DS75 DALLAS [Dallas Semiconductor], DS75 Datasheet
DS75
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DS75 Summary of contents
Page 1
... No additional components are required; the device is truly a “temperature–to–digital” converter. The DS75 has three address bits that allow a user to multidrop up to eight sensors along the 2–wire bus, greatly simplifying the bussing of distributed temperature sensing networks. ...
Page 2
... The power–up state of the DS75 is in the comparator mode with a single fault generating an active O.S. Digital data is written to/read from the DS75 via a 2–wire interface, and all communication is MSb first. Multipoint sensing is possible with the DS75 by uniquely setting the 3–bit address parts on the 2– ...
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... Table 2 describes the exact relationship of output data to measured temperature. The table assumes the DS75 is configured for 12–bit resolution; if the device is configured in a lower resolution mode, those bits will contain zeros. The data is transmitted serially over the 2–wire serial interface, MSb first. The MSb of the temperature register contains the “ ...
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... OPERATION–Thermostat Control In its comparator operating mode, the DS75 functions as a thermostat with programmable hysteresis, as shown in Figure 2. When the DS75’s temperature meets or exceeds the value stored in the high tempera- ture trip register ( consecutive number of times defined by the configuration register, the output ...
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... T OS The DS75 will power up with the temperature register selected. If the host wishes to change the data pointer, it simply addresses the DS75 in the write mode (R/W=0), receives an acknowledge, and writes the 8 bits that correspond to the new desired location. The last pointer location is always maintained so that consecutive reads from the same register do not require the host to always provide a pointer address. The only exception is at power– ...
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... The power–up default state is “0” (continuous conversion mode Thermostat mode. If TM=“0”, the DS75 is in the comparator mode. TM=“1” sets the device to the interrupt mode. See “OPERATION–Thermostat Control” section for a description of the difference between the two modes. The power– ...
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... C If the user does not wish to take advantage of the thermostat capabilities of the DS75, the 24 bits can be used for general storage of system data that need not be maintained following a power loss. The O.S. output should be left floating if this is done. ...
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... START and STOP conditions. The DS75 operates as a slave on the two–wire bus. Connections to the bus are made via the open–drain I/O lines SDA and SCL. ...
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... A control byte is the first byte received following the START condition from the master device. The control byte consists of a four bit control code; for the DS75, this is set as 1001 binary for read and write operations. The next three bits of the control byte are the device select bits (A2, A1, A0). They are used by the master device to select which of eight devices are to be accessed ...
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... SERIAL COMMUNICATION WITH DS75 Figure DS75 ...
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... Exposure to absolute maximum rating conditions for extended periods of time may affect reliability. The Dallas Semiconductor DS75 is built to the highest quality standards and manufactured for long term reliability. All Dallas Semiconductor devices are made using the same quality materials and manufacturing methods. However, the DS75 is not exposed to environmental stresses, such as burn– ...
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... MAX UNITS 2 bits 125 150 ms 250 300 500 600 1000 1200 MIN TYP MAX UNITS 400 100 1.3 4.7 0.6 4.0 1.3 4.7 0.6 4.0 0.6 4.7 0 0.9 0 100 250 20 300 + 0.1C 1000 B 20 300 + 0.1C B 0.6 4.0 400 5 DS75 V 5.5V) DD NOTES 9 V 5.5V) DD NOTES KHz ...
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... SCL signal. If such a device does stretch the LOW period of the SCL signal, it must output the next data bit to the SDA line t RMAX 8. Cb – total capacitance of one bus line in pF. Internal heating caused by O.S. loading will cause the DS75 to read approximately 0.5 C higher if 9. O.S. is sinking the max rated current. TIMING DIAGRAMS Figure 1000+250 = 1250 ns before the SCL line is released ...