Rainbow Electronics DS2409 - Manual (Page 18)

DS2409
18 of 18
AC ELECTRICAL CHARACTERISTICS (-40°C to +85°C, V
DD
= 5V ±10%)
PARAMETER SYMBOL MIN TYP MAX UNITS NOTES
Time Slot t
SLOT
60 120 µs
Write 1 Low Time t
LOW1
1 15 µs 10
Write 0 Low Time t
LOW0
60 120 µs
Read Low Time t
LOWR
1 15 µs 10
Read Data Valid t
RDV
15 µs 9
Release Time t
RELEASE
0 15 45 µs
Read Data Setup t
SU
1 µs 6
Recovery Time t
REC
1 µs
Reset Time High t
RSTH
480 µs 5
Reset Time Low t
RSTL
480 960 µs 7
Presence Detect High t
PDH
15 60 µs
Presence Detect Low t
PDL
60 240 µs
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 µs of this falling edge.
7. The reset low time (t
RSTL
) should be restricted to a maximum of 960 µs, to allow interrupt signaling,
otherwise, it could mask or conceal interrupt pulses. The DS2409 may perform a power-on reset cycle
and deactivate both 1-Wire outputs if the 1-Wire input is low for minimum 8 ms. A low time of 12 ms
or more will always cause a power-on reset cycle.
8. The main output has a slew rate controlled output. The indicated current is a DC value. The sink
current typically reaches 80% of its DC value 1 µs after turning on the transistor.
9. 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.
10. 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.