ATMEL MSL3082CS 8-string, high-power, white or rgb led driver for tv, blacklighting, or intelligent solid-state lighting Datasheet

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 DriverMSL3082 compact, highpower 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 I2C 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
2
PART
INTERFACE
PACKAGE
MSL3082CS
8-channel LED driver
44-pin, 7x7x0.85mm QFN
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
• Video Frame (Vsync) and Line (Hsync) Sync Inputs
• Fast, 1MHz I C/Smbus Interface Supports up to
16 Devices per Bus
• Sync Loss Detectors Optionally Disable Led Strings
2
• 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
• 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
• Global LED Intensity Control via Serial Interface
• I2C/SMBus Broadcast Mode Simplifies Configuration
• Supports Direct Pwm Control of all Led Strings
with a Single Pwm Input Signal
• -40°C to +105°C Operating Temperature Range
• Lead-free, Halogen-free, RoHS-compliant Package
• ±1% Current Accuracy and Current Balance
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.
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 I2C/
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.
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.
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.
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 I2C/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.
Table 1. Atmel LED Driver-MSL3082 LED Common Backlight Drive Architectures
BACKLIGHT TYPE
STRING SUPPLY OPTIONS
White LED - bottom edge-lit
White LED - top/bottom edge-lit
White LED - four sides edge-lit
1 or more MSL3082 per
efficiency optimized supply
White LED - direct back-lit
RGB LED - direct back-lit
4
See MSL2100 datasheet
MOTION BLUR REMOVAL
LED ZONE MANAGEMENT
No
No
No
No
No
No
Yes - LED strip phasing
Higher contrast ratio
(area dimming)
Yes - LED strip phasing
Higher contrast ratio and
color gamut
Atmel LED Driver-MSL3082
Table 2. Atmel LED Driver-MSL3082 Timing and LED Intensity Control Capability
LED INTENSITY CONTROL
RESOLUTION
LED string current
External resistors set maximum current for each LED string up to at least 500mA
Individual LED string current
6-bit ISTR registers reduce string current from maximum set by global resistor
Global LED string pulse width
6-bit GINT register or PWM input (accepts 20Hz To 50kHz, 0% to 100% duty cycle)
Individual LED string pulse width
8-bit PWM registers set individual string pulse width
Global temperature derating
6-bit temperature pulse width derating, individually applied to each string
Total LED string pulse width control
10-bit LED string pulse width, computed from global and individual pulse width settings
AD1
GND
PWM
GSC
PHI
NC
CGND
CGND
CGND
NC
EN
Package Pin-out - Atmel LED Driver-MSL3082-TB
44
43
42
41
40
39
38
37
36
35
34
SCL
1
33 VDD
SDA
2
32 VIN
AD0
3
31 D7
FLTB
4
30 G7
FBI
5
29 S7
FBO
6
28 D6
GND
7
MSL3082
Figure 1. 44-pin, 7mm x 7mm x 0.85mm QFN
(0.5mm pin pitch) with Exposed Pad
27 G6
(TOP VIEW)
12
13
14
15
16
17
18
19
20
21
22
G4
D4
23 S5
S4
S1 11
D3
24 G5
G3
D0 10
S3
25 D5
D2
9
G2
G0
S2
26 S6
D1
8
G1
S0
Figure 2. 44-pin TQFN Package Dimensions
Atmel LED Driver-MSL3082
5
Pin Descriptions
6
PIN #
NAME
DESCRIPTION
1
SCL
I²C serial clock Input
SCL is the I²C serial interface clock input.
2
SDA
I²C serial data I/O
SDA is the I²C serial interface data I/O.
3, 44
AD1,
AD0
I²C slave ID selection inputs
AD0 and AD1 select the device I²C slave address.
4
FLTB
Fault output (open drain, active low)
FLTB sinks current to GND when the MSL3082 detects a fault.
FLTB remains low until the fault registers have been read or EN is toggled low.
5
FBI
Efficiency Optimizer input
Connect FBI to FBO of the next device when chaining the Efficiency Optimizers.
If unused connect FBI to GND close to the device.
6
FBO
Efficiency Optimizer output
Connect FBO through a Schottky diode to the string power supply’s feedback node (Figure 4),
or to FBI of the previous device (Figure 5).
