BD9479FV ROHM [Rohm], BD9479FV Datasheet - Page 15

• 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
● ● ● ● OVP/SCP setting procedure (OVP Pin)
BD9479FV.The one is OVP detection, another is OVP
feedback.
higher than 2.25V.when OVP pin voltage is between 2.25V with
2.5V, the operation of DCDC is continued and CP start to
charge only.When OVP pin voltage reaches 2.5V, until then
the feedback voltage control will be switch from BSｘ pin to
OVP pin （ please refer to below figure ） .For this reason, its
prevent the voltage of OVP pin become 2.5V or higher when
LED column has closed with impendence causing the rising of
DCDC voltage.
but also the external CR of phase compensation is needed.Basically, it is needed to aligned with the feedback gain to LED
driver section.If R3 is same as R2（1k～10kΩ）, the breakdown voltage of C which connected to it should be confirmed first
（And in series of two or more if necessary）, about 0.1uF is assumed and need to be decided in real system.
There
Basically, the CP pin start to charge when OVP pin voltage
use of resistive dividers R1 and R2.
Assuming that voltage of VOUT rising abnormally and detecting OVP is “VOVP
the following equation.
（R2 will also affect phase compensation of feedback section, please set 1k ～ 10kΩ as basic.）
The OVP feedback 「VOVP
The SCP setting「VSCP
OVP pin is also used for feedback control, please noted that not only the resistor divider of monitoring normal voltage,
○ ○ ○ ○ OVP detection setting equation
○ ○ ○ ○ OVP feedback setting equation
○ ○ ○ ○ SCP detection setting
The following section describes setting procedures to be followed if the VOUT pin voltage to be detected is setby the
VSCP
VOVP
R
1
are
DET
R
FEED
[ 2
two
k
0
]
2 .
2
5 .
V
type
(
V
VOVP
(
DET
R
(
[ 1
of
R
」 voltage is calculated as below when R1,R2 is decided above:
FEED
[ 1
DET
k
. 2
R
k
over
]
[ 2
[
25
R
」 voltage is calculated as below when R1,R2 is decided above:
V
]
[ 2
k
]
[
R
V
k
[ 2
R
]
]
. 2
voltage
[ 2
k
]
25
k
])
[
V
])
])
[
V
protection
[
]
V
[
k
]
]
15/26
in
FB
+
+
-
+
-
-
0.2V
2.25V
DET”
2.5V
, R1 and R2 setting will be made by
TSZ02201-0F1F0C100020-1-2
OVP
C1
R3
9.Aug.2012 Rev.001
R2
R1
Datasheet
VOUT