Rainbow Electronics DS1920 - Manual (Page 21)

DS1920
21 of 22
AC ELECTRICAL CHARACTERISTICS:
1-WIRE INTERFACE
(-55°C to +100°C; V
PUP
=2.8V to 6.0V)
PARAMETER SYMBOL MIN TYP MAX UNITS NOTES
Time Slot t
SLOT
60 120
µ
s
Write 1 Low Time t
LOW1
1 15
µ
s
Write 0 Low Time t
LOW0
60 120
µ
s
Read Data Valid t
RDV
exactly 15
µ
s
Release Time t
RELEASE
0 15 45
µ
s
Read Data Setup t
SU
1
µ
s 8
Recovery Time t
REC
1
µ
s
Reset Time High t
RSTH
480
µ
s
Reset Time Low t
RSTL
480 4800
µ
s 6,7
Presence Detect High t
PDHIGH
15 60
µ
s
Presence Detect Low t
PDLOW
60 240
µ
s
NOTES:
1. Temperature conversion will work with ±2°C accuracy down to V
PUP
= 3.4V.
2. All voltages are referenced to ground.
3. I
DD
specified with low impedance pull up to 5.0V.
4. Active current refers to temperature conversion.
5. Writing to EEPROM consumes approximately 200
µ
A.
6. t
RSTL
may be up to 4800
µ
s. With longer times, the result of temperature conversion may get lost.
7. The reset low time should be restricted to a maximum of 960 ms, to allow interrupt signaling,
otherwise it could mask or conceal interrupt pulses.
8. Read data setup time refers to the time the host must pull the 1-Wire bus low to read a bit. Data is
guaranteed to be valid within 1
µ
s of this falling edge and will remain valid for 14
µ
s minimum. (15
µ
s total from falling edge on 1-Wire bus.)
9. Capacitance on the data contact could be 800 pF when power is first applied. If a 5k
Ω
resistor is used
to pull up the data line to V
CC
, 5
µ
s after power has been applied, the parasite capacitance will not
affect normal communications.
10. Under certain low voltage conditions V
ILMAX
may have to be reduced to as much as 0.5V to always
guarantee a presence pulse.
11. See Typical Curve for specification limits outside the 0°C to 70°C range. Thermometer error reflects
sensor accuracy as tested during calibration.