DS1923-F5 Maxim Integrated Products, DS1923-F5 Datasheet - Page 18

• Manufacturer Part Number: DS1923-F5
• Description: Board Mount Temperature Sensors
• Manufacturer: Maxim Integrated Products

Specifications of DS1923-F5

• Full Temp Accuracy: +/- 0.5 C
• Package / Case: F5 MicroCan
• Digital Output - Bus Interface: Serial (1-Wire)
• Digital Output - Number Of Bits: 12 bit
• Maximum Operating Temperature: + 85 C
• Minimum Operating Temperature: - 20 C
• Output Type: Digital
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

Hygrochron Temperature/Humidity Logger
iButton with 8KB Data-Log Memory
The DS1923’s temperature range begins at -20°C and
ends at +85°C. Temperature values are represented as
an 8-bit or 16-bit unsigned binary number with a resolu-
tion 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:
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:
18
Table 1. Temperature Conversion Examples
Table 2. Temperature Alarm Threshold Examples
ADDRESS
020Ch
020Dh
______________________________________________________________________________________
MODE
16-Bit
16-Bit
-10.0
(°C) = TRH/2 - 41 + TRL/512 (16-bit mode,
25.5
8-Bit
8-Bit
(°C)
(°C) = TRH/2 - 41 (8-bit mode, TLFS = 0,
TLFS = 1, see address 0213h)
BIT 7
T10
T2
TALM = 2 x (°C) + 82
see address 0213h)
Temperature Conversion
HEX
85h
3Eh
BIT 6
HEX
54h
17h
54h
17h
T1
T9
TALM
TRH
BIT 5
T0
T8
DECIMAL
DECIMAL
Latest Temperature Conversion Result Register Bitmap
133
62
84
23
84
23
BIT 4
T7
0
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 hexadec-
imal 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-bit or 16-bit),
only the most significant byte of a temperature conver-
sion is used to determine whether an alarm is generated.
In addition to temperature, the DS1923 can log humidi-
ty data in an 8-bit or 16-bit format. Humidity values are
represented as 8-bit or 16-bit unsigned binary numbers
with a resolution of 0.64%RH in the 8-bit mode and
0.04%RH in the 16-bit mode.
The DS1923 reads data from its humidity sensor when-
ever a Forced Conversion command is executed (see
the Memory and Control Function Commands section)
or during a mission if the device is set up to log humidi-
ty data. Regardless of its setup, the DS1923 always
reads 16 bits from the humidity sensor. The result of the
latest humidity reading is found at address 020Eh (low
byte) and 020Fh (high byte). The most significant bit
read from the humidity sensor can always be found as
H11 at address 020Fh. Due to the 12-bit digital output
of the humidity sensor, the lower 4 bits in 16-bit format
are undefined.
BIT 3
T6
0
HEX
00h
60h
—
—
BIT 2
T5
0
TRL
DECIMAL
BIT 1
T4
96
—
—
0
0
Humidity Conversion
BIT 0
T3
0
-29.3125
1.000
-29.5
1.0
(°C)
BYTE
TRH
TRL