Datasheet
DS1990A
Serial Number i
Button
2 _______________________________________________________________________________________
ABSOLUTE MAXIMUM RATINGS
ELECTRICAL CHARACTERISTICS
(T
A
= -40°C to +85°C.)
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional
operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to
absolute maximum rating conditions for extended periods may affect device reliability.
Note 1: All voltages are referenced to ground.
Note 2: External pullup voltage. See Figure 4.
Note 3: System requirement.
Note 4: Full R
PUP
range is guaranteed by design and simulation and not production tested. Production testing performed at a
fixed R
PUP
value. 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 recov-
ery times. For more heavily loaded systems, an active pullup such as that found in the DS2480B may be required.
Note 5: Capacitance on the IO pin could be 800pF when power is first applied. If a 5kΩ resistor is used to pull up the IO line to
V
PUP
, 5µs after power has been applied the parasite capacitance will not affect normal communications.
Note 6: Guaranteed by design, simulation only. Not production tested.
Note 7: Input load is to ground.
IO Voltage Range to GND .....................................-0.5V to +6.0V
IO Sink Current....................................................................20mA
Junction Temperature......................................................+125°C
Storage Temperature Range .............................-55°C to +125°C
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
IO PIN: GENERAL DATA
1-Wire Pullup Voltage V
PUP
(Notes 1, 2) 2.8 6.0 V
1-Wire Pullup Resistance R
PUP
(Notes 3, 4) 0.6 5 k
Input Capacitance C
IO
(Notes 5, 6) 100 800 pF
Input Load Current I
L
(Note 7) 0.25 μA
Input Low Voltage V
IL
(Notes 1, 3, 8) 0.3 V
Input High Voltage V
IH
(Notes 1, 9) 2.2 V
Output Low Voltage at 4mA V
OL
(Note 1) 0.4 V
Operating Charge Q
OP
(Notes 6, 10) 30 nC
Recovery Time t
REC
(Note 3) 1 μs
Time Slot Duration t
SLOT
(Note 3) 61 μs
IO PIN: 1-Wire RESET, PRESENCE-DETECT CYCLE
Reset Low Time t
RSTL
(Notes 3, 11) 480 μs
Reset High Time t
RSTH
(Notes 3, 12) 480 μs
Presence-Detect High Time t
PDH
15 60 μs
Presence-Detect Low Time t
PDL
(Note 13) 60 240 μs
Presence-Detect Sample Time t
MSP
(Note 3) 60 75 μs
IO PIN: 1-Wire WRITE
Write-Zero Low Time t
W0L
(Notes 3, 14) 60 120 μs
Write-One Low Time t
W1L
(Notes 3, 14) 1 15 μs
IO PIN: 1-Wire READ
Read Low Time t
RL
(Notes 3, 15) 1 15 - μs
Read Sample Time t
MSR
(Notes 3, 15) t
RL
+ 15 μs