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PDF IW7023 Data sheet ( Hoja de datos )
| Número de pieza | IW7023 | |
| Descripción | 16-Channel LED Driver | |
| Fabricantes | Dialog Semiconductor | |
| Logotipo |  |
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iW7023
16-Channel LED Driver for LCD Panel Backlighting
1.0 Features
2.0 Description
●● 16-channel LED driver, 60V (max) per channel
●● VIN: 9V to 28V
●● Fully-integrated current-sink FETs with minimum
external components
●● Two dynamic external boost or buck controller interfaces
to optimize system power efficiency
●● Patented BroadLED™ digital adaptive switch mode
technology for high current matching at maximum
efficiency
xx Channel-to-channel matching accuracy ±2%
xx Enables use of cheaper, loosely binned LED arrays
for lower BOM cost
●● High-speed PWM dimming via SPI interface
xx High-bandwidth PWM-based dynamic local dimming
xx PLL-locked VSYNC synchronized PWM
xx Dimming range: 1% to 99.9%, 12-bit resolution
xx Dimming frequency support for NTSC, PAL and 3D
game modes with 5-bit programmability in normal
mode (controlled by SPI dimming interface)
●● Direct and unsynchronized dimming via external PWM
●● Per-channel current
xx Up to 150mA average
xx Up to 240mA peak
●● Comprehensive protection features:
xx LED open and short-circuit fault protection
xx Over-temperature shutdown
The iW7023 is a high efficiency driver for LEDs. It is designed
for use with mid-size LCD panels that use arrays of LEDs as
a backlight source. It is able to communicate with up to one
external step-up or step-down PWM DC-DC converter to
drive up to 16 separate strings of multiple series-connected
LEDs.
The iW7023 features dynamic output voltage control, which
automatically chooses the lowest active LED source voltage
to adjust the feedback voltage of a step-up or step-down
converter. Through this function, the iW7023 is able to
dynamically adjust the output voltage of up to two external
step-up or step-down converters to optimize the system
power efficiency.
The iW7023 also provides 16 constant current sinks with
maximum ±2% current matching. The LED PWM dimming
can be adjusted dynamically through a high bandwidth SPI
interface, which provides users flexibility to control the light
intensity of LEDs. In addition, users can provide versatile
configurations of the iW7023 through SPI interface registers.
The iW7023 can maintain very high efficiency even with the
existence of LED channel total forward voltage mismatch,
with the proprietary digital power management and patent
pending adaptive switch mode LED current regulation
technology.
The iW7023 has multiple features to protect the LED
channels from fault conditions, and these protections are
LED PWM cycle-by-cycle based to ensure system reliability
and provide consistent operation.
3.0 Applications
●● Direct & Segment-Edge LED Backlit LCD TV
●● 48-lead QFN-7m-48L package
●● Edge Type global dimming LED backlit LCD TV
●● Medical, Industrial Monitors and Public Displays
iW7023
Datasheet
Rev. 1.0
1 of 35
© 2015 Dialog Semiconductor (UK) Ltd.
1 page  
iW7023
16-Channel LED Driver for LCD Panel Backlighting
Pinout Description (cont.)
Pin #
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
Name
FAULTB
LED9
LED10
EPGND
EPGND
LED11
LED12
NC
XO
SYNCLK
CPLL
NC
VSYNC
LED13
LED14
EPGND
EPGND
LED15
LED16
TESTEN
EXTLDO3
TEST
Type
Analog Output
Pin Description
Fault status (Active Low) - Open drain. Pull-up to LDO3 with a100kW
+0.1% resistor.
Analog Output LED cathode connection for string 9.
Analog Output LED cathode connection for string 10.
Ground
Exposed bottom pad used as the high current LED return current path.
Ground
Exposed bottom pad used as the high current LED return current path.
Analog Output LED cathode connection for string 11.
Analog Output LED cathode connection for string 12.
N/A No connection.
Analog Output External crystal connection XO pin with SYNCLK acting as XI pin.
Digital Input
External clock input for the multiple chip system solution. Logic high is
defined as 3.3V.
Analog Output PLL compensation output.
N/A No connection.
Digital Input
Vertical SYNC input. [Optional direct PWM control] Logic high is defined
as 3.3V.
