Precision Resistor ASTRO2 - wirewound

Wirewound precision resistor with extremely wide application range and low inductance

The precision resistors of the ASTRO2 series are designed for demanding measurement and reference tasks where high accuracy, stable characteristics and a very wide resistance range are required. The electrical resistance is realized by a wirewound resistive element encapsulated in an epoxy housing. The multi-layer multi-chamber (bifilar) winding significantly reduces inductance despite the wirewound construction, allowing the resistors to be used in measurement paths where inductive effects would otherwise be problematic.

With a resistance range from 0.01 Ω to 6 MΩ and resistance tolerances from ±0.005%, ASTRO2 covers an exceptionally wide spectrum of applications – from low-ohmic measurement branches and shunt functions up to precise high-resistance and reference resistors in the MΩ range. Depending on the type, rated powers from 0.08 W to 1.5 W are available, with a maximum working voltage up to 900 V and an operating temperature range from −55 °C to +145 °C (with power derating according to the specified curve).

The temperature coefficient is graded according to resistance value, starting at ±10 ppm/°C for R > 100 Ω, with ±20 ppm/°C and ±30 ppm/°C in intermediate ranges, and ±50 ppm/°C and optional ±90…±150 ppm/°C in the low-ohmic range below 1 Ω. For special requirements, custom TC configurations from −20 ppm/°C up to +6000 ppm/°C can be implemented, for example to compensate the temperature behaviour of other components in the circuit.

To enhance long-term stability, the wirewound resistors are subjected to a power conditioning (ageing) process during production. This reduces later drift in field operation; typical stability is ±100 ppm/year, with optional versions down to ±20 ppm/year. These properties make the ASTRO2 series particularly suitable for use in laboratory and calibration equipment, high-accuracy amplifier circuits, bridge networks, reference networks and other precision circuits where voltage capability, resistance range and accuracy need to be combined in a single solution.

Options

• Resistance range: 0.01 Ω to 6 MΩ, freely selectable values (in xxxxkxxx format e.g. 10k000, 10k100)
• Resistance tolerances: ±0.1%, ±0.05%, ±0.01%, ±0.005% and optional ±0.001% (for defined resistance ranges)
• Temperature coefficients: standard ±10…±50 ppm/°C (depending on value), optional configurations from −20 ppm/°C to +6000 ppm/°C and special versions down to ±1 ppm/°C
• Resistor sets with very tight combined tolerances, e.g. down to ±0.001% and ±0.5 ppm/°C for matched measurement chains
• Lead materials optionally with Balco or platinum leads for defined high TC values
• Custom lead forming options to match specific customer layouts