LM3430_07 NSC [National Semiconductor], LM3430_07 Datasheet - Page 4

• Manufacturer Part Number: LM3430_07
• Description: LED Backlighting Solution with LM3430 and LM3432
• Manufacturer: NSC [National Semiconductor]

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Configuration of the Demonstration Board for Evaluation
Analog PWM Dimming Mode
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Leave jumper JP3 open to enable the Analog Dimming
Mode;
Short pins 1-2 of jumper JP5 to select the Analog control
input;
The VR1 is used to derive the analog control voltage from
LM3432's VCC output (5V nominal) and pass to LM3432's
DIM input pin to control the dimming of the LED;
Adjust VR5 to change the LED brightness. The ON current
of the LED is still maintained, only the duty ratio of ON time
is adjusted to achieve the effect of dimming. This ensures
the correct color is preserved even in dimmed output
conditions.
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Digital PWM Dimming Mode
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Short jumper JP3 to enable the Digital Dimming Mode;
Short pins 2-3 of jumper JP5 to select the Digital control
input;
The external PWM dimming control signal applied to CN2
is then routed to LM3432's DIM input pin;
The control of LED current ON-OFF is passed to the
externally applied PWM dimming control signal. The ON
duty of the PWM control signal governs the LED
brightness.
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