DS1922E(2008) Просмотр технического описания (PDF) - Maxim Integrated

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DS1922E
(Rev.:2008)

High-Temperature Logger iButton with 8KB Data-Log Memory

Maxim Integrated 

High-Temperature Logger iButton with 8KB

Data-Log Memory

Note 1: Operation above +125°C is restricted to mission operations only. Communication and 1-Wire pin specifications are not

specified for operation above +125°C.

Note 2: System requirement.

Note 3: Maximum allowable pullup resistance is a function of the number of 1-Wire devices in the system and 1-Wire recovery

times. The specified value here applies to systems with only one device and with the minimum 1-Wire recovery times. For

more heavily loaded systems, an active pullup such as that in the DS2480B can be required.

Note 4: Capacitance on the data pin could be 800pF when VPUP is first applied. If a 2.2kΩ resistor is used to pull up the data line

2.5µs after VPUP has been applied, the parasite capacitance does not affect normal communications.

Note 5: VTL and VTH are a function of the internal supply voltage, which is a function of VPUP and the 1-Wire recovery times. The

VTH and VTL maximum specifications are valid at VPUPMAX (5.25V). In any case, VTL < VTH < VPUP.

Note 6: Voltage below which, during a falling edge on I/O, a logic 0 is detected.

Note 7: The voltage on I/O must be less than or equal to VILMAX whenever the master drives the line low.

Note 8: Voltage above which, during a rising edge on I/O, a logic 1 is detected.

Note 9: After VTH is crossed during a rising edge on I/O, the voltage on I/O must drop by VHY to be detected as logic 0.

Note 10: The I-V characteristic is linear for voltages less than 1V.

Note 11: The earliest recognition of a negative edge is possible at tREH after VTH has been previously reached.

Note 12: Numbers in bold are not in compliance with the published iButton standards. See the Comparison Table.

Note 13: Interval during the negative edge on I/O at the beginning of a presence-detect pulse between the time at which the volt-

age is 90% of VPUP and the time at which the voltage is 10% of VPUP.

Note 14: ε in Figure 13 represents the time required for the pullup circuitry to pull the voltage on I/O up from VIL to VTH. The actual

maximum duration for the master to pull the line low is tW1LMAX + tF - ε and tW0LMAX + tF - ε, respectively.

Note 15: δ in Figure 13 represents the time required for the pullup circuitry to pull the voltage on I/O up from VIL to the input high

threshold of the bus master. The actual maximum duration for the master to pull the line low is tRLMAX + tF.

Note 16: To conserve battery power, use 8-bit temperature logging whenever possible.

Note 17: This number was derived from a test conducted by Cemagref in Antony, France, in July 2000:

www.cemagref.fr/English/index.htm Test Report No. E42.

Note 18: Includes +0.1°C/-0.2°C calibration chamber measurement uncertainty.

Note 19: Warning: Not for use as the sole method of measuring or tracking temperature in products and articles that could affect

the health or safety of persons, plants, animals, or other living organisms, including but not limited to foods, beverages,

pharmaceuticals, medications, blood and blood products, organs, and flammable and combustible products. User shall

assure that redundant (or other primary) methods of testing and determining the handling methods, quality, and fitness of

the articles and products should be implemented. Temperature tracking with this product, where the health or safety of

the aforementioned persons or things could be adversely affected, is only recommended when supplemental or redun-

dant information sources are used. Data-logger products are 100% tested and calibrated at time of manufacture by

Maxim to ensure that they meet all data sheet parameters, including temperature accuracy. User shall be responsible for

proper use and storage of this product. As with any sensor-based product, user shall also be responsible for occasionally

rechecking the temperature accuracy of the product to ensure it is still operating properly.

Note 20: Guaranteed by design and not production tested.

Note 21: Devices leave the factory after having been run through a few cycles above +125°C. This is required for calibration of the

device but should not affect lifetime of the device as specified. However, this process results in a nonzero value in the

Device Samples Counter register (0223h–0225h), which provides evidence the device has been factory calibrated.

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