ROHM BD6592MUV Technical data
LED Drivers for LCD Backlights
White Backlight LED Driver
for Medium to Large LCD Panels
(Switching Regulator Type)
BD6592MUV
●Description
BD6592MUV is white LED driver IC with PWM step-up DC/DC converter that can boost max 42.5V and current driver that
can drive max 40mA. The wide and precision brightness can be controlled by external PWM pulse. BD6592MUV 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=1MHz), max efficiency 93%
2) High accuracy & good matching (±3%) current drivers 6ch
3) Drive up to 12
4) Wide input voltage range (2.7V ~ 22V)
5) Rich safety functions
・Over-voltage protection (OVP)
・Over current limit
・External SBD open detect
・Thermal shutdown
6) Small & thin package (VQFN024V4040) 4.0 × 4.0 × 1.0mm
●Applications
All middle size LCD equipments backlight of Notebook PC, portable DVD player, car navigation systems, etc.
●Absolute maximum ratings (Ta=25℃)
Parameter Symbol Ratings Unit Condition
Maximum applied voltage 1 VMAX1 7 V
Maximum applied voltage 2 VMAX2 25 V
Maximum applied voltage 3 VMAX3 50.5 V VDET
Power dissipation 1 Pd1 500 mW
Power dissipation 2 Pd2 780 mW
Power dissipation 3 Pd3 1510 mW
Operating temperature range Topr -30 ~ +85 ℃
Storage temperature range Tstg -55 ~ +150 ℃
*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
*3 4 layer (JEDEC Compliant board) has been mounted.
Copper foil area 1layer 6.28mm
●Recommended operating range (Ta=-30℃ ~ +85℃)
Parameter Symbol
*
in series, 6 strings in parallel =72 white LEDs (*white LED Vf=3.5Vmax)
TEST, VREG, SENSP, SENSN, SW,
RSTB, PWMPOW, PWMDRV,
FAILSEL, ISETH, ISETL
LED1, LED2, LED3, LED4, LED5,
LED6, VBAT
*1
*2
*3
2
, When it’s used by more than Ta=25℃, it’s reduced by 6.2mW/℃.
2
, Copper foil area 2~4layers 5655.04mm2, When it’s used by more than Ta=25℃, it’s reduced by 12.1mW/℃.
Ratings
Min. Typ. Max.
Unit Condition
No.11040ECT33
Power supply voltage VBAT 2.7 12.0 22.0 V
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1/25
2011.06 - Rev.C
BD6592MUV
●Electrical characteristic (Unless otherwise specified, VBAT=12V, RSTB=2.5V, Ta = +25℃)
Parameter Symbol
[FAILSEL,PWMDRV Terminal]
EN threshold voltage (Low) VthL 0 - 0.2 V
EN threshold voltage (High) 1 VthH1 1.4 - 5.0 V VBAT>5.0V
EN threshold voltage (High) 2 VthH2 1.4 - VBAT V VBAT<5.0V
EN terminal input current Iin - 8.3 14.0 µA Input=2.5V
[PWMPOW Terminal]
Low Input Voltage range PWML 0 - 0.2 V
High Input Voltage range1 PWMH1 1.4 - 5.0 V VBAT>5.0V
High Input Voltage range2 PWMH2 1.4 - VBAT V VBAT<5.0V
PWM pull down resistor PWMR 300 500 700 k
[RSTB Terminal]
Low Input Voltage range RSTBL 0 - 0.2 V
Min. Typ. Max.
Limits
Unit Condition
Technical Note
High Input Voltage range1 RSTBH1 2.25 2.5 5.0 V VBAT>5.0V
High Input Voltage range2 RSTBH2 2.25 2.5 VBAT V VBAT<5.0V
Current Consumption IRSTB - 89 134 µA RSTB=2.5V, LED1-6=3V
[Regulator]
VREG Voltage VREG 4.0 5.0 6.0 V No load
Under Voltage Lock Out UVLO 2.05 2.25 2.65 V
[Switching Regulator]
Quiescent Current 1
Quiescent Current 2
Current Consumption
LED Control voltage
Over Current Limit voltage
SBD Open Protect
Switching frequency
Duty cycle limit
Over voltage limit
Iq1 - 0.6 3.4 µA RSTB=0V, VBAT=12V
Iq2 - 4.6 10 µA RSTB=0V, VBAT=22V
Idd - 3.4 5.1 mA VDET=0V,ISETH=24k
VLED 0.4 0.5 0.6 V
Ocp 70 100 130 mV
Sop - - 0.1 V Detect voltage of VDET pin
fSW 0.8 1.0 1.2 MHz
Duty 92.5 95.0 99.0 % LED1-6=0.3V
Ovl 43.0 44.7 46.4 V LED1-6=0.3V
*1
[Current driver]
LED maximum current
LED current accuracy
LED current matching
ISET voltage
LED Terminal
Over Voltage Protect
*1 This parameter is tested with DC measurement.
