VIPER15

Manufacturer Part NumberVIPER15
DescriptionVIPerPlus family: quasi-resonant high performance off line high voltage converter
ManufacturerSTMicroelectronics
VIPER15 datasheet
 


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Operation description
nd
7.16
2
level overcurrent protection and hiccup mode
The
is protected against short-circuit of the secondary rectifier, short-circuit on the
VIPER15
secondary winding or a hard-saturation of fly-back transformer. Such as anomalous
condition is invoked when the drain current exceed the threshold I
page 8
.
To distinguish a real malfunction from a disturbance (e.g. induced during ESD tests) a
“warning state” is entered after the first signal trip. If in the subsequent switching cycle the
signal is not tripped, a temporary disturbance is assumed and the protection logic will be
reset in its idle state; otherwise if the I
switching cycles a real malfunction is assumed and the power MOSFET is turned OFF.
The shutdown condition is latched as long as the device is supplied. While it is disabled, no
energy is transferred from the auxiliary winding; hence the voltage on the V
decays till the V
DD
The start up HV current generator is still off, until V
V
. After this condition the V
DD(RESTART)
and the converter switching restarts if the V
the device enters in auto-restart mode. This behavioral results in a low-frequency
intermittent operation (Hiccup-mode operation), with very low stress on the power circuit.
See the timing diagram of
Figure 39. Hiccup-mode OCP: timing diagram
V
Vcc
DD
V
DD
ON
V
DD
OFF
V
Vcc
Vcc
DD
rest
rest
I
DRAIN
I
I
Dmax
Dmax
V
DS
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threshold is exceeded for two consecutive
DMAX
under voltage threshold (V
DDoff
capacitor is charged again by 600 µA current,
DD
occurs. If the fault condition is not removed
DDon
Figure 39
.
Secondary diode is shorted here
Secondary diode is shorted here
Doc ID 15455 Rev 5
, see
Table 8 on
DMAX
capacitor
DD
), which clears the latch.
voltage goes below its restart voltage,
DD
VIPER15
t
t
t
t
t
t