Document Number: 31019 For technical questions, contact: ff2aresistors@vishay.com www.vishay.com
Revision: 05-May-08 87
PTF
Metal Film Resistors, Precision, Ultra-High Stability Vishay Dale
DIMENSIONS
Note:
(1) 1.08 ± 0.125 [27.43 ± 3.18] if tape and reel
L1 max.
LD
1.50 ± 0.125 (1)
[38.10 ± 3.18]
d
GLOBAL
MODEL
DIMENSIONS in inches [millimeters]
LDL
1 max. d
PTF51 0.150 ± 0.020
[3.81 ± 0.51]
0.070 ± 0.010
[1.78 ± 0.25]
0.200
[5.08]
0.016
[0.41]
PTF56 0.250 ± 0.031
[6.35 ± 0.79]
0.091 ± 0.009
[2.31 ± 0.23]
0.300
[7.62]
0.025
[0.64]
PTF65 0.375 ± 0.062
[9.53 ± 1.57]
0.145 ± 0.016
[3.68 ± 0.41]
0.475
[12.07]
0.025
[0.64]
PERFORMANCE
TEST CONDITIONS OF TEST TEST RESULTS
Life MIL-PRF-55182 Paragraph 4.8.18
1000 h rated power at + 85 °C ≤ ± 0.04 %
Thermal Shock MIL-STD-202, Method 107
- 55 °C to + 85 °C ≤ ± 0.02 %
Short Time Overload MIL-R-10509, Paragraph 4.7.6 ≤ ± 0.01 %
Low Temperature Operation MIL-PRF-55182, Methods 4.8.10 ≤ ± 0.02 %
Moisture MIL-PRF-55182, Paragraph 4.8.15 ≤ ± 0.08 %
Resistance to Soldering Heat MIL-STD-202, Methods 210 ≤ ± 0.02 %
Damp Heat IEC 60068-2-3 56 days at 40 °C and 92 % RH ≤ ± 0.08 %
Dielectric Withstanding Voltage MIL-STD-202, Methods 301 and 105 ≤ ± 0.01 %
MATERIAL SPECIFICATIONS
Element: Precision deposited nickel chrome
alloy with controlled annealing
Encapsulation: Specially formulated epoxy
compounds. Coated construction
Core: Fire-cleanded high purity ceramic
Termination:
Standard lead material is
solder-coated copper. Solderable and
weldable per MIL-STD-1276, Type C.
AMBIENT TEMPERATURE IN °C
DERATING
RATED POWER IN %
0
20
40
60
80
100
120
- 55
- 25 0 25 50 75 100 125 150 175 200
85
TEMPERATURE COEFFICIENT OF RESISTANCE
Temperature coefficient (TC) of resistance is normally stated as
the maximum amount of resistance change from the original
+ 25 °C value as the ambient temperature increases of
decreases. This is most commonly expressed in parts per
million per degree centigrade (ppm/°C).
The resistance curve over the operating temperature range is
usually a non-linear curve within predictable maximum limits.
PTF resistors have a very unifom resistance temp.
characteristic when measured over the operating range of
- 20 °C to + 85 °C. The standard temperature coefficients
available are
X = ± 15 ppm/°C, Y = ± 10 ppm/°C and Z = ± 5 ppm/°C.
Some applications of the PTF require operation beyond the
specifications of - 20 °C to + 85 °C. The change in temperature
coeffecient of resistance is very small (less than ± 0.05 ppm/°C)
over the expanded temperature range of - 55 °C to ± 150 °C.
Therefore, when operating outside the range - 20 °C to + 85 °C,
the designer can plan for a worst case addition of
± 0.05 ppm/°C for each degree centigrade beyond either
- 20 °C or + 85 °C as indicated in the graph. This applies to all
three temperature coefficient codes.
Example: Assume the operating characteristics demand a
temperature range from - 55 °C to + 125 °C. This requires a
± 35 °C Δ below - 20 °C and a ± 40 °C Δ above + 85 °C. The
extreme Δ being ± 40 °C means that the worst case addition to
the specified TC limit of ± 0.05 ppm/°C times ± 40 °C or
± 2 ppm/°C. Therefore, a Z which is characterized by a base TC
limit of ± 5 ppm/°C over the temperature range of - 20 °C to
± 85 °C will exhibit a maximum temperature coefficient of
± 7 ppm/°C over the expanded portion of the temperature range
of - 55 °C to + 125 °C.
4
3
2
1
0
- 50 - 40 - 30 - 20 90 100 110 120 130 140 150
EXPANDED
OPERATING RANGE
- 55 °C TO - 20 °C
EXPANDED
OPERATING RANGE
- 85°
C TO + 150 °C
- 20 °C TO + 85°
C
BASE TC LIMIT
X, Y
or Z
/
mp
p?C
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