Atmel LED Drivers
MSL1061/MSL1064
6-string PWM LED Driver with Digitally Compensated, 1.1MHz,
48V Boost Regulator, ±1.5% Current Balance, I2C Interface
Datasheet Brief
Atmel LED Drivers-MSL1061/MSL1064
6-string PWM LED Driver with Digitally Compensated, 1.1MHz,
48V Boost Regulator, ±1.5% Current Balance, I2C Interface
General Description
The Atmel® LED DriversMSL1061 and MSL1064 are
LED drivers with integrated
boost regulators capable of
driving six LED strings at
30mA up to 48V for lighting
applications to 8W, allowing
up to 72 LEDs per driver
backlighting applications.
The MSL1061/64 incorporates a current mode PWM boost regulator with
50V internal switch and a wide, 4.75V to 36V input voltage range. The
1.1MHz switching frequency uses a small-sized inductor and output capacitors
while maintaining high efficiency and low ripple voltage and noise. The boost
regulator uses digital control and requires no external compensation.
An I2C/SMB compatible serial interface operates up to 1MHz, giving access
to internal 8-bit PWM dimming and 4-bit analog current adjustment for 12bit current control. Individual string enable and fault reporting are available.
The MSL1061 operates with one of four I2C slave addresses selected from a
single input pin (AD0), whereas the lower cost MSL1064 has one fixed I2C
slave address.
The MSL1061/64 is also easy to employ without using an I2C interface,
dimming with an external PWM signal.
Analog dimming of LED string current is available for use with an ambient
light sensor (ALS) and/or temperature management with a thermistor or IC
temperature sensor.
The MSL1064 comes in a 5 x 5mm, 24-pin TQFN package, and the MSL1061
in a 5 x5mm, 28-pin TQFN. Both packages are lead-free, halogen-free and
RoHS-compliant, and operate over a -40°C to 85°C temperature range.
Applications
Long Life, Efficient LED Backlighting for:
• Notebook PCs and Desktop PC Monitors
• Medical and Industrial Instrumentation
• Portable Media Players (PMPs)
• Automotive Audio-visual Displays
Traffic Lights
Signage
Ordering Information
2
PART
DESCRIPTION
PACKAGE
MSL1061AV
6-ch LED driver
28-pin, 5x5x0.75mm TQFN
MSL1064AW
6-ch LED driver
24-pin, 5x5x0.75mm TQFN
Atmel LED Drivers-MSL1061/MSL1064
Atmel LED Drivers-MSL1061/MSL1064
6-string PWM LED Driver with Digitally Compensated, 1.1MHz,
48V Boost Regulator, ±1.5% Current Balance, I2C Interface
Key Features
• Drives 6 Strings of up to 12 LEDs per String
• Individual Open-circuit and Short-circuit
Fault Detection
• Drives 72 White LEDs at 30mA for 8W Backlight
• Faults Automatically Disable the Faulty String
• Better than ±1.5% String-to-string Current Accuracy
• Fault Reporting and Fault Reset Through I2C/SMB
• 4.75V to 36V Wide Input Supply Range
• FLTB Logic Output Indicates Faults
• Integrated Boost Regulator with 50V Internal Switch
• Enable Input Simplifies Operation Without I2C/SMB
• 1.1MHz Current Mode PWM Boost for Low Noise
• PWM Input Synchronizes PWM to System Clock
and Allows Logic PWM Control Without I2C
• Up to 92% Boost Converter Efficiency
• Internal, Automatic Power Supply Management
• Adjustable Over-voltage Protection
• Adjustable LED Current up to 30mA per String
• Serial I2C/SMB Compatible Interface to 1MHz
• String Outputs can be Paralleled for >30mA LEDs
• Four selectable I2C Slave Addresses (MSL1061)
• 256:1 Internal PWM Dimming Range Through I2C
• GUI Software for Ease of Evaluation
• 16:1 Internal Analog Dimming Range Through I2C
• -40°C - +85°C Operating Temperature Range
• 12-Bit Total Internal PWM + Analog Dimming Range
• Lead-free, Halogen-free, RoHS-compliant Package
• ALS Interface for Automatic Brightness Setting
• NTC Interface for Temperature Derating
Application Circuit
VIN = 4.75V to 36V
VOUT = 48V max
EN
Fault
Alert
OVP
Up to 12
White
LEDs per
String
FLTB
OSC
ALS or
NTC
….
SW
VIN
IADJ
ILED
MSL1061
MSL1064
STR0
.
.
..
