MP3308 – STEP-UP WHITE LED DRIVER WITH DUAL PWM DIMMING INPUT CONTROL
MP3308 Rev. 1.02 www.MonolithicPower.com 4
7/19/2012 MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited.
© 2012 MPS. All Rights Reserved.
PIN FUNCTIONS
Pin # Name Description
1 SW
Power Switch Output. Drain of the internal MOSFET switch. Connect to the power
inductor and the output rectifier. SW can swing between GND and 40V.
2
PGND,
Exposed Pad
Power Ground. Connect exposed pad to GND plane for proper thermal performance.
3 IN Input Supply Pin. Locally bypassed.
4 PWMIA
PWM Input A.
pply one PWM signal on this pin for brightness control. This signal is
uniform and filtered at PWMOA pin.
5 PWMIB
PWM Input B.
pply the other PWM signal on this pin for brightness control. This signal
is uniform and filtered at PWMOB pin.
6 EN ON/OFF Control. Hold EN pin low to turn off part, high to turn of part.
7 FSET
PWM Dimming Frequency Programmer. Connect a capacitor from this pin to GND to set
the PWM-dimming frequency as the formula, F
PWM
(Hz)
= 16176 / C
FSET
(nF)
8 PWMOB PWM Filtered Output B. Connect a capacitor from this pin to GND.
9 PWMOA PWM Filtered Output A. Connect a capacitor from this pin to GND.
10,14 GND Ground.
11 OVP
Over-Voltage Protection. Connect a resistor divider from output to this pin to adjust the
OVP threshold. When this pin voltage reaches the shutdown threshold 0.9V, the switch
turns off.
12 LED
LED Current Input. Open-drain output of an internal dimming control switch. Connect the
LED cathode to this pin.
13 ISET
LED Current Set. This pin is the source output of an internal dimming control switch. The
MP3308 regulates the voltage across the current setting resistor. Tie a current-setting
resistor from this pin to ground. Regulates the voltage to 200mV.
