VIPER25 STMicroelectronics, VIPER25 Datasheet - Page 27

• Manufacturer Part Number: VIPER25
• Description: VIPerPlus family: quasi-resonant high performance off line high voltage converter
• Manufacturer: STMicroelectronics

VIPER25
Equation 6
Where:
●
●
●
●
●
●
●
Than, fixed R
Equation 7
The resistor values will be such that the current sourced and sunk by the ZCD pin be within
the rated capability of the internal clamp.
Figure 33. OVP timing diagram
V
V
designer
N
N
V
V
R
COUNTER
COUNTER
COUNTER
COUNTER
STATUS
STATUS
OVP
OUT OVP
DSEC
DAUX
AUX
SEC
OVP
STROBE
STROBE
RESET
RESET
VAUX
ZCD
FAULT
FAULT
V
OVP
OVP
OVP
0
0
is the OVP threshold (see
is the auxiliary winding turns
is the secondary winding turns
together R
is the auxiliary diode forward voltage
is the secondary diode forward voltage
0
0
LIM,
N
N
O
O
is the converter output voltage value to activate the OVP (set by designer)
R
R
M
M
A
A
according to the desired I
2 µs
2 µs
L
L
O
O
0
0
P
P
E
E
R
R
LIM
A
A
T
T
O I
O I
N
N
0.5 µs
0.5 µs
make the output voltage divider
0
0
Doc ID 15585 Rev 4
0 →1
0 →1
T
T
E
E
M
M
R
P
P
O
O
R
R
OVP
k
A
A
OVP
Table 8 on page 8
R
R
Y
Y
1 →2
1 →2
D
D
S I
S I
T
T
=
U
U
=
R
R
B
B
R
Dlim
A
A
N
N
--------------------------------- -
R
LIM
2 →0
2 →0
C
C
E
E
LIM
, the R
R
×
+
LIM
1 k
---------------------- -
R
–
k
0
0
OVP
OVP
OVP
OVP
)
can be calculating by:
0 →1
0 →1
F
F
E
E
E
E
D
D
B
B
A
A
1 → 2
1 → 2
C
C
K
K
L
L
O
O
O
O
Operation description
P
P
F
F
A
A
L I
L I
2 →3
2 →3
U
U
R
R
E
E
3 → 4
3 → 4
t
t
t
t
t
t
t
t
t
t
t
t
t
t
t
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