STR5
SDA
PWM
SCL
GND
Atmel LED Drivers-MSL1061/MSL1064
AD0
Set
String
current
1.5% maximum current
mismatch between
Strings
I C or
SMBus
I C address selection
(MSL1061 only)
3
Quick Start Guide
This section summarizes for quick evaluation
the capabilities of, and differences between, the
MSL1061 and MSL1064.
The MSL1061 and MSL1064 are LED string drivers
with integrated boost regulators, which power, monitor,
and dim multiple LEDs at high efficiency for backlighting
and signage applications. Each MSL1061/64 contains six
outputs, each capable of sinking up to 30mA through a
string of series-connected LEDs.
How Many LEDs Can the Atmel LED
Drivers-MSL1061/64 Drive?
The MSL1061/64 includes 6 current sinks (STR0
through STR5) that each control the LED current of
multiple series-connected white LEDs. Any combination
of the 6-strings may be enabled, and not all the strings
need to be used.
Make sure that each enabled string contain the same
number of the same type of LED so that the total voltage
drop for each string is the same because the single boost
regulator supplies power to all six strings. Use a single
MSL1061/64 LEDs of a single color/chemistry, such
as white LED backlighting or single-color signage. For
multicolor applications (e.g. RG, RGB, RGGB, RGBA),
use separate MSL1061/64s per LED color/chemistry
type. Each MSL1061/64 manages its integrated boost
regulator to optimize efficiency for its strings of identical
LEDs with matched electrical characteristics.
4
The maximum number of LEDs allowed in a string is
determined by the maximum voltage rating of the boost
regulator’s internal power FET, which is 50V minus 2V
for switching noise transients, leaving 48V. The FET
is protected by the OVP trip, which has a 2% voltage
tolerance, plus another 1% for the external setting
resistors R8 and R9 (Figure 6 on page 15) reducing the
maximum voltage to 46.5V. The total voltage needed
to drive a string is the forward voltage drop across the
desired LED strings, plus the headroom needed across
a string output’s current sink (600mV) to maintain
regulation, plus the boost regulator’s rectifier forward
voltage (normally under 900mV) leaves 46.5V - 0.6V 0.9V = 45V maximum for the LED string. The number of
LEDs that the MSL1061/4 can drive per string is 45V /
{maximum LED forward voltage per LED}, or 12 LEDs
per string using 3.75V maximum forward voltage LEDs.
Differences Between Atmel LED
Drivers-MSL1061/64
Use the MSL1061 for applications where multiple
drivers are connected to a single I2C bus such as RGB
and RGGB lighting. Use the lower cost MSL1064 for
single-driver applications, and multi-driver applications
that do not require all drivers on the same I2C
interface (Table 1).
Atmel LED Drivers-MSL1061/MSL1064
Atmel LED Drivers-MSL1061/MSL1064
6-string PWM LED Driver with Digitally Compensated, 1.1MHz,
48V Boost Regulator, ±1.5% Current Balance, I2C Interface
Table 1. Atmel LED Drivers-MSL1061 and MSL1064 Comparison
FEATURE
I2C interface
Package
IPC2221A-2003
compliance
MSL1061
MSL1064
APPLICATION AND SUITABILITY
4 selectable slave addresses by
AD0 pin (0x60, 0x61, 0x62, 0x63)
1 fixed slave address (0x62)
28-lead, 5mm x 5mm TQFN,
0.5mm pitch
24-lead, 5mm x 5mm TQFN,
0.65mm pitch
0.2mm min gap between SW pins
and adjacent conductors. Compliant
to 100V with board coating, 15V
without coating
0.6mm min total gap between SW
pins and adjacent conductors.
Compliant to 100V with or without
board coating
Only one MSL1064 is uniquely
addressed on an I2C bus
If compliance is necessary use
the MSL1064 or MSL1061 with
board coating.
Capabilities With and Without Using the Serial Interface
MSL1061/64 operates as stand alone LED drivers with full digital (PWM) and analog (DAC) LED brightness control
and fault reporting through I/O controls. Alternatively, LED dimming and fault reporting is managed over an I2C or SMB
serial interface, allowing software/firmare LED intensity control. More detailed fault management reporting and software
controlled shutdown (Table 2) via the serial interface.
