DS1835 | GUILCOR SENSORS

DS1835
Temperature sensors

High-accuracy 1‑Wire temperature sensor designed for precise measurements in electronics, automation, and control systems.

Maximum precision
+/- 2,0°K

Minimum temperature
-40°C

Maximum temperature
+85°C

Minimum dimensions
4 x 6 x 27

Response time
Medium

Self-heating
Medium

Price
Medium

Drift
Low

What is a DS2835 sensor ?

The DS1835 from Maxim Integrated is a 1-Wire interface supervision circuit.

It includes:

a calibrated digital temperature sensor,
a voltage reset circuit (watchdog),
an internal EEPROM to store data or configurations.

It is aimed at embedded systems where temperature, voltage, and processor status need to be monitored, all through a single communication line.

Operating principle

The DS1835 measures the internal temperature and compares the supply voltage to a reset threshold; if the voltage drops, it automatically sends a RESET signal to protect the system.

The temperature is provided via the 1-Wire bus as follows:

T(°C) = Brut Value / 16

The data or states (alarm, flags) can be stored in the 256-bit EEPROM.

Technical specifications

Parameter	Typical Value
Measurement range	−40 → +85 °C
Typical precision	±2 K
Resolution	0.125 °C (10 bits)
Threshold reset	4.63 V (version R-10) / 3.08 V (version R-5)
Reset delay	250 ms (typ.)
Interface	1-Wire Digital
EEPROM	256 bits (read/write)
Case	TO-92 or SOT-223
Annual drift	Average (±0.5 K/year)

Wiring configuration

Type	Description
VDD	Main food source
GND	Mass
DQ	1-Wire Line (communication)
RESET	Surveillance tension exit
VOUT	Supervised tension / memory output

Self-heating

Low (< 0.3 °C).

The thermal impact is almost negligible, with the casing effectively dissipating heat.

Application areas

⚙️ Supervision of industrial or embedded power supplies

🔋 Protection of microcontrollers / IoT boards

🧠 Systems requiring temperature + reset + local storage

🧱 Critical applications (safety, energy, monitoring)

Should I choose a DS1835 sensor ?

Strengths points

⚙️ Three functions in one single component
→ LThe DS1835 combines temperature measurement, voltage supervision (reset), and integrated EEPROM, which significantly simplifies the electronics of an embedded system.
🔗 Universal 1-Wire Interface
→ Compatible with the libraries and buses of the DS18B20, it can integrate into an existing network of sensors while adding system control functions.
🧠 Integrated microcontroller protection
→ The automatic reset circuit protects the board in case of voltage drop or crash, preventing memory corruption and erratic restarts.

Weaknesses points

🌡️ Average thermal precision
→ With an accuracy of ±2 K, it does not compete with purely thermal sensors (such as the DS18B20 or the DS28EA00).
💾 Limited memory capacity
→ The integrated EEPROM (256 bits) is sufficient for configurations, but not for massive storage.
💰 Higher cost than a simple sensor
→ Its combined functions (reset, memory, temperature) make it a more expensive component — relevant only if these three functions are useful together.

Useful information

Here is some useful information regarding the DS1835 sensors.

Resolution and precision

The DS1835 uses a 10-bit ADC converter for temperature measurement, identical to that of the DS2438, and features a built-in comparator for voltage monitoring.

Measure	Resolution	Typical accuracy (−10 → +85 °C)	Remarks
Temperature	10 bits (0,125 °C)	±2,0 K	Internal measurement, factory calibrated
Reset voltage	—	±1 %	Automatic triggering according to model
EEPROM	256 bits	—	Non-volatile data storage
Annual drift	—	±0.5 K/year (temperature sensor)	Correct stability for monitoring

🔹 Notes:

The temperature is available via the 1-Wire bus.
The reset threshold (Vtrip) depends on the version (3.08 V / 4.63 V).
Stable drift due to the internal compensation of the voltage comparator.

Application example – Equations and interpretation

🔹 Temperature Measurement

The DS1835 returns a 10-bit binary value, identical to that of the DS2438.

The conversion equation is therefore:

T(°C) = Raw Value / 16

Example:

Raw value = 0x0780 = 1920

T = 1920 / 16 = 120 °C

✅ Measured temperature = 120 °C

🔹 Low voltage detection (Reset)

The DS1835 continuously compares the supply voltage VDD to its trigger threshold (Vtrip).

RESET = { LOW, if VDD < Vtrip

{ HIGH, if VDD > Vtrip

Version	Threshold Reset (Vtrip)	Typical tolerance
DS1835-5	3,08 V	±1 %
DS1835-10	4,63 V	±1 %

✅ When a voltage drop is detected, the RESET output goes low for approximately 250 ms, ensuring a clean restart of the microcontroller.

🔹 EEPROM Memory

The internal EEPROM of 256 bits (32 bytes) can hold:

custom thresholds,
system identifiers,
or calibration data.

Writing and reading are done via the 1-Wire bus, with a typical cycle of 10 ms per write.

Integration diagram in an electronic system

The DS1835 integrates directly between the microcontroller and the power supply.

It supervises the voltage, provides a RESET signal, measures the internal temperature, and communicates via 1-Wire.

🔹 Typical components

Component	Function
DS1835	Temperature sensor, voltage supervisor, EEPROM
Pull resistance (4.7 kΩ)	Keeps the DATA line high
Microcontroller (ESP32, STM32, etc.)	Master 1-Wire, monitored by the DS1835
Power Supply 3.3 V / 5 V	Supervised Source VDD
Decoupling capacitor (100 nF)	Voltage filtering

🔹 Functional diagram (ASCII)

+5V / +3.3V │ [C1] │ ┌──────────────┐ │ DS1835 │ │──────────────│ │ VDD RESET│───► µC Reset DATA ──────│ DQ │ GND ──────│ GND │ └──────────────┘ │ GND

💡 The DS1835 monitors the VDD voltage and restarts the microcontroller if a drop is detected, while providing the temperature on the 1-Wire bus.

🔹 Operating Principle

1️⃣ The DS1835 monitors the supply voltage (VDD).

2️⃣ If it drops below the Vtrip threshold, the RESET signal goes to 0.

3️⃣ Once the voltage returns to normal, the reset remains active for 250 ms.

4️⃣ In parallel, the internal temperature sensor is accessible via the 1-Wire bus (command 0x44).

Multi-point advantage – Security and addressing

Each DS1835 has a unique 64-bit identifier (family code 0x18), allowing it to be integrated into a mixed 1-Wire network with DS18B20, DS2438, etc.

Function	Description
Surveillance tension + temperature	Ideal for sensitive systems (energy, data, IoT)
Integrated EEPROM	Configuration storage or ID
Signal Reset equipment	Automatic microcontroller protection
Unique 1-Wire Addressing	Identification on shared bus