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ILMAX - - 40 mA
ILACCU - - ±5 %
ILMAT - - ±3 %
Iset 0.5 0.6 0.7 V
LEDOVP 10.0 11.5 13.0 V
2/25
ILED=30mA
Each LED current/Average (LED1- 6)
ILED=30mA
RSTB=PWMDRV=2.5V
2011.06 - Rev.C
BD6592MUV
●Reference data
4.5
4.0
3.5
3.0
2.5
2.0
Iin [mA]
1.5
1.0
0.5
0.0
0 2 4 6 8 10 12 14 16 18 20 22
Current Consumption - VBAT
25℃
-30℃
VBAT [V]
Fig.1
2.6
2.5
2.4
2.3
VBAT [V]
2.2
2.1
2
-50 - 25 0 25 50 75 100
Ta [℃]
Fig.4
UVLO - Temperature
30
25
20
(mA)
15
10
LED c urrent
VBAT=6V, 12V, 16V
5
0
0 10 203040 50607080 90100
LED current - PWMDRV-HI Duty
30
25
(mA)
LED c urrent
VBAT=6V, 12V, 16V
20
15
10
5
0
0 102030405060708090100
Ta=-30,+25,+85℃
Duty (%)
Fig.7
PWM = 200Hz
Ta=-30,+25,+85℃
Duty (%)
Fig.10
LED current - PWMPOW-HI Duty
PWM = 200Hz
85℃
Technical Note
8
7
6
5
4
Ist[µA]
3
2
1
0
0 2 4 6 8 10121416182022
85℃
25 ℃
-30℃
VBAT[V]
Fig.2
Quiescent current - VBAT
100%
95%
90%
85%
80%
Effici ency
75%
70%
65%
60%
0 10203040 5060708090100
Duty [%]
VBAT=12V
Fig.5
Efficiency - PWMPOW-HI Duty
ISETH=24k, PWM=200Hz
1.0
0.9
0.8
0.7
VBAT=6V, 12V, 16V
(mA)
0.6
0.5
0.4
LED c urrent
0.3
0.2
0.1
0.0
00.51 1.522.53
Ta=-30,+25,+85℃
Duty (%)
Fig.8
LED current - PWMDRV-HI Duty
( Expansion) PWM = 200Hz
1.0
0.9
0.8
0.7
(mA)
0.6
0.5
0.4
LED c urrent
0.3
0.2
0.1
0.0
00.51 1.522.53
16V
12V
6V
Ta=-30,+25,+85℃
Duty (%)
Fig.11
LED current - PWMPOW-HI Duty
( Expansion) PWM = 200Hz
1.20
1.15
1.10
1.05
1.00
0.95
Fr equency [M Hz]
0.90
0.85
0.80
0 2 4 6 8 10 12 14 16 18 20 22
25℃
-30℃
85℃
VBAT [V]
Fig.3
Oscillation frequency - VBAT
100%
95%
90%
85%
80%
Effici ency
75%
70%
65%
60%
0 10203040 5060708090100
Duty [%]
VBAT=12V
Fig.6
Efficiency - PWMDRV-HI Duty
ISETH=24k, PWM=200Hz
30
25
20
(mA)
15
10
LED C urr ent
5
0
200Hz
0 1020 30405060708090100
1kHz
10kHz
Duty (%)
Fig.9
LED current - PWMDRV-HI Duty
PWM = 200Hz, 1kHz,10kHz
30
25
20
(mA)
15
10
LED C urr ent
5
0
200Hz
10kHz
1kHz
0 102030405060708090100
Duty (%)
Fig.12
LED current - PWMPOW-HI Duty
PWM = 200Hz, 1kHz,10kHz
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3/25
2011.06 - Rev.C
c
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BD6592MUV
3.0
2.0
Max Matching = Max LED Current/Average Current
1.0
0.0
-1.0
Cur rent M atching ( %)
Min Matching = Min LED Current/Average Current
-2.0
-3.0
0% 20% 40% 60% 80% 100%
PWM HI Duty
Fig.13
LED current matching - PWMDRV-HI Duty
PWM = 200Hz
3.0
2.0
Max Matching = Max LED Current/Average Current
1.0
0.0
-1.0
Cur rent M atching ( %)
Min Matching = Min LED Current/Average Current
-2.0
-3.0
0% 20% 40% 60% 80% 100%
PWM HI Duty
Fig.16
LED current matching - PWMPOW-HI Duty
PWM = 200Hz
35
34
33
32
31
30
29
LED C urr ent [m A]
28
27
26
25
-50 -25 0 25 50 75 100
5V, 7V, 12V, 22V
2.7V
temp [
]
℃
Fig.19
LED current - Temperature
PWMDRV=H, ISETH=30k (16mA setting)
VOUT
Ic
Fig.22
VOUT@OVP (LED OPEN)
3.0
2.0
Max Matchin g = Max LED Current/Ave rage Current
1.0
0.0
-1.0
Cur rent M atching ( %)
Min Matching = Min LED Current/Average Current
-2.0
-3.0
0% 2% 4% 6% 8% 10%
PWM HI Duty
Fig.14
LED current matching - PWMDRV-HI Duty
(Expansion) PWM = 200Hz
3.0
