The Pt5000 follows the standardized Callendar–Van Dusen equation, identical to that of other platinum sensors:

R(T) = R₀ [1 + A·T + B·T² + C·(T − 100)·T³]

avec :

• R₀ = 5000 Ω

• A = 3,9083 × 10⁻³

• B = −5,775 × 10⁻⁷

• C = −4,183 × 10⁻¹² (pour T < 0 °C)

This equation is valid from −200 °C to +600 °C and ensures excellent linearity.

🔹 Example 1: calculation of resistance at 100 °C

R(100) = 5000 × [1 + 3,9083 × 10⁻³ × 100 − 5,775 × 10⁻⁷ × 100²]

R(100) = 5000 × (1 + 0,39083 − 0,005775)

R(100) = 5000 × 1,385055 = 6925,27 Ω

✅ Result : at 100 °C, the resistance of the Pt5000 is approximately 6925 Ω.

🔹 Example 2 : calculating the temperature from a measured resistance

We measure R=5850Ω.

What is the corresponding temperature?

T = (−A + √(A² − 4B(1 − R/R₀))) / (2B)

T = (−3,9083 × 10⁻³ + √[(3,9083 × 10⁻³)² − 4 × (−5,775 × 10⁻⁷) × (1 − 5850 / 5000)]) / [2 × (−5,775 × 10⁻⁷)]

T ≈ 38 °C

✅ Result : the equivalent temperature is approximately 38 °C.

🔹 Practical notes

• The equation can be directly integrated into modern microcontrollers (STM32, ESP32, Arduino).
• Due to its high resistance, the Pt5000 can be powered by a very low current source without loss of accuracy.
• The R(T) curve remains almost linear: the error is < ±0.03 °C between −50 °C and +300 °C.

The Pt5000 generates a high signal proportional to the temperature, directly usable by most high-resolution ADCs.

Its high resistance significantly reduces noise effects, making it perfect for long-distance measurements and low-power systems.

🔹 Typical components of the assembly

              +3.3 V / +5 V
                   │
       Power source (0.1 mA)
                   │
                [ Pt5000 ]
         (2 or 3 armored wires)
           │             │
           │             │
      Measuring bridge → ADC 24 bits
                          │
                   [ Microcontroller ]
              (Calculation T = f(R) + display)

🔹 Operating principle

1️⃣ Constant current : a low current (0.1 mA) flows through the probe.

​→ At 0 °C: V = 5000 Ω × 0.1 mA = 0.5 V

​→ At 100 °C: V ≈ 6925 Ω × 0.1 mA = 0.69 V

2️⃣ Direct measurement : the voltage is read via a 24-bit ADC (resolution < 0.01 °C).

3️⃣ Numerical calculation : the microcontroller applies the Callendar–Van Dusen equation.

🔹 Best practices

• 🧩 Use 2 wires for short distances; 3 wires beyond 2 m.
• ⚡ Limit the current to 0.1 mA to avoid self-heating.
• 💧 Protect the sensor from moisture: ceramic or glass encapsulation recommended.
• 🔄 Calibrate regularly (0 °C and 100 °C).
• 🧲 Use twisted and shielded cables for industrial environments.