DS1921 DALLAS [Dallas Semiconductor], DS1921 Datasheet - Page 41

• Manufacturer Part Number: DS1921
• Description: High-Resolution Thermochron iButton
• Manufacturer: DALLAS [Dallas Semiconductor]

NOTES
IO pin, 1-Wire Reset, Presence Detect Cycle
Reset Low Time
Presence Detect High
Time
Presence Detect Low
Time
Presence Detect
Sample Time
IO pin, 1-Wire Write
Write-0 Low Time
Write-1 Low Time
IO pin, 1-Wire Read
Read Low Time
Read Sample Time
Real-Time Clock
Frequency Deviation
Temperature Converter
Tempcore Operating
Range
Conversion Time
Thermal Response
Time Constant
Conversion Error
Number of
Conversions
1) System Requirement.
2) Maximum allowable pull-up resistance is a function of the number of 1-Wire devices in the
3) Capacitance on IO could be 800pF when power is first applied. If a 2.2k resistor is used to pull
4) Input load is to ground.
5) All voltages are referenced to ground.
6) V
7) Voltage below which, during a falling edge on IO, a logic 0 is detected.
8) The voltage on IO needs to be less or equal to V
PARAMETER
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
pull-up such as that found in the DS2480B may be required.
up the data line, 2.5µs after V
communication.
TL
, V
TH
are a function of the internal supply voltage.
SYMBOL
N
t
t
t
t
t
t
t
CONV
t
T
RSTL
RESP
CONV
W0L
W1L
t
MSR
PDH
PDL
MSP
RL
TC
F
PUP
Standard Speed,
V
Standard Speed
Overdrive Speed
Standard Speed
Overdrive Speed
Standard Speed
Overdrive Speed
Standard Speed
Overdrive Speed
Standard Speed
Overdrive Speed
Standard Speed
Overdrive Speed
Standard Speed
Overdrive Speed
Standard Speed
Overdrive Speed
-5°C to +46°C
DS1921H
DS1921Z
PUP
has been applied the parasite capacitor will not affect normal
CONDITIONS
> 4.5V
41 of 44
ILMAX
whenever the master drives the line low.
t
t
RL
RL
MIN
480
540
-48
1.1
7.5
48
15
60
60
60
15
75
-5
-1
6
6
5
1
5
1
+
+
(see graphs)
TYP
130
MAX UNITS NOTES
15 -
15 -
2 -
2 -
640
640
270
120
+46
+26
360
8.6
80
24
75
15
15
46
+1
60
6
2
PPM
ms
°C
°C
—
µs
µs
µs
µs
µs
µs
µs
µs
s
DS1921H/Z
17, 18
14, 16
1, 15
1, 16
1, 15
1, 11
1, 12
1, 12
15
15
13