MP3312 － 2.7V-5.5V INPUT, 38V OVP, DUAL-CHANNEL WHITE LED DRIVER

MP3312 Rev. 1.02

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12

1/13/2015

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Cycle-by-Cycle Current Limit Protection

MP3312 provides cycle-by-cycle current limit

protection to avoid any damage due to too large

current rating. During startup, the current limit is

clamped to 1A for around 6ms to avoid output

overshoot and inrush current. After that, the

current limit returns back to normal 1.8A.

Open String Protection

Open string protection is achieved by detecting

the VOUT pin. If the LED string is open, the

feedback voltage is lower than the reference

voltage, thus the COMP rises up and keeps

charge the output capacitor until VOUT pin hits

the protection point VOVP. Then the IC stops

switching and shuts down till VIN and EN is reset

for enable again.

Unused LED Channel

In some cases, if one LED current channel is not

used, connect the corresponding LEDx to GND

to remove it from the control loop.

Short String Protection

The MP3312 monitors the LEDX pin voltage to

judge if the short string occurs. If one string is

short, the respective LEDX pin will be pulled up

to the boost output and tolerate high voltage

stress. If the LEDX pin voltage is higher than 5 V

and LED current is larger than 8% full-scale

setting current, the short string condition is

detected and if such condition lasts longer than

8ms, the fault string current source is disabled till

VIN and EN is reset for enable again.

Thermal Shutdown Protection

To prevent the IC operate at exceedingly high

temperature, thermal shutdown is implemented in

this chip by detecting the silicon die temperature.

When the die temperature exceeds the upper

threshold 150℃, the IC shutdowns and recovers

to normal operation when die temperature drops

below lower threshold. Typically, the hysteresis

value is 25°C.