Datasheet

DocID14419 Rev 9 19/32
VIPER17 Operation descriptions
32
Equation 2
Equation 3
Where:
• V
OVP
is the OVP threshold (see Table 9 on page 8)
• V
OUT OVP
is the converter output voltage value to activate the OVP (set by designer)
• N
AUX
is the auxiliary winding turns
• N
SEC
is the secondary winding turns
• V
DSEC
is the secondary diode forward voltage
• V
DAUX
is the auxiliary diode forward voltage
• R
OVP
together R
LIM
make the output voltage divider
Than, fixed R
LIM,
according to the desired I
DLIM
, the R
OVP
can be calculating by:
Equation 4
The resistor values will be such that the current sourced and sunk by the CONT pin be
within the rated capability of the internal clamp.
k
OVP
V
OVP
N
AUX
N
SEC
-------------- V
OUTOVP
V
DSEC
+()V
DAUX
–⋅
---------------------------------------------------------------------------------------------------=
k
OVP
R
LIM
R
LIM
R
OVP
+
----------------------------------=
R
OVP
R
LIM
1k
OVP
–
k
OVP
-----------------------×=