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Document No.: 63187
Revision: 01-Nov-2016
Z Series (Z Foil)
TABLE 4 – “Z” SERIES SPECIFICATIONS
Stability (1)
Load life at 2000 h
Load life at 10000 h
±0.015% (150 ppm)
±0.005% (50 ppm)
±0.050% (500 ppm)
±0.015% (100 ppm)
Maximum ∆R at 0.3 W/+125°C
Maximum ∆R at 0.1 W/+70°C
Maximum ∆R at 0.3 W/+125°C
Maximum ∆R at 0.1 W/+70°C
Current Noise 0.010 μV
RMS
/V of applied voltage (<–40 dB)
High Frequency Operation
Rise time
Inductance (L)
(2)
Capacitance (C)
1.0 ns at 1 kΩ
0.1 μH maximum; 0.08 μH typical
1.0 pF maximum; 0.5 pF typical
Voltage Coefficient <3 ppm/V
(3)
Thermal EMF
(4)
0.05 μV/°C typical
1 μV/W (Model Z201)
Notes
(1)
Load life ∆R maximum can be reduced by 80%, please contact applications engineering.
(2)
Inductance (L) due mainly to the leads.
(3)
The resolution limit of existing test equipment (within the measurement capability of the equipment.)
(4)
μV/°C relates to EMF due to lead temperature difference and μV/watt due to power applied to the resistor.
THERMAL EMF
In a resistor, the resistance is composed of a resistance
element of one material and two terminations of a
different material. When the junction of the element and
the termination is heated in a closed circuit, there is a
DC voltage generated in the circuit (see Seebeck and
Peltier Effects). Hence, if both termination junctions
of the resistor are at exactly the same temperature
across terminations there is no net thermal EMF voltage
generated in the circuit due to thermal EMF error voltages
in the resistor.
In fact, however, the terminals are very seldom at the
same temperature because their temperatures are
influenced by uneven power dissipation within the
resistor, differential heating from other components
on the board, and heat conducted along the board
itself. Obviously, in a sense resistor that’s supposed to
accurately convert a current to a voltage, the presence
of an extraneous thermal EMF voltage could constitute
a significant error source in the system. That is why it’s
important that Bulk Metal Foil resistors have a thermal
EMF voltage of less than 0.1 mV/°C difference across the
element to termination junction.
POST MANUFACTURING OPERATIONS (PMO)
Many analog applications can include requirements for
performance under conditions of stress beyond the normal
and over extended periods of time. This calls for more than
just selecting a standard device and applying it to a circuit.
The standard device may turn out to be all that is needed
but an analysis of the projected service conditions should
be made and it may well dictate a routine of stabilization
known as post manufacturing operations or PMO. The
PMO operations that will be discussed are only applicable
to Bulk Metal
®
Foil resistors. They stabilize Bulk Metal Foil
resistors while they are harmful to other types. Short time
overload, accelerated load life, and temperature cycling
are the three PMO exercises that do the most to reduce
drifts down the road. VFR Bulk Metal Foil resistors are
inherently stable as manufactured. These PMO exercises
are only of value on Bulk Metal Foil resistors and they
improve the performance by small but significant
amounts. Users are encouraged to contact Vishay Foil
Resistors’ applications engineering for assistance in
choosing the PMO operations that are right for their
application.
FIGURE 6 – LOAD LIFE TEST FOR
10000 HRS @ 0.3 W +125°C; Z201, N=24
250 500 1000 2000 4000 6000 8000 10000
100R
1K
10K
Time (hrs)
(ppm)
R
–300.0
–200.0
–100.0
0.0
100.0
200.0
300.0
FIGURE 7 – IMPROVED STABILITY
WITH THROUGH-HOLE
Connection
Distant
from
Solder
Point
PCB
A - AA
A
Through-hole achieve better stability because they are not subjected to
thermo-mechanical stresses from the PCB
