NCL30486 datasheet(21/29 Pages) ONSEMI

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NCL30486

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Figure 57. PDIM Internal Waveforms

VDIM_sec

IPDIM

IPDIM(THR)

IPDIM(THD)

VPDIM_int

Ton

Tsw

Practically, the controller extracts the duty−cycle by

measuring the current inside PDIM pin which is directly the

opto coupler collector current.

If PDIM pin is left open, the controller delivers 100% of

Iout. If the pin is pulled down for longer than 25 ms, the

controller is disabled.

If the PWM dimming signal is removed during dimming,

the controller delivers 100% of Iout.

The NCL30486 set 100% of output current when the

duty−cycle of the signal applied on PDIM is above 93%.

Analog Dimming

The pin ADIM pin allows implementing analog dimming

of the LED light.

If the power supply designer applies an analog signal

varying from VDIM(EN) to VDIM100 to the DIM pin, the

output current will increase or decrease proportionally to the

voltage applied. For VDIM = VDIM100, the power supply

delivers the maximum output current (VREFX = 1 V).

If a voltage lower than VADIM(MIN) is applied to ADIM

pin, the output current is clamped to the selected dimming

clamp value (see Dimming clamp section below)

NCL30486 Datasheet(PDF) 21 Page - ON Semiconductor