14. Input Attenuator Module (IAM/ MI-IAM)

14. Input Attenuator Module (IAM / MI-IAM)
Design Guide & Applications Manual
For VI-200 and VI-J00 Family DC-DC Converters and Configurable Power Supplies
OVERVIEW
EMC
The IAM is a component-level, DC input front-end filter
that when used in conjunction with the Vx-200 and
Vx-J00 Family of DC-DC converters provides a highly
efficient, high density power system with outputs from
1 – 95 Vdc and power expansion from 25 – 800 W.
EMC performance is guaranteed when the IAM is used in
conjunction with the recommended Vicor converters
within the permissible power rating and in accordance
with the recommended installation procedure. (Figure14–3)
The capacitor shown across the input of the converter and
bypass capacitors shown on the –IN and +IN of the DC-DC
converters to ground are required to meet EMC specifications.
The capacitors should be Y-rated (interference suppression).
Y capacitors have high voltage breakdown ratings to meet
the isolation characteristics of the module’s input to
baseplate specification, self-healing properties, and safety
agency approvals.
There are five input attenuator modules available for the
commercial market that comply with telecommunication
and industrial control EMC specifications: Refer to data
sheets for applicable standards at vicorpower.com.
Input
Voltage Range
VI-A11-xU
24 V (21 – 32 V)
VI-AWW-xU 24 V “W” (18 – 36 V)
VI-A33-xQ
48 V (42 – 60 V)
VI-ANN-xQ 48 V “N” (36 – 76 V)
VI-A66-xQ
300 V (200 – 400 V)
Model
[a]
Maximum Output Power[a]
of Converter Combinations
200 W
200 W
400 W
400 W
400 W
INPUT REVERSE POLARITY PROTECTION
A Zener diode in the EMC filter provides reverse polarity
protection when used with a properly rated fuse external
to the IAM. The characteristics of the recommended input
line fuses permit normal full load operation with
protection in the event of a reverse polarity by clearing of
the fuse. (Table 4–3).
Based on DC-DC converters with 5 V outputs or higher.
Table 14 –1 — Output power capability
There are two input attenuator modules available for the
defense market that comply with military EMC specifications,
transient specifications and spike specifications. Refer to
product data sheet for applicable standards at vicorpower.com.
Model
MI-A22-xU
MI-A66-xU
Input
Voltage Range
28 V (16 – 50 V)
270 V (125 – 400 V)
INPUT TRANSIENT PROTECTION
A Zener diode, inductor and capacitor in the EMC filter
protect against short term transients. Transient voltages
that persist beyond these limits are dropped across an
N-channel enhancement FET, Q1. It is necessary that the
FET be kept in saturation mode during normal operation.
Thus it is necessary to connect the DC-DC converters’
GATE OUT to the IAM’s GATE OUT to charge pump the
Maximum Output Power
of Converter Combinations
200 W
200 W
Table 14 –2 — Output power capability
+OUT
+IN
Q1
+IN
D1
C2
Vref 1
EMI Filter
OV
U2
Vref
2
OC
–IN
D2
Level
Shift
GATE OUT
10V
PARALLEL
GATE IN
Q2
U1
–OUT
–IN
Figure 14–1 — Block diagram of Input Attenuator Module (IAM)
VI-200 and VI-J00 Family Design Guide
Page 43 of 98
Rev 3.5
Apps. Eng. 800 927.9474
vicorpower.com
800 735.6200
14. Input Attenuator Module (IAM / MI-IAM)
Design Guide & Applications Manual
For VI-200 and VI-J00 Family DC-DC Converters and Configurable Power Supplies
INPUT CURRENT
gate of the FET to a voltage in excess of its source. In the
case where multiple DC-DC Driver modules are connected
to one IAM, an external charge pump through the PARALLEL
pin (connected to the gate of the FET) must be added to
ensure that the FET remains enhanced in the event GATE
OUT enhancement is lost (Figure 14 – 4). The additional
circuitry, C2, D1 and D2 are added externally to charge
pump through the PARALLEL pin.
