Application Note

VISHAY VITRAMON
Capacitor Products
Application Note
Space-Saving HVArc Guard® Capacitors for
Passive Snubber Applications
sizes as small as 0805. Designers can thus save on board
space while maintaining the same capacitance and voltage
ratings for a wide range of medium- to high-voltage snubber
applications.
A wide range of passive devices can be used to make a
passive snubber that absorbs energy from the reactance in a
power switching circuit. Snubbers can be used to clamp
ringing noise or reduce power dissipation during turn-off;
another application is to reduce peak switching voltages.
They are a critical circuit for improving the efficiency of
most switching semiconductor circuits.
Small Size Advantages
The small dimensions of HVArc Guard surface-mount
MLCCs make them ideal for snubber circuits. Their high
voltage breakdown performance is particularly useful in
applications requiring snubber capacitors or capacitors in
the high-voltage inverter section. In fact, the breakdown
voltage of HVArc Guard MLCCs is more than twice that of
the comparable standard commercial high-voltage
capacitor.
There are several different passive component options for
snubber design. For example, film polypropylene capacitors
are often used as a snubber to control the voltage rate of rise
(dV/dt) in high pulse applications. High-voltage, standard
MLCCs are likewise used as a snubber to clamp the voltage
to a fixed level during device turn-on. They can also be used
to clamp harmful transient voltages on semiconductor
switching devices such as bipolar or MOS transistors.
The disadvantage with these solutions is their size. Film
capacitors are leaded, through-hole devices that require
significant board space. High-voltage, 390 pF, 1 kV MLCCs
have until now been available only in the 1812 size.
Good Surge Capability
Vishay has conducted various surge tests on HVArc Guard
capacitors. The basic surge waveform is shown below. Pulse
rise times as fast as 1.2 µs were tested on HVArc Guard
devices.
New HVArc Guard® high-voltage MLCCs remove these
limitations. They combine high breakdown voltages, low
impedance, and a wide operating frequency range in case
Vpk
90 %
Rise Time, tr = t2 - t1
Duration, td = t4
Capability = tr x td
10 %
t0
t1
t2
The results of surge testing on both the X7R and NP0
HVArc Guard capacitors are shown in the follwing table:
Document Number: 45059
Revision: 17-Aug-07
t4
Time (µs)
Waveform
C0G (N0P) HVArc Guard X7R HVArc Guard
1.2 µs x 50 µs
1650 V
500 V
10 µs x 700 µs
1800 V
1200 V
10 µs x 160 µs
> 1500 V
1200 V
For technical support, contact
mlcc.specials@vishay.com
www.vishay.com
1
APPLICATION NOTE
50 %
Application Note
Vishay Vitramon
Space-Saving HVArc Guard® Capacitors for
Passive Snubber Applications
Designing Snubbers with HVArc Guard
A simple passive R-C snubber is used in power circuitry to
dissipate energy and clamp voltages during turn-on and
turn-off cycles. For example, in an application where
high-voltage MOSFETs are used as the switching device,
rapid changes occur as the drain-to-source voltage steps up
during MOSFET operation. These changes create voltage
transient noise on the gate of the MOSFET. A capacitor
snubber is used on source-drain as a bypass cap for the
harmful switching noise.
Used in these applications, HVArc Guard MLCCs will
typically require significantly less space than standard
high-voltage capacitors. Shown below is an example of a
snubber used in a totem pole configured MOSFET circuit.
VBIAS
VDRV
R
VCC
PWM
controller
RGATE
OUT
GND
HVArc Guard Capacitors Ordering Information
HVArc-Guard MLCCs are available in both C0G (NPO)
and X7R dielectrics and in a variety of popular surface
mount EIA standard case sizes. Ordering is easy using the
codes below.
HVArc Guard C0G (NP0) Dielectric Ordering Code
APPLICATION NOTE
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)
Expressed in
picofarads (pF).
The first two
digits are
significant, the
third is a
multiplier.
Examples:
102 = 1000 pF
J=±5%
K = ± 10 %
M = ± 20 %
X = Ni barrier
100 % tin
plated
matte finish
F = AgPd
G = 1000 V
R = 1500 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
www.vishay.com
2
For technical support, contact
mlcc.specials@vishay.com
Document Number: 45059
Revision: 17-Aug-07
Application Note
Vishay Vitramon
Space-Saving HVArc Guard® Capacitors for
Passive Snubber 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
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Document Number: 45059
Revision: 17-Aug-07
For technical support, contact
mlcc.specials@vishay.com
www.vishaymg.com
3
APPLICATION NOTE
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