Datasheet

4
LTC1503-1.8/LTC1503-2
TYPICAL PERFOR A CE CHARACTERISTICS
UW
LTC1503-X Output Short-Circuit
Current vs Input Voltage
LTC1503-X Start-Up Time
vs Soft-Start Capacitor
INPUT VOLTAGE (V)
2
OUTPUT CURRENT (mA)
20
30
6
1503-1.8/2 G10
10
0
3
4
5
40
V
OUT
SHORTED TO GND
T
A
= –40°C
T
A
= 85°C
T
A
= 25°C
SOFT-START CAPACITOR (nF)
0.01
START-UP TIME (ms)
1
10
100
1503-1.8/2 G10
0.1
0.01
0.1
1
10
100
V
IN
= 3.6V
T
A
= –40°C
T
A
= 25°C
T
A
= 85°C
Output Load Transient Response
(LTC1503-1.8,1mA to 100mA Step)
I
OUT
50mA/DIV
V
OUT
50mV/DIV
AC COUPLED
100mA
1mA
1ms/DIV
1503-1.8/2 G12
Output Ripple, C
OUT
= 10µF
V
OUT
10mV/DIV
AC COUPLED
5µs/DIV
1503-1.8/2 G13
V
IN
= 3.6V
V
OUT
= 2V
I
OUT
= 100mA
C
OUT
= 10µF CERAMIC
Output Ripple, C
OUT
= 22µF
V
OUT
10mV/DIV
AC COUPLED
5µs/DIV
1503-1.8/2 G14
V
IN
= 3.6V
V
OUT
= 2V
I
OUT
= 100mA
C
OUT
= 22µF CERAMIC
V
OUT
(Pin 1): Regulated Output Voltage. V
OUT
is discon-
nected from V
IN
during shutdown. Bypass V
OUT
to ground
with a ≥10µF low ESR capacitor.
C1
–
(Pin 2): Flying Capacitor One Negative Terminal.
C1
+
(Pin 3): Flying Capacitor One Positive Terminal.
V
IN
(Pin 4): Input Voltage. V
IN
may be between 2.4V and
6V. Bypass V
IN
to ground with a ≥10µF low ESR capacitor.
SHDN/SS (Pin 5): Shutdown/Soft-Start Control. The pin
is designed to be driven with an external open-drain
output. Holding the SHDN/SS pin below 0.25V will force
the part into shutdown mode. An internal pull-up current
of 2µA will force the SHDN/SS voltage to climb to V
IN
once
the device driving the pin is forced into a Hi-Z state. To
limit inrush current on start-up, connect a capacitor
between the SHDN/SS pin and ground. Capacitance on
the SHDN/SS pin will limit the dV/dt of the pin during turn-
on which, in turn, will limit the dV/dt of V
OUT
. By selecting
an appropriate soft-start capacitor for a known output
capacitor, the user can control the inrush current during
UU
U
PI FU CTIO S