LT1933 Linear Technology, LT1933 Datasheet - Page 5

• Manufacturer Part Number: LT1933
• Description: 600mA 500kHz Step-Down Switching Regulator in SOT-23
• Manufacturer: Linear Technology

BLOCK DIAGRA
PI FU CTIO S
BOOST (Pin 1): The BOOST pin is used to provide a drive
voltage, higher than the input voltage, to the internal
bipolar NPN power switch.
GND (Pin 2): Tie the GND pin to a local ground plane below
the LT1933 and the circuit components. Return the feed-
back divider to this pin.
FB (Pin 3): The LT1933 regulates its feedback pin to
1.245V. Connect the feedback resistor divider tap to this
pin. Set the output voltage according to V
(1 + R1/R2). A good value for R2 is 10k.
ON OFF
V
U
IN
R3
C2
C4
U
5
4
V
SHDN
IN
U
INT REG
UVLO
AND
W
OSC
SLOPE
FREQUENCY
FOLDBACK
COMP
Σ
2
V
GND
C
OUT
= 1.245V
g
m
R
S
Q
Q
1.245V
SHDN (Pin 4): The SHDN pin is used to put the LT1933 in
shutdown mode. Tie to ground to shut down the LT1933.
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.
V
internal regulator and to the internal power switch. This
pin must be locally bypassed.
SW (Pin 6): The SW pin is the output of the internal power
switch. Connect this pin to the inductor, catch diode and
boost capacitor.
R2
IN
(Pin 5): The V
3
FB
R1
DRIVER
IN
pin supplies current to the LT1933’s
Q1
BOOST
SW
www.DataSheet4U.com
1
6
IN
D1
pin. SHDN also
C3
D2
L1
LT1933
1933 BD
C1
5
1933f
V
OUT