Precision Resistor MR - metal foil

Metal foil precision resistor for high temperatures and long-term stable measurement circuits

The MR series precision resistors are designed for applications where precision, temperature stability and long-term behaviour are critical – even under demanding environmental conditions. Metal foil technology on an insulating substrate ensures very small resistance changes over temperature and lifetime, while the encapsulated epoxy housing reliably protects the resistor against moisture and mechanical influences. As a result, once-adjusted measurement and reference circuits remain stable over long periods.

A key feature of the series is the extended operating temperature range from −65 °C to +175 °C combined with a power rating up to 0.5 W at 125 °C. Power is derated according to the specified derating curve, which allows MR resistors to be used in environments where other precision resistors reach their thermal limits. Typical applications include weighing systems, high-accuracy amplifiers, bridge circuits and control systems as found in automation, medical and aerospace equipment.

The resistance range from 1 Ω to 400 kΩ covers many common measurement and reference tasks – from low-ohmic measurement branches to precision voltage dividers. Resistance tolerances from ±1% down to ±0.005% allow very fine adjustment of the circuit without the need for additional trimming. For the temperature coefficient, graded classes are available depending on the resistance value: ±15 ppm/°C in the low-ohmic range, ±5 ppm/°C, ±2.5 ppm/°C and, as an option, ±1 ppm/°C from 30 Ω upwards. This enables measurement chains in which both absolute value and temperature drift are tightly specified.

In addition, the MR series offers low current noise, a very small voltage coefficient and low thermal EMF (typically around 1 µV/°C). Together with the specified tests – including power conditioning, load life, damp heat, temperature cycling, high-temperature storage, shock and vibration – this results in a precision resistor that delivers reliable results even in long-term demanding measurement setups.

Options

• Case types: MR9101, MR9102, MR9103 with graded power and voltage ratings
• Resistance range: 1 Ω–400 kΩ depending on type, with freely selectable values (in xxxkxxx format e.g. 10k100)
• Resistance tolerances: ±1%, ±0.5%, ±0.1%, ±0.05%, ±0.02%, ±0.01%, ±0.005% (depending on resistance value and type)
• Temperature coefficients: ±15 ppm/°C (low-ohmic range), ±5 ppm/°C, ±2.5 ppm/°C and optional ±1 ppm/°C from 30 Ω
• Lead spacing depending on type: 3.81 mm, 5.08 mm or 7.5 mm (radial, tinned copper leads)