Rainbow Electronics DS2890 - Manual (Page 27)

DS2890
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AC ELECTRICAL CHARACTERISTICS - REGULAR 1-WIRE SPEED
2.8V £ V
PUP
£ 6.0V, -40°C £ T
A
£ +85°C
PARAMETER SYMBOL MIN TYP MAX UNITS NOTES
Time Slot t
SLOT
60 120 µs
Write 1 Low Time t
LOW1
1 15 µs
Write 0 Low Time t
LOW0
60 120 µs
Read Low Time t
LOWR
1 15 µs
Read Data Valid t
RDV
15 µs 1
Release Time t
RELEASE
0 15 45 µs
Read Data Setup t
SU
1 µs 2
Recovery Time t
REC
1 µs
Reset High Time t
RSTH
480 µs 3
Reset Low Time t
RSTL
480 µs 4
Presence Detect High t
PDH
15 60 µs
Presence Detect Low t
PDL
60 240 µs
Notes:
1. The optimal sampling point for the master is as close as possible to the end time of the 15 ms 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 the line 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 (t
RELEASE
= 0).
2. 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 µs of this falling edge.
3. An additional reset or communication sequence cannot begin until the reset high time (t
RSTH
) has
expired.
4. 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.
AC ELECTRICAL CHARACTERISTICS - OVERDRIVE 1-WIRE SPEED
2.8V £ V
PUP
£ 6.0V, -40°C £ T
A
£ +85°C
PARAMETER SYMBOL MIN TYP MAX UNITS NOTES
Time Slot t
SLOT
6 16 µs
Write 1 Low Time t
LOW1
1 2 µs
Write 0 Low Time t
LOW0
6 16 µs
Read Low Time t
LOWR
1 2 µs
Read Data Valid t
RDV
2 µs 1
Release Time t
RELEASE
0 1.5 4 µs
Read Data Setup t
SU
1 µs 4