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PDF BD9421F Data sheet ( Hoja de datos )
| Número de pieza | BD9421F | |
| Descripción | LED Drivers | |
| Fabricantes | ROHM Semiconductor | |
| Logotipo |  |
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Datasheet
LED Drivers for LCD Backlights
White LED Driver for large LCD Panels
(DCDC Converter Type)
BD9421F
General Description
BD9421F is high efficiency driver for white LED. This is
designed for large sized LCD. BD9421F is built-in
DCDC converters that supply appropriate voltage for
light source.
BD9421F is also built-in protection function for
abnormal state such as OVP: over voltage protection,
OCP: over current limit protection of DCDC, SCP: short
circuit protection, open detection of LED string.
Thus this is used for conditions of large output voltage
and load conditions.
Features
6ch LED constant current driver(External PNP Tr
Type)
Maximum LED setting current 500mA(VREF Pin
setting)
±2% LED current accuracy(VREF=0.9V setting)
Built-in DC/DC converter
Analog Dimming(Linear) function
LED protection function(OPEN/SHORT
protection)[PWM-independent Type]
Individual detection and individual LED OFF for both
OPEN and SHORT circuit
VOUT Over Voltage Protection(OVP) and reduced
voltage protection(SCP) circuit
Built-in under voltage lockout function(UVLO) and
over voltage protection(OVP)
Built-in VOUT discharge circuit while shutdown
Key Specifications
VCC Supply Voltage Range:
9.0V to 35.0V
DCDC Oscillation Frequency: 150kHz(RT=100kΩ)
Operation Circuit Current:
5mA(Typ)
Operating Temperature Range: -40°C to +85°C
Applications
LED driver for TV, Monitor and LCD Back Light
Package
SOP24
W(Typ) x D(Typ) x H(Max)
15.00mm x 7.80mm x 2.01mm
Pin Pitch 1.27mm
Figure 1. SOP24
Typical Application Circuit
Figure 2. Typical Application Circuit
〇Product structure : Silicon monolithic integrated circuit
.www.rohm.com
© 2013 ROHM Co., Ltd. All rights reserved.
TSZ22111 • 14 • 001
〇This product has no designed protection against radioactive rays
1/27
TSZ02201-0F1F0C100310-1-2
31.Jan.2014 Rev.002
http://www.Datasheet4U.com
1 page  
BD9421F
Pin Descriptions
Pin No.
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
Pin Name
REG75
N
PGND
CS
FB
VREF
BS1
BS2
BS3
BS4
BS5
BS6
CL6
CL5
CL4
CL3
CL2
CL1
PWM
OVP
RT
AGND
STB
VCC
Function
7.5V regulator output for N output pin
DC/DC switching output pin
Power GND
DCDC external NMOS current monitor pin
DCDC phase-compensation pin
LED voltage setting pin
PNP Tr Base connecting pin1
PNP Tr Base connecting pin2
PNP Tr Base connecting pin3
PNP Tr Base connecting pin4
PNP Tr Base connecting pin5
PNP Tr Base connecting pin6
PNP Tr collector ・current detection pin6
PNP Tr collector ・current detection pin5
PNP Tr collector ・current detection pin4
PNP Tr collector ・current detection pin3
PNP Tr collector ・current detection pin2
PNP Tr collector ・current detection pin1
Dimming signal input pin
Overvoltage protection detection pin
DCDC frequency setting resistor connection pin
Analog GND
Enable pin
Power supply pin
Datasheet
www.rohm.com
© 2013 ROHM Co., Ltd. All rights reserved.
TSZ22111 • 15 • 001
5/27
TSZ02201-0F1F0C100310-1-2
31.Jan.2014 Rev.002
http://www.Datasheet4U.com
5 Page 
BD9421F
Datasheet
●LED current setting (VREF pin, CLx pin)
Please decide VREF pin input voltage first. When Analog dimming is performed,
please be noted that VREF pin input voltage range is (0.6V ～ 3.0V), and decide the
input voltage in normal operation. Basically, if VREF pin voltage is high, it will cause
power dissipation of external PNP Tr become high, so it is preferred to set the VREF pin
voltage lower.
Later, VREF=0.9V will be set as basic. For example if you create 0.9V from REG75, it
is possible to use resistive divider by setting 88kohm and 12kohm.
The LED current detection is performed by CLx pin. CLx pin is controlled so that the
voltage of 1/3V(typ.) of VREF voltage. If VREF=0.9V, CLx=0.3V to control external PNP
Tr. Therefore, if 「RCL」 is set as a resistance which between CLx pin and GND, and
VREF pin voltage is set as 「VVREF」, LED current 「ILED」can be calculated as below.
RCL
[ohm]
VVREF [V ]
I LED [ A] 3
For current setting, set at each channel. For this reason, in 1ch～3ch and 4ch～6ch, it
is possible to change current by setting 「RCL」value.
●DCDC operation frequency setting (RT Pin)
The operation frequency of DCDC output is set by resistance which connected to RT pin.
○The relationship between operation and RT resistance (ideal)
RRT
15000
fSW [kHz]
[k]
Here, fsw＝DCDC converter oscillation frequency[kHz]
Above is ideal equations which do not putted with correction terms.
For accurate frequency setting, please confirm on the real system.
But the frequency setting range is 100kHz～800kHz.
【Setting Example】
If DCDC frequency is set to be 200kHz, RRT as below:
RRT
15000 15000 75
f sw[kHz] 200[kHz]
[k]
www.rohm.com
© 2013 ROHM Co., Ltd. All rights reserved.
TSZ22111 • 15 • 001
11/27
TSZ02201-0F1F0C100310-1-2
31.Jan.2014 Rev.002
http://www.Datasheet4U.com
11 Page | ||
| Páginas | Total 30 Páginas | |
| PDF Descargar | [ Datasheet BD9421F.PDF ] | |
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