MAX31820PAR 1-Wire, Parasite-Power, Ambient Temperature Sensor General Description Benefits and Features The MAX31820PAR ambient temperature sensor pro- Uniq ue 1-Wire Interface Requires Only One Port Pin vides 9-bit to 12-bit Celsius temperature measurements for Communication with 0.5C accuracy over a +10C to +45C temperature Derives Power from Data Line (Parasite Power) No range. Over its entire -55C to +125C operating range, Local Power Supply Needed the device has 2.0C accuracy. The device communicates over a 1-Wire bus that, by Multidrop Capability Simplifies Distributed definition, requires only one data line (and ground) for Temperature-Sensing Applicati ons communication with a central microprocessor. In addi- Requ ires No External Components tion, the device derives power directly from the data line (parasite power), eliminating the need for an external Measures Temperatures from -55C to +125C (-67F power supply. Requiring so few pins enables the device to +257F) to be placed in a 3-pin TO-92 package. The form factor 0.5C Accuracy from +10C to +45C of this package allows the device to be placed above the board and thus measure the ambient temperature of Thermometer Resolution is User-Selectable from a system, as opposed to the board temperature that a 9 Bits to 12 Bits surface-mount package would measure. Converts Temperature to 12-Bit Digital Word in Each MAX31820PAR has a unique 64-bit serial code, which 750ms (Max) allows multiple MAX31820PAR devices to function on the same 1-Wire bus. Therefore, it is simple to use one micropro- User-Definable Nonvolatile (NV) Alarm Settings cessor to control many devices distributed over a large area. Alarm Search Command Identifies and Addresses Applications Devices Whose Temperature is Outside Programmed Limits (Temperature Alarm Condition) HVAC Environmental Contr ols Temperature Monitoring Sy stems Inside Buildings, Available in 3-Pin TO-92 Package Equipment, or Machinery Software Compatible with the DS1822-PAR and Process Monitoring and Co ntrol Systems Thermostatic Controls DS18B20-PAR Industrial Systems Consumer Products Ordering Information appears at end of data sheet. Thermometers Any Thermally Sensitive Sy stem For related parts and recommended products to use with this part, refer to www.maximintegrated.com/MAX31820PAR.related. Block Diagram V PU PARASITE-POWER MEMORY 4.7k CIRCUIT CONTROL LOGIC MAX31820PAR DQ TEMPERATURE REGISTER 64-BIT ROM AND ALARM HIGH TRIGGER (T ) H REGISTER (EEPROM) 1-Wire PORT C PP SCRATCHPAD ALARM LOW TRIGGER (T ) L REGISTER (EEPROM) GND CONFIGURATION REGISTER (EEPROM) 8-BIT CRC GENERATOR 1-Wire is a registered trademark of Maxim Integrated Products, Inc. 19-6732 Rev 0 6/13MAX31820PAR 1-Wire, Parasite-Power, Ambient Temperature Sensor Absolute Maximum Ratings Voltage Range on Any Pin Relative to Ground .... -0.5V to +6.0V Storage Tempera ture Range ............................ -55C to +125C Operating Temperature Range ......................... -55C to +100C Soldering Temperature (reflow) .......................................+260C Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. DC Electrical Characteristics (V = 3.0V to 3.7V, T = -55C to +100C, unless otherwise noted.) (Note 1) PU A PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS Pullup Supply Voltage V (Notes 2, 3) 3.0 3.7 V PU +10C to +45C 0.5 Thermometer Error T C ERR -55C to +100C 2 Input Logic-Low V (Notes 2, 4, 5) -0.3 +0.8 V IL Input Logic-High V (Notes 2, 6) 3.0 3.7 V IH Sink Current I V = 0.4V (Note 2) 4.0 mA L I/O Active Current I (Note 7) 1 1.5 mA DQA DQ Input Current I (Note 8) 5 A DQ Drift (Note 9) 0.2 C Maxim Integrated 2 www.maximintegrated.com