Rainbow-electronics DS1720 Manual do Utilizador Página 1

DS1720Econo – Digital Thermometer andThermostatDS1720PRELIMINARY030598 1/12FEATURES• Requires no external components• Supply voltage range covers from

DS1720030598 10/12ABSOLUTE MAXIMUM RATINGS*Voltage on Any Pin Relative to Ground –0.5V to +7.0VOperating Temperature –55°C to +125°CStorage Temperatur

DS1720030598 11/12AC ELECTRICAL CHARACTERISTICS (–55°C to +125°C; VDD=2.7V to 5.5V)PARAMETER SYMBOL MIN TYP MAX UNITS NOTESTemperature Conversion Tim

DS1720030598 12/12DS1720 TYPICAL THERMOMETER ERROR–55 –25 –10 5 20 45 60 75 90 100DS1720 TYPICAL THERMOMETER ERRORTHERMOMETER ERROR (C)AMBIENT TEMPERA

DS1720030598 2/12OPERATION–MEASURING TEMPERATUREA block diagram of the DS1720 is shown in Figure 1.The DS1720 measures temperatures through the use of

DS1720030598 3/12TEMPERATURE MEASURING CIRCUITRY Figure 2SLOPE ACCUMULATORPRESETPRESETCOUNTERCOUNTER=0=0STOPINCCOMPARETEMPERATURE REGISTERLOW TEMPERAT

THIGHTLOWTCOMTL THT (°C)DS1720030598 4/12DETAILED PIN DESCRIPTION Table 2PIN SYMBOL DESCRIPTION1 DQ Data Input/Output pin for 3–wire communication por

DS1720030598 5/12OPERATION AND CONTROLThe DS1720 must have temperature settings resident inthe TH and TL registers for thermostatic operation. Aconfig

DS1720030598 6/12falling edge of the clock, and remain valid through therising edge.When reading data from the DS1720, the DQ pin goesto a high impeda

DS1720030598 7/12DS1720 COMMAND SET Table 3INSTRUCTION DESCRIPTION PROTOCOL3–WIRE BUSDATA AFTERISSUINGPROTOCOLNOTESTEMPERATURE CONVERSION COMMANDSRea

DS1720030598 8/12FUNCTION EXAMPLEExample: CPU sets up DS1720 for continuous conversion and thermostatic function.CPU MODEDS1720 MODE(3–WIRE)DATA (LSB

DS1720030598 9/12READ DATA TRANSFER Figure 4RSTCLKDQtCCtCDHtDCtCDDtCDZtCCHLSBDATAMSBDATA017PROTOCOLtRDZWRITE DATA TRANSFER Figure 5RSTCLKDQPROTOCOLLSB