DS1820S Dallas Semiconductor, DS1820S Datasheet
DS1820S
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DS1820S Summary of contents
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... DD NC – No Connect Because each DS1820 contains a unique silicon serial number, multiple DS1820s can exist on the same 1–Wire bus. This allows for placing temperature sen- sors in many different places. Applications where this feature is useful include HVAC environmental controls, sensing temperatures inside buildings, equipment or machinery, and in process monitoring and control ...
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... DS1820S (16–pin SSOP): All pins not specified in this table are not to be connected. OVERVIEW The block diagram of Figure 1 shows the major compo- nents of the DS1820. The DS1820 has three main data components: 1) 64–bit lasered ROM, 2) temperature sensor, and 3) nonvolatile temperature alarm triggers TH and TL. The device derives its power from the 1– ...
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PARASITE POWER The block diagram (Figure 1) shows the parasite pow- ered circuitry. This circuitry “steals” power whenever the I pins are high. I/O will provide sufficient power DD as long as the specified timing and voltage require- ...
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DS1820 USING V TO SUPPLY TEMPERATURE CONVERSION CURRENT Figure 3 DD +5V 4.7K P OPERATION – MEASURING TEMPERATURE The DS1820 measures temperature through the use of an on–board proprietary temperature measurement technique. A block diagram of the temperature mea- surement ...
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... This flag is updated with every temperature measure- ment. As long as the alarm flag is set, the DS1820 will respond to the alarm search command. This allows many DS1820s to be connected in parallel doing simul- taneous temperature measurements. If somewhere the temperature exceeds the limits, the alarming device(s) can be identified and read immediately without having to read non– ...
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... Figure 7. Additional information about the Dallas 1–Wire Cyclic Redundancy Check is available in Application Note 27 entitled “Understanding and Using Cyclic Redundancy Checks with Dallas Semiconductor Touch Memory Products”. The shift register bits are initialized to zero. Then start- ing with the least significant bit of the family code, one bit at a time is shifted in ...
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ROM FUNCTIONS FLOW CHART Figure 6 33h N READ ROM MATCH ROM COMMAND COMMAND Y DS1820 T FAMILY MASTER T X CODE 1 BYTE DS1820 T X SERIAL NUMBER MATCH? 6 BYTES DS1820 T X MASTER T CRC BYTE MATCH? ...
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DS1820 1–WIRE CRC CODE Figure 7 (MSB) MEMORY The DS1820’s memory is organized as shown in Figure 8. The memory consists of a scratchpad RAM and a nonvolatile, electrically erasable (E stores the high and low temperature triggers TH and ...
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BUS SYSTEM The 1–Wire bus is a system which has a single bus mas- ter and one or more slaves. The DS1820 behaves as a slave. The discussion of this bus system is broken down into three topics: hardware ...
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DS1820 Read ROM [33h] This command allows the bus master to read the DS1820’s 8–bit family code, unique 48–bit serial num- ber, and 8–bit CRC. This command can only be used if there is a single DS1820 on the bus. ...
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The data obtained from the two reads of the 3–step routine have the following interpretations: 00 There are still devices attached which have conflicting bits in this position. 01 All devices still coupled have a 0–bit in this bit position. ...
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DS1820 I/O pin, the DS1820 waits 15–60 s and then transmits the presence pulse (a low signal for 60–240 s). MEMORY COMMAND FUNCTIONS The following command protocols are summarized in Table 2, and by the flowchart of Figure 10. 021497 ...
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MEMORY FUNCTIONS FLOW CHART Figure 10 MASTER T MEMORY X OR CONTROL COMMAND 4Eh N WRITE SCRATCHPAD ? Y DS1820 SETS ADDRESS COUNTER TO 2 MASTER T DATA BYTE X TO SCRATCHPAD Y MASTER T RESET ...
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DS1820 MEMORY FUNCTIONS FLOW CHART Figure 10 (cont’d) 48h COPY SCRATCHPAD ? Y N PARASITE POWER ? MASTER ENABLES STRONG PULLUP FOR MASTER DISABLES MASTER T X RESET ? N NONVOLATILE N MEMORY BUSY ? MASTER R “1”s X 021497 ...
