREQ (Pin 4): A resistor from the FREQ pin to ground
programs the operating frequency of the chip. The nomi-
nal voltage at the FREQ pin is 0.6V.
MODE/SYNC (Pin 5): This input controls the operating
mode of the converter and allows for synchronizing the
LTC1871
PI FU CTIO S
6
TH
U
(Pin 2): Error Amplifier Compensation Pin. The cur-
U
U
IN
supply current is kept to a low
operating frequency to an external clock. If the MODE/
SYNC pin is connected to ground, Burst Mode operation
is enabled. If the MODE/SYNC pin is connected to INTV
or if an external logic-level synchronization signal is
applied to this input, Burst Mode operation is disabled
and the IC operates in a continuous mode.
GND (Pin 6): Ground Pin.
GATE (Pin 7): Gate Driver Output.
INTV
gate driver and control circuits are powered from this
voltage. Decouple this pin locally to the IC ground with a
minimum of 4.7 F low ESR tantalum or ceramic
capacitor.
V
to ground.
SENSE (Pin 10): The Current Sense Input for the Control
Loop. Connect this pin to the drain of the power MOSFET
for V
SENSE pin may be connected to a resistor in the source
of the power MOSFET. Internal leading edge blanking is
provided for both sensing methods.
IN
(Pin 9): Main Supply Pin. Must be closely decoupled
DS
CC
(Pin 8): The Internal 5.20V Regulator Output. The
sensing and highest efficiency. Alternatively, the
CC
,