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 DS18B20-PAR 
 Temperature sensors 

Parasitic-powered 1‑Wire sensor for easy installation and precise temperature monitoring in compact electronic systems.

 Maximum precision
+/- 0.5°K

 Minimum temperature
-55°C

 Maximum temperature
+125°C

 Minimum dimensions
4 x 6 x 27

 Response time
Fast

 Self-heating
Low

 Price
Low

Drift
Low

What is a DS18B20-PAR sensor ?Operating principleTechnical specificationsWiring configurationSelf-heatingApplication areas

What is a DS18B20-PAR sensor ?

The DS18B20-PAR (for Parasite Power) is a version of the DS18B20 optimized to operate without a dedicated power supply.

It only requires two wires:

  • one for the signal + power,
  • one for ground (GND).

It draws its energy directly from the DATA line of the 1-Wire bus, thanks to an internal capacitor.

Result: minimal wiring, ultra-low power consumption, and simplified integration into standalone systems.

Operating principle

The DS18B20-PAR converts the measured temperature into a 12-bit digital signal transmitted via the DATA line, while powering itself from that same line.

T = Raw Value / 16

During the conversion phase (up to 750 ms), the sensor consumes the energy stored in its internal capacitor, without external power supply.

Technical specifications

Parameter Typical value
Measurement range −55 °C → +125 °C
Typical precision ±0,5 K (−10 → +85 °C)
Resolution 9 to 12 bits configurable
Conversion time 93,75 to 750 ms
Alimentation Parasitic mode only (DATA + GND)
Interface 1-Wire Digital
Unique identifier 64 bits (family 0x28)

Annual drift

Low (±0.2 K/year)

Case

TO-92, waterproof IP68 cable or encapsulated stainless steel

Wiring Configuration

Type Description

Precision

2-wires (parasite)

DATA + GND only

✅ Standard

Multi-drop 1-Wire

Several sensors on the same DATA line

🏗️ Low power wide area networks

Self-heating

Very low (< 0.2 °C) due to the low operating voltage.

The DS18B20-PAR can be used for continuous measurement without degradation of accuracy.

Application areas

⚙️ Battery-powered or limited energy systems

💧 Temperature monitoring in humid environments (waterproof versions)

🧠 Long-distance distributed sensors (single cable)

🔋 Minimalist IoT projects (Arduino, ESP, Raspberry Pi)

🧱 Applications without external power (fixed or mobile installations)




Should I choose a KTY84-130 sensor ?

Strengths points

  • 🔋 Ultra simplified diet
         → The DS18B20-PAR operates without a dedicated VDD, using only the DATA line + GND. Ideal for systems where every wire counts: IoT, remote sensors, constrained environments.
  • 🎯 Stable and factory-calibrated precision
    → Same accuracy as the classic version (±0.5 K) despite its parasitic power supply — no loss of performance.
  • 💧 Perfect for waterproof environments
         → Thanks to its 2-wire design, it easily integrates into encapsulated or submerged probes without the need for additional power cables.
DS18B20-PAR

Weaknesses points

  • ⚡ Limited current on the bus
         → The 1-Wire bus must provide a stable current during the conversion; otherwise, the measurement may be distorted.
  • ⏱️ Conversion time a bit longer
         → In parasite mode, the full conversion (12 bits) sometimes takes 800–900 ms, slightly slower than the standard version.
  • → The voltage drops increase beyond 15–20 m of cable without external power — to be avoided in extensive installations.

Useful information

Here is some useful information regarding the DS18B20-PAR sensors.

The DS18B20-PAR offers the same performance as the classic DS18B20, but draws all its power from the DATA bus.

Its accuracy is guaranteed at ±0.5 K within the useful range, and it maintains a programmable resolution of 9 to 12 bits.

Resolution No measurement (°C)
 Conversion time
 Accuracy (−10 → +85 °C)
 Extended accuracy (−55 → +125 °C)
9 bits 0,5 °C 93,75 ms ±0,5 K ±1,0 K
10 bits 0,25 °C 187,5 ms ±0,5 K ±1,0 K
11 bits 0,125 °C 375 ms ±0,5 K ±1,0 K
12 bits 0,0625 °C 750–900 ms ±0,5 K ±0,75 K

🔹 Remarks:

  • Power supply only via the DATA line.
  • The internal capacitor powers the sensor during conversion.
  • Low annual drift (±0.2 K/year), identical to the standard DS18B20.
  • Guaranteed accuracy in the range −10 → +85 °C.

Like all DS18xx sensors, the DS18B20-PAR returns a 16-bit numeric value converted to temperature by the equation:

T(°C) = Raw Value / 16


🔹 Example 1 – Positive Reading

The sensor returns:

  • LSB = 0xB8
  • MSB = 0x09

Raw value 0x09B8 = 2488₁₀ T = 2488 / 16 = 155,5 °C

✅ Result: measured temperature ≈ 155.5 °C (simulated value).


🔹 Example 2 – Negative reading

The sensor returns:

  • LSB = 0xF0
  • MSB = 0xFF

Raw value (two's complement):

0xFFF0 = -16₁₀ T = -16 / 16 = -1,0 °C

✅ Result: measured temperature = −1.0 °C


🔹 Practical notes:

  • Reading via the “Read Scratchpad” command (0xBE).
  • Conversion triggered with “Convert T” (0x44).
  • Requires a strong pull-up phase (bus held at VDD) during the conversion to recharge the internal capacitor.

The DS18B20-PAR operates without external VDD, using the data line for its power supply.

This mode significantly simplifies wiring while remaining compatible with the standard 1-Wire bus.

🔹 Typical components

Component
 Function
DS18B20-PAR Capteur numérique 1-Wire alimenté en parasite
Résistance de tirage (4,7 kΩ) Maintient la ligne DATA à l’état haut
Microcontrôleur (Arduino, ESP32, Raspberry Pi, STM32) Maître du bus 1-Wire
Alimentation 3,3 V ou 5 V (via la ligne DATA uniquement)

🔹 Schéma fonctionnel (ASCII)

Connexion 2 fils (mode parasite)

     +3.3V / +5V
         │
        [4.7kΩ]
         │
DATA ────┼─────────────── DS18B20-PAR
         │
        GND

🔸 Le capteur se recharge à chaque période “haut” du signal DATA grâce à un condensateur interne.

🔸 Le microcontrôleur doit maintenir la ligne DATA = HIGH pendant la conversion pour garantir une alimentation suffisante.

🔹 Principe de fonctionnement

1️⃣ Le microcontrôleur initialise le bus par un reset pulse.

2️⃣ Le capteur renvoie son identifiant 64 bits.

3️⃣ La commande “Convert T” démarre la mesure.

4️⃣ Durant la conversion, le DS18B20-PAR utilise son condensateur interne pour s’alimenter.

5️⃣ Après 750–900 ms, la température est lue via “Read Scratchpad”.

Le mode parasite du DS18B20-PAR permet de simplifier drastiquement les installations multipoints.

Avantage Description
Câblage minimal Un seul fil DATA + GND pour des dizaines de capteurs
ID unique 64 bits Chaque capteur est identifiable individuellement
Maintenance simplifiée Pas d’alimentation séparée ni polarité à respecter
Compatibilité complète Fonctionne avec toutes les bibliothèques DS18B20 existantes
Exemple d’adresse unique :
28-FF-6A-41-93-16-04-2D
✅ Les capteurs peuvent être chaînés en série ou en dérivation sur plusieurs mètres de câble tout en gardant leur adressage unique.

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