Rainbow Electronics DS2415 - Manual (Page 14)

DS2415
14 of 14
AC ELECTRICAL CHARACTERISTICS
(-40°C to +85°C, V
PUP
= 2.5V to 6.0V, V
BAT
= 2.5V to 5.5V)
PARAMETER SYMBOL MIN TYP MAX UNITS NOTES
Time Slot t
SLOT
60 120 ms
Write 1 Low Time t
LOW1
1 15 ms 14
Write 0 Low Time t
LOW0
60 120 ms
Read Low Time t
LOWR
1 15 ms 14
Read Data Valid t
RDV
15 ms 13
Release Time t
RELEASE
0 15 45 ms
Read Data Setup t
SU
1 ms 6
Recovery Time t
REC
1 ms
Reset Time High t
RSTH
480 ms 5
Reset Time Low t
RSTL
480 960 ms 8
Presence Detect High t
PDH
15 60 ms
Presence Detect Low t
PDL
60 240 ms
NOTES:
1. All voltages are referenced to ground.
2. Measured with outputs open.
3. V
PUP
= external pullup voltage.
4. Input load is to ground.
5. An additional reset or communication sequence cannot begin until the reset high time has expired.
6. Read data setup time refers to the time the bus master must pull the I/O line low to read a bit. Data is
guaranteed to be valid within 1 ms of this falling edge.
7. Under certain low voltage conditions V
IL1MAX
may have to be reduced to as much as 0.5V to always
guarantee a Presence Pulse.
8. The reset low time (t
RSTL
) should be restricted to a maximum of 960 ms, to allow interrupt signaling,
otherwise, it could mask or conceal interrupt pulses.
9. When V
BAT
ramps up, the oscillator is always off.
10. At V
BAT
= 3V ± 10%
11. At V
BAT
= 5V ± 10%
12. V
IH1
has to be V
BAT
-0.3V or higher.
13. The optimal sampling point for the master is as close as possible to the end time of the 15µs t
RDV
period without exceeding t
RDV
. For the case of a Read-One Time Slot, this maximizes the amount of
time for the pull-up resistor to recover to a high level. For a Read-Zero Time Slot, it ensures that a
read will occur before the fastest 1-Wire device(s) release the line.
14. The duration of the low pulse sent by the master should be a minimum of 1µs with a maximum value
as short as possible to allow time for the pull-up resistor to recover the line to a high level before the
1-Wire device samples in the case of a Write-One Time or before the master samples in the case of a
Read-One Time.