Table 2. Atmel LED Drivers-MSL1061/64 Stand Alone Capabilities and I2C Controlled Features
FUNCTION
CONTROLS AVAILABLE ON PINS
ADDITIONAL CONTROLS AVAILABLE VIA I2C
Global on/off control
EN pin (Table 3 on page 9)
Run mode/sleep mode
Individual LED string on/off control
Not available
String enables register
Analog LED current adjustment
ILED pin (Table 3 on page 8)
Current setting register
PWM LED current adjustment
PWM pin (Table 3 on page 8)
PWM frequency register
PWM duty ratio register
Ambient light sensor (ALS) and/
or auto-matic temperature LED
current adjustment
IADJ pin (Table 3 on page 9)
Current setting register
Fault monitoring
FLTB pin indicates open-string, shortedstring, and over-temperature faults
Status register identifies open/short circuit and overtemperature faults to individual strings
Atmel LED Drivers-MSL1061/MSL1064
5
Packages and Pin Connections
VIN
EN
N/C
SW
SW
N/C
Atmel LED Drivers-MSL1061/64 – 24-pin, 5mm x 5mm x 0.75mm TQFN package with 0.65mm lead pitch
24
23
22
21
20
19
VCC
1
18 OVP
VDD
2
17 STR0
TEST1
3
16 STR1
TEST2
4
MSL1064
15 STR2
SDA
5
(TOP VIEW)
14 STR3
SCL
6
Figure 1. 24-pin, 5mm x 5mm x 0.75mm TQFN
(0.65mm pin pitch) with Exposed Pad
7
8
9
10
11
12
PWM
FLTB
OSC
ILED
IADJ
STR5
13 STR4
Figure 2. 24-pin TQFN Package Dimensions
6
Atmel LED Drivers-MSL1061/MSL1064
Atmel LED Drivers-MSL1061/MSL1064
EN
SW
SW
SW
SW
N/C
6-string PWM LED Driver with Digitally Compensated, 1.1MHz,
48V Boost Regulator, ±1.5% Current Balance, I2C Interface
VIN
28
27
26
25
24
23
22
3
19 STR0
TEST2
4
MSL1061
18 STR1
SDA
5
(TOP VIEW)
17 STR2
SCL
6
16 STR3
AD0
7
15 STR4
8
9
10
11
12
13
14
STR5
TEST1
IADJ
20 TEST3
ILED
2
N/C
VDD
OSC
21 OVP
FLTB
1
PWM
VCC
Figure 3. 28-pin, 5mm x 5mm x 0.75mm
TQFN (0.5mm pin pitch) with Exposed Pad
Figure 4. 28-pin TQFN Package Dimensions
Atmel LED Drivers-MSL1061/MSL1064
7
Pin Descriptions
Table 3. Pin Assignments
PIN NAME
MSL1064
PIN DESCRIPTION
VCC
1
1
6V internal linear regulator output
VCC powers the internal power FET switch driver.
Bypass VCC to GND either with a 10µF or greater ceramic capacitor, or with a 10µF or
greater tantalum capacitor in parallel with a 1µF ceramic capacitor.
If the voltage at VIN is less than 6.5V, connect VCC directly to VIN to bypass the internal
linear regulator, and power the driver directly from VIN
VDD
2
2
2.9V internal linear regulator output
VDD powers internal logic. Bypass VDD to GND with at least a 4.7µF ceramic capacitor
TEST1
3
3
Factory test connection. Leave unconnected
TEST2
4
4
Factory test connection. Connect to GND
SDA
5
5
I²C serial data I/O
SDA is the data I/O for the I²C serial interface
SCL
6
6
I²C serial clock input
SCL is the clock input for the I²C serial interface
AD0
7
-
I²C slave ID selection input
For MSL1061, connect AD0 to GND, VDD, SCL, or SDA to set the I²C slave ID to 0x60,
0x61, 0x62, or 0x63. The MSL1064 I²C slave ID is fixed at 0x62, and is not user-selectable
PWM
8
7
PWM control input
Drive PWM with a PWM signal up to 40kHz to pulse-width-modulate the LED current
FLTB
9
8
Fault indication output (active low)
FLTB sinks current to GND whenever the MSL1061/64 detects a fault.
Once a fault is detected, FLTB remains low until EN is toggled low/high, input power is
cycled off/on, or the fault status is reset through the I²C interface.
OSC
10
9
Oscillator control input
Connect a 115kΩ, 1% resistor from OSC to GND to set the internal oscillator frequency
to 11MHz and the boost regulator switching frequency to 1.1MHz
TEST3
11
-
Factory test connection with internal 1.8kΩ pull-up to VDD. Leave unconnected
ILED
8
MSL1061
12
10
Maximum LED current control input
Connect a resistor from ILED to GND to set the full-scale LED string current.
For example, connect a 100kΩ resistor to GND to set a 20mA sink current through
each LED string
Atmel LED Drivers-MSL1061/MSL1064
Atmel LED Drivers-MSL1061/MSL1064
6-string PWM LED Driver with Digitally Compensated, 1.1MHz,
48V Boost Regulator, ±1.5% Current Balance, I2C Interface
PIN NAME
MSL1061
MSL1064
PIN DESCRIPTION
IADJ
13
11
Analog LED current dimming input
Apply a voltage between 0V to 1.22V to linearly control the LED current from 0 to 100%.
