WHITE LED CURRENT SETTING

For backlighting applications, the white LED current is pro-

grammed by the careful choice of the R2 resistor.

Backlight:

V

En

≥ 0.9V

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I

White LED Current.

V

R2:

Resistor.

The feedback voltage is with respect to the voltage at the

Sw2 pin, not ground. For example, if the voltage on the Sw2

pin were 0.1V then the voltage at the Fb pin would be 0.61V

(typical).

ADJUSTING OVER-VOLTAGE PROTECTION

If the over-voltage protection (OVP) threshold is too low for a

particular application, a resistor divider circuit can be used to

adjust the OVP threshold of a given application. Instead of

having the Ovp pin connected to the output voltage, it can be

adjusted through a resistor divider circuit to only experience

a fraction of the output voltage magnitude. The resistor

divider circuit bias current should be at least 100 times

greater than the Ovp pin bias current. Using Figure 3, the

following equation can be used to adjust the output voltage:

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V

V

R3:

Resistor.

R4:

Resistor.

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FIGURE 3. Programmable Output Voltage

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