VIPER16 STMicroelectronics, VIPER16 Datasheet - Page 13

• Manufacturer Part Number: VIPER16
• Description: VIPerPlus family: fixed frequency high performance off line high voltage converter
• Manufacturer: STMicroelectronics

7
8
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
allow 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.
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
voltage reaches the V
voltage current generator is turned OFF. The VIPer16 is powered by the energy stored in the
V
In steady state condition, if the self biasing function is used, the high voltage current
generator is activated between V
I
Figure 21 on page
The device can also be supplied through the auxiliary winding; in this case the high voltage
current source is disabled during steady-state operation, provided that VDD is above
V
At converter power-down, the V
below V
Figure 21. Power on and power off
DDch2
DRAIN_START
DD
DDCSon
capacitor.
, see
V
DRAIN_START
DDoff
.
V
V
DDCSon
V
V
DRAIN
I
I
DDoff
DDch2
V
DDon
DDch1
V
I
Table 7 on page 6
DD
IN
DD
threshold (see
threshold, sourcing a I
13).
Power-on
DDon
Without internal self-supply
With internal self-supply
threshold, the power section starts switching and the high
Table 7 on page
Doc ID 15232 Rev 5
to the V
DD
DDCSon
voltage drops and the converter activity stops as it falls
DDch1
DS(on)
DD
and V
capacitor during the MOSFET off time (see
current (see
of 20 Ω. It includes a SenseFET structure to
Normal operation
6).
DDon
(see
Table 7 on page
Table 7 on page
regulation is lost here
Power-off
V
HV startup is no more activated
IN
< V
6); as the V
DRAIN_START
6), delivering
t
t
t t
t
t
DD
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