Datasheet

12
Atmel MSL3086/MSL3088 Datasheet
8-String 60mA LED Drivers with Integrated Boost Controller and Phase Shifted Dimming
8.0 Detailed Description
The MSL3086/88 are LED drivers with eight internal current regulators capable of driving up to 60mA LED current each. The MSL3086/88
feature an integrated boost regulator controller to power the LED strings. They provide a complete LED driver solution for multi-LED string
applications. A single resistor sets the LED current for all strings. The MSL3086/88 support PWM LED dimming up to 4095:1 and feature
automatic phase shifted dimming, and dimming synchronized with external digital signals. The MSL3088 features independent frequency and
duty cycle control inputs. All devices feature optional register-set PWM dimming, fault and other controls via the I
2
C serial interface; for interface
information see the “MSL3040/50/60/80/86/87/88/89 Programming Guide”.
The MSL3086/88 include comprehensive fault monitoring and automatic fault handling. Automatic fault handling allows the MSL3086/88 to
operate without any microcontroller or FPGA, while control via I
2
C allows customized fault handling and device control for more complex
applications.
The small 4x4mm VQFN package allows a small overall LED driver solution, while the high package power dissipation offers high output power
capability.
8.1 Differences between the MSL3086 and MSL3088
The MSL3086 requires only power and a single PWM input to set both the frequency and duty cycle of the LED drive signals, and
includes a boost converter controller. The MSL3088 accepts an additional SYNC signal that sets the frequency of the LED dimming
signals, while the PWM input sets the LED duty cycle. Similar devices are presented in Table 8.1 for comparison:
Table 8.1. LED Driver Comparison with Similar Parts
PART
NUMBER
OF LED
STRINGS
MAX
CURRENT
PER
STRING
PHASE
SHIFTED
STRING
DRIVERS
INTERNAL
BOOST
CONTROLLER
RESISTOR SET
LED SHORT
CIRCUIT
THRESHOLD
SEPARATE
SYNC
INPUT*** BEST FOR
MSL3086 8 60mA YES YES YES NO MONITOR, INDUSTRIAL PANEL
MSL3087* 8 60mA YES NO YES NO SMALL TV
MSL3088 8 60mA YES YES NO YES SMALL TV
MSL3080
8 60mA NO YES YES NO MONITOR, INDUSTRIAL PANEL
4** 120mA NO YES YES NO MONITOR, INDUSTRIAL PANEL
2** 240mA NO YES YES NO MONITOR, INDUSTRIAL PANEL
1** 480mA NO YES YES NO MONITOR, INDUSTRIAL PANEL
MSL3040* 4 120mA YES YES YES NO MONITOR, AUTOMOTIVE
MSL3041* 4 120mA YES YES YES YES MONITOR, AUTOMOTIVE
MSL3050*
5 60mA NO YES YES NO INDUSTRIAL PANEL
1** 300mA NO YES YES NO INDUSTRIAL PANEL
MSL3060*
6 60mA NO YES YES NO MONITOR, INDUSTRIAL PANEL
3** 120mA NO YES YES NO MONITOR, INDUSTRIAL PANEL
2** 180mA NO YES YES NO MONITOR, INDUSTRIAL PANEL
1** 360mA NO YES YES NO MONITOR, INDUSTRIAL PANEL
* Future product, contact factory for information.
** Drivers without phase shift allow parallel connection of string drive outputs for increased string current.
*** Drivers with separate SYNC input expect two control signals, one for dimming duty cycle and one for dimming frequency.
8.2 Operating the MSL3086/88
The MSL3086/88 are simple to operate; set up the boost regulator (see the section “Boost Regulator” beginning on page 17), set the
string on-current (see the section “Setting the LED Current” beginning on page 16), supply a PWM control signal to the PWM input
(MSL3088 requires a second control signal applied to the SYNC input), set the LED short circuit threshold voltage (see the section
“Setting the LED Short-Circuit Threshold” beginning on page 16), connect the LED strings and apply power (decoupled as instructed
in the section “Bypassing VIN and PVIN” beginning on page 16).