viper100bsp STMicroelectronics, viper100bsp Datasheet - Page 15

• Manufacturer Part Number: viper100bsp
• Description: Smps Primary I.c.
• Manufacturer: STMicroelectronics

frequency source. Figure 20 shows one possible
schematic to be adapted depending the specific
needs. If the proposed schematic is used, the
pulse duration must be kept at a low value (500ns
is sufficient) for minimizing consumption. The
optocoupler must be able to provide 20mA
through the optotransistor.
PRIMARY PEAK CURRENT LIMITATION
The primary I
effect, the output power can be limited using the
simple circuit shown in figure 21. The circuit
based on Q1, R
the COMP pin in order to limit the primary peak
current of the device to a value:
Figure 18: Typical Compensation Network
Figure 20:External Clock Synchronization
OSC
DPEAK
1
10 k
13V
VDD
and R
+
-
current and, as resulting
C2
2
VIPer100B
COMP SOURCE
OSC
clamps the voltage on
R 1
C 1
F C00121B
13V
VDD
DRAIN
-
+
VIPer100B
COMP SOURCE
FC00220B
DRAIN
I
where:
V
The suggested value for R
220K .
OVER-TEMPERATURE PROTECTION:
Over-temperature protection is based on chip
temperature sensing. The minimum junction
temperature at which over-temperature cut-out
occurs is 140
The device is automatically restarted when the
junction temperature decreases to the restart
temperature threshold that is typically 40
Figure 19: Slope Compensation
Figure 21:Current Limitation Circuit Example
DPEAK
COMP
V
0.6
COMP
R2
C1
x
H
o
OSC
C while the typical value is 170
R
ID
R1
R3
1
Q1
R
13V
0.5
VDD
2
R
OSC
2
+
-
R1
R2
13V
VDD
VIPer10 0B
C2
COMP SOURCE
-
+
1
+R
VIPer100B
FC0 0240B
VIPER100B/BSP
COMP SOURCE
2
Q1
C3
DRAIN
FC0 0141B
is in the range of
DRAIN
o
C below
15/20
o
C.