Connect IADJ to VDD if unused
STR5
14
12
LED string 5 current sink output
Connect the cathode of LED String 5 to STR5. Connect STR5 to GND if unused
STR4
15
13
LED string 4 current sink output
Connect the cathode of LED String 4 to STR4. Connect STR4 to GND if unused
STR3
16
14
LED string 3 current sink output
Connect the cathode of LED String 3 to STR3. Connect STR3 to GND if unused
STR2
17
15
LED string 2 current sink output
Connect the cathode of LED String 2 to STR2. Connect STR2 to GND if unused
STR1
18
16
LED string 1 current sink output
Connect the cathode of LED String 1 to STR1. Connect STR1 to GND if unused
STR0
19
17
LED string 0 current sink output
Connect the cathode of LED String 0 to STR0. Connect STR0 to GND if unused
OVP
21
18
Overvoltage detection input
Connect a resistive voltage divider from the boost output voltage to OVP to set the
overvoltage protection set point. OVP threshold is 1.28V
N/C
22
19
No internal connection. Leave unconnected
SW
23, 24, 25,
26
20, 21
N/C
-
22
No internal connection. Leave unconnected
EN
27
23
Enable input (active high)
Drive EN high to turn on the MSL1061/64, and drive it low to turn it off.
For automatic startup, connect EN to VIN through a 100kΩ resistor
Supply voltage input
Connect the input supply voltage to VIN.
VIN powers the internal linear regulator that powers VCC.
Bypass VIN to GND with a 1µF or greater ceramic capacitor
VIN
28
24
GND
Exposed
pad
Exposed
pad
Atmel LED Drivers-MSL1061/MSL1064
Drain of the internal boost power MOSFET switch
Connect all SW pins together and to the boost regulator inductor and rectifier
Ground
9
Absolute Maximum Ratings
Voltage (With Respect to GND Exposed Pad on Package Underside)
VIN.................................................................................................................................................................................................................. -0.3V to +40V
VCC, EN.........................................................................................................................................................................................................-0.3V to +8V
VDD, OVP, IADJ, FLTB, ILED, SDA, SCL, AD0, OSC, PWM..................................................................-0.3V to +3.6V
SW................................................................................................................................................................................................................. -0.3V to +50V
STR0, STR1, STR2, STR3, STR4, STR5.................................................................................................................... -0.3V to +45V
Current (Into Pin)
SW.............................................................................................................................................................................................................................................±3A
STR0, STR1, STR2, STR3, STR4, STR5..................................................................................................................................... ±35mA
All other pins...........................................................................................................................................................................................................±20mA
Continuous Power Dissipation at 70°C
24-Pin TQFN (see Note 8, Note 9)......................................................................................................................................... 2286mW
28-Pin TQFN (see Note 8, Note 9)......................................................................................................................................... 2286mW
Ambient Operating Temperature Range TA = TMIN to TMAX...................................................... -40°C to +85°C
Junction Temperature ............................................................................................................................................................................. +125°C
Storage Temperature Range.................................................................................................................................... -65°C to +125°C