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MEMORY FUNCTIONS FLOW CHART Figure 10 (cont’d) B8h RECALL DS1820 RECALLS 2 FROM E PROM MASTER T RESET X ? DEVICE N BUSY CONVERTING TEMPERATURE ? MASTER MASTER R “1” POWER SUPPLY Y PARASITE ...
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DS1820 INITIALIZATION PROCEDURE “RESET AND PRESENCE PULSES” Figure 11 Master T 480 s minimum 960 s maximum V CC 1–WIRE BUS GND LINE TYPE LEGEND: DS1820 COMMAND SET Table 2 INSTRUCTION Convert T Initiates temperature conversion. Read Scratchpad Reads bytes ...
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Read Scratchpad [BEh] This command reads the contents of the scratchpad. Reading will commence at byte 0, and will continue through the scratchpad until the 9th (byte–8, CRC) byte is read. If not all locations are to be read, the ...
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DS1820 READ/WRITE TIMING DIAGRAM Figure 12 MASTER WRITE “0” SLOT 60 s< 1–WIRE BUS GND MIN MASTER READ “0” SLOT V Ç Ç Ç Ç Ç Ç Ç Ç CC 1–WIRE Ç Ç Ç ...
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DETAILED MASTER READ “1” TIMING Figure 1–WIRE BUS GND T >1 S INIT RECOMMENDED MASTER READ “1” TIMING Figure 1–WIRE BUS GND INIT RC SMALL SMALL LINE TYPE LEGEND: T ...
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... Related Application Notes The following Application Notes can be applied to the DS1820. These notes can be obtained from the Dallas Application Note 27: “Understanding and Using Cyclic Redundancy Checks with Dallas Semiconductor Touch Memory Product” Application Note 55: “Extending the Contact Range of Touch Memories” ...
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MEMORY FUNCTION EXAMPLE Table 3 Example: Bus Master initiates temperature conversion, then reads temperature (parasite power assumed). MASTER MODE DATA (LSB FIRST <64–bit ROM code> <I/O LINE HIGH> <64–bit ROM ...
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DS1820 MEMORY FUNCTION EXAMPLE Table 4 Example: Bus Master writes memory (parasite power and only one DS1820 assumed). MASTER MODE DATA (LSB FIRST <2 data bytes> <9 data bytes> TX ...
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MEMORY FUNCTION EXAMPLE Table 5 Example: Temperature conversion and interpolation (external power supply and only one DS1820 assumed). MASTER MODE DATA (LSB FIRST <1 data byte> <9 data bytes> TX ...
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DS1820 ABSOLUTE MAXIMUM RATINGS* Voltage on Any Pin Relative to Ground Operating Temperature Storage Temperature Soldering Temperature * This is a stress rating only and functional operation of the device at these or any other conditions above those indicated in ...
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AC ELECTRICAL CHARACTERISTICS: PARAMETER Temperature Conversion Time Time Slot Recovery Time Write 0 Low Time Write 1 Low Time Read Data Valid Reset Time High Reset Time Low Presence Detect High Presence Detect Low Capacitance NOTES: 1. Temperature conversion will ...
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DS1820 1–WIRE WRITE ZERO TIME SLOT t REC 1–WIRE READ ZERO TIME SLOT 1–WIRE RESET PULSE RESET PULSE FROM HOST 1–WIRE PRESENCE DETECT 021497 26/27 t SLOT t LOW0 t SLOT t REC t RDV t RSTL START OF NEXT ...
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TYPICAL PERFORMANCE CURVE –55 –35 –15 LOWER LIMIT SPECIFICATION DS1820 DIGITAL TERMOMETER AND THERMOSTAT TEMPERATURE READING ERROR –1 –2 –3 TEMPERATURE (deg. C) SPECIFICATION DS1820 UPPER LIMIT 105 125 TYPICAL ...