If unused leave FBO unconnected.
7, 43
GND
Power ground
Connect GND to system ground, to CGND and to EP with short, wide traces.
8, 11, 14, 17,
20, 23, 26, 29
S0 - S7
String 0 thru 7 source sense inputs
Connect Sn to the source of external MOSFETn, and to the current sense resistor for LED stringn.
The full-scale LED current is reached when 500mV is across the current sense resistor.
9, 12, 15, 18,
21, 24, 27, 30
G0 - G7
String 0 thru 7 external MOSFET gate drive outputs
Connect Gn to the gate of the external MOSFETn.
10, 13, 16, 19,
22, 25, 28, 31
D0 - D7
String 0 thru 7 external MOSFET drain sense inputs
Connect Dn to the drain of external MOSFETn through a 10MΩ resistor.
32
VIN
Supply voltage input
Connect a 12V ±10% supply to VIN. Bypass VIN to GND with a 1µF ceramic capacitor placed close to VIN.
33
VDD
Internal 2.5V regulator capacitor connection
Bypass VDD to GND with a 10µF ceramic capacitor placed close to the device.
34
EN
Enable input (active high)
Drive EN high to turn on the MSL3082, drive EN low to turn off the MSL3082.
For automatic start-up, connect EN to VIN through a 100kΩ resistor.
35, 39
NC
No connection
Make no connection to NC.
36, 37, 38
CGND
40
PHI
Phase synchronization input
Drive PHI with an external signal from 40Hz to 10kHz to synchronize the PWM dimming to the signal at PHI.
Connect PHI to GND if unused.
41
GSC
Gate shift clock input
Drive GSC with the gate shift clock of the video signal up to 5MHz. GSC sets the resolution of PWM dimming.
Connect GSC to GND if unused.
42
PWM
PWM input
Drive PWM with a pulse-width-modulated signal with a duty cycle of 0% to 100% and frequency of 20Hz
to 50kHz to control the brightness of all LED strings.
Exposed Pad
EP
Power ground
Connect EP to system ground, GND and CGND using short, wide traces. EP offers thermal relief to the die.
Connect to ground
Connect CGND to system ground, to GND and to EP using short, wide traces.
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
Absolute Maximum Ratings
Voltage (With Respect to GND)
VIN, EN, D0-D7, G0-G7............................................................................................................................................... -0.3V to +16V
SDA, SCL, AD0, AD1, FLTB.......................................................................................................................................-0.3V to +5.5V
PHI, GSC, PWM, S0-S7, FBI, FBO..................................................................................................... -0.3V to (VDD + 0.3V)
VDD.............................................................................................................................................................................................-0.3V to +2.75V
Current (Into Pin)
VIN....................................................................................................................................................................................................................... 50mA
GND................................................................................................................................................................................................................-500mA
All other pins................................................................................................................................................................................................20mA
Continuous Power Dissipation (See Note 8, Note 9)
44-Pin 7mm x 7mm QFN (derate 47.6mW/°C above 70°C).............................................................. 2619mW
Ambient Operating Temperature Range TA = TMIN to TMAX........................................... -40°C to +105°C
JunctionTemperature .................................................................................................................................................................. +125°C
Storage Temperature Range......................................................................................................................... -65°C to +125°C
Lead Soldering Temperature, 10s................................................................................................................................... +300°C
