Datasheet

4
Atmel MSL3086/MSL3088 Datasheet
8-String 60mA LED Drivers with Integrated Boost Controller and Phase Shifted Dimming
2.0 Pin Descriptions
Table 2.1 Pin Assignments
Name
MSL
Pin Description3086 3088
FB 1 1
V
LED
Voltage Regulator Feedback Input: Connect a resistive voltage divider from the boost regulator output, V
LED
, to FB to set the un-optimized
boost regulator output voltage. The feedback regulation voltage is 2.5V.
VIN 2 2 Power Supply Input: Power supply input. Apply 4.5V to 5.5V to VIN. Decouple VIN to GND a 1uF or greater capacitor placed close to VIN.
SDA 3 3
I²C Serial Data I/O: SDA is the I²C serial interface data input/output. Connect SDA to VIN when unused. For interface information see the
MSL3040/50/60/80/86/87/88/89 Programming Guide.
SCL 4 4
I²C Serial Clock Input: SCL is the I²C serial interface clock input. Connect SCL to VIN when unused. For interface information see the
MSL3040/50/60/80/86/87/88/89 Programming Guide.
SYNC - 5
PWM Synchronization Input: A signal of 20Hz to 50kHz applied to SYNC controls the LED PWM dimming frequency. The signal at PWM
controls the LED PWM dimming duty cycle. For serial interface controlled PWM dimming, connect SYNC to GND and refer to the register definitions
section for registers 0x10 through 0x14 in the MSL3040/50/60/80/86/87/88/89 Programming Guide.
SCTH 5 -
String Short Circuit Threshold Level Setting Input: SCTH programs the LED string short-circuit detection threshold. Connect a resistor from
SCTH to GND to set the short-circuit threshold level to 4.9V (1kΩ), 5.8V (27kΩ), 6.8V (68kΩ) or 7.6V (330kΩ). A short circuit is detected when
the STRn voltage is above the threshold while STRn is on.
STR0 6 6 LED String 0 Current Sink: Connect the cathode end of series LED String 0 to STR0. If not used, connect STR0 to GND.
STR1 7 7 LED String 1 Current Sink: Connect the cathode end of series LED String 1 to STR1. If not used, connect STR1 to GND.
STR2 8 8 LED String 2 Current Sink: Connect the cathode end of series LED String 2 to STR2. If not used, connect STR2 to GND.
STR3 9 9 LED String 3 Current Sink: Connect the cathode end of series LED String 3 to STR3. If not used, connect STR3 to GND.
STR4 10 10 LED String 4 Current Sink: Connect the cathode end of series LED String 4 to STR4. If not used, connect STR4 to GND.
STR5 11 11 LED String 5 Current Sink: Connect the cathode end of series LED String 5 to STR5. If not used, connect STR5 to GND.
STR6 12 12 LED String 6 Current Sink: Connect the cathode end of series LED String 6 to STR6. If not used, connect STR6 to GND.
STR7 13 13 LED String 7 Current Sink: Connect the cathode end of series LED String 7 to STR7. If not used, connect STR7 to GND.
PWM
14 -
PWM Dimming and Synchronization Input: Drive PWM with a pulse-width modulated signal with duty cycle of 0% to 100% and frequency of
20Hz to 50kHz to control the duty cycle and the frequency of all LED strings. For serial interface controlled PWM dimming connect PWM to GND and
refer to the register definitions section for registers 0x10 through 0x14 in the MSL3040/50/60/80/86/87/88/89 Programming Guide.
- 14
PWM Dimming Input: Drive PWM with a pulse-width modulated signal with duty cycle of 0% to 100% and frequency of 20Hz to 50kHz to control
the duty cycle of all LED strings. The frequency of the signal applied to SYNC controls the LED PWM frequency. For serial interface controlled PWM
dimming, connect PWM to GND and refer to the register definitions section for registers 0x10 through 0x14 in the MSL3040/50/60/80/86/87/88/89
Programming Guide.
CGND 15 15 Connect To Ground: Connect to CGND to GND close to driver.
ILED 16 16
Maximum LED Current Control Input: Connect a resistor from ILED to GND to set the full-scale LED current. See the section “Setting the LED
Current” beginning on page15 for more information.
PGND 17 17 Power Ground: Ground of the boost regulator gate driver. Connect PGND to CGND and EP as close to the MSL3086/88 as possible.
GATE 18 18 Gate Drive Output: Connect GATE to the gate of the boost regulator switching MOSFET
PVIN 19 19
Boost Regulator Power Supply Input: PVIN is the power supply input for the external MOSFET gate driver. Apply 4.5V to 5.5V to PVIN.
Decouple PVIN with two 1uF capacitors placed close to PVIN.
FLTB 20 20
Fault Output: FLTB sinks current to GND when a fault is detected. The Boost Over-Voltage Fault does not latch; the fault goes away when the fault
condition no longer exists, all other faults latch. Clear faults by toggling EN low and then high, or by cycling input power off and on. Additionally,
fault control is available through the I
2
C compatible serial interface; see the MSL3040/50/60/80/86/87/88/89 Programming Guide for information.
EN 21 21
Enable Input: Drive EN high to turn on the device, drive it low to turn it off. For automatic startup connect EN to VIN. Toggle EN low then high to
reset FLTB.
CS 22 22
Boost Regulator Current Sense Input: Connect the current sense resistor from CS and the MOSFET source to GND to set the boost regulator
current limit. The current limit threshold is 100mV. See the section “Setting the Current Limit” beginning on page 20 for more information.
COMP 23 23
Boost Regulator Compensation Node: Connect the compensation network components from COMP to FB to compensate the boost regulator
control loop, as shown in the Typical Applications Circuit on page 11. See the section “Loop Compensation” beginning on page 21 for more
information.
GND 24 24 Signal Ground: Connect GND to EP as close to the device as possible.
EP EP EP
Exposed Die-Attach Paddle : Connect EP to CGND, PGND and to the system ground. EP is the return path for the LED current as well as the
primary thermal path to remove heat generated in the MSL3086/88. Use a large circuit board trace to connect from EP to the boost supply output
capacitor ground and to the input supply ground return. Connect EP to a large copper ground plane for best thermal and electrical performance.