Datasheet

8
LT1301
APPLICATIONS INFORMATION
WUU
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Capacitor Selection
Low ESR capacitors are required for both input and output
of the LT1301. ESR directly affects ripple voltage and
efficiency. For surface mount applications AVX TPS series
tantalum capacitors are recommended. These have been
specially designed for SMPS and have low ESR along with
high surge current ratings. For through-hole applications
Sanyo OS-CON capacitors offer extremely low ESR in a
small size. Again, if peak switch current is reduced using
the I
LIM
pin, capacitor requirements can be relaxed and
smaller, higher ESR units can be used. Suggested capaci-
tor sources are listed in Table 2.
Diode Selection
Best performance is obtained with a Schottky rectifier
diode such as the 1N5817. Phillips Components makes
this in surface mount as the PRLL5817. Motorola makes
the MBRS130LT3 which is slightly better and also in
surface mount. For lower output power a 1N4148 can be
used although efficiency will suffer substantially.
Layout Considerations
The LT1301 is a high speed, high current device. The input
capacitor must be no more than 0.2˝ from V
IN
(pin 6) and
ground. Connect the PGND and GND (pins 8 and 1)
together under the package. Place the inductor adjacent to
SW (pin 7) and make the switch pin trace as short as
possible. This keeps radiated noise to a minimum.
TYPICAL APPLICATIONS N
U
Four-Cell to 5V Converter
C3
100µF

L2
33µH
0.1µF

5V OUTPUT
200mA
80 to 83% EFFICIENT
AT I
LOAD
> 10mA
+
L1
33µH
C2
100µF
1N5817
C1
100µF
4 CELLS
SW
NC
I
LIM
PGND
GND
SENSE
LT1301
SELECT
LT1301 TAO3
SHDN
SHUTDOWN
V
IN
+
+
1N5817
2N4403
5V, 200mA
+
L1*
10µH
*SUMIDA CD54-100LC 
COILCRAFT DO3316-223
100µF
100µF
470Ω
0.1µF
2×
AA
CELL
SW
I
LIM
PGND
GND
SENSE
LT1301
SELECT
LT1301 TA4
SHDN
NC
NC
SHUTDOWN
V
IN

+
Step-Up Converter with Automatic Output Disconnect