Datasheet

DS1920
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DS1920 MEMORY AND CONTROL FUNCTION COMMANDS Table 2
INSTRUCTION DESCRIPTION PROTOCOL
1-Wire BUS
AFTER ISSUING
PROTOCOL
NOTES
TEMPERATURE CONVERSION COMMANDS
Convert
Temperature
Initiates temperature
conversion
44h strong pullup 1
MEMORY COMMANDS
Read Scratchpad
Reads bytes from scratchpad
and reads CRC byte.
BEh
<read up to 9 data
bytes>
Write Scratchpad
Writes bytes into scratchpad
at addresses 2 and 3 (TH and
TL temperature triggers).
4Eh
<write data into 2
bytes at addr. 2 and
addr. 3>
Copy Scratchpad
Copies Scratchpad into
nonvolatile memory
(addresses 2 and 3 only).
48h strong pullup 2
Recall
Recalls values stored in
nonvolatile memory into
scratchpad (temperature
triggers).
B8h idle
NOTES:
1. Temperature conversion takes up to 0.75 seconds. After receiving the Convert Temperature
command, the data line for the DS1920 must be held high for at least 0.75 seconds to provide power
during the conversion process. As such, no other activity may take place on the 1-Wire bus for at least
this period after a Convert Temperature command has been issued.
2. After receiving the Copy Scratchpad command, the data line for the DS1920 must be held high for at
least 10ms to provide power during the copy process. As such, no other activity may take place on the
1-Wire bus for at least this period after a Copy Scratchpad command has been issued.
READ/WRITE TIMING DIAGRAM Figure 11
Write-1 Time Slot
60µs ≤ t
SLOT
< 120µs
1µs ≤ t
LOW1
< 15µs
1µs ≤ t
REC
< ∞
RESISTOR
MASTER