NCP3063 ONSEMI [ON Semiconductor], NCP3063 Datasheet - Page 9

• Manufacturer Part Number: NCP3063
• Description: 1.5 A, Step−Up/Down/Inverting Switching Regulators
• Manufacturer: ONSEMI [ON Semiconductor]

The Following Converter Characteristics Must Be Chosen:
less than 10% of the average inductor current I
set by R
converter output current capability.
value since it will directly affect line and load regulation. Capacitor C
electrolytic designed for switching regulator applications.
9. V
10. V
11. The calculated t
(See Notes 9, 10, 11)
V
V
I
DI
f − Maximum output switch frequency.
V
out
out
in
ripple(pp)
SWCE
F
L
I
− Output rectifier forward voltage drop. Typical value for 1N5819 Schottky barrier rectifier is 0.4 V.
V
− Nominal operating input voltage.
pk (Switch)
− Desired output current.
− Desired peak−to−peak inductor ripple current. For maximum output current it is suggested that DI
− Desired output voltage.
ripple(pp)
t on
t off
I
L(avg)
R
V
SC
C
t
on
L
− Darlington Switch Collector to Emitter Voltage Drop, refer to Figures 5, 6, 7 and 8.
SC
out
T
. If the design goal is to use a minimum inductance value, let DI
− Desired peak−to−peak output ripple voltage. For best performance the ripple voltage should be kept to a low
on
/t
off
must not exceed the minimum guaranteed oscillator charge to discharge ratio.
DI L
V in * V SWCE * V out
V in * V SWCE * V out
V TH
I L(avg) )
I pk (Switch)
8 f C O
V out ) V F
Step−Down
f
DI L
1
0.20
t on
t off
I out
R 2
R 1
t on
t off
) 1
) 1
NCP3063, NCP3063B, NCV3063
2
DI L
) (ESR)
2
L(avg)
Figure 13. Design Equations
t on
. This will help prevent I
2
http://onsemi.com
C T + 381.6 @ 10
9
[
V in * V SWCE
t on I out
V out ) V F * V in
f osc
V in * V SWCE
I out
C O
V TH
I L(avg) )
I pk (Switch)
f
Step−Up
DI L
O
t on
t off
0.20
*6
t on
t off
R 2
R 1
should be a low equivalent series resistance (ESR)
) DI L @ ESR
t on
t off
) 1
pk (Switch)
* 343 @ 10
) 1
) 1
L
DI L
2
= 2(I
t on
from reaching the current limit threshold
L(avg)
*12
). This will proportionally reduce
[
V in * V SWCE
t on I out
Voltage−Inverting
V in * V SWCE
I out
C O
V TH
I L(avg) )
|V out | ) V F
I pk (Switch)
f
DI L
t on
t off
0.20
t on
t off
R 2
R 1
) DI L @ ESR
t on
t off
L
) 1
be chosen to be
) 1
) 1
DI L
2
t on