Precision Resistor ASTRO5 - wirewound

Wirewound precision resistor for demanding measurement and reference applications

The ASTRO5 precision resistor series is designed for demanding applications where high accuracy and a stable resistance characteristic are required. The resistance is realized by a wirewound element encapsulated in an epoxy housing. Thanks to the special multi-chamber / bifilar winding, inductance is significantly reduced, so ASTRO5 can be used in measurement paths and reference circuits where conventional wirewound resistors would behave too inductively.

The resistance range from 1 Ω to 1 MΩ supports both very low-ohmic applications – such as current sensing or shunt resistors – and precise resistors in the upper kΩ to MΩ range for voltage and reference dividers. Depending on the type, rated powers of 0.125 W, 0.25 W, 0.4 W and 0.5 W at 70 °C are available; power is derated according to the specified curve down to 0 W at +145 °C. Maximum working voltages range from 150 V to 400 V, depending on type.

The temperature coefficient is graded by resistance value:
For R > 100 Ω, ±10 ppm/°C is specified, for 10…100 Ω ±20 ppm/°C, for 5…10 Ω ±30 ppm/°C, and for 1…5 Ω ±50 ppm/°C. In addition, special TC configurations from −20 ppm/°C to +6000 ppm/°C can be implemented on request, for example to compensate the temperature behaviour of other circuit elements.

To improve long-term stability, ASTRO5 wirewound resistors are subjected to a power conditioning (ageing) process during manufacture. This reduces drift in operation; typical stability is ±100 ppm/year, with optional versions down to ±20 ppm/year. Combined with low inductance, radial lead configuration and high voltage capability, the ASTRO5 series is particularly suitable for measuring instruments, laboratory equipment, precision amplifier circuits, bridge networks and current sensing in low- to mid-power applications.

Options

• Types: ASTRO5-100, -125, -250, -700 with graded power ratings, permissible resistance ranges and maximum working voltages
• Resistance range: 1 Ω to 1 MΩ, depending on type, with freely selectable value
• Resistance tolerances: ±0.005% and optional ±0.001% for defined resistance ranges
• Temperature coefficients: standard ±10…±50 ppm/°C (depending on value)
• Resistor sets with very tight combined tolerances, e.g. down to ±0.001% and ±0.5 ppm/°C for matched measurement chains