ncp3120 ON Semiconductor, ncp3120 Datasheet - Page 15

• Manufacturer Part Number: ncp3120
• Description: Dual 2.0 A, Step-down Dc/dc Switching Regulator
• Manufacturer: ON Semiconductor

Output Rectifier Diode
magnetic field in the inductor. During off time, the internal
MOSFET switch is off. Since the current in the inductor has
to discharge, the current flows through the rectifying diode
to the output. A Schottky diode is recommended due to low
diode forward voltage and very short recovery times, which
positively impacts the step down voltage converter's overall
efficiency. Another choice could be fast recovery or
ultra-fast recovery diodes. It should be noted that some
types of these diodes with an abrupt turn-off characteristic
may cause instability or EMI troubles.
MBRS2040LT3G
MBRS230LT3G
MBRS240LT3G
SS24T3G
MBRA340T3G
MBRS330T3G
Table 2. Inductor Examples
Table 3. Schottky Diode Example
When the high-side switch is on, energy is stored in the
Part Number
[mH]
8.2
5.6
5.4
5.2
3.9
3.8
33
22
15
10
L
MSS1246T-153
PG0015.223NL
PG0015.153NL
PF0698.333NL
PF0560.333NL
PF0560.223NL
PA0390.472NL
PA0390.332NL
DO3316P-333
MSS1038-333
DO3340P-223
MSS1038-223
DO3316P-153
DO3308P-103
MSS6132-822
MSS6132-562
DO3316T-392
DS3316P-103
DS3316P-822
P0762.103NL
Part Number
P1167.103NL
P1167.542NL
2 A, 40 V Low V
2 A, 30 V Low V
2 A, 40 V Low V
2 A, 40 V Schottky Rectifier
3 A, 40 V Schottky Rectifier
3 A, 30 V Schottky Rectifier
Description
f
f
f
Schottky Rectifier
Schottky Rectifier
Schottky Rectifier
Non-shielded
Shielded/
N
S
N
S
N
S
N
S
N
S
N
S
N
N
S
S
S
S
S
N
N
N
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V
2.85
1.95
2.27
2.65
2.95
I
[A]
2.1
2.3
2.8
2.2
2.5
2.5
3.1
3.4
2.3
2.1
2.5
2.2
5.3
2.9
NCP3120
rms
RRM
2
2
2
[V]
40
30
40
40
40
30
15
min
voltage. The peak conducting current is clamped by the
current limit of the NCP3120. Use of Schottky barrier diodes
reduces diode reverse recovery input current spikes. For
switching regulators operating at low duty cycles, it is
beneficial to use rectifying diodes with somewhat higher
RMS current ratings (thus lower forward voltages). This is
because the diode conduction interval is much longer than
that of the transistor. Converter efficiency will be improved
if the voltage drop across the diode is lower. The average
current can be calculated from:
The peak reverse voltage is equal to the maximum input
DCR max
V
[mW}
54.4
42.8
100
100
101
F
110
0.43
0.49
0.43
0.45
93
65
93
66
73
73
46
56
80
85
50
85
70
60
33
15
0.5
0.5
[V]
max
I
I
O(rec)
D(AVG)
Manufacturer
[A]
2
2
2
2
3
3
Coilcraft
Coilcraft
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PULSE
PULSE
PULSE
PULSE
PULSE
PULSE
PULSE
PULSE
PULSE
PULSE
max
+
I
LOAD
Package
V
SMC
SMB
SMB
SMB
SMB
SMA
IN
V
IN
* V
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OUT
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