NCP1207AP Ver la hoja de datos (PDF) - ON Semiconductor

Número de pieza

componentes Descripción

Fabricante

NCP1207AP

PWM Current-Mode Controller for Free Running Quasi-Resonant Operation

ON Semiconductor 

NCP1207A, NCP1207B

Operation Shots

Below are some oscilloscope shots captured at

Vin = 120ĂVDC with a transformer featuring a 800ĂmH

primary inductance.

VGATE (5 V/div)

VRsense (200 mV/div)

200 mA X RSKIP

Current Sense Pin (200 mV/div)

Figure 25.

This plot gathers waveforms captured at three different

operating points:

1st upper plot: free run, valley switching operation,

Pout = 26 W

2nd middle plot: min Toff clamps the switching frequency

and selects the second valley

3rd lowest plot: the skip slices the second valley pattern

and will further expand the burst as Pout goes low

Figure 26.

This picture explains how the 200 mA internal offset

current creates the skip cycle level.

VCC (5 V/div)

VGATE (5 V/div)

Figure 27.

The short-circuit protection forces the IC to enter burst in

presence of a secondary overload.

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