Switching Converters, Regulators & Controllers VIPer28 Rugged 800V Fixed freq 115 kHz

VIPER28HE

Manufacturer Part NumberVIPER28HE
DescriptionSwitching Converters, Regulators & Controllers VIPer28 Rugged 800V Fixed freq 115 kHz
ManufacturerSTMicroelectronics
VIPER28HE datasheet
 

Specifications of VIPER28HE

Output Voltage800 VOutput Current3 A
Output Power20 WInput Voltage8.5 V to 23.5 V
Switching Frequency115 KHzOperating Temperature Range- 40 C to + 150 C
Mounting StyleThrough HolePackage / CaseSDIP-10
Lead Free Status / RoHS StatusLead free / RoHS Compliant  
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Operation descriptions
7.7
Current mode conversion with adjustable current limit set
point
The device is a current mode converter: the drain current is sensed and converted in voltage
that is applied to the non inverting pin of the PWM comparator. This voltage is compared
with the one on the feed-back pin through a voltage divider on cycle by cycle basis.
The
has a default current limit value, I
VIPER28
the electrical specification, by the R
page
11.
The CONT pin has a minimum current sunk needed to activate the I
R
or with high R
LIM
Table 8 on page
7).
7.8
Overvoltage protection (OVP)
The VIPER28 has integrated the logic for the monitor of the output voltage using as input
signal the voltage V
the voltage from the auxiliary winding tracks the output voltage, through the turn ratio
N
AUX
--------------
N
SEC
The CONT pin has to be connected to the auxiliary winding through the diode D
resistors R
and R
OVP
the voltage V
CONT
on page
7) the overvoltage protection will stop the power MOSFET and the converter enters
the auto-restart mode.
In order to bypass the noise immediately after the turn off of the power MOSFET, the voltage
V
is sampled inside a short window after the time T
CONT
the
Figure 26 on page
digital signal and increments the internal counter. The same counter is reset every time the
signal OVP is not triggered in one oscillator cycle.
Referring to the
Figure
Equation 2
Equation 3
18/32
Dlim
resistor connected to the CONT see
LIM
(i.e. 100 kΩ) the current limit is fixed to the default value (see I
LIM
during the OFF time of the power MOSFET. This is the time when
CONT
as shows the
Figure 27 on page 20
LIM
exceeds, four consecutive times, the reference voltage V
19. The sampled signal, if higher than V
17, the resistors divider ratio k
V
k
=
-------------------------------------------------------------------------------------------------- -
OVP
N
AUX
(
--------------
V
OUTOVP
N
SEC
R
k
=
--------------------------------- -
OVP
R
LIM
Doc ID 15028 Rev 4
, that the designer can adjust according
Figure 16 on
adjustment: without
Dlim
When, during the OFF time,
OVP
, see
Table 8 on page 7
STROBE
, trigger the internal OVP
OVP
will be given by:
OVP
OVP
) V
+
V
DSEC
DAUX
LIM
R
+
OVP
VIPER28
,
Dlim
and the
OVP
(see
Table 8
and