VIPER26

Manufacturer Part NumberVIPER26
DescriptionVIPerPlus family: fixed frequency high performance off line high voltage converter
ManufacturerSTMicroelectronics
VIPER26 datasheet
 
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VIPER26
7
Power section
The power section is implemented with an n-channel power MOSFET with a breakdown
voltage of 800 V min. and a typical R
a virtually lossless current sensing and the thermal sensor.
The gate driver of the power MOSFET is designed to supply a controlled gate current during
both turn-ON and turn-OFF in order to minimize common mode EMI. During UVLO
conditions, an internal pull-down circuit holds the gate low in order to ensure that the power
MOSFET cannot be turned ON accidentally.
8
High voltage current generator
The high voltage current generator is supplied by the DRAIN pin. At the first start up of the
converter, it is enabled when the voltage across the input bulk capacitor reaches the
V
threshold, sourcing the I
DRAIN_START
voltage reaches the V
high voltage current generator is turned OFF. The VIPer26 is powered by the external
source. After the start-up, the auxiliary winding or the diode connected to the output voltage
have to power the VDD capacitor with voltage higher than V
on page
6). During the switching, the internal current source is disabled and the
consumptions are minimized. In case of fault the switching is stopped and the device is self
biased by the internal high voltage current source; it is activated between the levels V
and V
delivering the current I
DDon
Figure 22 on page
see
At converter power-down, the V
below V
threshold (see
DDoff
Figure 22. Power on and power off
V
IN
V
DRAIN_START
V
DD
V
DDon
V
DDCSon
V
DDoff
V
DRAIN
I
DD
I
DDch2
I
DDch1
of 7 Ω . It includes a SenseFET structure to allow
DS(on)
current (see
DDch1
start-up threshold, the power section starts switching and the
DDon
to the V
DDch2
DD
13.
voltage drops and the converter activity stops as it falls
DD
Table 7 on page
6).
Normal operation
Power-on
Doc ID 17736 Rev 2
Power section
Table 7 on page
6); as the V
threshold (see
DDCSon
capacitor during the MOSFET off time,
V
< V
IN
DRAIN_START
HV startup is no more activated
regulation is lost here
Power-off
DD
Table 7
DDCSon
time
time
time
time
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