Lead Soldering Temperature, 10s...............................................................................................................................................+300°C
10
Atmel LED Drivers-MSL1061/MSL1064
Atmel LED Drivers-MSL1061/MSL1064
6-string PWM LED Driver with Digitally Compensated, 1.1MHz,
48V Boost Regulator, ±1.5% Current Balance, I2C Interface
Electrical Characteristics
(Circuit of Figure 6, VVIN = 12V, default register settings of Table 7, TA = -40°C to +85°C, unless otherwise noted. Typical values are at TA = +25°C) (Note 1)
PARAMETER
CONDITIONS AND NOTES
MIN
TYP
MAX
UNIT
DC ELECTRICAL CHARACTERISTICS
VIN operating supply voltage
V VIN = V VCC
4.75
6.5
V
VCC unconnected
6.5
36
V
VIN quiescent supply current
VEN = 3V, VPWM = 0V
VIN shutdown supply current
VEN = VPWM = 0V
VVIN = 12V
4
14
mA
VVIN = 6V, VVCC = 6V
4
14
mA
4
10
µA
5.6
6
6.3
V
1
2
5
mV
VCC output voltage
1
VCC line regulation
6.5V < VVIN < 36V
VCC dropout voltage
VVIN = 6V, IVCC = 5mA, VPWM = 0V
100
300
550
mV
VCC short-circuit current
VVCC = 0V
30
80
150
mA
VCC UVLO threshold
VVCC rising, hysteresis = 150mV
4.1
4.3
4.5
V
VDD output voltage
IVDD = 1mA
2.7
2.9
3.1
V
VDD short-circuit current
VVDD = 0V
10
35
60
mA
VDD UVLO threshold
VVDD rising, hysteresis = 80mV
2.4
2.5
2.6
V
Thermal shutdown threshold (rising)
135
°C
Thermal shutdown hysteresis
10
°C
PARAMETER
CONDITIONS AND NOTES
MIN
TYP
MAX
UNIT
DC ELECTRICAL CHARACTERISTICS - LED CURRENT CONTROL STR0 TO STR5
ILED regulation voltage
R5 = 100kΩ
1.195
1.22
1.245
V
STR0 to STR5 full scale sink current
VSTRn = 1V, R5 = 100kΩ, VIADJ = VPWM = 3V
19.7
20
20.3
mA
STR0 to STR5 maximum sink current
VSTRn = 1V, R5 = 60kΩ, VIADJ = VPWM = 3V
(Note 10)
30
STR0 to STR5 current matching
VSTRn = 1V, R5 = 100kΩ, VPWM = 3V (Note 11)
STR0 to STR5 leakage current
mA
1.5
%
VEN = 0V, VSTRn = 40V
0.1
1
µA
VEN = 3V, VSTRn = 40V, VPWM = 3V
0.1
1
µA
4.4
4.8
V
STR0 to STR5 short circuit detection threshold
4
STR0 to STR5 open circuit detection threshold
0.1
PARAMETER
CONDITIONS AND NOTES
MIN
TYP
V
MAX
UNIT
DC ELECTRICAL CHARACTERISTICS - LOGIC I/OS
EN logic high input voltage
2.3
EN logic low input voltage
EN logic input current
Atmel LED Drivers-MSL1061/MSL1064
VEN = 3V
V
0.8
V
20
µA
11
PARAMETER
EN logic input series resistance
CONDITIONS AND NOTES
MIN
Between EN input package pin and internal
Zener clamp
EN logic input Zener clamp
SCL, SDA, AD0,
PWM logic high input voltage
TYP
kΩ
5.8
V
2
V
0.9
SDA, SCL, AD0 input capacitance
10
SDA output low voltage
Sinking 6mA
FLTB output low voltage
Sinking 1mA
pF
V
0.2
V
10
µA
TYP
MAX
UNIT
0.4
0.6
Ω
1.245
V
0.1
MIN
V
0.4
IADJ, FLTB, PWM, SCL, SDA,
AD0 leakage current
CONDITIONS AND NOTES
UNIT
10.5
SCL, SDA, AD0,
PWM logic low input voltage
PARAMETER
MAX
DC ELECTRICAL CHARACTERISTICS - BOOST REGULATOR
SW on resistance
ISW = 100mA
SW current limit
2
OSC regulation voltage
R4 = 115kΩ ±1%
STR0-STR5 boost regulation voltage
R5 = 100kΩ, PWM=100% (Note 12)
OVP threshold
VOVP rising
1.195
1.22
A
600
1.25
OVP hysteresis
1.28
mV
1.31
60
OVP leakage current
PARAMETER
VOVP = 3.6V
CONDITIONS AND NOTES
V
mV
1
µA
MAX
UNIT
0
50
kHz
0
100
%
MIN
TYP
AC ELECTRICAL CHARACTERISTICS
PWM input frequency
PWM input duty ratio
PWM input minimum string on time
INTPWM bit D3=0 in control register to select
external PWM input to be used for direct LED
string dimming control
PWM input minimum string off time
PWM input frequency, external PWM clock mode
PWM input duty ratio, external PWM clock mode
PWM frequency (internal oscillator)
INTPWM bit D3=1, EXTCLK bit D2=1 in
control register to select external PWM
input to be used as clock for internal PWM
dimming control
R4 = 115kΩ ±1%, INTPWM bit D3=1,
EXTCLK bit D2=0 in control register to select
internal oscillator to be used as clock for
internal PWM dimming control
14
µs
3.2
µs
0
12
MHz
30
70
%
9
11
12
MHz
1.21
MHz
Boost regulator switching frequency
R4 = 115kΩ ±1%
0.99
1.1
Boost regulator maximum duty ratio
R4 = 115kΩ ±1%
89
92
Boost regulator startup time
12
100
%
120
ms
Atmel LED Drivers-MSL1061/MSL1064
Atmel LED Drivers-MSL1061/MSL1064
PARAMETER
6-string PWM LED Driver with Digitally Compensated, 1.1MHz,
48V Boost Regulator, ±1.5% Current Balance, I2C Interface
SYMBOL
CONDITIONS AND NOTES
MIN
TYP
MAX
UNIT
1000
kHz
