an30888b Panasonic Corporation of North America, an30888b Datasheet - Page 23

• Manufacturer Part Number: an30888b
• Description: High Brightness Led Driver Ic
• Manufacturer: Panasonic Corporation of North America

(6) Inductor selection
Inductor value, L is set by the required inductor ripple current desired.
The general trend for lower inductor value is a smaller inductor physical size, but a larger input ripple current. Similarly, an increase in
inductor value will decease input ripple current.
Users are advice to choose an inductor that can handle the peak current I
with lower series resistance are preferred to provide better operating efficiency.
The following equation gives a general guideline in selection inductor value based on 30% peak to peak ripple current across the
inductor.
Please note that the 0.3 factor can be altered if 30% peak to peak current is changed.
i.e, if percentage of peak to peak current needed is 40%, this factor will be 0.4.
AN30888B
Technical Data (continued)
Functions and properties descriptions (continued)
L = ————————————— ………………………
L = ————————————— ………………………
(V
(V
V
V
T
I
I
LED
IN
OFF
OUT
IN
OUT
IN
is input current from supply voltage
= Input supply voltage
= LED output current
– V
= Fixed off time design at 1 μs
= Output voltage
– V
0.3 × I
0.3 × I
OUT
IN
) × T
) × T
Eq[7]
- - - - - - - - - - - - - - - L * 2
P K
CS
I V FB
R =
- - - - - - - - - - - -
PK
CS
I R =
IN
LED
OFF
OFF
SDG00005AEB
PK
Eq[4]
Eq[5]
, flowing across it without saturating. In addition, inductor
(Boost mode，Buck-Boost mode)
(Buck mode)
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