STEP UP, 4 STRINGS, MAX. 350MA/STRING ANALOG AND PWM DIMMING, WHITE LED CONTROLLER

MP3398A Rev. 1.04

www.MonolithicPower.com

9

5/26/2017

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© 2017 MPS. All Rights Reserved.

PIN FUNCTIONS

TSSOP16-EP

&SOIC16

Pin #

SOIC20

Pin #

Name

Description

1

1

COMP

Step-up Converter Compensation Pin. This pin compensates the regulation

control loop. Connect a ceramic capacitor from COMP to GND.

2

2

EN

Enable Control Input. A voltage greater than 1.8V will turn the part on and less

than 0.6 V will turn the part off. Do not let this pin float.

3

3

PWM

Input Signal for PWM Brightness Control. By applying a PWM signal on this

pin, the LED current can be chopped and the average current is equal to

Iset*D_dim (I_set is the LED current value set by a resistor connected to PIN

6; D_dim is the duty cycle of the PWM dimming duty cycle). Make sure the

The input PWM signal frequency mainly determines the LED current dimming

ratio. Lower dimming frequency, smaller dimming current can be gotten. In

general, 200Hz to 2kHz can be used to cover most of the customers’ LED

current dimming requests. Internally weakly pulled to GND if this pin is floated.

If

PWM

dimming

is

not

required,

pulling

this

pin

to

high

voltage(1.25V<Vpwm<5V),

4

5

GND

Ground.

5

7

OSC

Switching Frequency Set. Connect a resistor between OSC and GND to set

the step-up converter switching frequency. The voltage at this pin is regulated

to 1.23V. The clock frequency is proportional to the current sourced from this

pin.

6

8

ISET

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

program the current in each LED string. This pin voltage is regulated to

1.225V. The LED current is proportional to the current through the ISET

resistor.

7

9

ADIM

Signal Input for Analog Brightness Control. The LED current amplitude is

determined by this pin and the input signal can be either a PWM signal or a

DC voltage signal. An internal RC filter (10Mohm resistor and 100pF

capacitor) is integrated to this pin. So, if a PWM signal applied to this

pin, >20kHz frequency is recommended to get a better PWM signal filtering

performance and make sure the amplitude voltage is higher than 1.5V and low

level voltage is less than 0.4V. For DC signal input, please apply a DC input

signal range from 0.4V to 1.5V to linearly set the LED current from 0% to

100%. Internally weakly pulled to GND if this pin is floated. If Analog dimming

is not required, pulling this pin to high voltage(1.54V<Vpwm<5V),

8

10

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.

9

11

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.

10

12

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.

11

13

LED1

LED String 1 Current Input. This pin is the open-drain output of an internal

dimming control switch. Connect the LED String 1 cathode to this pin.

12

14

OVP

Over-Voltage Protection Input. Connect a resistor divider from output to this

pin to program the OVP threshold. When this pin voltage reaches 1.23V, the

MP3398A triggers Over Voltage Protection mode.