Datasheet
Boost 1channel white LED driver
For large LCDs
BD9488F
●General
Description
BD9488F is a high efficiency driver for white LEDs and
designed for large LCDs. This IC is built-in a boost
DCDC converters that employ an array of LEDs as the
light source. BD9488F has some protect function against
fault conditions, such as the over-voltage protection
(OVP), the over current limit protection of DCDC (OCP),
LED over current protection (LEDOCP), the open
detection of LED string. Therefore BD9488F is available
for the fail-safe design over a wide range output voltage.
●Features
Current mode DCDC converter
Vout discharge circuit as shutdown
LED protection circuit (OPEN protection, LED OCP
protection)
LED protect detection as small PWM dimming signal
Over-voltage protection (OVP) for the output voltage.
Adjustable soft start time constant
The wide range of analog dimming 0.2V-3.5V
The built-in transformation circuit from pulse to DC
2 PWM dimming signal
The UVLO detection for the input voltage of the power
stage
FAIL logic output
●Applications
TV, PC display and other LCD backlight system.
●Key
Specifications
Input voltage range:
9.0V to 18.0V
DCDC oscillation frequency: 150kHz (RT=100kΩ)
Active current consumption:
1.2mA(Typ.)
Operating temperature range:
-40℃ to +85℃
●Package(s)
SOP18
W(Typ.) x D(Typ.) x H(Max.)
11.20mm x 7.80mm x 2.01mm
Pin pitch 1.27mm
Figure 1.
SOP18
●Typical
Application Circuit(s)
VCC
VIN
VCC
TC54
STB
UVLO
OVP
GATE
RT
Css
SS
FAILB
PWM1
PWM2
ADIM_P
FB
ADIM
GND
DIMOUT
CS
ISENSE
Figure 2. Typical application circuit
○Product
structure：Silicon monolithic integrated circuit
.
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© 2012 ROHM Co., Ltd. All rights reserved.
TSZ22111・14・001
○This
product is not designed protection against radioactive rays
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TSZ02201-0F1F0C100040-1-2
27.May 2014 Rev.003
BD9488F
●Absolute
Maximum Ratings (Ta=25℃)
Parameter
Input voltage
STB pin voltage
OVP, UVLO, SS, RT,
ISENSE, FB, CS, TC54
pin voltage
PWM1, PWM2, FAILB,
ADIM, ADIM_P pin voltage
DIMOUT, GATE pin voltage
Power Dissipation
Operating Temperature Range
Junction Temperature
Storage Temperature Range
Symbol
Vccmax
STB
OVP, UVLO, SS, RT,
ISENSE, FB, CS, TC54
PWM1, PWM2, FAILB,
ADIM, ADIM_P
DIMOUT, GATE
Pd
Topr
Tjmax
Tstg
Ratings
20
VCC
7
20
VCC
687 (*1)
-40 to +85
150
-55 to +150
Unit
V
V
V
V
V
mW
℃
℃
℃
Datasheet
*1 Pd derated at 5.5 mW/℃ for temperature above Ta=25℃,
mounted on 70mm×70mm×1.6mm 1 layer glass-epoxy PCB.
●Operation
range
Parameter
VCC Power source voltage
DC/DC oscillation frequency
The effective range of ADIM signal
PWM input frequency range
Symbol
VCC
fsw
VADIM
FPWM
Range
9.0 to 18.0
50 to 800
0.2 to 3.5
90 to 100k
Unit
V
kHz
V
Hz
●Pin
Configuration
●Package
dimension, marking diagram
OVP
UVLO
SS
RT
PWM1
PWM2
FAILB
ADIM
ADIM_P
1
2
3
4
5
6
7
8
9
18
17
16
15
14
13
12
11
10
TC54
CS
FB
ISENSE
VCC
STB
GATE
DIMOUT
GND
BD9488F
Lot No.
Figure 3-1. Pin configuration
Figure 3-2. Package dimension
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TSZ02201-0F1F0C100040-1-2
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BD9488F
●1.1
Electrical character (Unless otherwise specified Ta=25℃，VCC=12V)
Limit
Parameter
Symbol
【Total
current consumption】
Circuit current
Standby current
Icc
IST
Datasheet
Min.
－
－
Typ.
1.2
0
Max.
