Datasheet

9
LTC1503-1.8/LTC1503-2
Figure 3. Output Ripple Reduction Techniques
+
V
OUT
LTC1503-X
LTC1503-X
V
OUT
10µF
TANTALUM
0.5Ω
1µF
CERAMIC
+
V
OUT
V
OUT
1503-1.8/2 F03
10µF
TANTALUM
+
10µF
TANTALUM
capacitor on V
OUT
to reduce both the low and high fre-
quency ripple. An RC filter may also be used to reduce high
frequency voltage spikes.
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 (V
OUT
< 150mV) exists to prevent damage to the
internal switches. During start-up, the 20mA current limit
is disabled once V
OUT
reaches 0.7V (typ). The part can
survive an indefinite short from V
OUT
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 C
IN
and C
OUT
, must be as
close as possible to the V
IN
and V
OUT
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.
C2
LTC1503-X
GNDC1
V
IN
C
IN
C
OUT
1503-1.8/2 F04
SHDN/SS
V
OUT
Figure 4. Recommended Component Placement and Grounding
APPLICATIO S I FOR ATIO
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