NCP1219PRINTGEVB
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The output voltage ripple is measured at 16 mV at high
line and full load. It is significantly less than the 50 mV
target. The output voltage ripple waveform at high line and
full load is shown in Figure 37. The ripple measured at the
switching frequency appears as expected. The output filter
eliminates the ripple associated with the switching
frequency, leaving only low amplitude spikes of noise that
are due to the switch transitions.
Figure 37. Output Voltage Ripple at High
−
line and Full Load
If the output ripple is observed on a longer time scale, a
component of the NCP1219 frequency jitter is observed.
The frequency jitter generated by the controller spreads the
energy generated during switching, reducing
electromagnetic interference, EMI. The bandwidth of the
system is not high enough to prevent this component. This
is shown in Figure 38. The output ripple due to the frequency
jitter is still within the target limits.
Figure 38. Frequency Jitter Component of Output Ripple at Nominal Load Current
