MP3393—8-STRING WHITE LED DRIVER WITH STEP-UP CONTROLLER

MP3393 Rev. 1.05

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15

3/26/2013

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the output voltage reaches the programmed OVP

threshold, the protection will be triggered.

To make sure the chip function properly, the OVP

setting resistor divider must be set with a proper

value. The recommended OVP point is about 1.1

Extending LED Channels applications

The MP3393 can be daisy-chained to expand the

number of LED channels using two or more

MP3393s in parallel. To connect two MP3393s

for a total of 16 LED strings, see Figure 5. Tie the

VCC pins of the master and the slave IC together

to provide power to the slave IC internal logic

circuitry. Also tie the COMP pins of the master

and the slave ICs together to regulate the voltage

of all 16 strings LEDs. The MOSFET driving

signals of the slave IC are not used, the boost

converter can be only driven by the master IC.

Do not leave the slave ISENSE pin floating; tie it

to GND. The EN and DIM signals should be

applied to both ICs. Use external PWM dimming

mode

to

achieve

accurate

dimming

synchronization of both parts.

Layout Considerations

Pay close attention to the PCB board layout and

components placement. Proper layout of the high

frequency switching path can prevent noise and

electromagnetic interference problems. The high-

frequency pulse current runs through the loop of

the external MOSFET (M2), output diode (D1,

D2), and output capacitor (C3, C4). This loop

must be must be as small as possible (See

Figure 3).

Figure 3: Layout Suggestion

The exposed IC pad internally connects to the

GND pin, and all logic signals refer to GND. The

PGND should connect externally to GND and

should be kept away from the logic signals.