Atmel LED Driver-MSL3082
8-string, High-power, White or RGB LED Driver for TV,
Blacklighting, or Intelligent Solid-state Lighting
Datasheet Brief
Atmel LED Driver-MSL3082
8-string, High-power, White or RGB LED Driver for TV,
Blacklighting, or Intelligent Solid-state Lighting
General Description
The Atmel
®
LED Driver-
MSL3082 compact, high-
power LED string driver uses
external MOSFETs to provide
up to at least 500mA per
string, with current accuracy
and matching better than
±1%. The MSL3082 drives
eight parallel strings of LEDs,
and offers fault detection and
management of open and
short circuit LEDs.
The MSL3082 features a 1MHz I
2
C serial interface. The interface supports
video frame-by-frame LED string intensity control for up to 16 interconnected
devices, allowing active area dimming when used for video displays. The
advanced PWM engine synchronizes with the video signal, and offers phase
shifted string drive, virtually eliminating waterfall noise and motion blur.
The MSL3082 adaptively controls the DC-DC converters that power the LED
strings, using patented Atmel's Adaptive SourcePower™ technology. These
efficiency optimizers minimize power use while maintaining LED current
accuracy, and allow up to eight interconnected devices to automatically
negotiate the optimum power supply voltage.
A unique combination of peak current control and pulse width dimming
management offers simple full-screen brightness control, versatile area
dimming, and a consistent white point. LED string current is set for each string
using a current sense (FET source) resistor. LED current is also digitally
controlled for all eight LED strings. Global string drive pulse width is adjusted
with a 6-bit global intensity register, and individual string pulse width is
modulated with 8-bit control. Additionally, the MSL3082 optionally throttles
back the PWM on time of all strings when the temperature of the LEDs
exceeds a programmable threshold.
The MSL3082 monitors for string open circuit, LED short circuit, loss-of-sync,
and over-temperature faults, and provides a hardware fault output to notify the
MCU. Detailed fault status and control are available through the serial interface.
Additionally, the MSL3082 includes an on-chip EEPROM that allows the
power-up default register settings to be customized via the serial interface.
The MSL3082 is offered in a 7 x 7 x 0.85mm, 44-pin QFN package, and
operates over a -40°C to +105°C temperature range.
Applications
•
Edge-lit LED Backlit TVs
•
High-contrast Monitors
•
Medical and Industrial Displays
•
High-power LED Arrays
•
Multi-string LED Lighting
•
Intelligent Solid-state Lighting (SSL)
Ordering Information
PART
MSL3082CS
INTERFACE
8-channel LED driver
PACKAGE
44-pin, 7x7x0.85mm QFN
2
Atmel LED Driver-MSL3082
Atmel LED Driver-MSL3082
8-string, High-power, White or RGB LED Driver for TV,
Blacklighting, or Intelligent Solid-state Lighting
Key Features
•
8-bit PWM String Dimming
•
Fast, 1MHz I
2
C/Smbus Interface Supports up to
16 Devices per Bus
•
4-bit Adaptive Power Correction Maximizes Efficiency
•
External Mosfets Allow >0.5a LED String Current
•
Drives up to Eight Parallel, High-power Led Strings
•
Multiple MSL3082s Share String Supply and
Automatically Negotiate Optimum Voltage
•
Supports Adaptive, Real-time 2-D Area Dimming
for Highest Dynamic Range LCD TVs and Monitors
•
Programmable String Phase Virtually Eliminates
Motion Blur and Improves Efficiency
•
Global LED Intensity Control via Serial Interface
•
Supports Direct Pwm Control of all Led Strings
with a Single Pwm Input Signal
•
±1% Current Accuracy and Current Balance
•
Video Frame (Vsync) and Line (Hsync) Sync Inputs
•
Sync Loss Detectors Optionally Disable Led Strings
•
Internal Eeprom Allows Custom Power-up
Default Settings
•
String Open Circuit and Led Short Circuit
Fault Detection
•
<1µA LED String Off-leakage Current
•
External Resistors Set Individual String
Peak Current
•
Programmable LED Over-temperature
Compensation
•
Automatic Die Over-temperature Protection
•
I
2
C/SMBus Broadcast Mode Simplifies Configuration
•
-40°C to +105°C Operating Temperature Range
•
Lead-free, Halogen-free, RoHS-compliant Package
Application Circuit
Atmel LED Driver-MSL3082
3
Quick Start Guide
The MSL3082 controls eight strings of series-connected
LEDs at up to at least 500mA per string, and up to
sixteen devices may share the serial interface. The
MSL3082 FET gate drive output is optimized for FETs
requiring no more than 10nC of charge. The MSL3082
PWM engine generates the PWM signal that drives the
strings, or optionally accepts an external PWM signal.
