EMC VI-J00, VI-200 User Manual

Design Guide & Applications Manual

For VI-200 and VI-J00 Family DC-DC Converters and Configurable Power Supplies

vicorpower.com 800-735-6200 Applications Engineering 1-800-927-9474 Rev. 2.1

Page 18 of 88

Figure 9–1 — Conducted input noise, no additional filtering

3 Amp Load 15 Amp Load 30 Amp Load

CONDUCTED NOISE

Conducted noise is the AC current flowing between the
source voltage and the power supply. It includes both
common-mode and differential-mode noise. Vicor zero­current-switching converters are 20 – 40 dB lower in
conducted noise than a traditional board-mounted PWM
converter; however, if a specific EMC specification such as
FCC or VDE must be met, additional filtering may be required.

Since the noise generated is ten to a hundred times lower
than fixed frequency converters, an existing filter should
provide equal or better performance when the conditions
in the

Module Do’s and Don’ts section are followed.

(Section 3)

In the event the system does not contain an existing filter,
the following will provide valuable information relative to
the attainment of system conducted noise objectives.
System requirements, such as Tempest (military) or UL544 /
EN60601 (medical), require a somewhat different approach.
Medical requirements vary as a function of the application
and country — please contact Vicor Applications
Engineering for additional details.

Common-Mode Noise with No Additional Filtering.
Common mode conducted noise current is the
unidirectional (in phase) component in both the +IN and
–IN pins to the module. This current circulates from the
converter via the power input leads to the DC source and
returns to the converter via the grounded baseplate or
output lead connections. This represents a potentially
large loop cross-sectional area which, if not effectively
controlled, can generate magnetic fields. Common-mode
noise is a function of the dv/dt across the main switch in
the converter and the effective input to baseplate and
input to output capacitance of the converter.

The most effective means to reduce common-mode current
is to bypass both input leads to the baseplate with
Y-capacitors (C2), keeping the leads short to reduce
parasitic inductance. Additionally, a common-mode choke
(L1) is usually required to meet FCC/ VDE A or B. (Figure
9–2)

9. EMC Considerations

Conducted Noise vs. Load

Typical Vicor Module

48 V Input, 5 V Output (VI-230-CV)

+OUT

+S

TRIM

–S

–OUT

C3

C3

Conditions:

C1 = 100 μF
C2 = 4,700 pF
C3 = 0.01 μF

Light Load = 3 A
Nominal Line = 48 V Nominal Load = 15 A
Full Load = 30 A

C1

C2

C2

+IN
GATE

IN
GATE

OUT
–IN

Design Guide & Applications Manual

For VI-200 and VI-J00 Family DC-DC Converters and Configurable Power Supplies

vicorpower.com 800-735-6200 Applications Engineering 1-800-927-9474 Rev. 2.1

Page 19 of 88

9. EMC Considerations

Common-Mode Noise with Common-Mode Choke.

There are no special precautions that must be exercised in
the design of input filters for Vicor converters. In fact, if
the system contains an EMC filter designed for typical
fixed frequency converters, it should be sufficient as is
(although not optimal in terms of size), as zero-current­switching converters inherently generate significantly less
conducted noise.

The plots in Figure 9–2 are representative of fixed
frequency converters with input filtering.

NOTE: In most cases, a fixed frequency converter
generates more input conducted noise with a filter
than Vicor’s zero-current-switching converter without
a filter. Also note that fixed frequency converters
using a construction technique involving control
circuitry on the same metal plate as power processing
components will generate significantly more input
noise than shown.

