NCL30080ASNT1G Просмотр технического описания (PDF) - ON Semiconductor

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NCL30080ASNT1G

Quasi-Resonant Primary Side Current-Mode Controller for LED Lighting

ON Semiconductor 

NCL30080

Application Information

The NCL30080 implements a current−mode architecture

operating in quasi−resonant mode. Thanks to proprietary

circuitry, the controller is able to accurately regulate the

secondary side current of the flyback converter without

using any opto−coupler or measuring directly the secondary

side current.

• Quasi−Resonance Current−Mode Operation:

implementing quasi−resonance operation in peak

current−mode control, the NCL30080 optimizes the

efficiency by switching in the valley of the MOSFET

drain−source voltage. Thanks to a smart control

algorithm, the controller locks−out in a selected valley

and remains locked until the input voltage or the output

current set point significantly changes.

• Primary Side Constant Current Control: thanks to a

proprietary circuit, the controller is able to compensate

for the leakage inductance of the transformer and allow

accurate control of the secondary side current.

• Line Feed−forward: compensation for possible

variation of the output current caused by system slew

rate variation.

• Open LED protection: if the voltage on the VCC pin

exceeds an internal limit, the controller shuts down and

waits 4 seconds before restarting switching.

• Brown−Out: the controller includes a brown−out

circuit with a validation timer which safely stops the

controller in the event that the input voltage is too low.

The device will automatically restart if the line recovers.

• Cycle−by−cycle peak current limit: when the current

sense voltage exceeds the internal threshold VILIM, the

MOSFET is turned off for the rest of the switching cycle.

• Winding Short−Circuit Protection: an additional

comparator with a short LEB filter (tBCS) senses the CS

signal and stops the controller if VCS reaches 1.5 x

VILIM. For noise immunity reasons, this comparator is

enabled only during the main LEB duration tLEB.

• Output Short−circuit protection: If a very low

voltage is applied on ZCD pin for 90 ms (nominal), the

controllers assume that the output or the ZCD pin is

shorted to ground and enters shutdown. The auto−

restart version (B suffix) waits 4 seconds, then the

controller restarts switching. In the latched version (A

suffix), the controller is latched as long as VCC stays

above the VCC(reset) threshold.

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