DS1921G Maxim, DS1921G Datasheet - Page 3

• Manufacturer Part Number: DS1921G
• Description: The DS1921G Thermochron® iButton® is a rugged, self-sufficient system that measures temperature and records the result in a protected memory section
• Manufacturer: Maxim

ELECTRICAL CHARACTERISTICS (continued)
(V
Note 1:
Note 2:
Note 3:
Note 4:
Note 5:
Note 6:
Note 7:
Note 8:
Note 9:
Note 10: Voltage above which, during a rising edge on IO, a logic 1 is detected.
Note 11: The I-V characteristic is linear for voltages less than 1V.
Note 12: Numbers in bold are not in compliance with the published iButton standards. See the Comparison Table .
Note 13: ε in Figure 15 represents the time required for the pullup circuitry to pull the voltage on the IO pin up from V
Note 14: δ in Figure 15 represents the time required for the pullup circuitry to pull the voltage on the IO pin up from V
Note 15: This number was derived from a test conducted by Cemagref in Antony, France, in July 2000.
Note 16: Total accuracy is Δϑ plus 0.25°C quantization due to the 0.5°C digital resolution of the device.
IO PIN: 1-Wire WRITE
Write-Zero Low Time
(Notes 1, 12, 13)
Write-One Low Time
(Notes 1, 13)
IO PIN: 1-Wire READ
Read Low Time (Notes 1, 14)
Read Sample Time
(Notes 1, 14)
REAL-TIME CLOCK
Frequency Deviation
TEMPERATURE CONVERTER
Tempcore Operating Range
Conversion Time
Thermal Response Time
Constant
Conversion Error
(Notes 16, 17)
Number of Conversions
PUP
= +2.8V 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 found in the DS2480B may be required.
Capacitance on IO could be 800pF when power is first applied. If a 2.2kΩ resistor is used to pull up the data line, 2.5µs
after V
These values are derived from simulation across process, voltage, and temperature and are not production tested.
Input load is to ground.
All voltages are referenced to ground.
V
V
Voltage below which, during a falling edge of IO, a logic 0 is detected.
The voltage on IO must be less than or equal to V
actual maximum duration for the master to pull the line low is t
high threshold of the bus master. The actual maximum duration for the master to pull the line low is t
http://www.cemagref.fr/English/index.htm Test Report No. E42
TL
TH
and V
and V
PUP
TH
_______________________________________________________________________________________
TL
has been applied, the parasite capacitor does not affect normal communication.
are functions of the internal supply voltage, which is a function of V
maximum specifications are valid at V
A
= -40°C to +85°C.)
SYMBOL
N
t
t
CONV
t
t
RESP
CONV
MSR
T
W0L
W1L
t
RL
TC
F
Standard speed
Overdrive speed, V
Overdrive speed
Standard speed
Overdrive speed
Standard speed
Overdrive speed
Standard speed
Overdrive speed
-5°C to +46°C
(Note 15)
-40°C to < -30°C
-30°C to +70°C
> +70°C to +85°C
(Notes 4, 18)
ILMAX
PUP
CONDITIONS
= 5.25V. In any case, V
whenever the master drives the line low.
PUP
W1LMAX
> 4.5V
Thermochron iButton
+ t
F
- ε and t
TL
PUP
< V
W0LMAX
and the 1-Wire recovery times. The
TH
t
t
(See the lifetime graphs.)
RL
RL
MIN
-1.3
-1.0
-1.3
-48
-40
8.5
60
19
< V
6
5
1
5
1
+
+
PUP
+ t
F
.
- ε, respectively.
TYP
130
RLMAX
15 -
MAX
+1.3
+1.0
+1.3
2 -
+46
+85
120
15
15
15
15
90
+ t
2
2
IL
IL
to V
to the input
F
.
TH
UNITS
ppm
. The
ms
μs
μs
μs
μs
°C
°C
—
s
3