lt3503edcb-trpbf Linear Technology Corporation, lt3503edcb-trpbf Datasheet - Page 6

• Manufacturer Part Number: lt3503edcb-trpbf
• Description: 1a, 2.2mhz Step-down Switching Regulator In 2mm X 3mm Dfn
• Manufacturer: Linear Technology Corporation

ON OFF
LT3503
PI FU CTIO S
FB (Pin 1): The LT3503 regulates its feedback pin to
780mV. Connect the feedback resistor divider tap to this
pin. Set the output voltage according to:
A good value for R2 is 10.0k.
GND (Pin 2): Tie the GND pin to a local ground plane below
the LT3503 and the circuit components. Return the feed-
back 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.
BLOCK DIAGRA
6
V
R
U
IN
1
=
R
2
R3
C2
C4
U
⎛
⎝ ⎜
0 78
5
6
V
.
OUT
V
SHDN
IN
V
–
U
1
⎞
⎠ ⎟
INT REG
UVLO
AND
W
OSC
SLOPE
FREQUENCY
FOLDBACK
COMP
Σ
2
V
GND
C
g
m
R
S
Q
Q
780mV
V
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 LT3503 in
shutdown mode. Tie to ground to shut down the LT3503.
Tie to 2.3V or more for normal operation. If the shutdown
feature is not used, tie this pin to the V
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.
IN
R2
(Pin 5): The V
1
FB
R1
DRIVER
IN
pin supplies current to the LT3503’s
Q1
BOOST
SW
3
4
IN
D1
pin. SHDN also
C3
D2
L1
C1
3503 BD
3503f
V
OUT