LTC1503-1.8/LTC1503-2
APPLICATIO S I FOR ATIO
capacitor on VOUT to reduce both the low and high fre-
quency ripple. An RC filter may also be used to reduce high
frequency voltage spikes.
LTC1503-X
VOUT
+
LTC1503-X
VOUT
+
10µF
TANTALUM
0.5Ω
+
10µF
TANTALUM
VOUT
1µF
CERAMIC
VOUT
10µF
TANTALUM
1503-1.8/2 F03
Figure 3. Output Ripple Reduction Techniques
Protection Features
The LTC1503-X contains both thermal shutdown and
short-circuit protection features. The charge pump will
shut down when the junction temperature reaches ap-
proximately 150°C and will resume operation once the
junction temperature has dropped back to 125°C. The part
will limit output current to 20mA (typ) when a short-circuit
condition (VOUT < 150mV) exists to prevent damage to the
internal switches. During start-up, the 20mA current limit
is disabled once VOUT reaches 0.7V (typ). The part can
survive an indefinite short from VOUT to GND.
Layout Considerations
For best regulation and noise performance, careful board
layout is required. Improper bypassing and grounding
may lead to poor load regulation and output ripple perfor-
mance. All capacitors, especially CIN and COUT, must be as
close as possible to the VIN and VOUT pins. Connecting the
GND pin and all bypass capacitors to an uninterrupted
ground plane is also advised. See Figure 4 for recom-
mended component placement and grounding.
COUT
VOUT
C1
VIN
LTC1503-X
GND
C2
SHDN/SS
CIN
1503-1.8/2 F04
Figure 4. Recommended Component Placement and Grounding
9