Max Matching = Max LED Current/Average Current
2.0
1.0
0.0
-1.0
Cur rent M atching ( %)
Min Matching = Min LED Current/Average Current
-2.0
-3.0
0% 2% 4% 6% 8% 10%
PWM HI Duty
Fig.17
LED current matching - PWMPOW-HI Duty
(Expansion) PWM = 200Hz
VBAT
VOUT
LED curren
400s
No peak
Fig.20
Line Transient (10V to 22V)
PWMDR
VOUT
LED Current
10mA/div
PWMPOW
VOUT
LED Current
10mA/div
VBAT
VOUT
LED current
Technical Note
350mV
Fig.15
VOUT response
Driver Control PWM (PWMDRV)
180mV
Fig.18
VOUT response
Power Control PWM (PWMPOW)
14ms
No peak
Fig.21
Line Transient (22V to 10V)
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4/25
2011.06 - Rev.C
BD6592MUV
Technical Note
●Block diagram, I/O equivalent circuit diagram
VBAT
RSTB
PWMPOW
300k
500k
TSD
REG
VREG
VIN detector
Internal Power suplly
SBD Open protect
FAIL SEL
SW
SENSP
SENSN
TEST
PWMD RV
ISETH
ISETL
300k
100k
300k
S
Q R
Current
Sence
GND
ISET H
Resistor driver
ISET L
Resistor driver
GND
1M
100K
Control
sence
GND
over voltage protect
PWMcom p
-
+
+
Over Voltage Protect
GND
ERRAMP
OSC
LED TERMINAL
Detect
LED TERMINAL
PWMDR V=H
On
PWMDRV=L
On
Fig.23 Block diagram Fig.24 I/O equivalent circuit diagram
●Pin assignment table
PIN
Name
In/Out
PIN
number
1 VDET In Detect input for SBD open and OVP C
2 N.C. - No connect pin F
3 GND - GND B
4 SW Out Switching Tr drive terminal G
5 SENSP In + Side Current sense terminal G
6 TEST In TEST input (Pull down 100k to GND) G
7 SENSN In - Side Current sense terminal A
8 GND - GND B
9 ISETH In Resistor connection for LED current setting at PWMDRV=H A
10 ISETL In Resistor connection for LED current setting at PWMDRV=L A
11 PWMDRV In PWM input pin for power ON/OFF only driver E
12 LED1 In Current sink for LED1 C
13 LED2 In Current sink for LED2 C
14 LED3 In Current sink for LED3 C
15 GND - GND B
16 LED4 In Current sink for LED4 C
17 LED5 In Current sink for LED5 C
18 LED6 In Current sink for LED6 C
19 FAILSEL In Latch selectable pin of protect function E
20 GND - GND B
21 RSTB In Reset pin L :Reset H :Reset cancel E
22 VREG Out Regulator output / Internal power-supply D
23 PWMPOW In PWM input pin for power ON/OFF E
24 VBAT In Battery input C
UVLO
+
-
+
-
-
-
-
-
-
+
+
-
Current Driver
VDET
LED1
LED2
LED3
LED4
LED5
LED6
VBAT VREG
PIN
GND
VBAT
PIN
GND
VBAT
PIN
GND
A
D
VREG
G
Function
PIN
PIN
VBAT
B
VBAT
5.5V
Clump
GND
E
Terminal equivalent
circuit diagram
PIN
GND
C
PIN
F
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2011.06 - Rev.C
y
BD6592MUV
Technical Note
●Application example
RTR020N05
10F
47m
Power
ON/OFF
200Hz
PWM
Battery
2.2F
4.7H
2.2F *
2.2F *
SW
SENSP
SENSN
RSTB
PWMPOW
PWMDRV
VREG
GND
VBAT
GND
GND
GND
FAILSEL
ISETL
ISETH
TEST
12k
Fig.25 10 series x 6parallel
Hi current 40mA setting
Current driver PWM application
VDET
LED1
LED2
LED3
LED4
LED5
LED6
Each 40mA
10LED x 6parallel
10F
RTR020N05
47m
Power
ON/OFF
200Hz
PWM
Battery
2.2F
4.7H
2.2F *
SENSP
SENSN
RSTB
PWMPOW
GND
SW
PWMDRV
VBAT
VREG
2.2F *
GND
TEST
GNDGND
Fig.26 10 series x 4parallel
Hi current 40mA setting
Current driver PWM application
* Please select the capacitor which the little bias fluctuation.
