Datasheet

LT3493
6
3493fb
BLOCK DIAGRAM
PIN FUNCTIONS
FB (Pin 1): The LT3493 regulates its feedback pin to
780mV. Connect the feedback resistor divider tap to this
pin. Set the output voltage according to V
OUT
= 0.78V •
(1 + R1/R2). A good value for R2 is 10k.
GND (Pin 2): Tie the GND pin to a local ground plane
below the LT3493 and the circuit components. Return the
feedback divider to this pin.
BOOST (Pin 3): The BOOST pin is used to provide a drive
voltage, higher than the input voltage, to the internal bipolar
NPN power switch.
SW (Pin 4): The SW pin is the output of the internal power
switch. Connect this pin to the inductor, catch diode and
boost capacitor.
V
IN
(Pin 5): The V
IN
pin supplies current to the LT3493’s
internal regulator and to the internal power switch. This
pin must be locally bypassed.
SHDN (Pin 6): The SHDN pin is used to put the LT3493 in
shutdown mode. Tie to ground to shut down the LT3493.
Tie to 2.3V or more for normal operation. If the shutdown
feature is not used, tie this pin to the V
IN
pin. SHDN also
provides a soft-start function; see the Applications Infor-
mation section.
Exposed Pad (Pin 7): The Exposed Pad must be soldered
to the PCB and electrically connected to ground. Use a
large ground plane and thermal vias to optimize thermal
performance.
1
3
R
DRIVER
Q1
S
OSC
SLOPE
COMP
FREQUENCY
FOLDBACK
INT REG
AND
UVLO
V
C
g
m
780mV
3493 BD
2
5
6
Q
Q
3
4
BOOST
SW
FB
R2 R1
V
OUT
L1
D2
C3
C1
D1
V
IN
C2
V
IN
ON OFF
GND
C4
R3
SHDN
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