Electrical Characteristics
(Circuit of Figure 3, VIN = 12V, TA = TMIN to TMAX, unless otherwise noted. Typical values are at VIN = 12V, TA = +25°C)
PARAMETER
CONDITIONS AND NOTES
MIN
TYP
MAX
UNIT
10.8
12.0
13.2
V
25.0
32.5
mA
10
20
μA
2.5
2.6
V
DC ELECTRICAL CHARACTERISTICS
VIN operating supply voltage
VIN operating supply current
All drivers on at 100% duty, I²C serial interface idle
VIN shutdown supply current
EN = 0, all digital inputs tied to VDD or GND
VDD regulation voltage
2.3
Input high voltage SDA, SCL, AD0, AD1
2.31
V
Input low voltage SDA, SCL, AD0, AD1
Input high voltage PHI, GSC, PWM
0.9
1.8
V
Input low voltage PHI, GSC, PWM
Input high voltage EN
0.7
0.9
1.36
Input low voltage EN
Input hysteresis EN
V
V
0.7
50
V
V
mV
Continued to Next Page
Atmel LED Driver-MSL3082
7
PARAMETER
CONDITIONS AND NOTES
MIN
Input quiescent current EN
SDA, FLTB output low voltage
TYP
MAX
UNIT
1
20
μA
0.4
V
Sinking 6mA
S0 thru S7 regulation resolution
% of
Full
Scale
1
Open circuit detect voltage
7.3
8.3
9.0
V
Short circuit detect voltage
6.5
7.8
9.0
V
D0 thru D7 leakage current
Voltage under 9V
0.1
Voltage between 9V to 16V
15
G0 thru G7 maximum gate drive voltage
10
G0 thru G7 gate drive current
Current sense regulation voltage
G0 thru G7 output current slew rate
-20
20
mA
488
500
508
mV
ISTRx = 0x1F
235
250
255
mV
Current rising (Note 7, Note 8)
10
Current falling (Note 7, Note 8)
10
Up to FBO maximum output current
FBO current step size
FBO feedback output current maximum
V
ISTRx = 0x3F
Thermal cutoff temperature
FBI to FBO current transfer error
μA
VFBO_= 0 to 1.8V
PARAMETER
CONDITIONS AND NOTES
mA/µs
135
°C
±2
%
3
μA
35
45
55
μA
MIN
TYP
MAX
UNIT
20
AC ELECTRICAL CHARACTERISTICS
OSC initial accuracy
f OSC
OSCCTRL = 0x04 (fOSC=20MHz); TA=25°C
18
PHI frequency
f PHI
(Note 7)
40
GSC frequency
f GSC
(Note 7)
PWM frequency
f PWM
PWMDIRECT = PWMEN = 1
PWMDIRECT = PWMEN = 1
PWM duty cycle
22
MHz
10000
Hz
5
MHz
20
50000
Hz
0
100
PHI DLL Lock Cycles
4
PARAMETER
CONDITIONS AND NOTES
MIN
%
PHI
Cycles
TYP
MAX
UNIT
1000
kHz
33
ms
I²C SWITCHING CHARACTERISTICS
SCL clock frequency
Bus timeout period
8
1/t S C L
t T IM E O U T
Bus timeout disabled (Note 1)
0
OSCCTRL = 0x04 (fOSC=20MHz); TA=25°C
27
30
STOP to START condition bus free time
t BUF
0.5
µs
Repeated START condition hold time
t H D : S TA
0.26
µs
Repeated START condition set-up time
t S U : S TA
0.26
µs
STOP condition set-up time
t SU:STOP
0.26
µs
SDA data hold time
t H D : D AT
15
ns
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
PARAMETER
CONDITIONS AND NOTES
MIN
TYP
MAX
UNIT
SDA data valid acknowledge time
t VD:ACK
(Note 2)
0.05
0.55
µs
SDA data valid time
t V D : D AT
(Note 3)
0.05
0.55
µs
SDA data set-up time
t S U : D AT
100
ns
SCL clock low period
tLOW
0.5
µs
SCL clock high period
tHIGH
0.26
µs
SDA, SCL fall time
tF
SDA, SCL rise time
tR
SDA, SCL input suppression
filter period
tSP
(Note 4, Note 5)
(Note 6)
120
ns
120
ns
50
ns
Note 1. Minimum SCL clock frequency is limited by the bus timeout feature, which resets the serial bus interface if either SDA or SCL is held low for tTIMEOUT. Disable bus timeout feature for DC operation
Note 2. tVD:ACK = SCL low to SDA (out) low acknowledge time
Note 3. tVD:DAT = minimum SDA output data-valid time following SCL low transition
Note 4. A master device must internally provide an SDA hold time of at least 300ns to ensure an SCL low state
Note 5. The maximum SDA and SCL rise times are 300ns. The maximum SDA fall time is 250ns. This allows series protection resistors to be
connected between SDA and SCL inputs and the SDA/SCL bus lines without exceeding the maximum allowable rise time
Note 6. The MSL3082 includes input filters on SDA, SCL, AD0, and AD1 inputs that suppress noise less than 50ns
Note 7. Parameter is guaranteed by design, and is not production tested
Note 8. Subject to thermal dissipation characteristics of the device
Note 9. When mounted according to JEDEC JEP149 and JESD51-12 for a one-layer PCB, θJA = 21°C/W and θJC = 1.3°C/W
Block Diagram
Atmel LED Driver-MSL3082
9
Atmel LED Driver-MSL3082 Typical Application Circuit
Figure 3. Typical Application Circuit
