DS1629 Dallas Semiconductor, DS1629 Datasheet
DS1629
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DS1629 Summary of contents
Page 1
... SOIC package DESCRIPTION The DS1629 2-Wire Digital Thermometer and Real Time Clock integrates the critical functions of a real time clock and a temperature monitor in a small outline 8-pin SOIC package. Communication to the DS1629 is accomplished via a 2-wire interface. The wide power supply range and minimal power requirement of the DS1629 allow for accurate time/temperature measurements in battery-powered applications ...
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... As conversions are performed in the background, reading the temperature register does not affect the conversion in progress. The host can modify DS1629 configuration such that it does not power up in the auto-convert or continuous convert modes. This could be beneficial in power-sensitive applications. The real time clock/calendar maintains a BCD count of seconds, minutes, hours, day of the week, day of the month, month, and year ...
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... The crystal frequency is internally divided by a factor that the user defines. The divided output is buffered and can be used to clock a microcontroller. The DS1629 features an open-drain alarm output. It can be configured to activate on a thermal event, time event, either thermal or time, or neither thermal nor time (disabled, power-up state). The thermal alarm becomes active when measured temperature is greater than or equal to the value stored in the TH thermostat register ...
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... Set” section. Details on how to change the settings after power-up are contained in the “OPERATION-Configuration” section. The DS1629 measures temperature by counting the number of clock cycles that an oscillator with a low temperature coefficient goes through during a gate period determined by a high temperature coefficient oscillator ...
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... For Fahrenheit usage, a lookup table or conversion factor must be used. Note that temperature is represented in the DS1629 in terms of a 0.5 C LSB, yielding the 9-bit format illustrated in Table 2. Higher resolutions may be obtained by implementing the algorithm in Application Note 105 and performing the following calculation. The 8-bit COUNT_REMAIN value can be obtained via the Read Counter (A8h) command and the COUNT_PER_C value (also 8-bit) is read via the Read Slope command (A9h) ...
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... CH = Clock halt bit. This bit is set enable the oscillator and set disable it. If the bit is changed during a write to the clock register, the oscillator will not be started (or stopped) until the bus master issues a STOP pulse. The DS1629 power-up default has the oscillator enabled (CH=0) so that OSC can be used for clocking a microcontroller at power-up. ...
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... OPERATION-Alarms The DS1629 features an open-drain alarm output with a user-definable active state (factory default is active low). By programming the configuration register, the user also defines the event, if any, would generate an alarm condition. The four possibilities are: Temperature alarm only Time alarm only Either temperature or time alarm Alarm disabled (power– ...
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... C0h command or the clock alarm register via the C7h command. The format of the clock alarm register is shown in Figure 4. The power-up default of the DS1629 has the clock alarm set to 12:00AM on Sunday. The register can be accessed over the 2-wire bus via the Access Clock Alarm (C7h) command ...
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... Data Bus” section). Data is read from or written to the configuration register MSb first. The format of the register is illustrated in Figure 5. The effect each bit has on DS1629 functionality is described along with the power-up state and volatility. The user has read/write access to the MSB and read-only access to the LSB of the register ...
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... Powers up in standby; upon Start Convert command, a single conversion will be performed and stored. A0 Alarm Mode. Table 6 defines the DS1629 alarm mode, based on the settings of the A0 and A1 bits. These bits define what event will activate the ALRM output. The alarm flags, CAF, TAF, CAL, TAL, are functional regardless of the state of these bits ...
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... CAL = Clock Alarm Latch. This volatile status bit will be set to "1" when the clock comparator becomes active. Once set, it will remain latched until DS1629 power is cycled. A "0" in this location indicates the clock has never been in an alarm condition since the DS1629 was powered-up. This is a read-only bit (writes to this location constitute a “ ...
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... START condition from the master device. The control byte consists of a 4-bit control code; for the DS1629, this is set as 1001 binary for read and write operations. The next 3 bits of the control byte are the device select bits (A2, A1, A0). All 3 bits are hard- wired high for the DS1629. Thus, only one DS1629 can reside on a 2-wire bus to avoid contention ...
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... SERIAL COMMUNICATION WITH DS1629 Figure DS1629 102299 ...
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... SERIAL COMMUNICATION WITH DS1629 Figure 6 (continued DS1629 102299 ...
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... This command stops temperature conversion. No further data is required. This command may be used to halt a DS1629 in continuous conversion mode. After issuing this command, the current temperature measurement will be completed, and then the DS1629 will remain idle until a Start Convert T is issued to resume conversions. ...
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... TL register. After issuing this command, the next two bytes W written to the DS1629, in the format described for thermostat set-points, will set the high temperature threshold for operation of the ALRM output and TAF flag read back. ...
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... Writing to E registers typically requires room temperature (50 ms max). After issuing a write command, no further writes should be requested for 50 ms. E under the conditions 2.7V bit in the 2-wire control byte 5.5V and 0°C T 70° DS1629 2 writes should only occur 102299 ...
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... Sample Command Sequence Table 9 Example: The bus master configures the DS1629 in the power-up one-shot mode. It sets the ALRM output active low with only the thermometer generating an ALRM and disables the oscillator output. It then sets the clock to 11:30AM on Thursday, January 1, 1998. It sets the thermostat with TH=50°C. ...
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... Sample Command Sequence Table 10 Example: Assuming the DS1629 is configured such that the clock is running and the thermometer is converting, read the current time and temperature. Also read the status of the alarm flags. BUS MASTER DS1629 MODE MODE ...
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... DD2 V =5. =2.7V DD DDT V =5. =2. =5. +0.3V) DD TYP MAX UNITS 5.5 V TYP MAX UNITS 0. +0 0.4 V 0.4 V +10 µA 0.1 µA 0.2 0.3 µA 1 100 µA 100 300 µA 500 500 µA 1000 DS1629 NOTES V 5.5V) DD NOTES 102299 ...
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... DC ELECTRICAL CHARACTERISTICS: DIGITAL THERMOMETER PARAMETER SYMBOL DS1629 Thermometer T Error Resolution Conversion Time t CONVT AC ELECTRICAL CHARACTERISTICS: 2-WIRE INTERFACE PARAMETER SYMBOL SCL Clock Period Data In Setup Time to SCL High Data Out Stable after SCL Low SDA Low Setup Time to SCL Low (START) SDA High Hold ...
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... Cb - total capacitance of one bus line in pF. 9. Refer to Application Note 58. 2-WIRE BUS TIMING DIAGRAM Figure 7 Typical DS1629 Thermometer Performance Curve Figure DS1629 102299 ...