LT1934 LINER [Linear Technology], LT1934 Datasheet - Page 5

• Manufacturer Part Number: LT1934
• Description: Micropower Step-Down Switching Regulators in ThinSOT
• Manufacturer: LINER [Linear Technology]

BLOCK DIAGRA
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 LT1934 and the circuit components. Return the feed-
back divider to this pin.
FB (Pin 3): The LT1934 regulates its feedback pin to 1.25V.
Connect the feedback resistor divider tap to this pin. Set
the output voltage according to V
or R1 = R2 (V
PI FU CTIO S
U
ON OFF
U
V
IN
OUT
/1.25 – 1).
C2
U
5
4
V
SHDN
IN
+
W
2
OUT
V
GND
REF
+
–
1.25V
= 1.25V (1 + R1/R2)
1.8 s DELAY
12 s DELAY
OFF TIME
ON TIME
R2
3
FB
R1
+
–
FEEDBACK
COMPARATOR
R
S
SHDN (Pin 4): The SHDN pin is used to put the LT1934 in
shutdown mode. Tie to ground to shut down the LT1934.
Apply 2.3V or more for normal operation. If the shutdown
feature is not used, tie this pin to the V
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.
IN
Q
Q
ENABLE
(Pin 5): The V
BOOST
IN
SW
pin supplies current to the LT1934’s
1
6
LT1934/LT1934-1
D1
C3
L1
D2
IN
1934 BD
C1
pin.
V
OUT
5
1934f