VIPER17_0810 STMICROELECTRONICS [STMicroelectronics], VIPER17_0810 Datasheet - Page 21

• Manufacturer Part Number: VIPER17_0810
• Description: Off-line high voltage converters
• Manufacturer: STMICROELECTRONICS [STMicroelectronics]

VIPER17
7.9
7.10
About CONT pin
Referring to the
1.
2.
The
needed to activate one or plus of the CONT pin functions.
Figure 27. CONT pin configuration
Table 9.
1. R
Feed-back and over load protection (OLP)
The VIPER17 is a current mode converter: the feedback pin controls the PWM operation,
controls the burst mode and actives the overload protection of the device.
page 23
With the feedback pin voltage between
typical values) 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 feedback pin through a voltage divider on
cycle by cycle basis. When these two voltages are equal, the PWM logic orders the switch
off of the power MOSFET. The drain current is always limited to I
In case of overload the feedback pin increases in reaction to this event and when it goes
higher than
Table 9 on page 21
LIM
Current Limit set point
Over voltage protection on the converter output voltage
Auxiliary
winding
Daux
have to be fixed before R
and
Function / component
I
Dlim
V
CONT pin configurations
I
Figure 29
FBlin
Dlim
reduction + OVP
Rov p
Figure
the drain current is limited or to the default I
reduction
OVP
27, through the CONT PIN, the below features can be implemented:
show the internal current mode structure.
referring to the
CONT
Rlim
FF
and R
OVP
OVP DETECTION
Figure
V
FBbm
LOGIC
See
See
To OVP Protection
≥ 80 KΩ
START
R
SOFT
and
27, lists the external resistance combinations
LIM
Figure 8
Figure 8
(1)
V
FBlin
, (respectively 0.5 V and 3.3 V,
Curr. Lim.
BLOCK
DLIM
See
See
From SenseFET
DLIM
Equation 4
Equation 4
R
value or the one imposed
Operation descriptions
No
OVP
value.
Current Limit Comparator
+
-
Figure 28 on
OCP
To PWM Logic
D
Yes
Yes
No
AUX
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