Detailed Description
The MSL3082 is a highly integrated, flexible, multi-string LED driver that uses external MOSFETs to allow high LED string
currents, and includes power supply control to maximize efficiency. The driver optionally connects to a video subsystem
to offer easy synchronization for use in LCD TV backlight applications. Up to sixteen devices may be connected together
to drive a large number of LED strings in a system. The drivers provide multiple methods of controlling LED brightness,
through both peak current control and pulse width control of the string drive signals. Peak current control offers excellent
color consistency, while pulse width control allows brightness management. An on-chip EEPROM holds all the default
control register values. At power-up the data in the EEPROM are automatically copied directly to the control registers,
setting up the device for operation. The factory programmed EEPROM values are changeable through the serial interface
if a different power-up condition is desired.
10
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
The device interfaces to an MCU via the I2C/SMBus
interface. The robust 1MHz I2C/SMBus interface
supports up to sixteen devices on the bus, and is fast
enough to support area dimming for 16 interconnected
devices. While typically the LED drive PWM signal is
internally generated by the PWM engine, the device
also accepts an external direct PWM drive signal
applied to the PWM input to set the frequency and
duty cycle of the LED drive signals. When using the
PWM engine, the MSL3082 allows phase spreading of
the LED drive signals, which helps reduce the transient
load on the LED power supply. Phase spreading is not
supported for direct PWM drive.
MSL3082 automatically reduces the power supply
voltage to the minimum voltage required to keep the
LEDs in current regulation. The devices are configured
to periodically perform this optimization to compensate
for changes in LED forward voltage, and to assure
continued optimum power savings.
The PWM frequency of the drivers is easily synchronized
to an external video signal applied to PHI. Typically, the
VSYNC signal from the video system is used as the PHI
input. A frame-rate multiplier (1x to 16x) processes
this signal for use by the PWM engine. The on-time of
each string is individually programmed via the device
registers, providing a peak resolution of 10 bits when
using the on-chip PWM generator. The actual resolution
of the PWM frequency depends on the ratio of the
GSC frequency (typically provided by a systems
HSYNC signal) to the PHI frequency because the on
time of a string is programmed as a function (8-bit
count) of the number of GSC cycles. This count can be
further scaled by a 6-bit global intensity register, when
enabled. The GSC clock is also used to precisely set
each string’s phase delay to be synchronized with its
physical position relative to the video frame. Additionally,
the MSL3082 features programmable temperature
compensation, which throttles back the PWM on time of
all strings when the temperature of the LEDs exceeds a
programmable threshold.
The enable input, EN, turns the VDD regulator on and off.
To turn on the MSL3082 force EN high with a 5V logic
level, and force EN low to turn it off. When EN is low,
the MSL3082 enters low-power mode, and the serial
interface is ignored. Toggling EN low also clears all fault
registers and releases FLTB. Faults re-establish if the
conditions that generated them persist.
The Efficiency Optimizers control a wide range of
different external DC-DC and AC-DC converter
architectures. Multiple drivers in a system communicate
in real time among themselves to select an optimized
operating voltage for the LEDs. This allows design of the
power supply for the worst case forward voltage (Vf)
of the LEDs without concern about excessive power
dissipation issues. During the start-up sequence, the
Atmel LED Driver-MSL3082
Internal Regulators and Enable Input
The MSL3082 includes an internal linear regulator
powered from VIN that provides 2.5V, VDD, to power
the internal circuitry. Bypass VDD to GND with a 10µF
or greater capacitor.
