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LTC3538 Datasheet, PDF (6/16 Pages) Linear Technology – 800mA Synchronous Buck-Boost DC/DC Converter
LTC3538
PIN FUNCTIONS
FB (Pin 1): Feedback Input to Error Amplifer. Connect
resistive divider tap from VOUT to this pin to set the output
voltage. The output voltage can be adjusted from 1.8V to
5.25V. Referring to the Block Diagram the output voltage
is given by:
VOUT = 1V • (1 + R1/R2)
VC (Pin 2): Error Amplifier Output. A frequency compensa-
tion network should be connected between this pin and FB
to compensate the loop. See Closing the Feedback Loop
section of the datasheet for further information. Pulling
VC below 0.25V disables the LTC3538.
GND (Pin 3): Ground.
BURST (Pin 4): Burst Mode Select Input.
BURST = Low for fixed frequency PWM operation
BURST = High for Burst Mode operation
VOUT (Pin 5): Power Supply Output. This pin should be
connected to a low ESR output capacitor. The capacitor
should be placed as close to the IC as possible and should
have a short return to GND.
SW2 (Pin 6): Switch Pin where the Internal Switches
C and D are Connected. An optional Schottky diode can
be connected from SW2 to VOUT for a moderate efficiency
improvement. Keep the trace length as short as possible
to minimize EMI.
SW1 (Pin 7): Switch Pin where the Internal Switches A and
B are Connected. Connect an inductor from SW1 to SW2.
An optional Schottky diode can be connected from SW1 to
ground for a moderate efficiency improvement. Keep the
trace length as short as possible to minimize EMI.
VIN (Pin 8): Input Supply. This input provides power to
the IC and also supplies current to switch A. A ceramic
bypass capacitor (4.7μF or larger) is recommended as
close to VIN and GND as possible.
Exposed Pad (Pin 9): GND. The exposed pad must be
electrically connected to the board ground for proper
electrical and thermal performance.
3538fb
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