Voltage Coefficient
Voltage coefficient is the change in resistance value per applied volt across the element, expressed in ppm/V; it captures the non-linear behaviour of resistive elements under high electric fields.
Definition
Often abbreviated VCR, the voltage coefficient describes how the resistance of a real element decreases as the applied voltage rises. The effect is driven by quantum tunnelling between resistive grains in thick-film inks and by field-emission micro-arcs in carbon composition material. Wirewound and metal-foil parts are essentially immune (< 0.1 ppm/V), while thick-film and especially carbon composition can show 100 – 1000 ppm/V.
For low-voltage signal circuits VCR is invisible, but in high-voltage dividers it is the dominant error source. A 1 GΩ thick-film resistor with 100 ppm/V in a 100 kV divider drifts by 10 % from cold to full voltage, swamping any tolerance or TCR budget. HV divider designs split the total voltage across many series elements to keep the per-element voltage low and use specially formulated low-VCR (≤ 5 ppm/V) thick films or ceramic-composition materials.
Low VCR also matters in load banks, snubbers and current-sense applications where the part sees high transient voltage but must remain linear for accurate measurement. Always check the datasheet VCR specification before using a resistor above a few hundred volts.
Related terms
VCR (Voltage Coefficient of Resistance)
VCR is the formal datasheet abbreviation for voltage coefficient of resistance, the relative change in resistance per applied volt, given in ppm/V; it is the dominant linearity spec for high-voltage and HV-divider resistors.
TCR (Temperature Coefficient of Resistance)
TCR is the relative change in resistance per degree Celsius of temperature change, expressed in parts per million per kelvin (ppm/K or ppm/°C); it determines how stable a resistor is over its operating temperature range.
Tolerance
The maximum allowable deviation of a resistor's actual resistance from its nominal value at room temperature and zero applied power, expressed as a percentage (e.g. ±1%, ±5%).
Related products
Sample Request
Standard samples are provided free of charge in reasonable quantities (shipped within 2–3 business days). Custom samples are delivered within 2–4 weeks. Please use the form on the right to tell us:
- Company and contact details
- Target part number or key specs (power / resistance / package)
- Application scenario and estimated annual volume
- Shipping address and expected delivery date