FAIL SEL
ISETH
12k
ISETL
10LED x 4aprallel
VDET
LED1
LED2
LED3
LED4
LED5
LED6
Each 40mA
VDET
LED1
LED2
LED3
LED4
LED5
LED6
Each 30mA
10LED x 6parallel
Batter
10F
RTR020N05
47m
Power
ON/OFF
200Hz
PWM
2.7V to 5.5V
4.7H
2.2F *
2.2F
2.2F *
SENSP
SENSN
PWMPOW
GND
SW
RSTB
PWMDRV
VBAT
VREG
GND
GNDGND
TEST
FAIL SEL
ISETH
12k
ISETL
Fig.28 Non-used Inside REG
or operating under 5V application
VDET
LED1
LED2
LED3
LED4
LED5
LED6
10LED x 6parallel
Each 40mA
10F
RTR020N05
47m
Power
ON/OFF
200Hz
PWM
Fig.27 10
Battery
4.7H
2.2F *
2.2F *
SW
SENSP
SENSN
RSTB
PWMPOW
PWMDRV
VBAT
VREG
2.2F
GND
GND
GND
series x 6parallel LED current 30mA setting
GND
FAIL SEL
ISETH
ISETL
TEST
16k
Power control PWM application
* Please select the capacitor which the little bias fluctuation.
●Terminal processing
TEST pin= Connect to GND
N.C. = Nothing specified in particular. Open is recommended.
VREG= When IC is driving from the outside of 2.7~5.5V, short VBAT and VREG, and put the voltage to VREG
FAILSEL, PWMDRV= Connect to GND in case of fixing at L level. Connect to VREG of IC or the power supply of more
than 1.4V in case of fixing at H level .
LED1-6= When each LED driver are not used, connect to GND of IC
GND = Each GND is connecting inside IC, but, connect to GND of all board
RSTB= RSTB is used as a power supply of internal circuit.
So, you mustn’t input RSTB voltage with pull up resistor of several k. And, please care about the relation between VBAT
and RSTB enough. (ref. P9)
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2011.06 - Rev.C
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BD6592MUV
Technical Note
●Description of Functions
1) PWM current mode DC/DC converter
While BD6592MUV is power ON, the lowest voltage of LED1, 2, 3, 4, 5, 6 is detected, PWM duty is decided to be 0.5V 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 external Nch Tr
via the RS latch. In the period where external Nch Tr gate is ON, energy is accumulated in the external inductor, and in the
period where external Nch Tr gate is OFF, energy is transferred to the output capacitor via external SBD.
BD6592MUV has many safety functions, and their detection signals stop switching operation at once.
2) Soft start
BD6592MUV 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 RSTB is changed L H, when PWMPOW is changed L H, soft start becomes effective for within 1ms 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 1ms, 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 RSTB L.
3) FAILSEL pin
When the error condition occurs, boost operating is stopped by the protection function, and the error condition is avoided.
On that occasion, the way to stop of boost operating by the protection function can be selected with FAILSEL pin. Details
are as shown in Fig.29, 30.
After power ON, when the protection function is operating under about 1ms have passed, the stop state of the boost
operating can be held through FAILSEL is H, the stop state can reset through RSTB is L.
And, boost operating is stopped when the protection function is operating through FAILSEL is L, but when the protection
function becomes un-detect, boost operating is started again. It never keeps holding the stop state of boost operating.
In PWM control by PWMDRV can’t use this function.
When it is off over 10ms on PWM control by PWMPOW using this function, it may be stopped the boost operating as
over current protection work at off on PWMPOW=L.
Object of protect function is as shown below.
