HVArc Guard® Surface-Mount Capacitors for Low

HVArc Guard® Surface-Mount Capacitors for Low
VISHAY VITRAMON
Capacitor Products
Application Note
HVArc Guard® Surface-Mount Capacitors for
Low-Power Voltage Multiplier Applications
Voltage multipliers can generate very high voltages due to
an inverter circuit that feeds a step-up transformer, which is
connected to the multiplier circuit. An example of a typical
voltage multiplier, which is simply a circuit comprised of
capacitors and diodes that charge and discharge in
alternating half cycles of the applied AC voltage, is shown
in the diagram below.
HVArc Guard® Capacitors
Vin
Out
GND
Figure 1. Series Multiplier for HV Applications
Cascading voltage doubler cells, as shown in the circuit,
result in a high-voltage output. Applications for voltage
multipliers include flyback converters, where a high
voltage is produced from a low battery or supply voltage in
medical X-ray systems, air ionizers, and oscilloscopes, and
instrumentation requiring a high-voltage power supply.
Surface Arc-Over Problems in High-Voltage Applications
be added to isolate the high-voltage section from other
sections of the board. Although coatings add cost to the
process and the design, they are required in some
applications to meet electrical safety standards.
Figure 1. Standard High Voltage MLCC with voltage applied causing
surface arc-over between terminations
Figure 2. Standard High Voltage MLCC surface typical
arc-over failure site
Document Number: 45058
Revision: 17-Aug-07
For technical support, contact
mlcc.specials@vishay.com
www.vishay.com
1
APPLICATION NOTE
When a high voltage potential is applied at > 1000 V, an
arc-over between the terminals, or from terminal to case,
will occur. To eliminate any arc-over, an overcoating can be
applied to the board, or additional board layout spacing can
Application Note
Vishay Vitramon
HVArc Guard® Surface-Mount Capacitors for
Low-Power Voltage Multiplier Applications
Figure 3. Example of typical surface arc-over failure site in an 1812-case-size X7R, 100 nF, 500 VDC rated MLCC
and a post-test cross section showing surface cracking
To avoid having to overcoat the components, coated disk
capacitors or conformal coated leaded through-hole
capacitors are commonly used in voltage multiplier
sections, but they take up a large amount of board space.
HVArc Guard surface-mount capacitors offer designers
a space-saving alternative. Because of their special
worldwide-patent-pending
internal
construction
APPLICATION NOTE
Figure 4. Carbon traces from surface arc-over on a
typical Standard High Voltage MLCC
technology, Vishay's HVArc Guard surface-mount
capacitors eliminate the need to conformal coat the part or
over-coat the circuit board to prevent surface arc-over. In
addition, HVArc Guard surface-mount capacitors offer cost
savings by eliminating the costly manual insertion processes
associated with through-hole devices.
Figure 5. Vishay HVArc Guard without surface arc-over
Impedance of HVArc Guard Surface-Mount Capacitors for Voltage Multiplier Applications
The basic voltage multiplier is termed capacitive since the
circuit can hold and store a charge. By series-connecting
HVArc Guard surface-mount capacitors, low-power voltage
multipliers can be designed so that the output voltage
increases as the number of cascaded stages increases.
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2
When selecting an HVArc Guard surface-mount
component, careful attention must be paid to the voltage
breakdown characteristics.
For technical support, contact
mlcc.specials@vishay.com
Document Number: 45058
Revision: 17-Aug-07
Application Note
Vishay Vitramon
HVArc Guard® Surface-Mount Capacitors for
Low-Power Voltage Multiplier Applications
10.00
Impedance (Ω)
Z HVArc Guard
Z Standard
1.00
ESR HVArc
Guard
ESR
Standard
0.10
0.01
105
106
107
108
Frequency (Hz)
The graph above compares the impedance vs. frequency,
ESR, and impedance of a standard commercial 500 V, X7R
capacitor in the 1206 case and an HVArc Guard
surface-mount capacitor with the same ratings. As
demonstrated in the graph, the impedance of the
HVArc Guard is similar to standard high-voltage
surface-mount capacitors.
