Datasheet

Testing the board AN4164
14/38 Doc ID 023660 Rev 1
5.3 Burst mode and output voltage ripple
When the converter is lightly loaded, the COMP pin voltage decreases. As it reaches the
shutdown threshold, VCOMPL (1.1 V, typical), the switching is disabled and the energy is
not transferred to the secondary side anymore. At this point, the feedback reaction to the
stop of the energy delivery makes the COMP pin voltage increase again. As it rises 40 mV
above the V
COMPL
threshold, the normal switching operation is resumed. This results in a
controlled on/off operation which is referred to as “burst mode”. This mode of operation
keeps the frequency-related losses low when the load is very light or disconnected, making
it easier to comply with energy saving regulations.
The figures below show the output voltage ripple when the converter is no/lightly loaded and
supplied with 115 V
AC
and with 230 V
AC
respectively.
Figure 17. Output voltage ripple at 115 V
AC
no load
Figure 18. Output voltage ripple at 230 V
AC
no load
AM11692v1
AM11693v1
Figure 19. Output voltage ripple at 115 V
AC
25 mA
Figure 20. Output voltage ripple at 230 V
AC
25 mA
AM11694v1
AM11695v1