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79
VH Hermetic
Vishay Foil Resistors
Document Number: 63004
Revision 02-Mar-05
THROUGH HOLE
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SALES
FIGURE 2 - POWER DERATING CURVE
NOTES:
1. Standard Resistance Tolerance: ± 0.005%; ± 0.01%;
± 0.02%; ± 0.05%; ± 0.1%; ± 0.25%; ± 0.5%; ± 1.0%.
2. Not to exceed power rating of resistor.
3. See Figure 2 below.
4. 0.200" (5.08 mm) lead spacing available (except VHS555)–
specify VH102J (S102C type), VH102L (S102K type).
5. Maximum is 1.0% A.Q.L. standard for all specifications
except TCR. (For TCR information see notes 6 -10.)
Typical is a designers reference which represents that
85% of the units supplied, over a long period of time, will
be at least the figure shown or better.
6. Vishay Nominal TCR is defined as the chord slopes of
the relative change of resistance/temperature, expressed
in ppm (parts per million), called (RT) curve from 0°C to
+ 25°C and + 25°C to + 60°C (“Instrument” Range); and
from – 55°C to + 25°C and + 25°C to + 125°C (“Military”
Range). These specifications and the definition of
Nominal TCR apply to all resistance values including
low-value resistors.
7. Vishay Standard TCR Spread is defined as a designers
reference which represents that at least 92% of the units,
and 82% of the lots, supplied by Vishay will be within
the stated band centered on the nominal curve. This
definition of the Vishay Standard TCR Spread from
Nominal applies to all resistance values. However, as
the resistance value decreases below 80 ohms, the
Vishay Standard TCR Spread from Nominal specification
starts to increase. (See Figure 3 in data sheet “7 Technical
Reasons to specify BMF Resistive Components.”)
Bulk Metal® Foil Technology
Hermetically Sealed Resistors, Aerospace
8. Vishay Maximum TCR Spread is defined as the 3 σ (Sigma)
limit of a normal Gaussian distribution (99.73% of a production
lot) which is within a band, centered on the nominal curve.
This Vishay Maximum TCR Spread is no greater than ±
2.5ppm/°C from nominal throughout the full temperature
range. This definition of the Vishay Maximum TCR Spread
from Nominal applies to all resistance values. However, as
the resistance value decreases below 80 ohms, the Vishay
maximum TCR Spread from Nominal specification starts to
increase. (See Figure 3 in datasheet “7 Technical Reasons
to Specify Vishay Bulk Metal® Foil Resistive Components.”)
9. Selected TCR Tracking is available for specially ordered lots
of resistors. The selected TCR tracking can be 3, 2, 1 and as
close as 0.5ppm/°C throughout the full temperature range.
10. TCR tracking is a measure of the similarity of resistance
value change in two or more resistors which are undergoing
the same temperature changes. Tracking could be
expressed as the difference in the temperature coefficients of
the resistors, expressed in ppm/°C as (∆R1/R1 – ∆R2/R2) x
10-6/∆T°C. When a number of resistors are referenced to a
nominal TCR, the spread or envelope around the nominal
would be the difference. If the spread is ± 1.5ppm/°C about a
nominal, the tracking, as defined above, will be 3ppm/°C.
11 Inductance (L) due mainly to the leads.
12. The resolution limit of existing test equipment (within the
measurement capability of the equipment, or “essentially
zero.”)
13. µV/°C relates to EMF due to lead temperature difference and
µV/watt due to power applied to the resistor.
14. Load life ∆R Maximum can be reduced through burn-in
procedure.
+100
+75
+50
+25
0
–75 –50 –25 0 +25 +50 +75 +100 +125 +150 +175 +200
Ambient Temperature (°C)
Percent of Rated Power @ +125°C
–55°C
+200
+70°C Double Rated Power
Rated Power
+175
+150
+125