7
LT1300
COMPONENT
PART NUMBER VENDOR L (
µ
H) DCR (Ω)I
LIM
PIN 50mA LOAD 200mA LOAD HEIGHT (mm) PHONE NUMBER
DO1608-103 Coilcraft 10 0.11 Float 83 83 3.5 (708) 639–6400
DO3316-223 Coilcraft 22 0.050 Float 85 85 5.5
DO1608-223 Coilcraft 22 0.31 Ground 85 — 3.5
CTX10-1 Coiltronics 10 0.038 Float 85 85 4.2 (407) 241–7876
CTX20-1 Coiltronics 20 0.175 Ground 86 — 4.2
LQH3C2204K0M00 Murata-Frie 22 0.7 Ground 81 — 2.0 (404) 436–1300
CD54-100M Sumida 10 0.11 Float 85 85 4.5 (708) 956–0666
CDRH62-220M Sumida 22 0.38 Ground 84 — 3.0
CDRH62-100M Sumida 10 0.17 Float 81 82 3.0
GA10-102K Gowanda 10 0.038 Float 85 86 6.6 Through-Hole (716) 532–2234
APPLICATIONS INFORMATION
WUU
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Table 1. Recommended Inductors
Inductor Selection
For full output power, the inductor should have a satura-
tion current rating of 1.25A for worst-case current limit,
although it is acceptable to bias an inductor 20% or more
into saturation. Smaller inductors can be used in conjunc-
tion with the I
LIM
pin. Efficiency is significantly affected by
inductor DCR. For best efficiency limit the DCR to 0.03Ω
or less. Toroidal types are preferred in some cases due to
their closed design and inherent EMI/RFI superiority.
Recommended inductors are listed in Table 1.
Capacitor Selection
Low ESR capacitors are required for both input and output
of the LT1300. 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 application
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. Low frequency
output ripple can be reduced by adding multiple output
capacitors. If capacitance is reduced, output ripple will
increase. Suggested capacitor sources are listed in Table 2.
Table 2. Recommended Capacitors
VENDOR SERIES TYPE PHONE#
AVX TPS Surface Mount (803)448–9411
Sanyo OS-CON Through-Hole (619) 661–6835
Panasonic HFQ Through-Hole (201) 348–5200
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 LT1300 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.
EFFICIENCY 2.5V
IN
, 5V
OUT
Information furnished by Linear Technology Corporation is believed to be accurate and reliable.
However, no responsibility is assumed for its use. Linear Technology Corporation makes no represen-
tation that the interconnection of its circuits as described herein will not infringe on existing patent rights.