・ Over-voltage protection
・ External SBD open detect
・ Thermal shutdown
・ LED terminal over-voltage protection
・ Over current limit
<FAILSEL=H>
RSTB
“H”
FAIL SEL
Protection
function
Boost
operating
<FAILSEL =L>
RSTB
Protection
“L”
function
Boost
operating
about 1ms
un-operating range
un-detection un-detection
normal operating off boost stop
about 1ms
un-operating range FAILSEL
un-detectio
normal operating off
detection
detection
boost stop
un-detection
normal
o
eratin
off
off normal operating
normal
< When it is off on PWMPOW>
RSTB
PWMDRV
PWMPOW
Outpu
voltage
Coil current
FAI LS EL
function
< When it is off on RSTB>
RSTB
PWMDRV
PWMPOW
Outpu
voltage
Coil current
FAI LS EL
function
invalid valid
invalid
Fig.29 FAILSEL operating description Fig.30 FAILSEL=H light off control
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BD6592MUV
4) External SBD open detect and over voltage protection
BD6592MUV has over boost protection by external SBD open and over voltage protection. It detects VDET voltage and is
stopped output Tr in abnormal condition. Details are as shown below.
External SBD open detect
In the case of external SBD is not connected to IC, the coil or external Tr may be destructed. Therefore, at such an error
as VOUT becoming 0.1V or below, the Under Detector shown in the figure works, and turns off the output Tr, and
prevents the coil and the IC from being destructed.
And the IC changes from activation into non-activation, and current does not flow to the coil (0mA).
Over voltage protection
At such an error of output open as the output DC/DC and the LED is not connected to IC, the DC/DC will boost too much
and the VDET terminal exceed the absolute maximum ratings, and may destruct the IC.
Therefore, when VDET becomes sensing voltage or higher, the over voltage limit works, and turns off the output Tr, and
the pressure up made stop.
At this moment, the IC changes from activation into non-activation, and the output voltage goes down slowly. And, when
the output voltage becomes the hysteresis of the over voltage limit or below, the output voltage pressure up to sensing
voltage once again and unless the application error is recovered, this operation is repeated.
5) Thermal shut down
BD6592MUV has thermal shut down function.
The thermal shut down works at 175C or higher, and the IC changes from activation into non-activation. Because
non-activation is different from RSTB=L, it doesn’t’ be reset inside IC. Moreover, even if thermal shut down function works,
soft start, FAILSEL, selection the number of LED lines of the current driver and starting current setting at PWMDRV=L
related RSTB are hold.
6) Over Current Limit
Over current flows the current detection resistor that is connected to switching transistor source and between GND,
SENSP pin voltage turns more than detection voltage, over current protection is operating and it is prevented from flowing
more than detection current by reducing ON duty of switching Tr without stopping boost.
As over current detector of BD6592MUV is detected peak current, current more than over current setting value does not flow.
And, over current value can decide freely by changing over current detection voltage.
<Derivation sequence of detection resistor>
Detection resistor =Over current detection voltage / Over current setting value
TYP value of over current detection voltage is 100mV, MIN = 70mV and MAX = 130mV and after the current value which
was necessary for the normal operation was decided, detection resistor is derived by using MIN value of over current
detection value.
For example, detection resistor when necessary current value was set at 1A is given as shown below.
Detection resistor =70mV / 1A = 70m
MAX current dispersion of this detection resistor value is
MAX current = 130mV / 70m = 1.86A
<The estimate of the current value which need for the normal operation >
As over current detector of BD6592MUV is detected the peak current, it have to estimate peak current to flow to the coil by
operating condition.
In case of, ○ Supply voltage of coil = VIN
○ Inductance value of coil = L
○ Switching frequency = fsw MIN=0.8MHz, Typ=1MHz, MAX=1.2MHz
○ Output voltage = VOUT
○ Total LED current = IOUT
○
○ Efficiency = eff (Please set up having margin, it refers to data on p.3.)
○ ON time of switching transistor = Ton
Ipeak = (VIN / L) × (1 / fsw) × (1-(VIN / VOUT))
Iave=(VOUT × IOUT / VIN) / eff
Ton=(Iave × (1-VIN/VOUT) × (1/fsw) × (L/VIN) × 2)
Each current is calculated.
As peak current varies according to whether there is the direct current superposed, the next is decided.
(1-VIN/VOUT) × (1/fsw) < Ton peak current = Ipeak /2 + Iave
(1-VIN/VOUT) × (1/fsw) > Ton peak current = Ipeak
Average current of coil = Iave
Peak current of coil = Ipeak
○
1/2
Technical Note
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