VIPER26HDTR datasheet(16/25 Pages) STMICROELECTRONICS

16 / 25 page

Burst mode

VIPER26

16/25

Doc ID 17736 Rev 2

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 6. As reaction at the energy delivery stop, the V

COMP 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 25 on page 16, 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 7) in order to

avoid the audible noise issue.

Figure 25.

Load-dependent operating modes: timing diagrams

Figure 24.

COMP pin voltage versus IDLIM

time

COMP

COMPL +VCOMPL_HYS

COMPL

DD1

DD0

DRAIN

Dlim_bm

Burst Mode

VIPER26HDTR Arkusz danych(PDF) 16 Page - STMicroelectronics