Setting LED String Currents
The maximum string current, ILED, for each string is set
by a resistor, RSn, connected to ground from the source
terminal of the external string drive MOSFET. The
feedback threshold is 500mV. Determine the resistor
value using:
RSn =
0 .5
ohms. I LED
, where ILED is in amperes and RSn is in
For example, a full-scale LED current of 500mA
returns RSn = 1.00Ω. The current for the LED strings is
individually reduced from the full-scale resistor set value
with 6-bit resolution using ISTRn, the string current
control registers 0x10 through 0x1F.
11
Connecting an LED String Power Supply
to an Efficiency Optimizer
Figure 4. FBO Connection to Power Supply Voltage Divider
The MSL3082 is designed to control an external LED
string power supply that uses a voltage divider (RTOP and
RBOTTOM in Figure 4) to set the output voltage, and whose
regulation feedback voltage is not more than 1.5V. The
efficiency optimizer improves power efficiency by injecting
a current of between 0 and 45µA into the voltage divider
of the external power supply, dynamically adjusting the
power supply's output to the minimum voltage required
by the LED strings. To select the resistors first determine
VOUT(MIN) and VOUT(MAX), the minimum and maximum string
supply voltage limits, using:
VOUT(MIN) = (Vf (MIN) *[#ofLEDs])+ 0.5 ,
and
VOUT(MAX) = (Vf (MAX) *[#ofLEDs])+ 0.5 ,
where Vf(MIN) and Vf(MAX) are the LED minimum and
maximum forward voltage drops at the peak current
set by RSn (page 11). For example, if the LED data
are Vf(MIN) = 3.5V and Vf(MAX) = 3.8V, and ten LEDs are
used in a string, then the total minimum and maximum
voltage drops across a string are 35V and 38V,
respectively. Adding an allowance of 0.5V for the string
drive MOSFET headroom brings VOUT(MIN) to 35.5V and
VOUT(MAX) to 38.5V. Then determine RTOP using:
RTOP =
VOUT (MAX) _ VOUT(MIN)
IFBO(MAX)
,
VFB
VOUT(MAX) _ VFB
,
where VFB is the regulation feedback voltage of the
power supply. Place a Schottky diode (CMPSH-3 or
similar) between FBO and the supply’s feedback node
to protect the MSL3082 against current flow into FBO.
12
Cascade multiple MSL3082 devices into a chain
configuration (Figure 5) with the FBI of one device
connected to the FBO of the next. Connect the first FBO
to the power supply feedback resistor node through a
CMPSH-3 or similar Schottky diode, and the unused FBI
input to ground as close to the MSL3082 as possible.
The chained devices work together to ensure that the
system operates at optimum efficiency. Note that the
accuracy of the feedback chain has the potential to
degrade through each link of the FBI/FBO chain by as
much as 2%. Determine the worst case maximum FBO
current, IFBO(MAX/MIN), using:
IFBO(MAX / MIN) = 45µA* (0.98)N-1 ,
where IFBO(MAX) is the 45µA maximum output current of
the efficiency optimizer output, FBO. Finally, determine
RBOTTOM using:
RBOTTOM = RTOP *
Using Multiple Atmel LED Driver-MSL3082s
to Control a Single Power Supply
where N is the number of MSL3082s connected in
series. Use this result in the above RTOP resistor equation
for the term IFBO(MAX) instead of using the 45µA figure
shown here.
Take care in laying out the traces for the efficiency
optimizer connections. Minimize the FBI/FBO trace
lengths as much as possible. Do not route the signals
close to traces with large variations in voltage or current
because noise may couple into FBI. If these traces must
be routed near noisy signals, shield them from noise by
using ground planes and/or guard traces.
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
Figure 5. Cascade Multiple Atmel LED Driver-MSL3082s to Control a Common Power Supply
Register Map Summary
Control the MSL3082 using the registers in the range 0x00 thru 0x59 (Table 3). Two additional registers, 0x90 and
0x91, allow access to, and programming of, the EEPROM. The power-up default values for all control registers are stored
within the on-chip EEPROM, and any of these EEPROM values may be changed through the serial interface.
