LED Drivers for LCD Backlights
White Backlight LED Driver
for Medium to Large LCD Panels
(Switching Regulator Type)
BD6590MUV
No.11040EBT14
●Description
BD6590MUV is white LED driver IC with PWM step-up DC/DC converter that can boost max 40V and current driver that can
drive max 30mA. The wide and precision brightness can be controlled by external PWM pulse.
BD6590MUV has very accurate current drivers, and it has few current errors between each strings.
So, it will be helpful to reduce brightness spots on the LCD.
Small package type is suited for saving space.
●Features
1) High efficiency PWM step-up DC/DC converter (fsw=1.25MHz)
2) High accuracy & good matching current drivers (MAX30mA/ch)
3) Integrated 50V power Nch MOSFET
4) Soft start
5) Drive up to 10 in series 6strings in parallel
6) Input voltage range (4.5V ~ 5.5V)
7) Rich safety functions
・Over-voltage
protection
・Over
current limit
・LED
terminal open/short protect
・External
SBD open detect / Output short protection
・UVLO
・Thermal
shutdown
8) Small & thin package (VQFN024V4040) 4.0 × 4.0 × 1.0mm
●Applications
All middle size LCD equipments backlight of Notebook PC, NetPC,portable DVD player, DPF, etc.
●Absolute
Maximum Ratings (Ta=25℃)
Parameter
Maximum applied voltage 1
Maximum applied voltage 2
Maximum applied voltage 3
Power dissipation 1
Power dissipation 2
Power dissipation 3
Operating temperature range
Storage temperature range
Symbol
VMAX1
VMAX2
VMAX3
Pd1
Pd2
Pd3
Topr
Tstg
Ratings
7
25
41
500
780
1510
-40 ~ +85
-55 ~ +150
Unit
V
V
V
mW
mW
mW
℃
℃
Condition
VBAT, ISET, TEST, RSTB, PWMDRV
PWMPOW, VDET, FAILFLAG, OCPSET
LED1, LED2, LED3, LED4, LED5, LED6
SW
*1
*2
*3
-
-
*1 Reduced 4.0mW/℃ With Ta>25℃ when not mounted on a heat radiation Board.
*2 1 layer (ROHM Standard board) has been mounted. Copper foil area 0mm
2
, When it’s used by more than Ta=25℃, it’s reduced by 6.2mW/℃.
*3 4 layer (JEDEC Compliant board) has been mounted. Copper foil area 1layer 6.28mm
2
, Copper foil area 2~4layers 5655.04mm
2
,
When it’s used by more than Ta=25℃, it’s reduced by 12.1mW/℃.
●Recommended
Operating Range (Ta=-40℃ ~ +85℃)
Parameter
Power supply voltage
Symbol
VBAT
Limits
Min.
4.5
Typ.
5.0
Max.
5.5
Unit
V
Condition
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© 2011 ROHM Co., Ltd. All rights reserved.
1/26
2011.07 - Rev.B
BD6590MUV
●Electrical
characteristic(Unless otherwise specified, VBAT=5V, Ta = +25℃)
Limits
Parameter
Symbol
Min.
Typ.
Max.
