NCP1421D 데이터 시트보기 (PDF) - ON Semiconductor
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NCP1421D
ON Semiconductor
NCP1421D Datasheet PDF : 14 Pages
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NCP1421
From the previous calculations, you need at least 18.75
mF in order to achieve the specified ripple level at the
conditions stated. Practically, a capacitor that is one level
larger is used to accommodate factors not taken into
account in the calculations. Therefore, a capacitor value of
22 mF is selected. The NCP1421 is internally compensated
for most applications, but in case additional compensation
16
14
12
10
8
IOUT = 500 mA
6
4
2
0
1.4 1.6 1.8 2.0 2.2 2.4 2.6 2.8 3.0
INPUT VOLTAGE (V)
Figure 27. Suggested Inductance of VOUT = 3.3 V
is required, the capacitor C4 can be used as external
compensation adjustment to improve system dynamics.
In order to provide an easy way for customers to select
external parts for NCP1421 in different input voltage and
output current conditions, values of inductance and
capacitance are suggested in Figure 27, 28 and 29.
21
18
15
12
9
6
3
IOUT = 500 mA
0
1.6 1.9 2.2 2.5 2.8 3.1 3.4 3.7 4.0
INPUT VOLTAGE (V)
Figure 28. Suggested Inductance of VOUT = 5.0 V
40
35
VOUT−RIPPLE = 40 mV
30
25
VOUT−RIPPLE = 45 mV
20
15
10
VOUT−RIPPLE = 50 mV
5
0
200
250 300 350 400 450 500 550
OUTPUT CURRENT (mA)
25
33
50
100
600
Figure 29. Suggested Capacitance for Output Capacitor
Table 1. Suggestions for Passive Components
Output Current
Inductors
500 mA
Sumida CR43, CR54,CDRH6D28 series
250 mA
Sumida CR32 series
Capacitors
Panasonic ECJ series
Kemet TL494 series
Panasonic ECJ series
Kemet TL494 series
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