NCP1013 Ver la hoja de datos (PDF) - ON Semiconductor
Número de pieza
componentes Descripción
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NCP1013 Datasheet PDF : 24 Pages
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NCP1010, NCP1011, NCP1012, NCP1013, NCP1014
100% Peak current
at nominal power
25%
Skip−cycle
current limit
Figure 20. Low Peak Current Skip−Cycle Guarantees Noise−Free Operation
Full power operation involves the nominal switching
frequency and thus avoids any noise when running.
Experiments carried on a 5.0 W universal mains board
unveiled a standby power of 300 mW @ 230 Vac with the
DSS activated and dropped to less than 100 mW when an
auxiliary winding is connected.
Frequency Jittering for Improved EMI Signature
By sweeping the switching frequency around its nominal
value, it spreads the energy content on adjacent frequencies
rather than keeping it centered in one single ray. This offers
the benefit to artificially reduce the measurement noise on
a standard EMI receiver and pass the tests more easily. The
EMI sweep is implemented by routing the VCC ripple
(induced by the DSS activity) to the internal oscillator. As a
result, the switching frequency moves up and down to the
DSS rhythm. Typical deviation is "3.3% of the nominal
frequency. With a 1.0 V peak−to−peak ripple, the frequency
will equal 65 kHz in the middle of the ripple and will
increase as VCC rises or decrease as VCC ramps down.
Figure 21 portrays the behavior we have adopted.
VCC Ripple VCCOFF
67.15 kHz
65 kHz
62.85 kHz
VCCON
Internal Sawtooth
Figure 21. The VCC ripple is used to introduce a frequency jittering on the internal oscillator sawtooth.
Here, a 65 kHz version was selected.
http://onsemi.com
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