DS1923 Maxim, DS1923 Datasheet - Page 4

• Manufacturer Part Number: DS1923
• Description: The DS1923 temperature/humidity logger iButton® is a rugged, self-sufficient system that measures temperature and/or humidity and records the result in a protected memory section
• Manufacturer: Maxim

Hygrochron Temperature/Humidity Logger
iButton with 8KB Data-Log Memory
ELECTRICAL CHARACTERISTICS (continued)
(V
Note 1:
Note 2:
Note 3:
Note 4:
Note 5:
Note 6:
Note 7:
Note 8:
Note 9:
Note 10: The earliest recognition of a negative edge is possible at t
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
Note 13:
Note 14:
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:
Note 17: For software-corrected accuracy, assume correction using calibration coefficients with calibration equations for error
Note 18: Software correction for humidity and temperature is handled automatically using the 1-Wire Viewer Software package
Note 19: Warning: Not for use as the sole method of measuring or tracking temperature and/or humidity in products and articles
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
Note 22: All DS1923 humidity measurements are 12-bit readings. Missioning determines 8-bit or 16-bit data logging. Battery life-
4
RH Accuracy and
Interchangeability
RH Nonlinearity
RH Hysteresis
RH Repeatability
Long-Term Stability
PUP
_______________________________________________________________________________________
= +3.0V to +5.25V, T
PARAMETER
System requirement.
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.
Capacitance on the data pin could be 800pF when V
2.5μs after V
V
V
Voltage below which, during a falling edge on IO, a logic 0 is detected.
The voltage on IO must be less than or equal to V
Voltage above which, during a rising edge on IO, a logic 1 is detected.
After V
The I-V characteristic is linear for voltages less than 1V.
is 90% of V
maximum duration for the master to pull the line low is t
threshold of the bus master. The actual maximum duration for the master to pull the line low is t
www.cemagref.fr/English/index.htm Test Report No. E42.
compensation.
available at: www.ibutton.com.
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.
40%RH, whichever is slower. Test was performed at 5L/min airflow.
time is the same no matter what RH resolution is logged.
TL
TH
in Figure 13 represents the time required for the pullup circuitry to pull the voltage on IO up from V
in Figure 13 represents the time required for the pullup circuitry to pull the voltage on IO up from V
and V
and V
TH
is crossed during a rising edge on IO, the voltage on IO must drop by V
TH
TL
PUP
PUP
are functions of the internal supply voltage, which is a function of V
maximum specifications are valid at V
and the time at which the voltage is 10% of V
A
has been applied, the parasite capacitance does not affect normal communications.
= -20°C to +85°C.) (Note 31)
SYMBOL
With software correction
(Notes 18, 19, 24, 25, 26)
With software correction (Note 18)
(Notes 27, 28)
(Note 29)
At 50%RH (Note 30)
ILMAX
PUP
PUP
CONDITIONS
W1LMAX
= 5.25V. In any case, V
whenever the master drives the line low.
is first applied. If a 2.2kΩ resistor is used to pull up the data line,
REH
PUP
after V
+ t
.
F
- and t
TH
has been previously reached.
W0LMAX
TL
PUP
< V
HY
and the 1-Wire recovery times. The
+ t
to be detected as logic 0.
TH
MIN
F
< V
- , respectively.
PUP
RLMAX
.
< 1.0
±0.5
TYP
< 1
0.5
±5
IL
IL
+ t
to V
to the input high
F
MAX
.
TH
. The actual
UNITS
%RH/
%RH
%RH
%RH
year