Analog Output LED cathode connection for string 13.
Analog Output LED cathode connection for string 14.
Ground
Exposed bottom pad used as the high current LED return current path.
Ground
Exposed bottom pad used as the high current LED return current path.
Analog Output LED cathode connection for string 15.
Analog Output LED cathode connection for string 16.
Digital I/O
Digital test pin.
Analog Input External LDO3 enable. Pull-up to LDO5 with a100kW pull-up resistor.
Analog Output Analog test pin.
iW7023
Datasheet
Rev. 1.0
5 of 35
© 2015 Dialog Semiconductor (UK) Ltd.
5 Page 
iW7023
16-Channel LED Driver for LCD Panel Backlighting
9.0 Operation Description
9.1 Adaptive Switching Algorithm
Adaptive switch mode current regulation improves the
power efficiency by programmatically controlling the Low
Drop Output (LDO) current regulation string in each channel
to an optimum level which minimizes the differences in total
voltage drop across each string (sharing the same LED
power supply) while still minimizing the current differences
in each string, thereby maintaining the reliability requirement
for the LED component with peak current limit control. The
adaptive switch mode also modifies the PWM duty cycle
as necessary to automatically compensate for the allowed
variances in the LDO current settings.
string while minimizing the power dissipation within the LDO
circuits.
The following illustration demonstrates the numerical PWM
on time compensation that is provided to maintain constant
peak current and PWM on time product proportional to the
brightness input.
PWM Brightness Info = 60%, Iset = 40mA
Traditional Analog
LDO where PWM
Duty Cycle equals
Brightness Input
PWM Brightness Info = 60%, Iset = 40mA
PWM = BI = 60 %
The following figure illustrates the power loss improvement
that is obtained using the adaptive switch method.
Vboost= 35.5V
Ch 0
Ch 1
Ch 1
Without
With
35V
Adaptive Switch
33V
Adaptive Switch
34V
PWM
DAC
0.1V
0.2V
0.2V
PWM
DAC
0.1V
2.2V
PWM*80%
DAC
0.2V
0. 125V
1. 125V
0.25V
Ch0 I (LDO)=40mA
Ch1 I ( LDO)= 50mA
(w/Adaptive Switch)
PWM = BI I Iset = 60% .04 = 60%
I LDO .04
PWM = BI I Iset = 60% .04 = 48%
I LDO .05
Wave Form and Timing Demonstration of
PWM Duty Cycle Compensation for
Variation In I(LDO) for each channel.
Ground
Figure 9.1: Power Loss Improvement Through Adaptive Switch
Method
This is carried out by an adaptive channel balance algorithm
performed during the power up sequence (referred to as
calibration) where the LDO current setting of each channel is
incremented while monitoring the multiple voltage potentials
on the LDO regulation loop to determine when the loop is
in the optimal operation point at the interface between the
current regulation and non-regulation regions.
Figure 9.2: PWM Duty Cycle Compensation
In addition to maintaining a constant peak current and
PWM on time product proportional to the desired brightness
setting, the algorithm also provides luminance compensation
and temperature compensation.
The following figure is a typical transfer function showing the
relationship between optical luminance and forward current
in an LED.
Each channel includes an LDO current regulator controlled
by a 4-bit DAC which creates the reference voltage for its
LDO. This 4-bit DAC is under control of the digital adaptive
switch algorithm controller. The value of the LDO DAC can
be observed in the register set where it is called “IDAC”.
This is initially performed during calibration. The optimal
DAC settings are retained and updated as necessary by the
digital controller. The operation point for each channel is
monitored in real time for continued adaptive switch mode
regulation for each LED string during normal operation.
This allows compensation for the total forward voltage drop
differences such that the same current and on-time product
can be maintained with different current and PWM dimming
code settings as necessary to match the brightness of each
Figure 9.3: Optical Luminance vs. Forward Current in an LED
iW7023
Datasheet
Rev. 1.0
11 of 35
© 2015 Dialog Semiconductor (UK) Ltd.
11 Page | ||
| Páginas | Total 30 Páginas | |
| PDF Descargar | [ Datasheet IW7023.PDF ] | |
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