Rainbow-electronics DS1821 Manuel d'utilisateur

1 of 17 040601maFEATURES Requires no external components Unique 1-Wire® interface requires only oneport pin for communication Operates over a -5

DS1821Page 10 of 17DS1821 FUNCTION COMMAND SET Table 4Command Description Protocol1-Wire Bus ActivityAfter Command is IssuedTEMPERATURE CONVERSION CO

DS1821Page 11 of 17INITIALIZATION TIMING Figure 7READ/WRITE TIME SLOTSThe bus master writes data to the DS1821 during write time slots and reads data

DS1821Page 12 of 17Figure 9 illustrates that the sum of TINIT, TRC, and TSAMPLE must be less than 15 µs for a read time slot.Figure 10 shows that sys

DS1821Page 13 of 17RELATED APPLICATION NOTESThe following Application Notes pertain to the DS1821. These notes can be obtained from the DallasSemicond

DS1821Page 14 of 17ABSOLUTE MAXIMUM RATINGS*Voltage on any pin relative to ground –0.5V to +7.0VOperating temperature –55°C to +125°CStorage temperatu

DS1821Page 15 of 17AC ELECTRICAL CHARACTERISTICS: (-55°C to +125°C; VDD=3.6V to 5.5V)PARAMETER SYMBOL MIN TYP MAX UNITS NOTESTemperature Conversion Ti

DS1821Page 16 of 17TYPICAL PERFORMANCE CURVE Figure 11MODE TOGGLE TIMING WHEN T/R¯ = 1 Figure 12

DS1821Page 17 of 17TIMING DIAGRAMS Figure 13

DS1821Page 2 of 17DETAILED PIN DESCRIPTIONS Table 1PR35 8-PINSOIC*SYMBOL DESCRIPTION1 2 GNDGround pin.21 DQOpen drain data input/output pin – 1-wire

DS1821Page 3 of 17counter is preset with a base count that corresponds to –55°C. If the counter reaches 0 before the gateperiod is over, the temperat

DS1821Page 4 of 17the 1-WIRE BUS SYSTEM section of this datasheet. These communications can include reading andwriting the high and low thermostat tr

DS1821Page 5 of 17configuration register to determine when the conversion status: DONE = 0 ― conversion in progress,DONE = 1 ― conversion complete. T

DS1821Page 6 of 17OPERATION – THERMOSTATWhen the DS1821 is in thermostat mode (T/R¯ = 1 in the status/configuration register), temperatureconversions

DS1821Page 7 of 17CONFIGURATION REGISTER BIT DESCRIPTIONS Table 3Bit Name(User Access)Functional DescriptionDONE — Temperature Conversion Done(Read O

DS1821Page 8 of 171-WIRE BUS SYSTEMThe 1-wire bus system uses a single bus master (i.e., a microprocessor) to control slave devices. TheDS1821 functi

DS1821Page 9 of 17INITIALIZATIONAll transactions on the 1-wire bus begin with an initialization sequence. The initialization sequenceconsists of a res