Datasheet
DS1922L/DS1922T
Note 7: The voltage on IO must be less than or equal to V
ILMAX
whenever the master drives the line low.
Note 8: Voltage above which, during a rising edge on IO, a logic 1 is detected.
Note 9: After V
TH
is crossed during a rising edge on IO, the voltage on IO must drop by V
HY
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 t
REH
after V
TH
has been previously reached.
Note 12: Numbers in bold are not in compliance with the published i
Button standards. See the
Comparison Table
.
Note 13: 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 V
PUP
and the time at which the voltage is 10% of V
PUP
.
Note 14: ε in Figure 13 represents the time required for the pullup circuitry to pull the voltage on IO up from V
IL
to V
TH
. The actual
maximum duration for the master to pull the line low is t
W1LMAX
+ t
F
- ε and t
W0LMAX
+ t
F
- ε, respectively.
Note 15: δ in Figure 13 represents the time required for the pullup circuitry to pull the voltage on IO up from V
IL
to the input-high
threshold of the bus master. The actual maximum duration for the master to pull the line low is t
RLMAX
+ t
F
.
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/-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, 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 redundant
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: Assumes using calibration memory with calibration equations for error compensation. Includes +0.1/-0.2°C calibration
chamber measurement uncertainty. Guaranteed by design.
Temperature Logger iButton with 8KB
Data-Log Memory
4 _______________________________________________________________________________________
COMPARISON TABLE
LEGACY VALUES DS1922L/DS1922T VALUES
STANDARD SPEED
(μs)
OVERDRIVE SPEED
(μs)
STANDARD SPEED
(μs)
OVERDRIVE SPEED
(μs)
PARAMETER
MIN MAX MIN MAX MIN MAX MIN MAX
t
SLOT
(including t
REC
) 61 (undefined) 7 (undefined) 65
*
(undefined) 9.5 (undefined)
t
RSTL
480 (undefined) 48 80 690 720 70 80
t
PDH
15 60 2 6 15 63.5 2 7
t
PDL
60 240 8 24 60 287 7 28
t
W0L
60 120 6 16 60 120 7.5 12
*
Intentional change; longer recovery time requirement due to modified 1-Wire front-end.
Note: Numbers in bold are not in compliance with the published iButton standards.
iButton CAN PHYSICAL SPECIFICATION
SIZE See the Package Information section.
WEIGHT Ca. 3.3 grams
SAFETY
Meets UL 913, 5th Ed., Rev. 1997-02-24; Intrinsically Safe Apparatus, approval under Entity Concept for use in
Class I, Division 1, Group A, B, C, and D Locations.
ELECTRICAL CHARACTERISTICS (continued)
(V
PUP
= +3.0V to +5.25V.)