Rev. J 08/16
19
TOP252-262
www.power.com
PI-4729-120307
DC
Input
Voltage
Sense Output Voltage
+
-
D M
S
C
V
UV
= I
UV
× R
LS
+
V
M
(I
M
= I
UV
)
V
OV
=
I
OV
×
R
LS
+
V
M
(I
M
= I
OV
)
For R
LS
= 4 MΩ
V
UV
= 102.8 VDC
V
OV
=
451 VDC
DC
MAX
@ 100 VDC = 76%
DC
MAX
@ 375 VDC = 41%
CONTROL
R
LS
4 MΩ
Figure 31. Line Sensing for Undervoltage, Overvoltage, Line Feed-Forward and
Latched Output Overvoltage Protection.
PI-4730-120307
DC
Input
Voltage
Sense Output Voltage
+
-
D M
S
C
V
UV
= I
UV
× R
LS
+
V
M
(I
M
= I
UV
)
V
OV
=
I
OV
×
R
LS
+
V
M
(I
M
= I
OV
)
For R
LS
= 4 MΩ
V
UV
= 102.8 VDC
V
OV
=
451 VDC
DC
MAX
@ 100 VDC = 76%
DC
MAX
@ 375 VDC = 41%
CONTROL
R
LS
4 MΩ
VR
OVP
R
OVP
R
OVP
>3kΩ
Figure 32. Line Sensing for Undervoltage, Overvoltage, Line Feed-Forward and
Hysteretic Output Overvoltage Protection.
PI-4731-120307
DC
Input
Voltage
+
-
D M
S
C
V
UV
= R
LS
× I
UV
+
V
M
(I
M
= I
UV
)
For Values Shown
V
UV
= 103.8 VDC
R
LS
6.2 V
4 MΩ
40 kΩ
CONTROL
PI-4732-120307
DC
Input
Voltage
+
-
D M
S
C
V
OV
= I
OV
×
R
LS
+
V
M
(I
M
= I
OV
)
For Values Shown
V
OV
= 457.2 VDC
CONTROL
R
LS
1N4148
4 MΩ
55 kΩ
Figure 33. Line Sensing for Undervoltage Only (Overvoltage Disabled).
Figure 34. Line Sensing for Overvoltage Only (Undervoltage Disabled). Maximum
Duty Cycle Reduced at Low Line and Further Reduction with
Increasing Line Voltage.
Typical Uses of MULTI-FUNCTION (M) Pin (cont.)
Figure 35. Externally Set Current Limit (Not Normally Required – See M Pin
Operation Description).
PI-4733-021308
DC
Input
Voltage
+
-
D M
S
C
For R
IL
= 12 kΩ
I
LIMIT
= 61%
CONTROL
R
IL
See Figures 55b for other
resistor values (R
IL
) to
select different I
LIMIT
values.
For R
IL
= 19 kΩ
I
LIMIT
= 37%
PI-4734-092107
DC
Input
Voltage
+
-
D M
S
C
CONTROL
R
IL
R
LS
2.5 MΩ
6 kΩ
100% @ 100 VDC
53% @ 300 VDC
I
LIMIT
=
I
LIMIT
=
Figure 36. Current Limit Reduction with Line Voltage (Not Normally Required –
See M Pin Operation Description).
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