TOP252-262
多功能（M）引脚的典型使用方法（继上）
VUV = IUV × RLS + VM (IM = IUV
VOV = IOV × RLS + VM (IM = IOV
)
)
+
+
VUV = IUV × RLS + VM (IM = IUV
VOV = IOV × RLS + VM (IM = IOV
)
)
For RLS = 4 M7
VUV = 102.8 VDC
VOV = 451 VDC
For RLS = 4 M7
VUV = 102.8 VDC
VOV = 451 VDC
Sense Output Voltage
RLS
RLS
4 M7
4 M7
ROVP
DC
Input
DC
Input
VROVP
Sense Output Voltage
Voltage
Voltage
DCMAX @ 100 VDC = 76%
DCMAX @ 375 VDC = 41%
DCMAX @ 100 VDC = 76%
DCMAX @ 375 VDC = 41%
D
S
M
D
S
M
CONTROL
CONTROL
C
C
ROVP >3k7
-
-
PI-4729-120307
PI-4730-120307
图 32. 实现欠压、过压、线电压前馈及输出过压迟滞保护的线电压检测
图 31. 实现欠压、过压、线电压前馈及输出过压锁存保护的线电压检测
+
+
VUV = RLS × IUV + VM (IM = IUV
)
VOV = IOV × RLS + VM (IM = IOV
)
4 M7
40 k7
4 M7
55 k7
For Values Shown
VUV = 103.8 VDC
For Values Shown
VOV = 457.2 VDC
RLS
RLS
DC
Input
Voltage
DC
Input
Voltage
1N4148
D
M
D
S
M
CONTROL
CONTROL
C
C
6.2 V
S
-
-
PI-4732-120307
PI-4731-120307
图 34. 仅实现过压的线路检测（禁止欠压）。低压时会降低最大占空比，
线电压增高时最大占空比进一步降低
图 33. 仅实现欠压的线电压检测（禁止过半压）
+
+
For RIL = 12 k7
ILIMIT = 61%
ILIMIT = 100% @ 100 VDC
53% @ 300 VDC
ILIMIT
=
RLS
2.5 M7
For RIL = 19 k7
ILIMIT = 37%
DC
Input
Voltage
DC
Input
Voltage
See Figures 55b for other
resistor values (RIL) to
select different ILIMIT values.
D
S
M
D
S
M
CONTROL
CONTROL
RIL
6 k7
C
C
RIL
-
-
PI-4734-092107
PI-4733-021308
图 36. 流限随电压降低而降低（通常无必要 - 参考M引脚工作描述）
图 35. 外部设定流限（通常无必要 - 参考M引脚工作描述）
19
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版本D 08/08
POWERINT [ Power Integrations ]
