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Número de pieza | BD6142AMUV | |
Descripción | 8-Channel White LED Driver | |
Fabricantes | ROHM Semiconductor | |
Logotipo | ||
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No Preview Available ! Datasheet
8-Channel White LED Driver
with Integrated FET for up to 80 LEDs
BD6142AMUV
●General Description
This IC is white LED driver IC with PWM step-up
DC/DC converter that can boost max 41V and current
driver that can drive max 30mA. The wide and
precision brightness can be controlled by external
PWM pulse. This IC 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
panel. Small package is suited for saving space.
●Features
High accuracy & good matching current drivers 8ch
(MAX30mA/ch)
Integrated 50V power Nch MOSFET
Soft Start function
Drive up to 11 LEDs in series, 8 strings in parallel
Rich safety functions
・Over-voltage protection
・External SBD open detect / Output Short
protection
・Over current limit
・CH Terminal open / GND short protect
・CH over voltage protect / LED short protect
・Thermal shutdown
・UVLO
Analog Brightness Control
●Key Specifications
Operating power supply voltage range: 4.2V to 27.0V
LED maximum current:
30mA (Max.)
Quiescent Current:
1.6μA (Typ.)
Switching frequency:
1.25MHz(Typ.)
Operating temperature range:
-40℃ to +85℃
●Package W(Typ.) x D (Typ.) x H(Max.)
VQFN024V4040
4.00mm x 4.00mm x 1.00mm
VQFN024V4040
Figure 1. Package
●Applications
All medium sized LCD equipments, Backlight of
Notebook PC, net book, monitor, light, Portable DVD
player, light source etc.
●Typical Application Circuit (8 Parallel)
10µF
7V to27V
10µH
2. 2µ F/50V
2.2µF
VOUT
10 serial x 8 parallel (80pcs)
2.1V to VIN
RESET
LX LX
ENAB LE
FAULT
VIN
VDC
OV P
PWM
PWM
fPW M=100Hz~25kHz
1kΩ
22nF
GND
PG ND
CO MP
PGND
B D 61 42 AM U V
PGND GND TEST FSET ABC ISET
CH1
CH2
CH3
CH4
CH5
CH6
CH7
CH8
56kΩ 1nF
36kΩ
Figure 2. Typical Application Circuit
2.2MΩ
68kΩ
20mA
○Product structure:Silicon monolithic integrated circuit
www.rohm.com
© 2011 ROHM Co., Ltd. All rights reserved.
TSZ22111・14・001
○This product is not designed protection against radioactive rays
1/30
TSZ02201-0G3G0C400340-1-2
03.Dec.2012 Rev.001
1 page BD6142AMUV
●Block Diagram
VIN VDC
FAULT
Datasheet
ENABLE
LX
LX
PGND
PGND
REG
TSD
UVLO
Clamp
Internal Power
Supply
Internal Power
Control
Current SENSE
Over Current Protect
Output short PROTECT
Internal Reset
Output Over Voltage PROTECT
FAULT
DETECTOR
Soft start
Control
SENSE
OSC
PWM COMP
+
ERRAMP
-
+
LED TERMINAL
OPEN/SHORT
DETECTOR
LED
RETURN
SELECT
Clamp
ISET
Resistor driver
8ch
+
-
Current Driver
TEST
FSET
COMP PWM ABC
ISET
GND
Pin number 24pin
Figure 4. Block diagram
OVP
CH1
CH 2
CH 3
CH 4
CH 5
CH 6
CH 7
CH 8
www.rohm.com
© 2011 ROHM Co., Ltd. All rights reserved.
TSZ22111・15・001
5/30
TSZ02201-0G3G0C400340-1-2
03.Dec.2012 Rev.001
5 Page BD6142AMUV
Datasheet
This section is especially mentioned here because the spec shown electrical characteristic is necessary to explain this
section.
Over voltage limit
LED control voltage
LED terminal over voltage protect
min 1.16V typ 1.20V max 1.24V
min 0.64V typ 0.80V max 0.96V
min 4.25V typ 5.00 V max 5.75V
1. Calculate the conditions that the total value of LED VF is MAX.
Example) In the case of serial 8 LEDs with VF=2.9V(min), 3.2V(typ), 3.5V(max) => 3.5V x 8=28V
2. Then calculate the biggest value of output with the following formula.
The biggest value of output = the biggest value calculated for 1 + the biggest value of LED terminal voltage. (0.96V)
Example) The biggest value of output = 28V + 0.96V =28.96V
3. Set the smallest value of over voltage larger than the biggest value of output.
If over voltage is closer to the total value of VF, it could be occurred to detect over voltage by ripple, noise, and so on.
It is recommended that some margins should be left on the difference between over voltage and the total value of VF.
This time around 6% margin is placed.
Example) Against the biggest value of output = 28.96V, the smallest value of over voltage = 28.96V x 1.06 = 30.70V
Ic over voltage limit min=1.16V, typ=1.20V, max=1.24V
typ = 30.70V×(1.20V/1.16V) = 31.76V
max = 31.76V×(1.26V/1.20V) = 33.35V
4. The below shows how to control resistor setting over voltage
Please fix resistor high between OVP terminal and output and then set over voltage after changing resistor between
OVP terminal and GND. While PWM is off, output voltage decreases by minimizing this resistor. Due to the decrease of
output voltage, ripple of output voltage increases, and singing of output condenser also becomes bigger.
Example) Selecting OVP resistor.
・OVP resistor selection
(Example. 1) VF=3.5V max, serial = 7 LED
OVP = 1.2V, R1 = 2.2MΩ, R2 = 95.3kΩ
VOUT = 1.2 × (2.2MΩ + 95.3kΩ)/ 95.3kΩ = 28.90V
(Example. 2) VF=3.5V max, serial = 8 LED
OVP = 1.2V, R1 = 2.2MΩ, R2 = 82kΩ
VOUT = 1.2 × (2.2MΩ + 82kΩ)/ 82kΩ = 33.40V
(Example. 3) VF=3.5V max, serial = 9 LED
OVP = 1.2V, R1 = 2.2MΩ, R2 = 73.2kΩ
VOUT = 1.2 × (2.2MΩ + 73.2kΩ)/ 73.2kΩ = 37.27V
(Example. 4) VF=3.5V max, serial = 10 LED
OVP = 1.2V, R1 = 2.2MΩ, R2 = 68kΩ
VOUT = 1.2 × (2.2MΩ + 68kΩ)/ 68kΩ = 40.02V
VOUT
OVP terminal
R1
R2
・External SBD open detect / Output Short protection
In the case of external SBD is not connected to IC, or VOUT is shorted to GND, the coil or internal Tr may be destructed.
Therefore, at such an error as OVP becoming 50mV(typ.) or below, 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).
・Thermal shut down
This IC has thermal shut down function.
The thermal shut down works at 130C (typ.) or higher, and the IC changes from activation into non-activation.
www.rohm.com
© 2011 ROHM Co., Ltd. All rights reserved.
TSZ22111・15・001
11/30
TSZ02201-0G3G0C400340-1-2
03.Dec.2012 Rev.001
11 Page |
Páginas | Total 30 Páginas | |
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