XC9133 TOREX [Torex Semiconductor], XC9133 Datasheet - Page 10

• Manufacturer Part Number: XC9133
• Description: Step-Up DC/DC Converter-LED Backlight Driver
• Manufacturer: TOREX [Torex Semiconductor]

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■APPLICATION INFORMATION (Continued)
<Separate Supply Source of the Step-up Circuit (V
Supply source of the step-up circuit can be used separately from V
Note: Please input 2.5V~6V to the V
<Startup Inrush Current>
<LED Open-circuit Protection>
If white LEDs are opened or damaged, the FB pin is pulled down, so that the operating duty ratio reaches the maximum.
Accordingly, the output voltage continues to increase, possibly causing the Lx pin voltage to exceed the absolute maximum
rating of 22V.
If white LEDs are opened or damaged, the detector built in the Lx pin causes the IC to stop oscillating, preventing excessive
increase of the output voltage. However, the detector may detect an overvoltage if the Lx pin voltage exceeds 18V, which is
the overvoltage limit, even when no LEDs are open. Therefore, care must be taken if four LEDs each having a forward
voltage of 4.45V or more are connected in series.
XC9133
The XC9133 series has no soft-start circuit built-in in order to minimize delay at startup. The inrush current can reach up
to the current limit I
In some cases, overshoot can occur.
Circuit example of separating supply source of
the step-up circuit from V
LIM
Series
.
IN
IN
pin when you use.
pin ( 3 LEDs)
IN
) from V
IN
Pin>
IN
pin.
Circuit example of separating supply source of
the step-up circuit from V
IN
pin ( 2 LEDs)