KP1830
www.vishay.com
Vishay Roederstein
Revision: 03-Feb-17
6
Document Number: 26016
For technical questions, contact: dc-film@vishay.com
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HEAT CONDUCTIVITY (G) AS A FUNCTION OF ORIGINAL PITCH AND CAPACITOR BODY
THICKNESS IN mW/°C
POWER DISSIPATION AND MAXIMUM COMPONENT TEMPERATURE RISE
The power dissipation must be limited in order not to exceed the maximum allowed component temperature rise as a function
of the free air ambient temperature.
The power dissipation can be calculated according type detail specification “HQN-384-01/101: Technical Information Film
Capacitors” with the typical t
gd
of the curves.
The component temperature rise (T) can be measured (see section “Measuring the component temperature” for more details)
or calculated by T = P/G:
• T = component temperature rise (°C)
• P = power dissipation of the component (mW)
• G = heat conductivity of the component (mW/°C)
MEASURING THE COMPONENT TEMPERATURE
A thermocouple must be attached to the capacitor body as in:
The temperature is measured in unloaded (T
amb
) and maximum loaded condition (T
C
).
The temperature rise is given by T = T
C
- T
amb
.
To avoid radiation or convection, the capacitor should be tested in a wind-free box.
APPLICATION NOTE AND LIMITING CONDITIONS
To select the capacitor for a certain application, the following conditions must be checked:
1. The peak voltage (U
p
) shall not be greater than the rated DC voltage (U
RDC
).
2. The peak-to-peak voltage (U
p-p
) shall not be greater than the maximum (U
p-p
) to avoid the ionization inception level.
3. The maximum component surface temperature rise must be lower than the limits.
4. The maximum application temperature must be lower than 105 °C.
5. There is no limit for the voltage pulse slope in the application.
W
max.
(mm)
HEAT CONDUCTIVITY (mW/°C)
PITCH 5 mm
4.5 3
5.5 4
7.5 6
9.0 7