Specific details regarding the impedance of specific
HVArc Guard surface-mount capacitors are available upon
request through your local Vishay sales office.
HVArc Guard Surface-Mount Capacitors Ordering Information
HVArc Guard surface-mount capacitors are available in
both NP0 and X7R dielectrics, and in a variety of popular
surface-mount EIA- standard case sizes.
HVArc Guard NP0 Dielectric Ordering Code
ORDERING INFORMATION
VJ0805
CASE
CODE
A
DIELECTRIC
0805
1206
1210
A = C0G
102
J
X
G
CAPACITANCE CAPACITANCE TERMINATION DC VOLTAGE
NOMINAL CODE TOLERANCE
RATING 1)
J=±5%
K = ± 10 %
M = ± 20 %
X = Ni barrier
100 % tin
plated
matte finish
F = AgPd
G = 1000 V
R = 1500 V
T
PACKAGING
5Z
PROCESS
CODE
A = Unmarked C = 7" reel/
paper tape
T = 7" reel/
plastic tape
P = 11 1/4" reel/
paper tape
B = Bulk
R = 11 1/4" reel/
plastic tape
W = Waffle tray
5Z = HVArc
Guard
Note:
1. DC voltage rating should not be exceeded in application
Document Number: 45058
Revision: 17-Aug-07
For technical support, contact
mlcc.specials@vishay.com
www.vishay.com
3
APPLICATION NOTE
Expressed in
picofarads (pF).
The first two
digits are
significant, the
third is a
multiplier.
Examples:
102 = 1000 pF
A
MARKING
Application Note
Vishay Vitramon
HVArc Guard® Surface-Mount Capacitors for
Low-Power Voltage Multiplier Applications
HVArc Guard X7R Dielectric Ordering Code
ORDERING INFORMATION
VJ1812
CASE
CODE
Y
DIELECTRIC
1206
1210
1808
1812
Y = X7R
102
J
X
P
CAPACITANCE CAPACITANCE TERMINATION DC VOLTAGE
NOMINAL CODE TOLERANCE
RATING 1)
Expressed in
picofarads (pF).
The first two
digits are
significant, the
third is a
multiplier.
Examples:
223 = 22 000 pF
J=±5%
K = ± 10 %
M = ± 20 %
X = Ni barrier
100 % tin
plated
F = AgPd
P = 250 V
E = 500 V
L = 630 V
G = 1000 V
A
MARKING
T
PACKAGING
A = Unmarked C = 7" reel/
paper tape
T = 7" reel/
plastic tape
P = 11 1/4" reel/
paper tape
B = Bulk
R = 11 1/4" reel/
plastic tape
W = Waffle tray
5Z
PROCESS
CODE
5Z = HVArc
Guard
Note:
1. DC voltage rating should not be exceeded in application
WORLDWIDE SALES AND TECHNICAL SUPPORT
APPLICATION NOTE
NOTICE Specifications of the products displayed herein are subject to change without notice. Vishay Intertechnology, Inc., or anyone on its behalf, assumes no responsibility or liability for any errors or inaccuracies. Information
contained herein is intended to provide a product description only. No license, express or implied, by estoppel or otherwise, to any intellectual property rights is granted by this document. Except as provided in Vishay’s terms
and conditions of sale for such products, Vishay assumes no liability whatsoever, and disclaims any express or implied warranty, relating to sale and/or use of Vishay products including liability or warranties relating to fitness for a
particular purpose, merchantability, or infringement of any patent, copyright, or other intellectual property right. The products shown herein are not designed for use in medical, life-saving, or life-sustaining applications. Customers
using or selling these products for use in such applications do so at their own risk and agree to fully indemnify Vishay for any damages resulting from such improper use or sale.
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For technical support, contact
mlcc.specials@vishay.com
Document Number: 45058
Revision: 17-Aug-07
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