Rainbow-electronics DS1920 Manual do Utilizador Página 1

1 of 22 081699SPECIAL FEATURES§ Digital thermometer measures temperaturesfrom -55°C to +100°C in typically 0.2seconds§ Zero standby power§ 0.5°C

DS192010 of 22Read ROM [33h]This command allows the bus master to read the DS1920’s 8-bit family code, unique 48-bit serialnumber, and 8-bit CRC. This

DS192011 of 22Read Scratchpad [BEh]This command reads the complete scratchpad. After the last byte of the scratchpad is read, the bus masterwill recei

DS192012 of 22MEMORY AND CONTROL FUNCTIONS FLOW CHART Figure 9

DS192013 of 22

DS192014 of 22MEMORY AND CONTROL FUNCTIONS FLOW CHART (cont’d) Figure 9FROM FIGURE 9FIRST PARTTO FIGURE 9THIRD PART

DS192015 of 22MEMORY AND CONTROL FUNCTIONS FLOW CHART (cont’d) Figure 91-WIRE SIGNALINGThe DS1920 requires strict protocols to ensure data integrity.

DS192016 of 22READ/WRITE TIME SLOTSThe definitions of write and read time slots are illustrated in Figure 11. All time slots are initiated by themaste

DS192017 of 22DS1920 MEMORY AND CONTROL FUNCTION COMMANDS Table 2INSTRUCTION DESCRIPTION PROTOCOL1-WIRE BUSAFTER ISSUINGPROTOCOL NOTES TEMPERATURE CO

DS192018 of 22READ/WRITE TIMING DIAGRAM (cont’d) Figure 11Write-0 Time Slot60 µs ≤ tLOW0 < tSLOT < 120 µs1 µs ≤ tREC < ∞Read-Data Time Slot60

DS192019 of 22MEMORY FUNCTION EXAMPLE Table 3Example: Bus Master initiates temperature conversion, then reads temperature.MASTER MODE DATA (LSB FIRST)

DS19202 of 22ORDERING INFORMATIONDS1920-F3 F3 MicroCanDS1920-F5 F5 MicroCanEXAMPLES OF ACCESSORIESDS9096P Self-Stick Adhesive PadDS9101 Multi-Purp

DS192020 of 22ABSOLUTE MAXIMUM RATINGS*Voltage on Any Pin Relative to Ground -0.5V to +7.0VOperating Temperature -55°C to +100°CStorage Temperature

DS192021 of 22AC ELECTRICAL CHARACTERISTICS:1-WIRE INTERFACE (-55°C to +100°C; VPUP=2.8V to 6.0V)PARAMETER SYMBOL MIN TYP MAX UNITS NOTESTi

DS192022 of 22TYPICAL PERFORMANCE CURVEDS1920 TEMPERATURE iButtonTRUE TEMPERATURE (°C)Error = Reading - True TemperatureWhen cold, the true temperatur

DS19203 of 22DS1920 BLOCK DIAGRAM Figure 1PARASITE POWERThe block diagram (Figure 1) shows the parasite-powered circuitry. This circuitry “steals” pow

DS19204 of 22STRONG PULL-UP FOR SUPPLYING DS1920 DURING TEMPERATURECONVERSION Figure 2OPERATION - MEASURING TEMPERATUREThe DS1920 measures temperature

DS19205 of 22The most significant (sign) bit is duplicated into all of the bits in the upper MSB of the 2-bytetemperature register in memory. This “si

DS19206 of 22OPERATION - ALARM SIGNALINGAfter the DS1920 has performed a temperature conversion, the temperature value is compared to thetrigger value

DS19207 of 2264-BIT LASERED ROM Figure 48-BIT CRC CODE 48-BIT SERIAL NUMBER 8-BIT FAMILY CODE (10H)MSB LSB MSB LSB MSB

DS19208 of 221-WIRE CRC CODE Figure 6MEMORYThe DS1920’s memory is organized as shown in Figure 7. The memory consists of a scratchpad and 2bytes of EE

DS19209 of 22HARDWARE CONFIGURATIONThe 1-Wire bus has only a single line by definition; it is important that each device on the bus be able todrive it