LT1303 データシートの表示（PDF） - Linear Technology
部品番号
コンポーネント説明
メーカー
LT1303 Datasheet PDF : 12 Pages
| |||
LT1303/LT1303-5
APPLICATIONS INFORMATION
LT1303 F08
Figure 8. This Inductor Saturates at IL≈1A. A Poor Choice
Capacitor Selection
Input and output capacitors should have low ESR for best
efficiency. Recommended capacitors include AVX TPS
series, Sprague 595D series, and Sanyo OS-CON. The
output capacitor’s ESR determines the high frequency
ripple amplitude. A 100µF capacitor is the minimum rec-
ommended for a 5V output. Higher output voltages can use
lower capacitance values. For example, a 12V output can
use a 33µF or 47µF capacitor. The VIN pin of the LT1303
should be decoupled with a 47µF or 100µF capacitor at the
pin. When driving a transformer, an additional decoupling
network of 10Ω and 0.1µF ceramic is recommended as
shown in Figure 10.
VIN
10Ω
LT1303 F09
Figure 9. Slight Exponential Shape to Inductor Current
Waveform Indicates Excessive DC Resistance
+
47µF
0.1µF
CERAMIC
VIN
SW
LT1303
•••
Diode Selection
The LT1303’s high switching speed demands a high speed
rectifier. Schottky diodes are preferred for their low for-
ward drop and fast recovery. Suitable choices include the
1N5817, MBRS120LT3, and MBR0520LT1. Do not use
signal diodes such as 1N4148. They cannot carry 1A
current. Also avoid “general-purpose” diodes such as
1N4001. These are far too slow and are unsuitable for any
switching regulator application. For high temperature
applications a silicon diode such as the MUR105 will have
less leakage.
GND
PGND
LT1303 F10
Figure 10. 10Ω-1µF Network to LT1303 VIN Pin Provides
Additional Decoupling. Recommended When Driving
Transformers.
Table 2. Recommended Capacitors
VENDOR
AVX
Sanyo
Panasonic
Sprague
SERIES
TPS
OS-CON
HFQ
595D
TYPE
Surface Mount
Through-Hole
Through-Hole
Surface Mount
PHONE
NUMBERS
(803) 448-9411
(619) 661-6835
(201) 348-5200
(603) 224-1961
8
Share Link: 