The PT4107 is a high voltage buck control IC for
constant LED current regulation. It allows efficient
operation of High Brightness (HB) LEDs from voltage
sources ranging from 18VDC up to 450VDC or
110VAC/220VAC. The PT4107 controls an external
MOSFET at fixed switching frequency from 25 kHZ to
200 kHZ. The frequency can be programmed using an
external resistor. A proprietary peak current control
method keeps constant average LED currents for wide
input and output ranges. The output current can be
programmed from a few milliamps up to more than 1A.
The output current on one LED string also can be
programmed to any value between zero and its
maximum value by applying an external control voltage
at the linear dimming control input of the PT4107.
Moreover, PT4107 provides a low-frequency PWM
dimming input that can accept an external control
signal with duty ratio of 0-100% and a frequency of up
to a few kilohertz.
Frequency jittering is used to reduce the EMI.