VIPER25 STMicroelectronics, VIPER25 Datasheet - Page 33

• Manufacturer Part Number: VIPER25
• Description: VIPerPlus family: quasi-resonant high performance off line high voltage converter
• Manufacturer: STMicroelectronics

VIPER25
Figure 38. Brown-out protection: BR external setting and timing diagram
V
IN_DC
R
R
H
L
Fixed the V
can be established for the calculation of the resistors R
Equation 12
Equation 13
For a proper operation of this function, V
minimum mains and V
minimum mains and maximum load.
The BR pin is a high impedance input connected to high value resistors, thus it is prone to
pick up noise, which might alter the OFF threshold when the converter operates or gives
origin to undesired switch-off of the device during ESD tests.
It is possible to bypass the pin to ground with a small film capacitor (e.g. 1-10 nF) to prevent
any malfunctioning of this kind.
If the brown-out function is not used the BR pin has to be connected to GND, ensuring that
the voltage is lower than the minimum of V
C
BR
VDD
I
BRhyst
INon
and the V
V
R
V
+
BRth
DIS
R
L
IN off
=
H
=
−
INoff
V
V
less than the minimum voltage on the input bulk capacitor at
I
BRhyst
+
+
-
-
BRhyst
INon
levels, with reference to
Doc ID 15585 Rev 4
−
Disable
V
+
V
I
BRhyst
in_OK
INoff
V
INon
IN on
−
V
DIS
V
V
V
−
DRAIN_START
INoff
DD(RESTART)
BRhyst
V
must be less than the peak voltage at
V
threshold (50 mV, see
INoff
in_OK
I
V
V
V
V
V
BRhyst
V
V
V
V
DDoff
I
DDon
V
BRth
OUT
INoff
−
INon
BR
DS
BR
IN
DD
V
−
×
BRth
R
V
Figure 38
BRhyst
L
H
+
and R
R
V
I
BRhyst
BRhyst
L
×
I
L
V
BRhyst
, the following relationships
:
BRth
Operation description
Table 8
). In order to
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