The power supply can use any topology that employs
external feedback resistors with a maximum feedback
voltage of 1.5V, and are typically DC-DC boost
converters. The efficiency optimizers rely on close
matching of the LEDs connected to a string supply; the
better the matching, the better the overall efficiency.
How Many LEDs and Drivers?
The MSL3082 drives eight strings of series-connected
LEDs using external N-channel MOSFETs and current
sense resistors. The LED drive capability (maximum
number of LEDs per string) is limited only by the
MOSFETs and the LED string power supply, not by
the MSL3082. Up to 16 MSL3082s may share an I
2
C/
SMBus serial interface, with both individual and broadcast
(all MSL3082s on a bus) addressing. The high LED drive
power of the MSL3082 makes it suitable for large LCD
TV and monitor backlights, as well as for LED signage
and general lighting.
Differences between Atmel LED
Drivers-MSL3082 and MSL2100
The MSL3082 includes a single Efficiency Optimizer,
is more suited for single-color LEDs, and is ideal for
driving white backlight LEDs in an LCD monitor or TV
application. The MSL2100 includes three independent
Efficiency Optimizer circuits to control three separate
string supplies (for RGB LEDs, for example).
Timing, PWM, Intensity Controls,
and Synchronization
The PWM LED drive signals synchronize to video frame
timing via the PHI input, and to pixel timing via the
GSC input. Suitability for LED backlight architectures is
shown in Table 1 and Table 2. Area LED dimming for
direct backlighting is supported for contrast and color
gamut improvement. With area dimming, motion blur is
reduced by setting each LED string’s PWM phasing to
synchronize string off times with the LCD update timing.
Also, the individual PWM intensity registers for eight
LED strings are updated with only 92 I
2
C/SMBus clocks.
Sixteen drivers (128 LED strings) update in 1.47ms
with a 1MHz bus speed, offering area dimming support
for frame rates up to 640Hz.
LEDs, the String Power Supply, and
the Efficiency Optimizer
The MSL3082 features an Efficiency Optimizer output
that dynamically adjusts the LED string power supply to
the minimum voltage necessary to drive the LED strings,
minimizing power use while assuring accurate LED
current flow. The Efficiency Optimizers features an input
that allows up to eight devices to be connected in a chain
configuration. When implemented, the chain automatically
negotiates, controls, and optimizes the string power
supply for all LED strings driven by the chain.
Table 1. Atmel LED Driver-MSL3082 LED Common Backlight Drive Architectures
BACKLIGHT TYPE
White LED - bottom edge-lit
White LED - top/bottom edge-lit
White LED - four sides edge-lit
White LED - direct back-lit
RGB LED - direct back-lit
STRING SUPPLY OPTIONS
MOTION BLUR REMOVAL
No
LED ZONE MANAGEMENT
No
No
No
Higher contrast ratio
(area dimming)
Higher contrast ratio and
color gamut
1 or more MSL3082 per
efficiency optimized supply
No
No
Yes - LED strip phasing
See MSL2100 datasheet
Yes - LED strip phasing
4
Atmel LED Driver-MSL3082
Table 2. Atmel LED Driver-MSL3082 Timing and LED Intensity Control Capability
LED INTENSITY CONTROL
LED string current
Individual LED string current
Global LED string pulse width
Individual LED string pulse width
Global temperature derating
Total LED string pulse width control
RESOLUTION
External resistors set maximum current for each LED string up to at least 500mA
6-bit ISTR registers reduce string current from maximum set by global resistor
6-bit GINT register or PWM input (accepts 20Hz To 50kHz, 0% to 100% duty cycle)
8-bit PWM registers set individual string pulse width
6-bit temperature pulse width derating, individually applied to each string
10-bit LED string pulse width, computed from global and individual pulse width settings
Package Pin-out - Atmel LED Driver-MSL3082-TB
CGND
CGND
PWM
GND
AD1
CGND
GSC
PHI
NC
NC
35
44
SCL
SDA
AD0
FLTB
FBI
FBO
GND
S0
G0
1
2
3
4
5
6
7
8
9
43
42
41
40
39
38
37
36
EN
34
33 VDD
32 VIN
31 D7
30 G7
29 S7
MSL3082
(TOP VIEW)
28 D6
27 G6
26 S6
25 D5
24 G5
23 S5
Figure 1. 44-pin, 7mm x 7mm x 0.85mm QFN
(0.5mm pin pitch) with Exposed Pad
D0 10
S1 11
12
G1
13
D1
14
S2
15
G2
16
D2
17
S3
18
G3
19
D3
20
S4
21
G4
22
D4
Figure 2. 44-pin TQFN Package Dimensions
Atmel LED Driver-MSL3082
5