Table 3. Atmel LED Driver-MSL3082 Register Map
REGISTER AND
ADDRESS
FUNCTION
REGISTER DATA
D7
D6
D5
D4
D3
D2
D1
D0
STR7EN
STR6EN
STR5EN
STR4EN
STR3EN
STR2EN
STR1EN
STR0EN
I2CTOEN
FBOEN
PHADLYEN
0x00
LED string
enables
POWERCTRL
0x02
Power
control
SLEEP
-
STRSCEN
STROCEN
PWMDIRECT
OSCCTRL
0x03
Oscillator
frequency
-
-
-
-
-
OTTEMP
0x04
Over-temp
threshold
OTTEMP[7:0]
SYSTEMP
0x05
System
temperature
SYSTEMP[7:0]
CONTROL
0x01
UNUSED
Atmel LED Driver-MSL3082
OSCFREQ[2:0]
13
Table 3. Atmel LED Driver-MSL3082 Register Map
REGISTER AND
ADDRESS
FUNCTION
REGISTER DATA
D7
D6
D5
D4
D3
D2
D1
D0
FBOCAL
FLTDET
OTSLOPE
0x06
Over-temp
derating
FLTSTATUS*
0x07
Fault status,
global
-
STRSCDET
STROCDET
-
-
PWMCTRL
0x08
PWM and
phase
control,
configuration
GSCDIVEN
GINTEN
PHIPOL
TDERATE
PHIMINEN
OCSTAT*
0x09
String open
circuit status
OC7
OC6
OC5
OC4
OC3
OC2
OC1
OC0
SCSTAT*
0X0A
LED short
circuit status
SC7
SC6
SC5
SC4
SC3
SC2
SC1
SC0
GINT
0x0B
Global
intensity
-
-
GSCDIV
0x0C
GSC divider
-
-
-
PHIMUL
0x0D
PHI
multiplier
-
-
-
STR03FBO
0x0E
STR47FBO
0x0F
ISTR0
0x10
to
ISTR7
0x1F
PHDLY0
0x20
to
PHDLY7
0x2F
PWM0
0x30
to
PWM7
0x3F
0x40
GSCMAX
PHIMIN
0x41
0x42
0x43
String FBO
enables
Individual
string
current
throttle
OTSLOPE[7:0]
0x47
0x50
FBOCTRL1
0x51
0X52 THRU 0X58
14
-
GSCDIV[3:0]
PHIMUL[4:0]
STR2FBO[1:0]
STR1FBO[1:0]
STR0FBO[1:0]
STR7FBO[1:0]
STR6FBO[1:0]
STR5FBO[1:0]
STR4FBO[1:0]
-
-
ISTR0[5:0]
-
-
to
-
-
ISTR7[5:0]
PHDLY0[7:0]
Individual
string
pulse width
settings
PWM0[7:0]
Max
oscillator
cycles
between
GSC pulses
GSCMAX[7:0]
to
PHDLY7[7:0]
to
PWM7[7:0]
GSCMAX[15:8]
PHIMIN[7:0]
-
-
-
-
PHIMIN[15:8]
UNUSED
Individual
string fault
monitoring
enables
FLTEN7
FLTEN6
FLTEN5
0X48 THRU 0X4F
FBOCTRL0
PWMEN
STR3FBO[1:0]
0X44 THRU 0X46
FAULTEN
GSCMAXEN OVRFLOEN
GINT[6:0]
Individual
string
phase delay
settings
Min GSC
pulses over
PHI period
-
FLTEN4
FLTEN3
FLTEN2
FLTEN1
FLTEN0
UNUSED
Efficiency
Optimizer
configuration
HDRMSTEP[1:0]
FBCLDLY[1:0]
STRSCCDLY[1:0]
-
FBSDLY[1:0]
-
-
FBCFDLY[1:0]
-
ACALEN
ICHKDIS
UNUSED
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
REGISTER AND
ADDRESS
FBODAC*
0x59
E2ADDR
0x90
E2CTRLSTA
0x91
FUNCTION
Efficiency
Optimizer
DAC
readback
REGISTER DATA
D7
D6
D5
FBOACT
-
-
D4
D3
D2
-
D1
D0
FBODAC[3:0]
DO NOT ACCESS ADDRESS RANGE 0X58 TO 0X8F
User
EEPROM
read/write
access
-
E2ADDR[6:0]
E2BUSY
BLDACT
E2ERR
-
-
RWCTRL[1:0]
* Read-only registers
Register Power-up Defaults
Register power-up default values are shown in Table 4.
