DS1920-F3 Maxim Integrated Products, DS1920-F3 Datasheet
DS1920-F3
Related parts for DS1920-F3
DS1920-F3 Summary of contents
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... Reduces control, address, data, and power to a single data contact § 8-bit device-generated CRC for data integrity § 8-bit family code specifies DS1920 communications requirements to reader § Special command set allows user to skip ROM section and do temperature ...
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... ORDERING INFORMATION DS1920-F3 F3 MicroCan DS1920-F5 F5 MicroCan iButton DESCRIPTION The DS1920 Temperature iButton provides 9-bit temperature readings which indicate the temperature of the device. Information is sent to/from the DS1920 over a 1-Wire interface. Power for reading, writing, and performing temperature conversions is derived from the data line itself. Because each DS1920 contains a unique silicon serial number, multiple DS1920s can exist on the same 1-Wire bus ...
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... This problem is particularly acute if several DS1920s are on the same data line and attempting to convert simultaneously. The way to assure that the DS1920 has sufficient supply current is to provide a strong pullup on the data line whenever temperature conversion or copying to the EEPROM is taking place. This may be accomplished by using a MOSFET to connect the data line directly to the power supply as shown in Figure 2 ...
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... The DS1920 can measure temperature over the range of -55°C to +100°C in 0.5°C increments. For Fahrenheit usage, a lookup table or conversion factor must be used. Note that temperature is represented in the DS1920 in terms of a ½°C LSB, yielding the following 9-bit format: MSB ...
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... C +25 C +½ -½ C -25 C -55 C (COUNT_PER _C - COUNT_REMA COUNT_PER_ C DIGITAL OUTPUT (BINARY) 00000000 11001000 00000000 00110010 00000000 00000001 00000000 00000000 11111111 11111111 11111111 11001110 11111111 10010010 DS1920 IN) SET/CLEAR LSB DIGITAL OUTPUT (HEX) 00C8H 0032H 0001H 0000H FFFFH FFCEH FF92H ...
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... Each DS1920 contains a unique ROM code that is 64 bits long. The first 8 bits are a 1-Wire family code (DS1920 code is 10h). The next 48 bits are a unique serial number. The last 8 bits are a CRC of the first 56 bits. (See Figure 4.) The 64-bit ROM and ROM Function Control section allow the DS1920 to operate as a 1-Wire device and follow the 1-Wire protocol detailed in the section “ ...
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... LASERED ROM Figure 4 8-BIT CRC CODE MSB ROM FUNCTIONS FLOW CHART Figure 5 48-BIT SERIAL NUMBER LSB MSB 8-BIT FAMILY CODE (10H) LSB MSB DS1920 LSB ...
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... TEMPERATURE MSB 1-WIRE BUS SYSTEM The 1-Wire bus is a system which has a single bus master and one or more slaves. The DS1920 behaves as a slave. The discussion of this bus system is broken down into three topics: hardware configuration, transaction sequence, and 1-Wire signaling (signal types and timing). ...
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... The presence pulse lets the bus master know that the DS1920 is on the bus and is ready to operate. For more details, see the “1-Wire Signaling” section. ...
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... This command allows the bus master to read the DS1920’ s 8-bit family code, unique 48-bit serial number, and 8-bit CRC. This command can only be used if there is a single DS1920 on the bus. If more than one slave is present on the bus, a data collision will occur when all slaves try to transmit at the same time (open drain will produce a wired AND result) ...
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... Recall [B8h] This command recalls the temperature trigger values stored in EEPROM to the scratchpad. This recall operation happens automatically upon power-up to the DS1920 as well, so valid data is available in the scratchpad as soon as the device has power applied ...
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... MEMORY AND CONTROL FUNCTIONS FLOW CHART Figure DS1920 ...
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... DS1920 ...
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... MEMORY AND CONTROL FUNCTIONS FLOW CHART (cont’ d) Figure 9 FROM FIGURE 9 FIRST PART DS1920 9 TO FIGURE THIRD PART ...
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... Strong Pullup. All these signals except Presence Pulse are initiated by the bus master. The initialization sequence required to begin any communication with the DS1920 is shown in Figure 10. A Reset Pulse followed by a Presence Pulse indicates the DS1920 is ready to accept a ROM command. The bus master transmits (TX) a Reset Pulse (t and goes into receive mode (RX) ...
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... DS1920. During write time slots, the delay circuit determines when the DS1920 will sample the data line. For a read data time slot transmitted, the delay circuit determines how long the DS1920 will hold the data line low overriding the 1 generated by the master. If the data bit the DS1920 will leave the read data time slot unchanged ...
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... Temperature conversion takes up to 0.5 seconds. After receiving the Convert Temperature command, the data line for the DS1920 must be held high for at least 0.5 seconds to provide power during the conversion process. As such, no other activity may take place on the 1-Wire bus for at least this period after a Convert Temperature command has been issued ...
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... READ/WRITE TIMING DIAGRAM (cont’ d) Figure 11 Write-0 Time Slot Read-Data Time Slot RESISTOR MASTER DS1920 < t < 120 s LOW0 SLOT < REC < 120 s SLOT < LOWR 0 t < RELEASE < REC RDV t < DS1920 ...
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... TX RX Reset Reset pulse( 480-960 s) Presence Presence pulse 55H Issue "Match ROM" command Issue address for DS1920 44H Issue "Convert Temperature" command Data line is held high for at least 0.5 seconds by bus master to allow conversion to complete. Reset Reset pulse Presence Presence pulse 55H Issue " ...
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... MIN TYP t 0.2 CONV t COPY (-55°C to +100°C) TYP MAX UNITS 5.0 6 +0.8 V =4.3V to 6.0V) PUP TYP MAX UNITS +½ C 1000 1500 0 MAX UNITS 800 pF =4.3V to 6.0V) PUP MAX UNITS 0.5 seconds 10 ms DS1920 NOTES 1 NOTES 11 11 3,4 2 =25°C) A NOTES 9 NOTES 5 ...
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... PDLOW , 5 s after power has been applied, the parasite capacitance will not CC may have to be reduced to as much as 0.5V to always ILMAX =2.8V to 6.0V) PUP MAX UNITS NOTES 120 120 4800 240 s = 3.4V. PUP resistor is used DS1920 8 6,7 ...
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... TYPICAL PERFORMANCE CURVE Error = Reading - True Temperature When cold, the true temperature is typically colder than the temperature reading DS1920 TEMPERATURE iButton TRUE TEMPERATURE ( DS1920 ...