AN3028 Datasheet, PDF (14/37 Pages) M/A-COM Technology Solutions, Inc. – ESD Protection of Broadband GaAs CATV & FTTx Amplifiers

Burst mode and output voltage ripple
6
Burst mode and output voltage ripple
AN3028
When the converter is lightly loaded, the COMP pin voltage decreases. As it reaches the
shutdown threshold, V_COMPL (1.1 V, typical), the switching is disabled and no more energy is
transferred to the secondary side. So, the output voltage decreases and the regulation loop
makes the COMP pin voltage increase again. As it rises 40mV above the V_COMPL threshold,
the normal switching operation is resumed. This results in a controlled on/off operation
(referred to as “burst mode) as long as the output power is low enough to require a turn-on
time lower than the minimum turn-on time of the VIPer16LN. 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 not loaded or lightly
loaded and supplied with 115 V_AC and with 230 V_AC respectively.
Figure 14. Output voltage ripple at 115 V_INAC Figure 15. Output voltage ripple at 230 V_INAC
no load
no load
Figure 16. Output voltage ripple at 115V_INAC Figure 17. Output voltage ripple at 230V_INAC
25 mA
25 mA
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Table 6 shows the measured value of the burst mode frequency ripple measured in different
operating conditions. The output voltage ripple in burst mode operation is very low.
Doc ID 16135 Rev 1