MP3388- 50V, 8-STRING WHITE LED DRIVERS

MP3388 Rev. 1.0

www.MonolithicPower.com

5

12/16/2011

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© 2011 MPS. All Rights Reserved.

PIN FUNCTIONS

QFN24

SOIC28

Name

Description

1

5

EN

Enable Control Input. Do not let this pin floating.

2

6

OSC

Switching Frequency Selection Input. When float this pin or connect this pin to

VCC, the step-up converter switching frequency is 1.25MHz. When connect this

pin to GND, the step-up converter switching frequency is 625kHz.

3

7

FSET

Dimming PWM Frequency Setting. Connect a capacitor between FSET and GND

4

8

PWMO

PWM Filter Output. To use external PWM dimming mode, connect a capacitor

between PWMO and GND to form a low-pass filter with an internal 400kΩ resistor.

It filters the external PWM logic signal on PWMI pin into a DC signal whose level is

inversely proportional to the duty-cycle of the input PWM signal. Then the DC

signal is converted to a DPWM dimming signal with the same duty-cycle as the

external PWM signal. To use DC input PWM dimming mode, directly apply a DC

voltage from 0.2V to 1.2V on PWMO pin for dimming PWM duty cycle control. The

DC input PWM dimming polarity is negative.

5

9

GND

Analog Ground.

6

10

PWMI

PWM Signal Input. To use the external PWM dimming mode, apply a PWM signal

on this pin for brightness control. This signal is filtered and its duty cycle is

converted into a DC signal to calculate the DPWM duty cycle. And the DPWM duty

cycle equals to the input PWM duty cycle. To use DC input PWM dimming mode,

float this pin.

7

11

LED8

LED String 8 Current Input. This pin is the open-drain output of an internal

dimming control switch. Connect the LED String 8 cathode to this pin. If this string

is not used, connect Vout to this pin.

8

12

LED7

LED String 7 Current Input. This pin is the open-drain output of an internal

dimming control switch. Connect the LED String 7 cathode to this pin. If this string

is not used, connect Vout to this pin.

9

13

LED6

LED String 6 Current Input. This pin is the open-drain output of an internal

dimming control switch. Connect the LED String 6 cathode to this pin. If this string

is not used, connect Vout to this pin.

10

14

LED5

LED String 5 Current Input. This pin is the open-drain output of an internal

dimming control switch. Connect the LED String 8 cathode to this pin. If this string

is not used, connect Vout to this pin.

11

16

ISET

LED Current Setting. Tie a current setting resistor from this pin to ground to

12

18

LED4

LED String 4 Current Input. This pin is the open-drain output of an internal

dimming control switch. Connect the LED String 4 cathode to this pin. If this string

is not used, connect Vout to this pin.

13

19

LED3

LED String 3 Current Input. This pin is the open-drain output of an internal

dimming control switch. Connect the LED String 3 cathode to this pin. If this string

is not used, connect Vout to this pin.

14

20

LED2

LED String 2 Current Input. This pin is the open-drain output of an internal

dimming control switch. Connect the LED String 2 cathode to this pin. If this string

is not used, connect Vout to this pin.