VIPER37HE STMicroelectronics, VIPER37HE Datasheet - Page 24

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VIPER37HE

Manufacturer Part Number
VIPER37HE
Description
AC/DC Switching Converters ViperPlus Fixed Freq 800V 30mQ 265 Vac
Manufacturer
STMicroelectronics
Type
Off Line Switcherr
Datasheet

Specifications of VIPER37HE

Product Category
AC/DC Switching Converters
Rohs
yes
Input / Supply Voltage (max)
23.5 V
Input / Supply Voltage (min)
8.5 V
Switching Frequency
115 kHz
Supply Current
3.5 mA
Operating Temperature Range
- 40 C to + 150 C
Mounting Style
Through Hole
Package / Case
SDIP-10
Maximum Operating Temperature
+ 125 C
Minimum Operating Temperature
- 25 C
Number Of Outputs
1
Output Power
25 W

Available stocks

Company
Part Number
Manufacturer
Quantity
Price
Part Number:
VIPER37HE
Manufacturer:
STMicroel
Quantity:
13 842
Operation description
8.8
24/35
Overvoltage protection (OVP)
The device can monitor the converter output voltage. This operation is done by the CONT
pin during Power MOSFET OFF-time, when the voltage generated by the auxiliary winding
tracks the converter's output voltage, through turn ratio
In order to perform the output voltage monitor, the CONT pin must be connected to the aux.
winding through a resistor divider made up of R
the voltage applied to the CONT pin exceeds the internal reference V
four consecutive times, the controller recognizes an overvoltage condition. This special
feature uses an internal counter; that is to reduce sensitivity to noise and prevent the latch
from being erroneously activated (see
signal is not triggered in one oscillator cycle.
Referring to
Equation 2
Equation 3
where:
Then, once the R
calculated by:
Equation 4
V
V
N
N
V
V
R
OVP
OUT OVP
DSEC
DAUX
AUX
SEC
OVP
is the OVP threshold (see
is the auxiliary winding turns
is the secondary winding turns
together with R
is the auxiliary diode forward voltage
is the secondary diode forward voltage
Figure 21
is the converter output voltage value to activate the OVP set by the user
LIM
value is fixed
, the resistors’ divider ratio k
k
OVP
LIM
make up the output voltage divider.
Doc ID 022218 Rev 1
=
-----------------------------------------------------------------------------------------------------
N
--------------
N
AUX
SEC
,
R
according to the desired I
OVP
k
OVP
Table 8
Figure 28
(
=
V
=
OUTOVP
R
--------------------------------- -
R
LIM
)
LIM
LIM
V
R
×
). The counter is reset every time the OVP
OVP
+
LIM
1 k
---------------------- -
+
OVP
R
and R
k
V
OVP
OVP
DSEC
OVP
is given by:
N
--------------
N
OVP
AUX
SEC
) V
Dlim
(see
DAUX
, the R
Figure 21
(see
OVP
OVP
Figure 28
(see
can be
or
Figure 29
Table 8
).
VIPER37
) for
). If

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