Specifications
| Attribute | Value |
| Supplier | Analog Devices Inc./Maxim Integrated |
| Package / Case | Tray |
| Part Status | Obsolete |
| Sensor Type | Digital, Local |
| Sensing Temperature - Local | -55°C ~ 125°C |
| Output Type | 1-Wire® |
| Voltage - Supply | 2.7V ~ 5.5V |
| Resolution | 8 b |
| Features | One-Shot, Output Switch, Programmable Limit, Standby Mode |
| Accuracy - Highest(Lowest) | ±1°C |
| Test Condition | 0°C ~ 85°C |
| Operating Temperature | -55°C ~ 125°C |
| Mounting Type | Through Hole |
Overview
Description
DS1821 is an older Dallas/Maxim 1-Wire digital temperature sensor.
- What it is: a temperature-sensor IC with a unique 64-bit ROM code, allowing multiple devices on one 1-Wire bus.
- Output: digital temperature reading over the 1-Wire bus (no external ADC needed).
- How it works: host sends reset, ROM command (SKIP/MATCH ROM), then CONVERT_T to start a measurement; after conversion, read the scratchpad for the temperature (two’s complement; resolution typically 9–12 bits depending on model).
- Power: can be powered from VDD or via parasite power on the DQ line, with a pull-up on the data line.
- Pinout: VDD, GND, DQ (data line).
- Applications: simple, low-pin-count temperature sensing for microcontrollers, data loggers, environmental monitoring.
- Note: part of the DS18x family; DS18B20 is more common for new designs.
- What it is: a temperature-sensor IC with a unique 64-bit ROM code, allowing multiple devices on one 1-Wire bus.
- Output: digital temperature reading over the 1-Wire bus (no external ADC needed).
- How it works: host sends reset, ROM command (SKIP/MATCH ROM), then CONVERT_T to start a measurement; after conversion, read the scratchpad for the temperature (two’s complement; resolution typically 9–12 bits depending on model).
- Power: can be powered from VDD or via parasite power on the DQ line, with a pull-up on the data line.
- Pinout: VDD, GND, DQ (data line).
- Applications: simple, low-pin-count temperature sensing for microcontrollers, data loggers, environmental monitoring.
- Note: part of the DS18x family; DS18B20 is more common for new designs.
Equivalent
DS1821 is a Dallas/Maxim Maxim 1‑Wire temperature sensor. Equivalents are other DS18x0 family devices: DS18S20, DS18B20, DS18B22; older DS1820 is in the same line. All use 1‑Wire and can serve as drop‑ins, with DS18B20 being the most common replacement (resolution varies by model).
Features
DS1821 features (concise):
- Digital thermometer with integrated temperature sensor and alarm
- Temperature range: -55°C to +125°C
- Resolution: selectable 9–12 bits (0.5°C to 0.0625°C steps)
- Accuracy: typically ±1°C to ±2°C over range (varies by grade)
- Power: single-supply operation 2.7–5.5 V
- Interface: compact serial digital output (low-pin-count, easy MCU interface)
- Alarm: programmable high and low temperature thresholds with alarm/status output
- Power/performance: suitable for low-power applications; conversion time depends on resolution
- Packaging: small 8-pin options (DIP-8/SOIC-8) for easy board integration
Ideal for temperature monitoring and alerting in HVAC, automotive, consumer, and industrial apps.
- Digital thermometer with integrated temperature sensor and alarm
- Temperature range: -55°C to +125°C
- Resolution: selectable 9–12 bits (0.5°C to 0.0625°C steps)
- Accuracy: typically ±1°C to ±2°C over range (varies by grade)
- Power: single-supply operation 2.7–5.5 V
- Interface: compact serial digital output (low-pin-count, easy MCU interface)
- Alarm: programmable high and low temperature thresholds with alarm/status output
- Power/performance: suitable for low-power applications; conversion time depends on resolution
- Packaging: small 8-pin options (DIP-8/SOIC-8) for easy board integration
Ideal for temperature monitoring and alerting in HVAC, automotive, consumer, and industrial apps.
Pinout
DS1821 pin count: 3 pins (Vcc, GND, DQ/data).
Function: a digital temperature sensor (1‑Wire/1‑Wire-like interface) that measures temperature and outputs a digital temperature value on the data line. It can operate with parasite power and supports programmable resolution and optional alarm features.
Function: a digital temperature sensor (1‑Wire/1‑Wire-like interface) that measures temperature and outputs a digital temperature value on the data line. It can operate with parasite power and supports programmable resolution and optional alarm features.
Manufacturer
- Manufacturer: Dallas Semiconductor (the DS prefix indicates Dallas Semiconductor products).
- What kind of company: A U.S. semiconductor company that designed and manufactured integrated circuits, sensors, and other ICs. Dallas Semiconductor was later acquired by Maxim Integrated (and Maxim is now part of Analog Devices).
- What kind of company: A U.S. semiconductor company that designed and manufactured integrated circuits, sensors, and other ICs. Dallas Semiconductor was later acquired by Maxim Integrated (and Maxim is now part of Analog Devices).
Application
DS1821 is a digital temperature sensor. Common application areas include:
- Environmental monitoring and data logging
- HVAC, refrigeration, and thermostat control
- Automotive applications (engine/battery temperature)
- Industrial automation and process control
- Consumer appliances and electronics cooling/temperature sensing
- Medical equipment temperature monitoring (where applicable)
- Over-temperature protection and safety interlocks
It provides accurate, low-power, digital temperature measurement suitable for embedded systems and monitoring tasks.
- Environmental monitoring and data logging
- HVAC, refrigeration, and thermostat control
- Automotive applications (engine/battery temperature)
- Industrial automation and process control
- Consumer appliances and electronics cooling/temperature sensing
- Medical equipment temperature monitoring (where applicable)
- Over-temperature protection and safety interlocks
It provides accurate, low-power, digital temperature measurement suitable for embedded systems and monitoring tasks.
Package
DS1821 comes in an 8-pin package, typically DIP-8 or SOIC-8 (some revisions also in MSOP-8). Always verify the exact package in the datasheet for your specific part.
