Datasheet

Burst mode VIPER26
16/25 Doc ID 17736 Rev 2
13 Burst mode
When the voltage V
COMP
drops below the threshold, V
COMPL
, the power MOSFET is kept in
OFF state and the consumption is reduced to I
DD0
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 V
COMPL
+ V
COMPL_HYS
, the converter starts switching again with
consumption level equal to I
DD1
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 I
Dlim_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 I
DLIM
!-V

9
&203
,
'5$,1
,
,
'OLPBEP
'OLP
9
&203+
9
&203/
time
time
time
V
COMP
V
COMPL
+V
COMPL_HYS
V
COMPL
I
DD1
I
DD0
I
DD
I
DRAIN
I
Dlim_bm
Burst Mode