3.0V / 3.3V微处理器监控电路
MAX690T / S / R ， 704T / S / R ， 802T / S / R ， 804-806T / S / R
V
IN
R
1
PFI
R
2
R
3
V
CC
R
1
PFI
R
2
C1*
PFO
*可选
TO
µP
R
3
V
IN
V
CC
C1*
PFO
MAX690T/S/R
MAX704T/S/R
MAX802T/S/R
MAX804T/S/R
MAX805T/S/R
MAX806T/S/R
GND
MAX690T/S/R
MAX704T/S/R
MAX802T/S/R
MAX804T/S/R
MAX805T/S/R
MAX806T/S/R
GND
*可选
TO
µP
PFO
0V
0V
V
L
V
旅
V
H
V
IN
PFO
0V
0V
+
(
R R R
)
1
2
2
V
旅
V
H
V
IN
V
旅
= V
PFT
(
R
1
+ R
2
R
2
)
(
)
1
R
3
V
CC
R
3
V
旅
= V
PFT
V
H
= (V
PFT
+ V
PFH
) (R
1
)
V
L
= R
1
V
PFT
(
1
1
+
+
R
1
R
2
1
1
1
+
+
–
R
1
R
2
R
3
)
其中，V
PFT
= 1.237V
V
PFH
= 10mV的
V
H
= R
1
(V
PFT
+ V
PFH
)
1
(
R
+
1
1
1
+
R
2
R
3
)
– (V
CC -
V
D
)
R
3
a
b
其中，V
PFT
= 1.237V
V
PFH
= 10mV的
V
D
=二极管的正向压降
V
L
= V
旅
图4. A）添加其他滞后于电源失效比较器
3.0V或3.3V
R
1
PFI
R
2
V
CC
b）将高于V的附加滞后
PFT
V
IN
R
1
V
CC
3.0V或3.3V
MAX690T/S/R
MAX704T/S/R
MAX802T/S/R
MAX804T/S/R
MAX805T/S/R
MAX806T/S/R
GND
PFO
PFI
R
2
MAX690T/S/R
MAX704T/S/R
MAX802T/S/R
MAX804T/S/R
MAX805T/S/R
MAX806T/S/R
GND
PFO
MR
*
V-
V
CC
PFO
V
L
V
旅
= R
2
(V
PFT
+ V
PFH
)
V
L
= R
2
(V
PFT
)
1
V
旅
V
CC
R
1
V-
0V
V
旅
= V
PFT
其中，V
PFT
= 1.237V
V
PFH
= 10mV的
注： V
旅
为负值
R
1
+
R
2
R
2
V
CC
PFO
V
旅
V
H
V
IN
(
R
1
+ R
2
)
–
1
V
CC
R
1
1
1
(
)
)
* MAX704T / S / R ，
MAX806T / S / R ONLY
(
R
1
+ R
2
)
–
V
H
= (V
PFT
+ V
PFH
)
(
R
1
+
R
2
R
2
a
b
图5.使用电源失效比较器监视其他电源
10
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MAXIM [ MAXIM INTEGRATED PRODUCTS ]
