NCP1422 ON Semiconductor, NCP1422 Datasheet - Page 12

• Manufacturer Part Number: NCP1422
• Description: Sync-Rect PFM Step-Up DC-DC Converter
• Manufacturer: ON Semiconductor

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 NCP1422 is internally compensated
for most applications, but in case additional compensation
Table 1. Suggestions for Passive Components
From the previous calculations, you need at least 18.75
12
10
8
6
4
2
0
1.8
Output Current
Figure 24. Suggested Inductance of V
800 mA
250 mA
2.0
2.2
INPUT VOLTAGE (V)
I
OUT
= 700 mA
2.4
Figure 26. Suggested Capacitance for Output Capacitor
40
35
30
25
20
15
10
5
0
100
Sumida CR43, CR54,CDRH6D28 series
2.6
200
OUT
Sumida CR32 series
2.8
300
OUTPUT CURRENT (mA)
= 3.3 V
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Inductors
NCP1422
400
3.0
12
V
OUT−RIPPLE
500
is required, the capacitor C4 can be used as external
compensation adjustment to improve system dynamics.
external parts for NCP1422 in different input voltage and
output current conditions, values of inductance and
capacitance are suggested in Figures 24, 25 and 26.
12
In order to provide an easy way for customers to select
9
6
3
0
2.2
Figure 25. Suggested Inductance of V
600
= 45 mA
2.5
700
2.8
INPUT VOLTAGE (V)
800
100
I
25
33
50
OUT
= 700 mA
3.1
Panasonic ECJ series
Panasonic ECJ series
Kemet TL494 series
Kemet TL494 series
Capacitors
3.4
OUT
3.7
= 5.0 V
4.0