DS1922E-F5- MAXIM [Maxim Integrated Products], DS1922E-F5- Datasheet - Page 13

• Manufacturer Part Number: DS1922E-F5-
• Description: High-Temperature Logger iButton with 8KB
• Manufacturer: MAXIM [Maxim Integrated Products]

The DS1922E’s temperature range begins at +15°C
and ends at +140°C. Temperature values are repre-
sented as an 8- or 16-bit unsigned binary number with
a resolution of 0.5°C in 8-bit mode and 0.0625°C in
16-bit mode.
The higher temperature byte TRH is always valid. In
16-bit mode, only the three highest bits of the lower
byte TRL are valid. The five lower bits all read 0. TRL is
undefined if the device is in 8-bit temperature mode. An
out-of-range temperature reading is indicated as 00h or
0000h when too cold and FFh or FFE0h when too hot.
With TRH and TRL representing the decimal equivalent
of a temperature reading, the temperature value is cal-
culated as:
Table 1. Temperature Conversion Examples
Table 2. Temperature Alarm Threshold Examples
ADDRESS
020Ch
020Dh
ϑ(°C) = TRH/2 + 14 + TRL/512 (16-bit mode,
ϑ(°C) = TRH/2 + 14 (8-bit mode, TLFS = 0,
MODE
16-Bit
16-Bit
65.5
30.0
8-Bit
8-Bit
(°C)
High-Temperature Logger iButton with 8KB
TLFS = 1, see address 0213h)
BIT 7
T10
T2
see address 0213h)
______________________________________________________________________________________
Temperature Conversion
HEX
67h
20h
BIT 6
HEX
54h
17h
54h
17h
T1
T9
TALM
TRH
BIT 5
T0
T8
DECIMAL
DECIMAL
103
32
84
23
84
23
BIT 4
T7
0
Latest Temperature Conversion Result Register
This equation is valid for converting temperature read-
ings stored in the data-log memory as well as for data
read from the Latest Temperature Conversion Result
register.
To specify the temperature alarm thresholds, the previ-
ous equations are resolved to:
Because the temperature alarm threshold is only one
byte, the resolution or temperature increment is limited
to 0.5°C. The TALM value must be converted into hexa-
decimal format before it can be written to one of the
Temperature Alarm Threshold registers (Low Alarm
address 0208h; High Alarm address 0209h).
Independent of the conversion mode (8- or 16-bit), only
the most significant byte of a temperature conversion is
used to determine whether an alarm is generated.
BIT 3
T6
0
HEX
00h
60h
—
—
BIT 2
Data-Log Memory
T5
0
TRL
TALM = 2 x ϑ(°C) - 28
DECIMAL
BIT 1
T4
—
—
96
0
0
BIT 0
T3
0
56.0000
25.6875
56.0
25.5
(°C)
BYTE
TRH
TRL
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