LT1300 查看數據表（PDF） - Linear Technology
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LT1300 Datasheet PDF : 8 Pages
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LT1300
APPLICATIONS INFORMATION
Table 1. Recommended Inductors
PART NUMBER
DO1608-103
DO3316-223
DO1608-223
CTX10-1
CTX20-1
LQH3C2204K0M00
CD54-100M
CDRH62-220M
CDRH62-100M
GA10-102K
VENDOR
Coilcraft
Coilcraft
Coilcraft
Coiltronics
Coiltronics
Murata-Frie
Sumida
Sumida
Sumida
Gowanda
L (µH)
10
22
22
10
20
22
10
22
10
10
DCR (Ω)
0.11
0.050
0.31
0.038
0.175
0.7
0.11
0.38
0.17
0.038
ILIM PIN
Float
Float
Ground
Float
Ground
Ground
Float
Ground
Float
Float
EFFICIENCY 2.5VIN, 5VOUT
50mA LOAD 200mA LOAD
83
83
85
85
85
—
85
85
86
—
81
—
85
85
84
—
81
82
85
86
COMPONENT
HEIGHT (mm)
3.5
5.5
3.5
4.2
4.2
2.0
4.5
3.0
3.0
6.6 Through-Hole
PHONE NUMBER
(708) 639–6400
(407) 241–7876
(404) 436–1300
(708) 956–0666
(716) 532–2234
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 ILIM 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 ILIM 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
AVX
Sanyo
Panasonic
SERIES
TPS
OS-CON
HFQ
TYPE
Surface Mount
Through-Hole
Through-Hole
PHONE#
(803)448–9411
(619) 661–6835
(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 VIN (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.
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.
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