Electronic Components Datasheet Search |
|
DS7505UT Datasheet(PDF) 6 Page - Maxim Integrated Products |
|
DS7505UT Datasheet(HTML) 6 Page - Maxim Integrated Products |
6 / 14 page Shutdown Mode For power-sensitive applications, the DS7505 offers a low-power shutdown mode. The SD bit in the configura- tion register controls shutdown mode. When SD is pro- grammed to 1, the conversion in progress is completed and the result stored in the temperature register, after which the DS7505 goes into a low-power standby state. The O.S. output is cleared if the thermostat is operating in interrupt mode and O.S remains unchanged in com- parator mode. The 2-wire interface remains operational in shutdown mode, and writing a 0 to the SD bit returns the DS7505 to normal operation. Upon power-up in shutdown mode, the DS7505 executes one tempera- ture measurement. The result is stored in the tempera- ture register, after which the DS7505 enters the shutdown state. Operation Thermostat The DS7505 thermostat can be programmed to power up in either comparator mode or interrupt mode, which activate and deactivate the open-drain thermostat out- put (O.S.) based on user-programmable trip points (TOS and THYST). The THYST and TOS registers contain Celsius temperature values in two’s complement format and consist of EEPROM that is shadowed by SRAM. Once written to the shadow SRAM, values can be stored in EEPROM by issuance of a Copy Data com- mand from the master (see the Command Set section for more details). The device can operate using the shadow SRAM only or using the EEPROM. If the EEPROM is used, the values are NV and can be pro- grammed prior to installation of the DS7505 for stand- alone operation. The factory power-up settings for the DS7505 are with the thermostat in comparator mode, active-low O.S. polarity, overtemperature trip-point (TOS) register set to 80°C, the hysteresis trip-point (THYST) register set to +75°C, and the number of con- secutive conversion to trigger O.S. set to 1. If these power-up settings are compatible with the application, the DS7505 can be used as a stand-alone thermostat (i.e., no 2-wire communication required) with no pro- gramming required prior to installation. If interrupt mode operation, active-high O.S. polarity, different TOS and THYST values, or a different number of conversions to trigger O.S. are desired, they must be programmed into the EEPROM either after initial power-up or prior to IC installation. The programmed values then become the new power-up defaults. In both operating modes, the user can program the thermostat-fault tolerance, which sets how many con- secutive temperature readings (1, 2, 4, or 6) must fall outside the thermostat limits before the thermostat out- put is triggered. The fault tolerance is set by the F1 and F0 bits in the configuration register. The default factory power-up setting for fault tolerance is 1 (F1 = 0, F0 = 0). The data format of the TOS and THYST registers is iden- tical to that of the temperature register (see Figure 3), i.e., a 2-byte two’s complement representation of the trip-point temperature in degrees Celsius with bits 3 through 0 hardwired to 0. After every temperature con- version, the measurement is compared to the values stored in the TOS and THYST registers. The O.S. output is updated based on the result of the comparison and the operating mode of the IC. The number of TOS and THYST bits used during the thermostat comparison is equal to the conversion resolution set by the R1 and R0 bits in the configuration register. For example, if the resolution is 9 bits, only the 9 MSBs of TOS and THYST are used by the thermostat comparator. The active state of the O.S. output can be programmed by the POL bit in the configuration register. The power- up factory default is active low (POL = 0). If the user does not wish to use the thermostat capabili- ties of the DS7505, the O.S. output should be left unconnected. Note that if the thermostat is not used, the TOS and THYST registers can be used for general storage of system data. Comparator Mode When the thermostat is in comparator mode, O.S. can be programmed to operate with any amount of hystere- sis. The O.S. output becomes active when the mea- sured temperature exceeds the T OS value a consecutive number of times as defined by the F1 and F0 fault tolerance (FT) bits in the configuration register. O.S. then stays active until the first time the tempera- ture falls below the value stored in THYST. Putting the device into shutdown mode does not clear O.S. in com- parator mode. Thermostat comparator mode operation with FT = 2 is illustrated in Figure 4. Digital Thermometer and Thermostat 6 _______________________________________________________________________________________ |
Similar Part No. - DS7505UT |
|
Similar Description - DS7505UT |
|
|
Link URL |
Privacy Policy |
ALLDATASHEET.COM |
Does ALLDATASHEET help your business so far? [ DONATE ] |
About Alldatasheet | Advertisement | Datasheet Upload | Contact us | Privacy Policy | Link Exchange | Manufacturer List All Rights Reserved©Alldatasheet.com |
Russian : Alldatasheetru.com | Korean : Alldatasheet.co.kr | Spanish : Alldatasheet.es | French : Alldatasheet.fr | Italian : Alldatasheetit.com Portuguese : Alldatasheetpt.com | Polish : Alldatasheet.pl | Vietnamese : Alldatasheet.vn Indian : Alldatasheet.in | Mexican : Alldatasheet.com.mx | British : Alldatasheet.co.uk | New Zealand : Alldatasheet.co.nz |
Family Site : ic2ic.com |
icmetro.com |