BD9479FV ROHM [Rohm], BD9479FV Datasheet - Page 19

• Manufacturer Part Number: BD9479FV
• Description: White LED Driver for large LCD Panels (DCDC Converter type)
• Manufacturer: ROHM [Rohm]

www.rohm.com
© 2012 ROHM Co., Ltd. All rights reserved.
TSZ22111・15・001
BD9479FV
shown above will be met.
current Imin so as to meet the following equation:
DCDC switching frequency=fsw[Hz]=200kHz
Inductor [H]=33µH
Furthermore, I
So must select the component of about 5A in order to meet the above result.
variations, and then conduct thorough verification on practical systems..
discontinuous mode.
output voltage.
【 【 【 【 Setting example】 】 】 】
Mean input current IIN required for the whole system is given by the following equation:
The inductor ripple current ∆IL [A] is given by the following equation:
As a result, the peak current Ipeak of IL is given by the following equation.
When RCS resistance is set to 0.1ohm, the VCS peak voltage will be given by the following equation:
Consequently, the result meets the condition.
DC/DC application components including FETs, inductors, and diodes should be selected so that the Equation
In addition, it is recommended to use continuous mode in DCDC application.And the lower limit value of coil ripples
Particularly, To select DC/DC components, give consideration to IC variations as well as individual component
The lower limit value of coil ripple current Imin is given by the following equation, the component will not be put into
A failure to meet this condition is referred to as discontinuous mode and this failure may result in an inadequate rise in
Output=VOUT[V]=40V
LED 1ch current=120mA, total LED current IOUT[A]=120mA×8ch=0.96A
DCDC input voltage=VIN [V] =24V
DCDC efficiency=η[%]=90%
I
IN
Δ
[
A
IL
I
peak
]
VCS
Ipeak
I
OCP
OCP
V
(
V
L
current at which OCP is detected is given by the following equation:
I
OUT
peak
[
V
OUT
I
min
H
OCP
IN
0
. 0
[
]
[
I
[ 1 .
V
[
V
[ 4
I
V
IN
Rcs
]
min
V
V
]
[
]
OUT
A
I
]
]
IN
I
V
]
OUT
[
IN
[
[%]
V
Ipeak
4
A
I
[
0 .
V
]
IN
[
]
IL
A
])
[
2
[
]
A
f
[
A
]
SW
IL
A
V
]
2
]
[
. 0
[
[
IN
40
A
Hz
A
[ 1
[
IL
]
]
V
24
[
2
[
V
]
[
]
A
[
A
. 1
]
]
V
]
]
78
[
]
. 2
. 2
. 0
33
A
. 1
[
19/26
]
51
51
96
A
0
78
]
9 .
[
10
[
[
[
A
0
A
A
A
(
. 1
]
]
40
]
]
6
45
[
[
H
2
. 0
V
. 1
. 0
[
. 4
A
]
251
]
73
78
]
[ 0
40
[
24
[
A
A
V
. 2
[
]
[
[
V
]
V
]
A
51
]
]
])
. 1
. 5
[
. 0
05
200
A
[ 0
[ 4
]
24
[
A
V
TSZ02201-0F1F0C100020-1-2
A
[
V
]
]
]
10
]
0
3
[
Hz
9.Aug.2012 Rev.001
]
. 1
45
Datasheet
[
A
]