I²C SWITCHING CHARACTERISTICS
SCL clock frequency
1/tSCL
TOEN bit D1=0 in control
register to disable bus
timeout
0
TOEN bit D1=1 in control
register to enable bus
timeout
0.066
tTIMEOUT
15
tBUF
0.5
µs
Repeated START condition
hold time
tHD:STA
0.26
µs
Repeated START condition
set-up time
tSU:STA
0.26
µs
STOP condition set-up time
tSU:STOP
0.26
µs
SDA data hold time
tHD:DAT
5
ns
SDA data valid acknowledge time
tVD:ACK
(Note 3)
0.05
0.55
µs
SDA data valid time
tVD:DAT
(Note 4)
0.05
0.55
µs
SDA data set-up time
tSU:DAT
100
ns
SCL clock low period
tLOW
0.5
µs
SCL clock high period
tHIGH
0.26
µs
Bus time-out period
STOP to START condition bus
free time
SDA, SCL fall time
tF
SDA, SCL rise time
tR
SDA, SCL input suppression
filter period
tSP
25
(Note 5, Note 6)
(Note 7, Note 10)
50
ms
120
ns
120
ns
ns
Note 1. All parameters are tested at TA=25°C, unless otherwise noted. Specifications at temperature are guaranteed by design
Note 2. 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 the bus timeout feature for DC operation
Note 3. tVD:ACK = SCL LOW to SDA (out) low acknowledge time
Note 4. tVD:DAT = minimum SDA output data-valid time following SCL low transition
Note 5. A master device must internally provide an SDA hold time of at least 300ns to ensure an SCL low state
Note 6. The maximum SDA and SCL rise times is 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 7. MSL1061/64 includes input filters on SDA, SCL, and AD0 inputs that suppress noise less than 50ns
Note 8. Subject to thermal dissipation characteristics of the device
Note 9. When mounted according to JEDEC JEP149 and JESD51-12 for a two-layer PCB, θJA = 24.1°C/W, and θJC = 2.7°C/W
Note 10.Guaranteed by design and characterization. Not production tested
Note 11.STR0 to STR5 current matching is the difference of any one string current and the average of all string currents divided by the average of
all string currents
Note 12.The MSL1061/64 selects the string (STR0 through STR5) with the lowest voltage to control the boost regulator voltage
Atmel LED Drivers-MSL1061/MSL1064
13
Block Diagram
The block diagram for the 28-pin MSL1061 is shown in Figure 5. The differences for the 24-pin MSL1064 are that the
MSL1064 provides only two pins for SW instead of four pins on the MSL1061, and the AD0 pin is not pinned out but
is instead bonded internally to SCL. The MSL1061 I2C slave address is selected using AD0 from one of the four address
pairs, 0xC0/0xC1 - 0xC6/0xC7, whereas the MSL1064 I2C slave address is fixed at 0xC4/0xC5.
Figure 5. Atmel LED Driver-MSL1061 Block Diagram
14
Atmel LED Drivers-MSL1061/MSL1064
Typical Application Circuit
Figure 6. Backlight Example Driving 60 White LEDs
4.7
Table 4. Typ. Application Circuit Parameters
PARAMETER
Minimum input voltage
Maximum input voltage (set by
minimum LEDs string voltage)
Table 5. Typ. Application Circuit Bill of Materials
VALUE
4.75V
30V
Number of LEDs
60
Number of LED strings
6
Number of LED per string
10
LED forward current (set by R5)
White LED
20mA
Osram LWY3SG
COMPONENT
C4, C5, C6, C7*
DESCRIPTION
VENDOR PART
NUMBER
1µF, 50V, X7R
C2
10µF, 10V, X7R or
tantalum (see note)
C3
33µF, 35V, X7R
C1
4.7µF, 6.3V, X7R
R8
1MΩ, 1%
R9
28.7kΩ, 1%
R4
115kΩ, 1%
Minimum LED forward voltage
2.9V
R5
100kΩ, 1%
Typical LED forward voltage
3.3V
R7
100kΩ, 5%
Maximum LED forward voltage
3.6V
R2
1MΩ, 5%
Minimum LED string voltage
29V
L1
10µH, 1.7A
Maximum LED string voltage
36V
D1
60V, 2A Schottky
Central Semi
CMSH2-60M
60 x 30mA LED
Osram LW-Y2SG
Oscillator frequency (set by R4)
Overvoltage protection (OVP) trip
point (set by R8 and R9)
1.1MHz
45.9V
LEDs
LED driver
MSL1060
Sumida CDRH6D28-100
MSL1060
* Note: C7 is only required if tantalum capacitor is used for C2
Atmel LED Drivers-MSL1061/MSL1064
15
Detailed Description
The MSL1061/64 is an LED driver with integrated boost
regulator for driving an array of LEDs with up to 8W of
power. The I²C/SMB serial interface, logic controls, and
fault management make the MSL1061/64 especially
suited to drive up to 72 white LEDs for portable device
backlighting. It is also ideal for industrial lighting and
signage applications, and can, for example, drive a 6
string x 18 series LED array totaling 108 red LEDs
(2.5V LED forward voltage drop).
