TOP242-249
Typical Uses of LINE-SENSE (L) and EXTERNAL CURRENT LIMIT (X) Pins
+
+
VUV = IUV x RLS
VOV = IOV x RLS
For RLS = 2 MΩ
VUV = 100 VDC
RLS
2MΩ
C L
X
S
F
D
VOV = 450 VDC
DC
DC
Input
Voltage
Input
Voltage
DCMAX@100 VDC = 78%
DCMAX@375 VDC = 38%
D
S
L
D
S
L
C
S
D
CONTROL
CONTROL
C
C
X
F
-
-
PI-2618-040501
PI-2617-050100
Figure 17. Line-Sensing for Under-Voltage, Overvoltage and
Line Feed Forward.
Figure 16. Three Terminal Operation (LINE-SENSE and
EXTERNAL CURRENT LIMIT Features Disabled.
FREQUENCY Pin can be tied to SOURCE or
CONTROL Pin).
+
+
VUV = RLS x IUV
VOV = IOV x RLS
2 MΩ
2 MΩ
For Value Shown
VUV = 100 VDC
For Values Shown
VOV = 450 VDC
RLS
RLS
DC
Input
Voltage
DC
Input
Voltage
22 kΩ
30 kΩ
1N4148
D
L
D
S
M
CONTROL
CONTROL
C
C
6.2 V
S
-
-
PI-2620-040501
PI-2510-040501
Figure 19. Line-Sensing for Overvoltage Only (Under-Voltage
Disabled). Maximum Duty Cycle will be reduced at
Low Line.
Figure 18. Line-Sensing for Under-Voltage Only (Overvoltage
Disabled).
+
+
I
LIMIT = 100% @ 100 VDC
For RIL = 12 kΩ
ILIMIT
=
63% @ 300 VDC
ILIMIT = 69%
RLS
2.5 MΩ
For RIL = 25 kΩ
ILIMIT = 43%
See fig. 55 for other
DC
Input
Voltage
DC
D
S
D
resistor values (RIL)
Input
CONTROL
X
CONTROL
Voltage
C
C
S
X
RIL
RIL
6 kΩ
-
-
PI-2624-040501
PI-2623-040501
Figure 21. Current Limit Reduction with Line Voltage.
Figure 20. Externally Set Current Limit.
E
7/01
August 8, 2000
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