LM35 vs DS18B20: Analog vs Digital Temp Sensors
One requires complex analog-to-digital math, the other has a digital ID chip built-in. Find out which temperature probe is best for you.
LM35 (Analog)
The LM35 is a precision analog temperature sensor. It outputs a voltage linearly proportional to the Centigrade temperature.
DS18B20 (Digital)
The DS18B20 is a digital 1-Wire temperature sensor. Its digital nature makes it incredibly accurate over long wire distances.
Specifications Comparison
| Specification | LM35 (Analog) | DS18B20 (Digital) |
|---|---|---|
| Output Type | Analog Voltage | Digital (1-Wire Protocol) |
| Temperature Range | -55°C to 150°C | -55°C to 125°C |
| Accuracy | ±0.5°C (at room temp) | ±0.5°C (from -10 to +85°C) |
| Scale Factor | 10mV per 1°C | — |
| Operating Voltage | 4V - 30V | 3V - 5.5V |
| Package | TO-92 (Transistor-like) | TO-92 or Waterproof Steel Probe |
| Price (India) | ₹30 - ₹50 | ₹80 (chip) - ₹150 (waterproof) |
| Resolution | — | 9 to 12-bit selectable |
LM35 (Analog)
Pros
- Extremely cheap and requires zero external libraries to read
- You can read it purely with an `analogRead()` and basic multiplication
- Outputs a perfectly linear 10mV/°C scale, no complex calibration needed
- Low self-heating
Cons
- Prone to electrical noise if wires are long
- Reading depends heavily on the accuracy of your Arduino's 5V reference; if the USB voltage drops, the temp reading changes
- Takes up a dedicated Analog pin for every single sensor you add
DS18B20 (Digital)
Pros
- Digital output means long wires create ZERO temperature drift/noise
- 1-Wire protocol means you can string 50+ sensors on a single Arduino digital pin!
- Available in a rugged, waterproof stainless steel probe format (perfect for liquids/aquariums)
- Every chip has a unique 64-bit ID burnt in, making identification easy
Cons
- Requires downloading specific libraries (OneWire & DallasTemperature)
- Code execution is slightly slower because it must digitally "ping" the sensor
- More expensive than the LM35
Our Recommendation
Choose the **LM35** if you are teaching the absolute basics of analog signals in a classroom, or just want a cheap ambient air reading on a breadboard. Choose the **DS18B20** for measuring liquids, long-distance outdoor reading, or anywhere you need 2 or more temperature sensors.
The Verdict
The DS18B20 in its waterproof steel casing is the undisputed king of robust DIY temperature measurement. The LM35 is strictly for breadboard learning.