2000 Aug 08
6
BCcomponents
Product specification
Metal film resistors
5063JD series (space miser)
0.25 to 0.40 W; 1% and 5%
Definition of symbols (see Figs 4, 5, 6 and 7)
Pulses
The permissible pulse-load is determined by the resistance
change as given for the endurance test after 8000 hours.
PULSE VOLTAGE LIMIT
The maximum permissible impulse voltage
is the
voltage pulse short overload depending on the impulse time
ti. High ohmic values are protected by the interdependence
of voltage limit and impulse time. this function is given by
the equation:
Vmax = maximum permissible continuous voltage;
ti = pulse time;
K = 100 s−1.
MAXIMUM PULSE-LOAD
The average load
must not exceed the rated dissipation.
For resistance values above the critical resistance the rated
dissipation is given by the resistance value and the limiting
element voltage Vmax:
CONTINUOUS AND SINGLE PULSE-LOAD
There is a difference between repetitive pulse-load
or
single pulse load (e.g. switching events
).
A higher pulse-load Pmax is accepted in the latter case.
SYMBOL
DESCRIPTION
applied peak pulse power
maximum permissible peak pulse power;
see Fig.4
applied peak pulse voltage; see Fig 6
maximum permissible peak pulse voltage;
see Fig.5
V(t)
pulse voltage
R
nominal resistance value
PU
rated dissipation at ambient temperature
Rnom
nominal resistance value
ti
pulse duration (rectangular pulses)
tp
pulse repetition time
P
ˆ
P
ˆ
max
V
i
ˆ
V
ˆ
max
V
ˆ
max
V
ˆ
max
2.5 V
max
⋅
1t
i
K
⋅
+
--------------------------
V
max
+
=
P
P
1
t
p R
---------
=
U
2
t1
t2
∫
t
()dt P
≤υ
P
t
i
t
p
---- P with P
power at the pulse time t
i
=
⋅
=
P0
>
PULSE SHAPES
Figure 6 shows the maximum pulse-load for a rectangular
pulse shape:
Other pulses should be converted into rectangular pulse
shapes (see Fig.7), having the same energy at a given peak
voltage. The following equation shows the calculation for
exponential pulses:
with
P
t
i
V
2
ˆ
⋅
t
p
R
⋅
--------------
=
P
τ
e
2t
p
⋅
------------
V
2
ˆ
R
------
⋅
=
τ
e
RC or
τ
e
L
R
----
=
⋅
=
Fig.6 Rectangular pulses.
MGA206
t i
V
Vi
t
t p
Fig.7 Exponential pulses.
V
t
τ
MGA207
t p
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