LT3587
6
3587fc
V
OUT3
(Pin 1): Boost3 Output Pin. This pin is the drain of
an output disconnect PMOS transistor.
CAP3 (Pin 2): Boost3 Output Capacitor Pin. This pin is the
source of an output PMOS disconnect. Connect a capacitor
from this pin to ground.
SW3 (Pin 3): Boost3 Switch Pin. Connect an inductor
from this pin to V
IN
. Minimize trace area at this pin to
minimize EMI.
GND (Pin 4, 7, 8, 12): Ground Pins.
FLT (Pin 5): Fault Pin. This pin is a bidirectional open-
drain pull-down pin. This pin pulls low when any of the
enabled outputs fall out of regulation for more than 16ms.
Each output is ignored during start-up until its respective
enable/soft-start pin allows for full inductor current. This
pin can also be externally forced low to disable all the
supply outputs. Once this pin goes low (either due to an
out of regulation condition or externally forced low), the
pin latches low until the inputs to EN/SS1 and EN/SS3 are
set low or the input supply pin is recycled. Pull up this pin
to V
IN
with a 200k resistor when not used.
FB2 (Pin 6): Inverter Output Voltage Feedback Pin. Con-
nect a resistor R
FB2
from this pin to the Inverter Output
(V
NEG
) such that:
R
FB2
= |V
NEG
|/8µA
Note that FB2 pin voltage is about 0V when in regulation.
There is an internal 153k resistor from the FB2 pin to the
internal reference.
SW2 (Pin 9): Inverter Switch Pin. Connect an inductor
between this pin and V
IN
, as well as the fl ying capacitor
from this pin to the anode of the lnverter ground return
diode. Minimize trace area at this pin to minimize EMI.
NC (Pin 10): No Connect Pin. Leave open or connect to
ground.
SW1 (Pin 11): Boost1 Switch Pin. Connect an inductor
from this pin to V
IN
. Minimize trace area at this pin to
minimize EMI.
CAP1 (Pin 13): Boost1 Output Capacitor Pin. This pin
is the source of an output PMOS disconnect. Connect a
capacitor from this pin to ground.
EN/SS1, EN/SS3 Shutdown
Threshold vs Temperature
CAP3 Overvoltage Clamp
vs Temperature
TYPICAL PERFORMANCE CHARACTERISTICS
Specifi cations are at T
A
= 25°C unless otherwise noted.
PIN FUNCTIONS
TEMPERATURE (°C)
–50
SHUTDOWN THRESHOLD VOLTAGE (V)
0.45
0.40
0.25
0.35
0.30
0.20
25075
3587 G17
125100–25 50
V
VIN
= 3.6V
TEMPERATURE (°C)
–50
CAP3 OV CLAMP VOLTAGE (V)
31
30
29
28
27
25075
3587 G18
125100–25 50
V
VIN
= 3.6V
