VIPER15

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


1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
Page 21
22
Page 22
23
Page 23
24
Page 24
25
Page 25
26
Page 26
27
Page 27
28
Page 28
29
Page 29
30
Page 30
31
32
33
34
35
36
37
38
39
40
Page 28/40

Download datasheet (2Mb)Embed
PrevNext
Operation description
7.12
Summary on ZCD pin
Referring to the
Figure 32 on page 26
implement the following functions:
1.
Current limit, I
2.
Line feed-forward compensation
3.
Output overvoltage protection (OVP)
4.
Zero current detection for QR operation
Chosen R
, R
LIM
FF
automatically defined.
Table 9
refers to the
activate one or more functions associated to the ZCD pin.
Table 9.
ZCD pin configurations
Function / component
I
set point
Dlim
OVP
Line feed-forward
I
set point and OVP
Dlim
OVP and line feed-forward
I
set point and line feed-forward
Dlim
I
reduction+ OVP +
Dlim
Line feed-forward
7.13
Feedback and overload protection (OLP)
The feedback pin (FB) controls the PWM operation, enters the burst mode and manages the
delayed overload protection.
The thresholds V
and the high limit of the PWM operations, where the drain current is sensed trough the
integrated resistor R
the power MOSFET as soon as the sensed voltage is equal to the voltage applied to the FB
pin and trough the integrated resistors network, see the
.
on page 14
As shows the IC block diagram reported in
comparator there is the OCP comparator that limits the drain current as maximum to the
value I
, reported on
Dlim
In case of higher load the voltage V
drain current is limited to I
As soon as the voltage V
protection turns off the IC. After, the auto-restart mode is activated using the low value of the
current I
, see
DDch
28/40
, the circuitry connected to the ZCD pin enables to
, set point
Dlim
and R
as described in previous paragraphs this function are
OVP
Figure 32
and list the external resistance combinations needed to
R
LIM
See
Equation 4
22 kΩ
22 kΩ
See
Equation 4
with R
=
FF
22 kΩ
See
Equation 4
See
Equation 4
and V
(reported on
Table 8 on page 8
FBbm
FBlin
and applied to the comparator PWM. The PWM logic turns OFF
SENSE
Figure 2 on page 4
Table 8 on page 8
.
increases, when it reaches the threshold V
FB
and the internal current starts the charge of the capacitor C
Dlim
reaches the threshold V
FB
Table 7 on page 7
.
Doc ID 15455 Rev 5
R
R
OVP
FF
Required for ZCD
Not required
See
Equation 7
Not required
Required for ZCD See
Equation 3
See
Equation 7
Not required
See
Equation 7
See
Equation 3
Required for ZCD See
Equation 3
See
Equation 7
See
Equation 3
) are respectively the low
Figure 2 on page 4
and
, in parallel with the PWM
, see
Figure 36 on page
FBolp
VIPER15
D
OVP
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Figure 20
the
FBlin
.
FB
31, the