DS1923-F5#W Maxim Integrated Products, DS1923-F5#W Datasheet - Page 41

• Manufacturer Part Number: DS1923-F5#W
• Description: Board Mount Temperature Sensors Hygrochron Temp/Hum Logger w/8KB DataLog
• Manufacturer: Maxim Integrated Products

Specifications of DS1923-F5#W

• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

The DS1923 requires strict protocols to ensure data
integrity. The protocol consists of four types of signaling
on one line: reset sequence with reset pulse and pres-
ence pulse, write-zero, write-one, and read-data. Except
for the presence pulse, the bus master initiates all these
signals. The DS1923 can communicate at two different
speeds: standard speed and overdrive speed. If not
explicitly set into the overdrive mode, the DS1923 com-
municates at standard speed. While in overdrive mode
the fast timing applies to all waveforms.
To get from idle to active, the voltage on the 1-Wire line
needs to fall from V
from active to idle, the voltage needs to rise from
V
voltage to make this rise is seen in Figure 12 as “ ” and
its duration depends on the pullup resistor (R
and the capacitance of the 1-Wire network attached.
The voltage V
determining a logical level, not triggering any events.
The initialization sequence required to begin any com-
munication with the DS1923 is shown in Figure 12. A
reset pulse followed by a presence pulse indicates the
DS1923 is ready to receive data, given the correct ROM
and memory function command. If the bus master uses
slew-rate control on the falling edge, it must pull down
the line for t
t
mode, returning the device to standard speed. If the
Figure 12. Initialization Procedure: Reset and Presence Pulse
RSTL
ILMAX
duration of 690μs or longer exits the overdrive
past the threshold V
V
IHMASTER
V
RSTL
ILMAX
V
V
PUP
Hygrochron Temperature/Humidity Logger
V
ILMAX
0V
TH
TL
______________________________________________________________________________________
+ t
PUP
F
is relevant for the DS1923 when
to compensate for the edge. A
below the threshold V
t
F
MASTER Tx "RESET PULSE"
TH
1-Wire Signaling
RESISTOR
iButton with 8KB Data-Log Memory
. The time it takes for the
t
RSTL
PUP
TL
. To get
) used
MASTER
DS1923 is in overdrive mode and t
than 80μs, the device remains in overdrive mode.
After the bus master has released the line, it goes into
receive mode (Rx). Now the 1-Wire bus is pulled to
V
DS2480B driver, through active circuitry. When the
threshold V
and then transmits a presence pulse by pulling the line
low for t
must test the logical state of the 1-Wire line at t
The t
t
t
nication. In a mixed population network, t
be extended to minimum 480μs at standard speed and
48μs at overdrive speed to accommodate other 1-Wire
devices.
Data communication with the DS1923 takes place in
time slots that carry a single bit each. Write time slots
transport data from bus master to slave. Read time slots
transfer data from slave to master. The definitions of the
write and read time slots are illustrated in Figure 13.
All communication begins with the master pulling the
data line low. As the voltage on the 1-Wire line falls
below the threshold V
timing generator that determines when the data line is
sampled during a write time slot and how long data is
valid during a read time slot.
RSTH
PDHMAX
PUP
t
PDH
RSTH
through the pullup resistor or, in the case of a
is expired, the DS1923 is ready for data commu-
t
MSP
PDL
, t
MASTER Rx "PRESENCE PULSE"
t
PDLMAX
TH
PDL
. To detect a presence pulse, the master
window must be at least the sum of
t
RSTH
is crossed, the DS1923 waits for t
, and t
TL
, the DS1923 starts its internal
t
REC
Read/Write Time Slots
RECMIN
DS1923
. Immediately after
RSTL
RSTH
is no longer
MSP
should
.
PDH
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