VIPER16HN datasheet(19/30 Pages) STMICROELECTRONICS

19 / 30 page

DocID15232 Rev 7

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VIPER16

Burst mode

When the voltage VCOMP drops below the threshold, VCOMPL, the power MOSFET is kept in

OFF state and the consumption is reduced to IDD0 current, as reported on Table 7 on

page 8. As reaction at the energy delivery stop, the VCOMP voltage increases and as soon

as it exceeds the threshold VCOMPL + VCOMPL_HYS, the converter starts switching again with

consumption level equal to IDD1 current. This ON-OFF operation mode, referred to as “burst

mode” and reported on Figure 24 on page 19, reduces the average frequency, which can go

down even to a few hundreds hertz, thus minimizing all frequency-related losses and

making it easier to comply with energy saving regulations. During the burst mode, the drain

current limit is reduced to the value IDlim_bm (reported on Table 8 on page 9) in order to

avoid the audible noise issue.

Figure 24. Load-dependent operating modes: timing diagrams

Figure 23. COMP pin voltage versus IDRAIN

time

COMP

COMPL +V COMPL_HYS

COMPL

DD1

DD0

DRAIN

Dlim_bm

Burst Mode

AM13269v1

VIPER16HN Datasheet(PDF) 19 Page - STMicroelectronics