DS1921 datasheet(42/44 Pages) DALLAS

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DS1921H/Z

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9) Voltage above which, during a rising edge on IO, a logic 1 is detected.

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

11)

ε represents the time required for the pull-up circuitry to pull the voltage on IO up from V

IL to

VTH.

12)

δ represents the time required for the pull-up circuitry to pull the voltage on IO up from V

IL to the

input high threshold of the bus master.

13) This number was derived from a test conducted by Cemagref in Antony, France, in July of 2000.

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

14) The number of temperature conversions (= Samples) possible with the built-in energy source

depends on the operating and storage temperature of the device. When not in use for a mission,

the RTC oscillator should be turned off and device should be stored at a temperature not

exceeding +25°C. Under this condition the shelf life time is 10 years minimum.

15) Highlighted numbers are not in compliance with the published iButton standards. See comparison

table below.

16) These values are derived from simulation across process, voltage, and temperature and are not

production tested.

17) Total accuracy is

∆ϑ plus 1/16°C quantization due to the 1/8°C digital resolution of the device.

18) WARNING: Not for use as the sole or primary 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, flammable, and combustible products. User shall

assure that other primary and redundant 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 is recommended only as a supplemental and redundant

information source. User shall be responsible for proper use, storage, and calibration of this

product.

Standard Values

DS1921H/Z Values

Parameter

Standard Speed

Overdrive Speed

Standard Speed

Overdrive Speed

Name

min

max

min

max

min

max

min

max

tSLOT (incl. tREC)

61µs

(undef.)

7µs

(undef.)

65µs

(undef.)

8µs

(undef.)

tRSTL

480µs

(undef.)

48µs

80µs

540µs

640µs

48µs

80µs

tPDH

15µs

60µs

2µs

6µs

15µs

60µs

1.1µs

6µs

tPDL

60µs

240µs

8µs

24µs

60µs

270µs

7.5µs

24µs

tW0L

60µs

120µs

6µs

16µs

60µs

120µs

6µs

15µs

1) Intentional change, longer recovery time between time slots.

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