Quiescent current
Current consumption
[PWMPOW Terminal]
Low input voltage range1
High input voltage range1
Pull down resistor1
[PWMDRV Terminal]
Low input voltage range2
High input voltage range2
Pull down resistor2
[FSEL Terminal]
Low input voltage range3
High input voltage range3
Pull down resistor3
[FAILFLAG]
Input resistor
Off current
[Regulator]
Under voltage lock out
[Switching Regulator]
LED control voltage
Switching frequency
Duty cycle limit
SW Nch FET RON
[Protection]
Over current limit
OCPSET open protect
Over voltage limit Input
SBD open protect
VDET leak current
[Current driver]
LED maximum current
LED current accuracy
LED current matching
LED current limiter
LED terminal over voltage protect
ISET voltage
ILMAX
ILACCU
ILMAT
ILOCP
LEDOVP
Iset
-
-
-
-
10.0
0.5
-
-
-
0
11.5
0.6
30
±3.0
±1.5
0.1
13.0
0.7
mA
%
%
mA
V
V
Ocp
OOP
Ovl
Sop
OVIL
1.4
-
0.96
0.02
-
2.0
0.0
1.00
0.05
0.1
2.6
0.1
1.04
0.08
1.0
A
A
V
V
µA
OCPSET=68kΩ
OCPSET=2MΩ
VLED
fsw
Duty
RON
0.56
1.00
91
-
0.70
1.25
95.0
0.48
0.84
1.50
99.0
0.58
V
MHz
%
Ω
UVLO
2.9
3.3
3.7
V
VBAT falling edge
FFIR
FFIST
1.0
-
2.0
0.1
3.0
2.0
kΩ
µA
FAILFLAG=2.5V
PWMPOW=0V
FSL
FSH
FSR
0
2.1
100
-
-
300
0.9
5.5
500
V
V
kΩ
PDRVL
PDRVH
DRVR
0
2.1
100
-
-
300
0.9
5.5
500
V
V
kΩ
POWL
POWH
POWR
0
2.1
100
-
-
300
0.9
VBAT
500
V
V
kΩ
PWMPOW=3V
Iq
Idd
-
-
0.1
3.2
4.4
4.8
Technical Note
Unit
µA
mA
Condition
PWMPOW=PWMDRV=RSTB=0V
VDET=0V,ISET=27kΩ
FSEL=L (GND short)
LED1-6=0.3V
ISW=80mA
*1
Detect voltage of VDET pin
Detect voltage of VDET pin
ILED=16mA
Each LED current/Average (LED1-6)
ILED=16~20mA
Current limit value at ISET
resistor 1kΩ setting
PWMDRV=2.5V
*1 This parameter is tested with DC measurement.
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© 2011 ROHM Co., Ltd. All rights reserved.
2/26
2011.07 - Rev.B
BD6590MUV
●Block
Diagram
VBAT
VBAT
FAILFLAG
Technical Note
SBD OPEN/
Output short PROTECT
VDET
UVLO
RSTB
Internal Power
Supply
Internal Reset
Output Over Voltage PROTECT
TSD
FAULT
DETECTOR
LED TERMINAL
OPEN/SHORT
DETECTOR
ERRAMP
PWM COMP
-
+
LED1
LED2
PWMPOW
Internal Power
Control
5.5V
Clamp
Soft start
SW
SW
Control
SENCE
LED
RETURN
LED3
LED4
LED5
LED6
OSC
Current SENCE
Over Current Protect
+
SELECT
8ch
PGND
+
-
ISET
Resistor driver
Current Driver
N.C. N.C. N.C.
OCPSET
TEST
GND
PWMDRV
ISET
GND
Fig.1 BD6590MUV block diagram
●Application
Example
Adapter
4.5V to 30V
Battery
4.5V to 5.5V
10µF
4.7µH
10S × 6P
2.2µF/50V
1µF
FAILFLAG
SW
SW
VBAT
VBAT
10kΩ
1MΩ
VDET
26.7kΩ
PWMDRV
10KΩ
PWM
PWMPOW
f
PWM
=100Hz~1kHz
RESET
RSTB
BD6590MUV
LED1
LED2
LED3
LED4
LED5
LED6
Each 16mA
TEST
OCPSET
68kΩ
PGND
GND
GND
ISET
27kΩ
Fig.2 Application example (10LED × 6parallel)
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© 2011 ROHM Co., Ltd. All rights reserved.
3/26
2011.07 - Rev.B
BD6590MUV
●Pin
Assignment Table
PIN No.
1
2
3
4
5
6
7
8
9
10
11
12
13
14
5
16
17
18
19
20
21
22
23
24
VBAT
Technical Note
PIN Name
SW
SW
N.C.
