Datasheet

DS1922L/DS1922T
Temperature Logger iButton with 8KB
Data-Log Memory
_______________________________________________________________________________________ 3
ELECTRICAL CHARACTERISTICS (continued)
(V
PUP
= +3.0V to +5.25V.)
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
Standard speed, V
PUP
> 4.5V 60 240
Standard speed (Note 12) 60 287
Overdrive speed, V
PUP
> 4.5V (Note 12) 7 24
Presence-Detect Low Time t
PDL
Overdrive speed (Note 12) 728
μs
Standard speed, V
PUP
> 4.5V 65 75
Standard speed 71.5 75
Presence-Detect Sample Time
(Note 2)
t
MSP
Overdrive speed 8 9
μs
IO PIN: 1-Wire WRITE
Standard speed 60 120
Overdrive Speed, V
PUP
> 4.5V (Note 12) 6 12
Write-Zero Low Time
(Notes 2, 14)
t
W0L
Overdrive speed (Note 12) 7.5 12
μs
Standard speed 5 15
Write-One Low Time
(Notes 2, 14)
t
W1L
Overdrive speed 1 1.95
μs
IO PIN: 1-Wire READ
Standard speed 5 15 - 
Read Low Time
(Notes 2, 15)
t
RL
Overdrive speed 1 1.95 - 
μs
Standard speed t
RL
+  15
Read Sample Time
(Notes 2, 15)
t
MSR
Overdrive speed t
RL
+  1.95
μs
REAL-TIME CLOCK
Accuracy
See RTC Accuracy
graphs
min/
month
-40°C to +85°C -300 +60
Frequency Deviation 
F
0°C to +125°C -600 +60
PPM
TEMPERATURE CONVERTER
8-bit mode 30 75
Conversion Time
(Note 16)
t
CONV
16-bit mode (11 bits) 240 600
ms
Thermal Response Time
Constant (Note 17)

RESP
iButton package 130 s
Conversion Error Without
Software Correction
 (Notes 18, 19)
See Temperature
Accuracy graphs
°C
Conversion Error with Software
Correction
 (Notes 19, 20)
See Temperature
Accuracy graphs
°C
Note 1: Guaranteed by design, not production tested to -40°C or +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 found in the DS2480B may be required.
Note 4: Capacitance on the data pin could be 800pF when V
PUP
is first applied. If a 2.2kΩ resistor is used to pull up the data line,
2.5µs after V
PUP
has been applied, the parasite capacitance does not affect normal communications.
Note 5: V
TL
and V
TH
are functions of the internal supply voltage, which is a function of V
PUP
and the 1-Wire recovery times. The
V
TH
and V
TL
maximum specifications are valid at V
PUP
= 5.25V. In any case, V
TL
< V
TH
< V
PUP
.
Note 6: Voltage below which, during a falling edge on IO, a logic 0 is detected.