Shut down of the DC-DC converters is accomplished by
saturating Q2 during an input overvoltage to prevent
possible damage to the converters. The IAM will automatically
restart when the input overvoltage is reduced to within
the input voltage range.
If the long term transient withstand specifications are
exceeded, the recommended external fuse will clear.
Input Voltage
Recommended Fuse
24 V
24 V “W”
48 V
48 V “N”
300 V
28 V
270 V
20 A / 32 V (AGC-20)
20 A / 36 V (AGC-20)
20 A / 60 V (3AB-20)
20 A / 80 V (3AB-20)
5 A / 250 V Bussman PC-Tron
20 A / 250 V (3AB-20 or F03A, 125 V, 20 A)
5 A / 250 V Bussman PC-Tron or F03A, 250 V, 4 A
Inrush current is a function of the number of DC-DC
converters that are connected to the input attenuator
module (modules are not gated off at turn-on) and the
amount of external capacitance added between the Input
Attenuator Module and the DC-DC converter. The inrush
current specification is 125% of steady state input current
for 10 ms. To avoid excessive dissipation in the element
controlling the inrush (Q1), the following maximum values
of external capacitance must be adhered to.
Input Voltage
Maximum Capacitance[a]
24 Vdc (21 – 32 V)
24 Vdc (18 – 36 V)
28 Vdc (18 – 50 V)
48 Vdc (42 – 60 V)
48 Vdc (36 – 76 V)
270 Vdc (125 – 400 V)
300 Vdc (200 – 400 V)
[a]
470 µF
470 µF
390 µF
220 µF
120 µF
27 µF
27 µF
Capacitance should be distributed across the input of each
DC-DC converter. (C1, Figure 14–3)
Table 14 –4 — Recommended distributed capacitance on input of
DC-DC converter(s)
Table 14 –3 — Recommended fusing based on input voltage
48 V Input
Wide Range
R.E.
100V
100V
R.E.
160V
I.S.W.
Full Load
S.D.
100V
36V
32V
1
10ms
Normal Operating Area
42V
0.1
18V
1000
100
48 V Wide Range Input
276V
125V
1
10ms
1000
R.E.
800V
500V
100V
S.D.
100
I.S.W.
Full Load
S.D.
400V
76V
Normal Operating Area
36V
0.1
1
10ms
100
Normal Operating Area
S.D.
1000
600
500
400
200V
0.1
500ms
1
10ms
100
1000
500ms
I.S.W.: Input surge withstand (no disruption of performance)
R.E.: Ratings exceeded
S.D.: Shut down
28 Vdc Input
Ratings Exceeded
300
200
100
OVP
0
-100
-200
-400
-500
-600
10-6
10-5
10-4
10-3
1ms
TIME (SECONDS)
270 Vdc Input
Page 44 of 98
Rev 3.5
Apps. Eng. 800 927.9474
10-2
10ms
100
1s
10-1
100ms
Ratings Exceeded
800
600
400
OVP
200
0
200
500
400
Reverse Polarity
400
600
10-6
10-5
10-4
vicorpower.com
800 735.6200
10-3
1ms
TIME (SECONDS)
Figure 14–2 — Safe operating area based on input voltage of IAM
VI-200 and VI-J00 Family Design Guide
50V
Reverse Polarity
-300
300 V Input
R.E.
I.S.W.
Full Load
S.D.
60V
Normal Operating Area
21V
0.1
I.S.W.
Full Load
VOLTS-PEAK VALUE OF SPIKE VOLTAGE
24 V Inputs
Standard
VOLTS-PEAK VALUE OF SPIKE VOLTAGE
Safe Operating Area
(1% duty cycle max., Zs = 0.5Ω, for short duration transient capability refer to specifications)
10-2
10ms
10-1
100ms
100
1s
14. Input Attenuator Module (IAM / MI-IAM)
Design Guide & Applications Manual
For VI-200 and VI-J00 Family DC-DC Converters and Configurable Power Supplies
OUTPUT OVERCURRENT / SHORT CIRCUIT PROTECTION
the Input Attenuator Modules to ensure equal potential at
these points when paralleling Input Attenuator Modules,
so as not to impact the effectiveness of the internal
common-mode choke.
