LTC1174
LTC1174-3.3/LTC1174-5
PI FU CTIO S
V
OUT
(V
FB
) (Pin 1):
For the LTC1174, this pin connects to the
main voltage comparator’s input. On the LTC1174-3.3 and
LTC1174-5 this pin goes to an internal resistive divider
which sets the output voltage.
LB
OUT
(Pin 2):
Open Drain of an N-Channel Pull-Down. This
pin will sink current when Pin 3 (LB
IN
) goes below 1.25V.
During shutdown the state of this pin is indeterminate.
LB
IN
(Pin 3):
The “–” Input of the Low-Battery Voltage
Comparator. The “+” input is connected to a reference
voltage of 1.25V.
GND (Pin 4):
Ground Pin.
SW(Pin5):
Drain of the P-Channel MOSFET Switch. Cathode
of Schottky diode must be closely connected to this pin.
V
IN
(Pin 6):
Input Supply Voltage. It must be decoupled
close to ground Pin 4.
I
PGM
(Pin 7):
Selects the Current Limit of the P-Channel
Switch. With I
PGM
= V
IN
, the current trip point is 600mA and
with I
PGM
= 0V, the current trip value is reduced to 340mA.
SHUTDOWN (Pin 8):
Pulling this pin to ground keeps the
internal switch off and puts the LTC1174 in micropower
shutdown.
FU CTIO AL DIAGRA
+
V
TH2
A5
SLEEP
A2
–
–
A4
g
m
V
FB
C
T
RESET
Q
V
OUT
(V
FB
)
+
SET
V
TH1
LB
IN
LB
OUT
2
–
A3
+
GND 4
6
W
U
U
U
U
U
(Pin 1 connection shown for LTC1174-3.3 and LTC1174-5, changes create LTC1174)
V
IN
6
V
LIM1
V
LIM2
I
PGM
R
SENSE
0.1Ω
+
–
7
×
R1*
3
1
5
SW
–
A1
1.25V
REFERENCE
SHUTDOWN
8
V
FB
31.5k
+
* R1 = 51k FOR LTC1174-3.3
R1 = 93.5k FOR LTC1174-5
1174 BD
1174fe
LINEAR [ LINEAR INTEGRATED SYSTEMS ]
