DS1825
− Programmable Resolution 1-Wire Digital Thermometer
with ID
MAX31826
− Digital Temperature Sensor with 1Kb Lockable EEPROM
MAX31850 MAX31851
− Cold-Junction Compensated Thermocouple
3B [.]XXXXXXXXXXXX[XX][/[ | latesttemp | power | prog_addr | temphigh | templow | tempres | ]]
3B [.]XXXXXXXXXXXX[XX][/[ temperature | latesttemp | power | memory | pages/page.[0-15|ALL] | prog_addr | ]]
3B [.]XXXXXXXXXXXX[XX][/[ temperature | latesttemp | thermocouple | fault | open_circuit | ground_short | vdd_short | power | prog_addr | ]]
3B
read-only,yes-no
Is the chip powered externally (=1) or from the
parasitically from the data bus (=0)?
read-only,
0-15
A distiguishing feature of the DS1825 (3) is the
ability to set hardware pins for an address (0-15). This is
an alternative to the unique 64-bit address that is
set in the factory.
read-only,
floating point
Measured temperature with 12 bit resolution.
For the MAX31850 MAX 31851 this is the cold-junction temperature -- the temperature at the chip. See thermocouple
read-only, floating point ( DS1825 only)
Measured temperature at 9 to 12 bit resolution. There is a tradeoff of time versus accuracy in the temperature measurement.
The MAX31826 MAX31850 MAX31851 measure all temperatures at 12 bit resoltion and will return that resolution to all the possible temperature properties.
read-only,
floating point
Measured temperature at 9 to 12 bit resolution, depending on
the resolution of the latest conversion on this chip.
Reading this node will never trigger a temperature
conversion. Intended for use in conjunction with
/simultaneous/temperature.
read-only,
floating point
Equivalent to temperature9
read-only, floating point ( MAX31850 MAX31851 only)
Measured temperature of the thermocouple at 16bit resolution. Cold-junction temperature compensated.
The actual thermocouple type used is set by the selected chip type, and is not discoverable in software.
The MAX31826 does NOT have temperature thresholds and temperature alarm.
Only the MAX31826 supports memory functions.
read/write,
binary
EEPROM memory pages of 8 bytes each. See the datasheet about
locking contents.
read/write,
binary
EEPROM memory of 128 bytes. See the datasheet about locking
contents.
Only the MAX31850 MAX31851 supports fault reporting.
read-only,
yes-no
Fault in last thermocouple conversion
read-only,
yes-no
Thermocouple leads disconnected.
read-only,
yes-no
Thermocouple lead shorted to ground.
read-only,
yes-no
Thermocouple lead shorted to supply voltage.
The DS1825 (3) is one of several available 1-wire temperature sensors. Alternatives are the DS18S20 (3), DS18B20 (3), and DS1822 (3) as well as temperature/voltage measurements in the DS2436 (3) and DS2438 (3). For truly versatile temperature measurements, see the protean DS1921 (3) Thermachron (3).
The DS1825 (3) can select between 4 resolutionsspanning the fastest/roughest and slowest/best.
The MAX31826 shares a family code with the DS1825 but has differences in some of its functions.
The MAX31826 has 128 btes of EEPROM memory (as 16 pages of 8 bytes) while the DS1825 has no memory available.
The MAX31826 measures temperature at 12 bit resolution as fast as the DS1825’s lowest resolution (and always uses 12-bit resolution). On the other hand it has no temperature thresholds or alarm function.
Both the MAX31826 and the DS1825 allow hardware selection of part of the address, which can assist selecting between chips is some circuit designs.
|
DS1825 |
http://pdfserv.maxim-ic.com/en/ds/DS1825.pdf |
MAX31826
http://datasheets.maxim-ic.com/en/ds/MAX31826.pdf
http://www.owfs.org
Paul Alfille ([email protected])