Burst mode
VIPER16
Figure 23. COMP pin voltage versus I
DRAIN
ꢎ
'5$,1
,
'OLP
,
'OLPBEP
&203
9
9&203/
9&203+
!-ꢀꢁꢀꢂꢆVꢁ
13
Burst mode
When the voltage V
drops below the threshold, V
, the power MOSFET is kept in
COMPL
COMP
OFF state and the consumption is reduced to I
current, as reported on Table 7 on
DD0
page 6. As reaction at the energy delivery stop, the V
voltage increases and as soon
COMP
as it exceeds the threshold V
+ V
, the converter starts switching again with
COMPL
COMPL_HYS
consumption level equal to I
current. This ON-OFF operation mode, referred to as “burst
DD1
mode” and reported on Figure 24 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
avoid the audible noise issue.
(reported on Table 8 on page 7) in order to
Dlim_bm
Figure 24. Load-dependent operating modes: timing diagrams
VCOMP
VCOMPL +VCOMPL_HYS
VCOMPL
time
IDD
IDD1
IDD0
time
time
IDRAIN
IDlim_bm
Burst Mode
16/25
Doc ID 15232 Rev 5
STMICROELECTRONICS [ ST ]