Figure 9–2 — Conducted input noise, typical fixed frequency converter with filter

3 Amp Load 15 Amp Load 30 Amp Load

Typical Fixed Frequency Converter (PWM)

48 V Input, 5 V Output

Conducted Noise vs. Load

C3

L1

C1

C2

+IN

–IN

–OUT

+OUT

C4

Conditions:

C1 = 2.2 μF
C2 = 100 μF
C3 = Internal
C4 = Internal
L1 = 3 mH

Nominal Line = 48 V

Light Load = 3 A
Nominal Load = 15 A
Full Load = 30 A

C3

C4

Design Guide & Applications Manual

For VI-200 and VI-J00 Family DC-DC Converters and Configurable Power Supplies

vicorpower.com 800-735-6200 Applications Engineering 1-800-927-9474 Rev. 2.1

Page 20 of 88

9. EMC Considerations

3 Amp Load 15 Amp Load 30 Amp Load

Conducted Noise vs. Load

Figure 9–3 — Conducted input noise, with common-mode choke

Typical Vicor Module (VI-230-CV)

48 V Input, 5 V Output

Three common-mode chokes are offered as standard accessories.

NOTE

: Common-mode filters may be common to one or

more modules, but only one

should be used with modules
interconnected via GATE IN’s or, GATE OUT to GATE IN. As
an example, Driver / Booster arrays or Drivers with GATE IN’s
tied together to provide a common disable function.

Part Inductance Maximum Resistance

Number Each Winding DC Current Each Winding

31743 1,000 µH 12 Amperes 6.5 mΩ
31742 3,000 µH 7 Amperes 18 mΩ
31943 2,163 µH 1 Ampere 42 mΩ

C2

a

L1

C4

C1 = 100 μF

C2a – C2b = 4,700 pF (Vicor Part # 01000)

C3a – C3b = 0.01 μF (Vicor Part # 04872)

C4 = 2.2 μF

L1 = 3,000 μH (Vicor Par t # 31742)

C1

C2

+IN
GATE

IN
GATE

OUT
–IN

b

C3

a

+OUT

+S

TRIM

–S

–OUT

C3

b

Conditions

Light Load = 3 A

Nominal Load = 15 A

Full Load = 30 A

Design Guide & Applications Manual

For VI-200 and VI-J00 Family DC-DC Converters and Configurable Power Supplies

vicorpower.com 800-735-6200 Applications Engineering 1-800-927-9474 Rev. 2.1

Page 21 of 88

9. EMC Considerations

Differential and Common-Mode Filter with More
than One Module. No special precautions are needed

when using two or more modules. The filter required will
have the same characteristics as a single module filter,

however the wire size on the magnetics will need to
reflect the increased input current. Shown below is the
input conducted noise for two modules sharing a
common input source.

Figure 9–4 — Conducted noise, multiple zero-current-switching converters

3 Amp / 3 Amp Load

3 Amp / 6 Amp Load

15 Amp / 15 Amp Load

3 Amp / 30 Amp Load

15 Amp / 30 Amp Load 30 Amp / 30 Amp Load

Differential and Common-Mode Filter with More than One Module

48 V Inputs, 5 V Outputs (Two Vicor VI-230-CV Modules)

Conducted Noise vs. Load

Three common-mode chokes are offered as standard accessories.

NOTE

: Common-mode filters may be common to one or
more modules, but only one should be used with modules
interconnected via GATE IN’s or, GATE OUT to GATE IN. As
an example, Driver / Booster arrays or Drivers with GATE IN’s
tied together to provide a common disable function.

Part Inductance Maximum Resistance

Number Each Winding DC Current Each Winding

31743 1,000 µH 12 Amperes 6.5 mΩ
31742 3,000 µH 7 Amperes 18 mΩ
31943 2,163 µH 1 Ampere 42 mΩ

C2

a

L2C4L1

C1

a

C1

C1a – C1b = 47 μF
C2a – C2d = 4,700 pF (Vicor Part # 01000)
C3a – C3d = 0.01 μF (Vicor Part # 04872)
C4 = 2.2 μF
L1 = 3,000 μH (Vicor Part # 31742)
L2 = 20 μH

+IN
GATE

IN
GATE
OUT
–IN

C2

b

C2

c

+IN
GATE

IN

b

GATE
OUT
–IN

C2

d

C3

a

+OUT

+S

T

–S

–OUT

C3

b

C3

c

+OUT

+S

T

–S

–OUT

C3

d

Conditions

Light Load = 3 A
Nominal Load = 15 A
Full Load = 30 A

Load 1

Load 2