DS1820S Maxim Integrated Products, DS1820S Datasheet
DS1820S
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DS1820S Summary of contents
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FEATURES Unique 1-wire interface requires only one port pin for communication Each device has a unique 64-bit serial code stored in an on-board ROM Multi-drop capability simplifies distributed temperature sensing applications Requires no external components Can be powered from ...
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DETAILED PIN DESCRIPTIONS Table 1 8-PIN SOIC* TO-92 SYMBOL DESCRIPTION 5 1 GND *All pins not specified in this table are “No Connect” pins. OVERVIEW Figure 1 shows a block diagram of the DS18S20, and pin ...
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OPERATION – MEASURING TEMPERATURE The core functionality of the DS18S20 is its direct-to-digital temperature sensor. The temperature sensor output has 9-bit resolution, which corresponds to 0.5 C steps. The DS18S20 powers- low-power idle state; to initiate a temperature ...
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OPERATION – ALARM SIGNALING After the DS18S20 performs a temperature conversion, the temperature value is compared to the user- defined two’s complement alarm trigger values stored in the 1-byte T The sign bit (S) indicates if the value is positive ...
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The use of parasite power is not recommended for temperatures above 100 C since the DS18S20 may not be able to sustain communications due to the higher leakage currents that can exist at these temperatures. For applications in which such ...
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MEMORY The DS18S20’s memory is organized as shown in Figure 7. The memory consists of an SRAM scratchpad with nonvolatile EEPROM storage for the high and low alarm trigger registers (T Note that if the DS18S20 alarm function is not ...
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CRC GENERATION CRC bytes are provided as part of the DS18S20’s 64-bit ROM code and in the 9 memory. The ROM code CRC is calculated from the first 56 bits of the ROM code and is contained in the most ...
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BUS SYSTEM The 1-wire bus system uses a single bus master to control one or more slave devices. The DS18S20 is always a slave. When there is only one slave on the bus, the system is referred to as ...
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INITIALIZATION All transactions on the 1-wire bus begin with an initialization sequence. The initialization sequence consists of a reset pulse transmitted by the bus master followed by presence pulse(s) transmitted by the slave(s). The presence pulse lets the bus master ...
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Alarm Search cycle (i.e., Alarm Search command followed by data exchange), the bus master must return to Step 1 (Initialization) in the transaction sequence. Refer to the OPERATION – ALARM SIGNALING section for an explanation of alarm flag operation. ...
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DS18S20 FUNCTION COMMAND SET Table 4 Command Description TEMPERATURE CONVERSION COMMANDS Convert T Initiates temperature conversion. Read Scratchpad Reads the entire scratchpad including the CRC byte. Write Scratchpad Writes data into scratchpad bytes 2 and 3 (T Copy Scratchpad Copies ...
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SIGNALING The DS18S20 uses a strict 1-wire communication protocol to insure data integrity. Several signal types are defined by this protocol: reset pulse, presence pulse, write 0, write 1, read 0, and read 1. All of these signals, with ...
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READ TIME SLOTS The DS18S20 can only transmit data to the master when the master issues read time slots. Therefore, the master must generate read time slots immediately after issuing a Read Scratchpad [BEh] or Read Power Supply [B4h] command, ...
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DETAILED MASTER READ 1 TIMING Figure 1-WIRE BUS GND T INT RECOMMENDED MASTER READ 1 TIMING Figure 1-WIRE BUS GND INT RC small small > ...
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ROM COMMANDS FLOW CHART Figure 14 Initialization Sequence 33h N READ ROM COMMAND Y DS18S20 T X FAMILY CODE 1 BYTE DS18S20 T X SERIAL NUMBER 6 BYTES DS18S20 T X CRC BYTE MASTER T X RESET PULSE DS18S20 T ...
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DS18S20 FUNCTION COMMANDS FLOW CHART Figure 15 44h MASTER T CONVERT X FUNCTION TEMPERATURE COMMAND ? Y N PARASITE POWER ? DS18S20 BEGINS CONVERSION DEVICE N CONVERTING TEMPERATURE ? Y MASTER MASTER R “0s” R “1s” B4h N ...
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DS18S20 OPERATION EXAMPLE 1 In this example there are multiple DS18S20s on the bus and they are using parasite power. The bus master initiates a temperature conversion in a specific DS18S20 and then reads its scratchpad and recalculates the CRC ...
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DS18S20 OPERATION EXAMPLE 3 In this example there is only one DS18S20 on the bus and it is using parasite power. The bus master initiates a temperature conversion then reads the DS18S20 scratchpad and calculates a higher resolution result using ...
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ABSOLUTE MAXIMUM RATINGS* Voltage on any pin relative to ground Operating temperature Storage temperature Soldering temperature *These are stress ratings only and functional operation of the device at these or any other conditions above those indicated in the operation sections ...
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AC ELECTRICAL CHARACTERISTICS: NV MEMORY PARAMETER NV Write Cycle Time EEPROM Writes EEPROM Data Retention AC ELECTRICAL CHARACTERISTICS PARAMETER Temperature Conversion Time Time to Strong Pullup On Time Slot Recovery Time Write 0 Low Time Write 1 Low Time Read ...
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TIMING DIAGRAMS Figure DS18S20 ...