Internal Oscillator - R4
The MSL1061/64 includes six current sinks (STR0
through STR5) that each control the LED current of
series-connected LEDs. A built-in step-up (boost)
regulator supplies power to the LEDs. The MSL1061/64
controls the output voltage of the boost regulator such
that all LED strings have sufficient voltage to maintain
regulated LED current. This control loop operates
automatically without any user interaction or set-up.
Setting the Full-scale LED String Current - R5
Application Information
The MSL1061/64 uses an internal oscillator with
frequency set by resistor R4 from OSC to GND (Figure
6). Use 115kΩ ±1% resistance value for R4. This sets
the internal LED dimming PWM frequency to 11MHz
and the boost regulator PWM frequency to 1.1MHz.
When using different values for R4 the MSL1061/64
performance is not guaranteed.
R5 sets the full-scale static LED current for all enabled
strings (Figure 6) from ILED to GND. The maximum fullscale LED current is 30mA. The equation for calculating
external resistor R5 (Figure 6) to set the full-scale LED
string current IILED is:
I ILED =
2000
R5
VCC and VDD Regulators
where R5 is in kilohms and ILED is in milliamperes.
The MSL1061/64 includes two linear voltage regulators
to generate the internal voltage rails, VDD and VCC. The
regulators allow the MSL1061/64 to operate directly
from the same higher voltage supply, VIN, which supplies
the LED boost regulator. Use the VDD and VCC regulators
only to power the MSL1061/64’s internal circuitry,
therefore do not draw any external current from them.
A value of 100kΩ for resistor R5 sets 20mA full-scale
LED current. The minimum allowed value for R5 is
66.7kΩ, which sets 30mA full-scale LED current.
Reduce the static LED current from full-scale using the
LED string current register. This register reduces LED
current proportional to the 4-bit IDAC register.
The VCC regulator generates a nominally 6V rail from VIN.
VCC powers the boost regulator’s power switch and the
VDD regulator. Bypass VCC to GND either with a 10µF
or greater ceramic capacitor or with a 10µF or greater
tantalum capacitor in parallel with a 1µF ceramic capacitor.
In applications where there is a local 4.75V to 6.5V
supply available, power VCC and VIN directly from this
supply. In this case use this supply or a separate higher
voltage supply to power the LED boost regulator. When
using a higher voltage supply connect it to the inductor,
L1 (Figure 6), and not to the MSL1061/64.
The VDD regulator generates a nominally 2.9V rail from
VCC. VDD operates the internal low-voltage circuits.
Bypass VDD to GND with a 4.7µF or greater capacitor.
16
Atmel LED Drivers-MSL1061/MSL1064
Atmel LED Drivers-MSL1061/MSL1064
6-string PWM LED Driver with Digitally Compensated, 1.1MHz,
48V Boost Regulator, ±1.5% Current Balance, I2C Interface
Boost Regulator Components
The boost regulator is internally compensated, includes
an internal high voltage power switch, and requires only
an inductor, rectifier, and bypass capacitors. The currentmode boost regulator operates in either continuous
conduction mode (CCM) or discontinuous conduction
mode (DCM). In CCM, the inductor current does not fall
to zero when operating at full power, keeping inductor
ripple current low and switching noise at a minimum.
The boost regulator switching frequency is 1.1MHz set
by the 115kΩ resistor R4 from OSC pin to GND (Figure
6). Select the inductor, rectifier diode, and output
capacitors per the following guidelines.
Boost Supply Over-voltage Protection
(OVP) - R8 and R9
The OVP input sets the boost regulator’s output voltage
upper limit, and protects the boost regulator from an
open-circuit LED fault. Set the OVP voltage VTRIP by
resistors R8 and R9 (Figure 6):
VTRIP = VOVP
( R8 + R 9 )
R9
where VOVP=1.28V, nominal.
To minimize losses in the rectifier, choose one with fast
switching and low forward voltage drop. Ensure that the
rectifier can withstand a reverse voltage equal to the
regulator output voltage. The average forward current
is equal to the total LED string current (for example 6
strings x 30mA = 180mA), while the peak current is
equal to the inductor peak current (2A).
