DS1923(2009) Просмотр технического описания (PDF) - Maxim Integrated

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DS1923
(Rev.:2009)

Hygrochron Temperature/Humidity Logger iButton with 8KB Data-Log Memory

Maxim Integrated 

Hygrochron Temperature/Humidity Logger

iButton with 8KB Data-Log Memory

ELECTRICAL CHARACTERISTICS (continued)

(VPUP = +3.0V to +5.25V, TA = -20°C to +85°C.)

PARAMETER

SYMBOL

CONDITIONS

MIN TYP MAX UNITS

RH Accuracy and

Interchangeability

RH Nonlinearity

RH Hysteresis

RH Repeatability

With software correction

(Notes 18, 19, 24, 25, 26)

With software correction (Note 18)

(Notes 27, 28)

(Note 29)

±5

<1

0.5

±0.5

%RH

%RH

%RH

Long-Term Stability

At 50%RH (Note 30)

< 1.0

%RH/

year

Note 1: System requirement.

Note 2: 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 may be required.

Note 3: 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 4: VTL and VTH are a function of the internal supply voltage.

Note 5: Voltage below which, during a falling edge on IO, a logic 0 is detected.

Note 6: The voltage on IO must be less than or equal to VILMAX whenever the master drives the line low.

Note 7: Voltage above which, during a rising edge on IO, a logic 1 is detected.

Note 8: After VTH is crossed during a rising edge on IO, the voltage on IO must drop by VHY to be detected as logic 0.

Note 9: The I-V characteristic is linear for voltages less than 1V.

Note 10: The earliest recognition of a negative edge is possible at tREH after VTH has been previously reached.

Note 11: Numbers in bold are not in compliance with the published iButton standards. See the Comparison Table.

Note 12: Interval during the negative edge on IO at the beginning of a presence-detect pulse between the time at which the voltage

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

Note 13: ε in Figure 13 represents the time required for the pullup circuitry to pull the voltage on IO up from VIL to VTH.

Note 14: δ in Figure 13 represents the time required for the pullup circuitry to pull the voltage on IO up from VIL to the input high

threshold of the bus master.

Note 15: To conserve battery power, use 8-bit temperature logging whenever possible.

Note 16: 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 17: For software-corrected accuracy, assume correction using calibration coefficients with calibration equations for error

compensation.

Note 18: Software correction for humidity and temperature is handled automatically using the 1-Wire Viewer Software package

available at: http://www.ibutton.com.

Note 19: Warning: Not for use as the sole method of measuring or tracking temperature and/or humidity 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 and/or humidity tracking with this

product, where the health or safety of the aforementioned persons or things could be adversely affected, is only recom-

mended when supplemental or redundant information sources are used. Data-logger products are 100% tested and cali-

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

Note 20: All humidity specifications are determined at +25°C except where specifically indicated.

Note 21: Response time is determined by measuring the 1/e point as the device transitions from 40%RH to 90%RH or 90%RH to

40%RH, whichever is slower. Test was performed at 5L/min airflow.

Note 22: All DS1923 humidity measurements are 12-bit readings. Missioning determines 8-bit or 16-bit data logging. Battery life-

time is the same no matter what RH resolution is logged.

Note 23: Reliability studies have shown that the device survives a minimum of 1000 cycles of condensation and drying, but this

product is not guaranteed for extended use in condensing environments.

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