M-FIAM5 Datasheet, PDF (4/5 Pages) Vicor Corporation – Military 28Vin Filter Input Attenuator Module

Addendum A
MIL-STD-704E Transient / Overvoltage Protection
The standard (COTS) 24V input 2nd Generation Converter Modules may be used in Military 28 volt applications. The
M-FIAM5 provides compliance to MIL-STD-461E conducted emissions and susceptibility standards. Additional circuitry,
as illustrated in the accompanying schematic (see Fig. 1), provides compliance to the MIL-STD-704E transient
overvoltage specification. The 24V input modules employ undervoltage and overvoltage protection. These converters,
shut down if the input falls below 18V or rises to 36V or above.18V is consistent with the MIL-STD-704E specification,
but the standard also requires uninterrupted performance in the event of an input voltage transient to 50V for a period
of 12.5 millisec. The above referenced circuit clamps the input voltage, in the event that it exceeds 32V, as illustrated in
figure 2. This performance prevents the converter from shutting down, thus meeting the transient overvoltage
specification of MIL- STD-704E.
+28V
R1
R2
2.0k
2.0k
Vicor FIAM & Mods
Vc
C3
Cbulk
880 Uf d
Vout
Input
C1
4.7uf, 63v
D1
15v, 1N5245B
+28v
rtn
R3
64.9k
R5
10K
R4
64.9k
8
3
+
2
–
U1A
LM258N
615001
1
4
R6
10K
R8
24.3k
8
5
U1B
LM258N
R10
2
4
Q1
R7
1.0k
+
7
1.0K
1
IRFP3710
ND PN
6_–
R9
3
4
14.0k
2
3
U2
LM4040CIZ-5.0
C2
.1ufd
Transient Surpressor Circuit
C1
4.7uF, 63V
C2
0.1uF
C3
880uF, 100V
D1
1N5245B
Q1
IRFP3710ND
R1
2.0K
R2
2.0K
R3
64.5K
R4
64.5K
R5
10K
R6
10K
R7
1K
R8
24.3K
R9
14K
R10
1K
U1
LM258N
U2
LM4040CIZ-5.0
Figure 1– Transient / Overvoltage protection circuit.
Volts
50
32
28
27
Vin
Vout
12.5 Millisec Max
Figure 2– Overvoltage clamping
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MFIAM5
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Rev. 1.7
Page 4 of 5