Output overcurrent protection is a foldback type, followed
by a timed latched shut down should the overcurrent
persist beyond 2 ms. If the overcurrent condition is
removed before the timeout interval, auto restart shall
occur. Should latched shut down occur, input power must
be recycled to restart.
Output Overcurrent Threshold
24 Vin “W”, 28 Vin, 48 Vin “N”
24 Vin, 48 Vin
270 Vin, 300 Vin
4,700 pF
20 A
15 A
4A
Table 14–5 — IAM overcurrent
To IAM
EXPANSION CAPABILITIES
The Input Attenuator Module incorporates a PARALLEL pin
permitting power expansion as long as the total output
power from the DC-DC converters does not exceed the
power rating of each Input Attenuator Module (EMC
specifications are guaranteed for up to two input
attenuators in parallel). It is necessary to include a 100 Ω,
1/4 W resistor between the negative outputs of
+
–
+IN
+OUT
+IN
–IN
GATE IN
PAR
GATE OUT
–IN
–OUT
+IN
GATE
IN
GATE
OUT
–IN
+IN
GATE
IN
GATE
OUT
–IN
D3
D1, D2, D3: 1N4148
C2: 470 pF/500V
D2
C2
+IN
GATE
IN
GATE
OUT
–IN
D3
D1
[a]
For bus voltages greater than 75 V,
a 1N4006 diode should be used for
the diodes (D3) connected to the
GATE IN pins.
D2
C2
+OUT
Driver
+S
Trim
–S
–Out
+OUT
Driver
+S
TRIM
–S
–OUT
+OUT
Driver
+S
TRIM
–S
–OUT
NOTE: x,y capacitors not shown for clarity
Figure 14–4 — IAM multiple Driver interconnection
VI-200 and VI-J00 Family Design Guide
Page 45 of 98
+OUT
+S
TRIM
–S
–OUT
Figure 14–3 — External x,y capacitors for EMC requirements
D3
D1
Driver/
Booster
Connection to module baseplate
or ground plane
connected to baseplate
4,700 pF
IAM
[a]
C1
+IN
GATE
IN
GATE
OUT
–IN
Rev 3.5
Apps. Eng. 800 927.9474
vicorpower.com
800 735.6200
14. Input Attenuator Module (IAM / MI-IAM)
Design Guide & Applications Manual
For VI-200 and VI-J00 Family DC-DC Converters and Configurable Power Supplies
SAFETY CONSIDERATIONS
Shock Hazard. Agency compliance requires that the
baseplate be grounded or made inaccessible.
+IN
+IN
+
–
–IN
–IN
Fusing. Safety agency conditions of acceptability require
module input fusing. See Table 14–3 for recommended
fuse ratings.
+OUT
GATE IN
PAR
GATE OUT
–OUT
IAM
[a]
Diodes: 1N4148
C2: 470 pf / 500 V
C2
+IN
GATE
IN
GATE
OUT
–IN
VI-200
Driver
+IN
GATE
IN
GATE
OUT
–IN
VI-200
Booster
+OUT
+S
TRIM
–S
–OUT
+OUT
+S
TRIM
–S
–OUT
+IN
GATE
IN
GATE
OUT
– IN
VI-200
Driver
+IN
GATE
IN
GATE
OUT
–IN
VI-200
Booster
+IN
GATE
IN
GATE
OUT
– IN
VI-200
Driver
+OUT
+S
TRIM
–S
–OUT
100Ω
+IN
+OUT
+IN
GATE IN
PAR
GATE OUT
–OUT
–IN
–IN
IAM
C2
[a]
For bus voltages greater than 75 V,
a 1N4006 diode should be used for the
diodes connected to the GATE IN pins.
+OUT
+S
TRIM
–S
–OUT
+OUT
+S
TRIM
–S
–OUT
NOTE: x,y capacitors not shown for clarity
Figure 14–5 — Paralleling connections for the IAM
VI-200 and VI-J00 Family Design Guide
Page 46 of 98
Rev 3.5
Apps. Eng. 800 927.9474
vicorpower.com
800 735.6200