NCV3065 ONSEMI [ON Semiconductor], NCV3065 Datasheet - Page 9

• Manufacturer Part Number: NCV3065
• Description: Up to 1.5 A Constant Current Switching Regulator for LEDs
• Manufacturer: ONSEMI [ON Semiconductor]

of the NCP3065. Two main converter topologies are
demonstrated with actual test data shown below each of the
circuit diagrams.
9. V
10. V
11. The calculated t
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.
(See Notes 9, 10, 11)
Figures 16 through 24 show the simplicity and flexibility
V
V
I
DI
f - Maximum output switch frequency.
V
out
out
in
ripple(pp)
SWCE
F
L
I
V
- Output rectifier forward voltage drop. Typical value for 1N5819 Schottky barrier rectifier is 0.4 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
I
L(avg)
out
R
V
SC
t
C
on
- Darlington Switch Collector to Emitter Voltage Drop, refer to Figures 7, 8, 9 and 10.
L
out
SC
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)
Step-Down
V
V out ) V F
8 f C O
f
ref
DI L
t on
t off
1
0.20
I out
L(avg)
R 2
R 1
t on
t off
R
) 1
Figure 16. Design Equations
sense
) 1
NCP3065, NCV3065
2
DI L
) (ESR)
. This will help prevent I
2
http://onsemi.com
APPLICATIONS
C T + 381.6 @ 10
t on
2
9
parameters. Additionally, a complete application design aid
for the NCP3065 can be found at www.onsemi.com.
f osc
Figure 16 gives the relevant design equations for the key
O
*6
should be a low equivalent series resistance (ESR)
pk (Switch)
* 343 @ 10
L
= 2(I
from reaching the current limit threshold
L(avg)
[
*12
V in * V SWCE
t on I out
V out ) V F * V in
). This will proportionally reduce
V in * V SWCE
I out
C O
V TH
I L(avg) )
I pk (Switch)
V
f
Step-Up
ref
DI L
t on
t off
0.20
t on
t off
R 2
R 1
) DI L @ ESR
t on
t off
R
) 1
sense
) 1
) 1
DI L
2
t on
L
be chosen to be