PGND
FAILFLAG
OCPSET
VDET
TEST
RSTB
ISET
GND
N.C.
LED1
LED2
LED3
LED4
LED5
LED6
N.C.
GND
PWMDRV
VBAT
PWMPOW
VBAT
In/Out
Out
Out
-
-
Out
In
In
In
In
In
-
-
In
In
In
In
In
In
-
-
In
In
In
In
Function
Switching Tr drive terminal
Switching Tr drive terminal
No connect pin
PGND for switching Tr
Fail Flag
Current Limiter setting
Detect input for SBD open and OVP
TEST signal
Reset
Resister connection for LED current setting
GND for Switching Regulator
No connect pin
Current sink for LED
Current sink for LED
Current sink for LED
Current sink for LED
Current sink for LED
Current sink for LED
No connect pin
GND for Current driver
PWM input pin for power ON/OFF only driver
Regulator output / Internal power-supply
PWM input pin for power ON/OFF
Switching Tr drive terminal
Terminal
diagram
H
H
F
D
C
A
A
J
J
A
B
F
C
C
C
C
C
C
F
B
G
I
E
I
VBAT
VBAT
PIN
PIN
PIN
PIN
GND
PGND
GND
GND
A
VBAT
B
VBAT
C
D
PIN
5.5V
Clump
GND
PIN
PIN
PIN
GND
PGND
E
VBAT
F
G
H
PIN
PIN
GND
PGND
GND
I
J
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© 2011 ROHM Co., Ltd. All rights reserved.
4/26
2011.07 - Rev.B
BD6590MUV
Technical Note
●Description
of Functions
1) PWM current mode DC/DC converter
While BD6590MUV is power ON, the lowest voltage of LED terms is detected, PWM duty is decided to be 0.7V and output
voltage is kept invariably. As for the inputs of the PWM comparator as the feature of the PWM current mode, one is
overlapped with error components from the error amplifier, and the other is overlapped with a current sense signal that
controls the inductor current into Slope waveform to prevent sub harmonic oscillation. This output controls internal Nch Tr
via the RS latch. In the period where internal Nch Tr gate is ON, energy is accumulated in the external inductor, and in the
period where internal Nch Tr gate is OFF, energy is transferred to the output capacitor via external SBD.
BD6590MUV has many safety functions, and their detection signals stop switching operation at once.
2) Soft start
BD6590MUV has soft start function.
The soft start function prevents large coil current.
Rush current at turning on is prevented by the soft start function.
After PWMPOW, RSTB is changed L→ H, soft start becomes effective for within 4ms and soft start doesn't become
effective even if PWMPOW is changed L→H after that.
And, when the H section of PWMPOW is within 4ms, soft start becomes invalid when PWMPOW is input to H more than
three times. The invalid of the soft start can be canceled by making PWMPOW, PWMDRV
→L.
PWMDRV
PWMPOW
PWMPOW
VREG
Soft start
OFF
ON
OFF
OFF
VREG
Max 1ms
Max 3ms
Soft start
Soft start
reset
OFF
ON
OFF
ON
OFF
OFF
ON
OFF
Reset
Reset
OFF
Fig.3 Soft start
Fig.4 Soft start reset and set
3) FAILFLAG
When the error condition occurs, boost operating is stopped by the protection function, and the error condition is outputted
from FAILFLAG. After power ON, when the protection function is operating under about 1ms have passed.
Object of protect function is as shown below.
・Over-voltage
protection
・External
SBD open detect/ Output Short protection
・LED
terminal open/short protection
・Over
current limit
PWMPOW
FAILFLAG
Protection
function
Boost
operating
about 1ms
un-detection
off
normal
detect
boost stop
normal
un-detection
off
normal
Fig.5 FAILFLAG operating description
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© 2011 ROHM Co., Ltd. All rights reserved.
5/26
2011.07 - Rev.B
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