PT4107 is really a higher voltage step-down kind PWM LED led panel light-driven controller, by means of the exterior resistor plus the internal zener diode which could be rectified 110V or 220V AC voltage clamp at 20V. Once the voltage Vin on over-voltage lockout threshold of 18V, the chips started to function, in accordance with the peak current manage mode to generate the external MOSFET. The exterior MOSFET’s supply and to the current sampling resistor indirectly, the resistor voltage directly to the PT4107 chip CS side. Once the CS terminal voltage exceeds the inner threshold voltage the current sample, GATE-side generate signal termination with the exterior MOSFET off. Threshold voltage may be internally set, or by applying a voltage to manage the LD side. If the required soft-start, end in LD parallel capacitor voltage wants to be elevated pace and elevated speed and constant LED current.
PT4107 most important technical characteristics: from 18V to 450V wide voltage input array, constant current output; Frequency jitter to lessen electromagnetic interference, use of random supply to modulate the oscillation frequency, it can extend the audio power spectrum, the power spectrum can be expanded effectively lower little band of electromagnetic interference, reducing system-level style problems; out there linear and PWM dimming to help hundreds of 0.06W LED driving apps, operating frequency of 25kHz-300kHz, might be set by exterior resistors.
Just click philosophy, designed to swap the entire voltage 20W fluorescent lamp power constant current supply schematic diagram demonstrated in Figure four. Through the appear into AC 220V, AC power entry has had 1A fuse FS1 and anti-surge of damaging temperature coefficient thermistor NTC, EMI filter adopted by the L1, L2, and CX1 composition. BD1 is actually a full-bridge rectifier, the internal pressure is four silicon diode. C1, C2, R1, D1 ~ D3 composition of passive energy aspect correction circuit. PT4107 chip from the T1, D4, C4, R2 ~ R4 formed soon after the power supply step-down regulator digital filter, the filter input impedance is substantial, the output impedance is incredibly modest, close to 300V DC high voltage just after rectification with the step-down to the transistor PT4107 Vin of about 18 ~ 20V voltage, to make sure that chip within the whole voltage range in stability.
