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

MP3393 Rev. 1.05

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3/26/2013

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strings maintain their off status until the chip

restarts.

Short String Protection

The MP3393 monitors the CTLx pin voltage to

determine the presence of a short string. If one or

more strings are shorted, the respective CTLx

pins pull up to the boost output and tolerate high

voltage stress. If a CTLx pin voltage exceeds

6.5V, it meets the short string condition. When

the short string fault (CTLx over-voltage fault)

continues longer than 3072 clock cycles, the

device marks off the shorted string and disables

it. Once a string is marked-off, its current

regulator disconnects from the output voltage

loop regulation. The marked-off LED strings

remain off until the chip restarts. If all strings in

use are shorted, the MP3393 shuts down the

step-up converter.

GND when the OVP pin voltage is lower than

70mV, and triggers the SCP. The VFAULT pin

which connects the input power source to the

step-up converter.

Fault-Flag Indicator

In normal mode, the FF rises to VCC through the

pull-up resistor. Under short-circuit, open-circuit,

or thermal shutdown conditions, the FF pin is

pulled to GND and indicates the appropriate fault

state.