Datasheet

5Atmel LED Driver-MSL1060
Quick Start Guide
This section summarizes the capabilities of, and
differences between, the MSL1060 and the similar Atmel
MSL1061 and Atmel MSL1064 with I²C interfaces.
The MSL1060 and MSL1061/64 are LED string drivers
with integrated boost regulators, which power, monitor,
and dim multiple LEDs at high efficiency for backlighting
and signage applications. Each MSL1060/61/64
contains six outputs, each capable of sinking up to
30mA through a string of series-connected LEDs
dropping up to 45V; 8W of lighting power.
How Many LEDs Can the Atmel LED
Drivers-MSL1060/61/64 Drive?
The MSL1060/61/64 includes six current sinks
(STR0 through STR5) that each control the LED
current of multiple, series-connected, white LEDs. Any
combination of the six strings may be enabled, and not
all the strings need to be used.
It is important 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. This is
necessary because there is only one boost regulator
(and, therefore, only one LED supply) available to serve
all six strings. Use a single MSL1060/61/64 to drive
multiple 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 a
separate MSL1060/61/64 per LED color/chemistry
type. Each MSL1060/61/64 manages its integrated
boost regulator to optimize efficiency for its strings of
identical LEDs with matched electrical characteristics.
The 48V maximum voltage rating of the boost
regulator’s internal power FET determines the
maximum number of LEDs allowed in a string. The
overvoltage protection (OVP) circuit protects the FET
as well as external components. The accuracy of the
OVP threshold is 2% plus another 1% for the external
setting resistors, R8 and R9 (Figure 16 on page 15)
reducing the operating 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
600mV headroom needed the string’s output current
sink (600mV) to keep it in regulation. Since the FET
voltage is higher than the boost voltage by the rectifier
forward voltage drop, the available voltage for LEDs is
approximately 46.5V - 0.6V - 0.9V or 45V. Thus the
MSL1060 can drive up to 12 series LEDs as long as the
LED forward voltage is less than 3.75V.
Differences Between Atmel LED
Drivers-MSL1060, MSL1061 and MSL1064
Use the MSL1061 in applications where one or more
LED drivers are directly controlled by a PWM input
signal. The PWM input signal globally controls the LED
dimming. Use the MSL1061/64 for applications where
the LED drivers communicate by an I²C/SMB interface.
The MSL1064 has a single slave address, while the
MSL1061 has four available addresses which allows
communication to all four LED drivers on the same I²C
interface (Table 1).
Atmel LED Driver-MSL1060
6-string PWM LED Driver with Digitally Compensated, 1.1MHz,
48V Boost Regulator and ±1.5% LED String Current Balance