Datasheet

Burst mode VIPER06
18/28 Doc ID 022794 Rev 1
Figure 23. COMP pin voltage versus I
DRAIN
13 Burst mode
When the voltage V
COMP
drops below the threshold, V
COMPL
, the power MOSFET is kept in
the OFF state and the consumption is reduced to the I
DD0
current, as reported on Ta bl e 6 o n
page 7. In reaction to the loss of energy, the V
COMP
voltage increases and as soon as it
exceeds the threshold V
COMPL
+ V
COMPL_HYS
, the converter starts switching again with a
level of consumption equal to the I
DD1
current. This ON-OFF operation mode, referred to as
“burst mode” and shown in Figure 24 on page 18, 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 burst mode, the drain
current limit is reduced to the value I
Dlim_bm
(given inTable 7 on page 8) in order to avoid the
audible noise issue.
Figure 24. Load-dependent operating modes: timing waveforms
AM01095v1
V
COMPH
V
COMPL
I
Dlim_bm
I
Dlim
I
DRAIN
V
COMP
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