Table 4. Atmel LED Driver-MSL3082 Register Power-up Defaults
REGISTER NAME
AND ADDRESS
0x00
CONTROL
POWER-UP CONDITION
REGISTERS INITIALIZED
FROM EEPROM
REGISTER DATA
D7
D6
D5
D4
D3
D2
D1
D0
HEX
All LED strings drive outputs are enabled
1
1
1
1
1
1
1
1
FF
String phase delay enabled
Efficiency Optimizer feedback output enabled
I2C bus timeout enabled
Direct PWM disabled
String open circuit detection enabled
String short circuit detection enabled
Device awake
0
1
1
1
0
1
1
1
77
04
0x02
POWERCTRL
0x03
OSCCTRL
Internal oscillator fOSC set to 20MHz
0
0
0
0
0
1
0
0
0x04
OTTEMP
Over-temperature threshold is 90°C
0
1
0
1
1
0
1
0
5A
0x05
SYSTEMP
System temperature set to 30°C
0
0
0
1
1
1
1
0
1E
0x06
OTSLOPE
Over-temperature slope set to 50°C
0
0
1
1
0
0
1
0
32
PWMCTRL
PWM operation enabled
String on-times truncated at end of frame
GSC low frequency fault detection disabled
PHI high frequency fault detection disabled
Over-temperature derating of string on times enabled
PWM frame synchronized to rising edge at PHI input
GINT global intensity control enabled
GSC input frequency division disabled
0
1
1
1
0
0
0
1
71
0x08
0x0B
GINT
Global intensity PWM duty cycle GINT = 15/64 = 23.4%
0
0
0
0
1
1
1
1
0F
0x0C
GSCDIV
GSC input frequency is divided by 2^0
0
0
0
0
0
0
0
0
00
0x0D
PHIMUL
PHI input frequency is multiplied by 1
0
0
0
0
0
0
0
1
01
0x0E
STR03FBO
1
1
1
1
1
1
1
1
FF
0x0F
STR47FBO
1
1
1
1
1
1
1
1
FF
Atmel LED Driver-MSL3082
All strings are monitored by the Efficiency Optimizer
15
REGISTER NAME
AND ADDRESS
POWER-UP CONDITION
REGISTERS INITIALIZED
FROM EEPROM
0 .5
REGISTER DATA
32
D7
D6
D5
D4
D3
D2
D1
D0
HEX
0
0
1
0
0
0
0
0
20
0x10
0x17
ISTR0 thru
ISTR7
0x20
0x27
PHDLY0 thru
PHDLY7
All string phase delays set to zero processed GSC cycles
0
0
0
0
0
0
0
0
00
0x30
0x37
PWM0 thru
PWM7
All strings PWM settings equal 48 processed GSC cycles
0
0
1
1
0
0
0
0
30
0
0
0
0
0
0
0
0
00
0
0
0
0
0
0
0
0
00
0
0
0
0
0
0
0
0
00
0
0
0
0
0
0
0
0
00
Fault detection is enabled for all strings
1
1
1
1
1
1
1
1
FF
0
0
0
0
1
1
0
0
0C
0x40
0x41
0x42
0x43
0x47
GSCMAX
PHIMIN
FAULTEN
Individual peak string current
=
RSn
∗
63
Maximum GSC pulse count is 0
Minimum PHI pulse count is 0
0x50
FBOCTRL0
Current source error confirmation delay is 4µs
FBO power supply settling time allowance is 8ms
Efficiency Optimizer auto recalibration delay is 1s
Efficiency Optimizer gives three steps for headroom
0x51
FBOCTRL1
Current source error detection enabled
Auto recalibration disabled
String short circuit confirmation delay is 4µs
0
0
0
0
0
0
0
0
00
0x90
E2ADDR
User EEPROM 7-bit address = 0x00
0
0
0
0
0
0
0
0
00
0x91
E2CTRLSTA
User EEPROM read/write disabled
0
0
0
0
0
0
0
0
00
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