The boost output capacitor holds the voltage at the
output of the boost regulator while the internal power
switch is on and the rectifier is not conducting. Use
ceramic capacitors for small size and high ripple current
capacity, and derate them for operating voltage because
of the voltage coefficient of capacitance which decreases
the effective capacitance with increased operating
voltage. Use two parallel-connected 1µF 100V X7R
ceramic capacitors and a 10µH inductor with a 1.7A
peak current rating.
Atmel LED Drivers-MSL1061/MSL1064
17
Register Map Summary
Control the MSL1061/64 through an I2C interface using nine registers (Table 6). The power-up defaults (Table 7) are such
that an MSL1061/64 operates as a standalone LED driver if the I2C interface is not used.
The Internal register addressing auto-increments through the register map allowing sequential reads or writes without
needing to write separate addresses for each byte.
Table 6. Atmel LED Drivers-MSL1061/64 Register Map
REGISTER
FUNCTION
ADDRESS
MSTRCNTRL
Run/sleep
mode
REGISTER DATA
D7
D6
D5
D4
D3
D2
D1
D0
0x00
-
-
-
-
-
-
-
SLEEP
CNTRL
PWM
source, I2C/
SMB bus
timeout,
fault pin
enable
0x01
-
-
-
-
INTPWM
EXTCLK
TOEN
FLTEN
-
UNUSED
0X02
STATUS
Fault status
summary
0x03
-
OTDET
SCDET
OCDET
-
-
-
FLTDET
OCSTATUS
Open circuit
fault status
0x04
-
-
OC5
OC4
OC3
OC2
OC1
OC0
SCSTATUS
Short circuit
fault status
0x05
-
-
SC5
SC4
SC3
SC2
SC1
SC0
PWMFREQ
PWM
frequency
prescaler
0x06
D7
D6
D5
D4
D3
D2
D1
D0
PWMDUTY
PWM duty
ratio
0x07
D7
D6
D5
D4
D3
D2
D1
D0
-
UNUSED
0X08
STREN
String
enables
0x09
-
unused
0x0A
writes to this register address are ignored, and reads return the value 0x00
-
unused
0x0B
writes to this register address are ignored, and reads return the value 0x00
-
unused
0x0C
writes to this register address are ignored, and reads return the value 0x00
-
unused
0x0D
writes to this register address are ignored, and reads return the value 0x00
-
unused
0x0E
writes to this register address are ignored, and reads return the value 0x00
-
unused
0x0F
writes to this register address are ignored, and reads return the value 0x00
IDAC
LED string
current
0x10
18
WRITES TO THIS REGISTER ADDRESS ARE IGNORED,
AND READS RETURN THE VALUE 0X00
WRITES TO THIS REGISTER ADDRESS ARE IGNORED,
AND READS RETURN THE VALUE 0X00
-
-
-
-
STR5EN
-
STR4EN
-
STR3EN
DAC3
STR2EN
DAC2
STR1EN
DAC1
STR0EN
DAC0
Atmel LED Drivers-MSL1061/MSL1064
Atmel LED Drivers-MSL1061/MSL1064
6-string PWM LED Driver with Digitally Compensated, 1.1MHz,
48V Boost Regulator, ±1.5% Current Balance, I2C Interface
Register Map Power-up Defaults
Table 7. Atmel LED Drivers-MSL1061/64 Register Power-up Defaults
REGISTER
MSTRCNTRL
POWER-UP CONDITION
ADDRESS
REGISTER DATA
D7
D6
D5
D4
D3
D2
D1
D0
Run mode
0x00
0
0
0
0
0
0
0
0
CNTRL
Fault detection is enabled
I²C bus timeout is disabled
PWM internal 11MHz clock is used,
prescaled by PWMFREQ
PWM control is by PWM pin.
PWMDUTY register is ignored
0x01
0
0
0
0
0
0
0
1
STATUS
No faults (open, short, or temperature)
are detected
0x03
0
0
0
0
0
0
0
0
OCSTATUS
None of the six LED outputs STR0 to
STR5 has an open circuit fault
0x04
0
0
0
0
0
0
0
0
SCSTATUS
None of the six LED outputs STR0 to
STR5 has a short circuit fault
0x05
0
0
0
0
0
0
0
0
PWMFREQ
Internal PWM frequency is the
maximum 43kHz
0x06
0
0
0
0
0
0
0
0
PWMDUTY
Internal PWM duty ratio is 0.39%
0x07
0
0
0
0
0
0
0
0
STREN
All of the six LED outputs STR0 to
STR5 are enabled
0x09
0
0
1
1
1
1
1
1
LED string current is 100% of the value
programmed by resistor R5
0x10
0
0
0
0
1
1
1
1
IDAC
Atmel LED Drivers-MSL1061/MSL1064
19
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