1.8
3
Unit
mA
μA
Condition
VSTB=3V, PWM1=PWM2=0V
VSTB=0V
【UVLO
block】
Operation voltage（VCC）
Hysteresis Voltage（VCC）
UVLO release voltage
UVLO hysteresis voltage
UVLO pin leak current
VUVLO_VCC
VUHYS_VCC
VUVLO
VUHYS
UVLO_LK
6.5
150
2.88
250
-2
7.5
300
3.00
300
0
8.5
600
3.12
350
2
V
mV
V
mV
μA
VCC=SWEEP UP
VCC=SWEEP DOWN
VUVLO=SWEEP UP
VUVLO=SWEEP DOWN
VUVLO=4V
【DC/DC
block】
ISENSE threshold voltage 1
ISENSE threshold voltage 2
ISENSE threshold voltage 3
Oscillation frequency
GATE pin MAX DUTY
output
GATE pin ON resistance
(as source)
GATE pin ON resistance
(as sink)
RT pin voltage
SS pin source current
SS pin Low output voltage
Soft start ended voltage
FB source current
FB sink current
OCP detect voltage
VLED1
VLED2
VLED3
FCT
NMAX_DUTY
RONSO
RONSI
VRT
ISSSO
VSS_L
VSS_END
IFBSO
IFBSI
VCS
1.47
3.33
-2
142.5
90
3.0
1.2
1.0
-4.20
-
2.7
-140
60
360
1.50
3.50
-
150
95
6.0
2.5
1.5
-3.0
0.20
3.0
-100
100
400
1.53
3.67
+2
157. 5
99
12.0
5.0
2.0
-2.14
0.50
3.3
-60
140
440
V
V
%
KHz
%
Ω
Ω
V
μA
V
V
μA
μA
mV
VADIM=1.5V
VADIM=5.0V (as mask analog dimming)
VADIM=0.7V
RT=100kohm
RT=100kohm
ION=-10mA
ION=10mA
RT=100kohm
VSS=2V
VSTB=0V, Ioss=50uA
SS=SWEEP UP
VISENSE=0.2V,
VFB=1.0V
VISENSE=2.0V,
VFB=1.0V
CS=SWEEP UP
VADIM=1.0V,
VADIM=1.0V,
【DC/DC
protection block】
OVP detect voltage
OVP detect hysteresis
OVP pin leak current
VOVP
VOVP_HYS
OVP_LK
2.88
50
-2
3.00
100
0
3.12
150
2
V
mV
μA
VOVP SWEEP UP
VOVP SWEEP DOWN
VOVP=4V
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TSZ02201-0F1F0C100040-1-2
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BD9488F
●1.2
Electrical character (Unless otherwise specified Ta=25℃，VCC=12V)
Limit
Parameter
【LED
protection block】
LED OCP detect voltage
LED OPEN detect voltage
【Analog
dimming block】
ADIM_P pin HIGH
voltage
ADIM_P pin LOW voltage
ADIM_P pin input mask
voltage
ADIM_P pin pull-down
resistance
ADIM pin output voltage
H
ADIM pin output voltage L
ADIM pin output
resistance
ADIM pin leak current
Symbol
VLEDOCP
VOPEN
Min.
3.8
0.05
Typ.
4.0
0.10
Max.
4.2
0.15
Unit
V
V
Condition
VISENSE=SWEEP UP
VISENSE=SWEEP DOWN
Datasheet
ADIM_PH
ADIM_PL
ADIM_PPU
RADIM_P
ADIMH
ADIML
ADIMR
ILADIM
2.0
-0.3
4.2
130
3.201
-
6.6
-2
-2
-
-
-
200
3.30
0.0
10
0
0
3.8
0.8
18
300
3.399
0.05
15
2
2
V
V
V
kΩ
V
V
kΩ
μA
μA
VADIM=4V, ADIM_P=5.0V
VISENSE=4V
VADIM_P=3.0V
ADIM_P=3.3V
ADIM_P=0.0V
ISENSE pin leak current
IL_ISENSE
【Dimming
signal output block】
DIMOUT source
on-resistance
RONSO
DIMOUT sink
on-resistance
RONSI
【TC54
block】
TC54 output voltage
TC54 available current
TC54_UVLO detect
voltage
TC54_UVLO hysteresis
TC54 discharge current
【STB
block】
STB pin HIGH voltage
STB pin LOW voltage
STB pin input current
【PWM
block】
PWM½ pin HIGH Voltage
VTC54
|ITC54|
TC54_TH
TC54_HYS
TC54_DIS
STBH
STBL
ISTB
PWM_H
6.0
1.7
5.2
100
2.232
50
5
2.2
-0.3
2.0
2.0
-0.3
130
0.75
-2
12.0
3.5
5.4
-
2.4
100
10
-
-
3.0
-
-
200
1.5
0
24.0
7.0
5.6
-
2.568
200
15
19
0.8
4.5
18
0.8
300
3.0
2
Ω
Ω
V
μA
V
mV
μA
V
V
μA
V
V
kΩ
kΩ
μA
ION=-10mA
ION=10mA
IO=0mA
VSTB=H, TC54=SWEEP DOWN
VSTB=H->L, TC54=SWEEP UP
VSTB=H->L, TC54=4V
VSTB=SWEEP UP
VSTB=SWEEP DOWN
VSTB=3.0V
VPWM½=SWEEP UP
VPWM½=SWEEP DOWN
VPWM½=3.0V
VFAIL=1.0V
VFAIL=15V
PWM½ pin LOW Voltage
PWM_L
PWM½ pin Pull Down
resistance
RPWM
【FAIL
block (OPEN DRAIN)】
FAILB pin on-resistance
FAILB pin leak current
RFAIL
ILFAIL
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TSZ02201-0F1F0C100040-1-2
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BD9488F
●1.3
Pin number, pin name, pin function
No.
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
name
OVP
UVLO
SS
RT
PWM1
PWM2
FAILB
ADIM
ADIM_P
GND
DIMOUT
GATE
STB
VCC
ISENSE
FB
CS
TC54
IN/OUT
In
In
Out
Out
In
In
Out
In/Out
In
-
Out
Out
In
-
In
In/Out
In
Out
function
Over voltage protection detection pin
Under voltage lock out detection pin
Slow start setting pin
For DC/DC switching frequency setting pin
External PWM dimming signal input pin1
External PWM dimming signal input pin2
Abnormality detection output pin
ADIM signal input-output pin
ADIM pulse signal input pin
Datasheet
rating[V]
-0.3 to 7
-0.3 to 7
-0.3 to 7
-0.3 to 7
-0.3 to 20
-0.3 to 20
-0.3 to 20
-0.3 to 20
-0.3 to 20
-0.3 to VCC
-0.3 to VCC
-0.3 to VCC
-0.3 to 20
-0.3 to 7
-0.3 to 7
-0.3 to 7
-0.3 to 7
-
Dimming signal pin for driving MOSFET
DC/DC switching output pin
IC On/OFF pin
Power supply pin
Current detection input pin
Error amplifier output pin
DC/DC output current detect pin,
OCP input pin
5.4V output pin, shutdown timer pin
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TSZ02201-0F1F0C100040-1-2
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